Issue #26305: Argument Clinic now escapes braces. No need to double them.

499 files changed, 23705 insertions, 6722 deletions

diff --git a/Lib/_collections_abc.py b/Lib/_collections_abc.py
index f89bb6f04b..31583731fc 100644
--- a/Lib/_collections_abc.py
+++ b/Lib/_collections_abc.py
@@ -10,7 +10,7 @@ from abc import ABCMeta, abstractmethod
 import sys
 
 __all__ = ["Awaitable", "Coroutine", "AsyncIterable", "AsyncIterator",
-           "Hashable", "Iterable", "Iterator", "Generator",
+           "Hashable", "Iterable", "Iterator", "Generator", "Reversible",
            "Sized", "Container", "Callable",
            "Set", "MutableSet",
            "Mapping", "MutableMapping",
@@ -240,6 +240,25 @@ Iterator.register(tuple_iterator)
 Iterator.register(zip_iterator)
 
 
+class Reversible(Iterable):
+
+    __slots__ = ()
+
+    @abstractmethod
+    def __reversed__(self):
+        return NotImplemented
+
+    @classmethod
+    def __subclasshook__(cls, C):
+        if cls is Reversible:
+            for B in C.__mro__:
+                if "__reversed__" in B.__dict__:
+                    if B.__dict__["__reversed__"] is not None:
+                        return True
+                    break
+        return NotImplemented
+
+
 class Generator(Iterator):
 
     __slots__ = ()
@@ -670,7 +689,7 @@ class ItemsView(MappingView, Set):
         except KeyError:
             return False
         else:
-            return v == value
+            return v is value or v == value
 
     def __iter__(self):
         for key in self._mapping:
@@ -685,7 +704,8 @@ class ValuesView(MappingView):
 
     def __contains__(self, value):
         for key in self._mapping:
-            if value == self._mapping[key]:
+            v = self._mapping[key]
+            if v is value or v == value:
                 return True
         return False
 
@@ -794,7 +814,7 @@ MutableMapping.register(dict)
 ### SEQUENCES ###
 
 
-class Sequence(Sized, Iterable, Container):
+class Sequence(Sized, Reversible, Container):
 
     """All the operations on a read-only sequence.
 
@@ -820,7 +840,7 @@ class Sequence(Sized, Iterable, Container):
 
     def __contains__(self, value):
         for v in self:
-            if v == value:
+            if v is value or v == value:
                 return True
         return False
 
diff --git a/Lib/_pydecimal.py b/Lib/_pydecimal.py
index c719424472..7bcf75f9af 100644
--- a/Lib/_pydecimal.py
+++ b/Lib/_pydecimal.py
@@ -148,7 +148,7 @@ __xname__ = __name__    # sys.modules lookup (--without-threads)
 __name__ = 'decimal'    # For pickling
 __version__ = '1.70'    # Highest version of the spec this complies with
                         # See http://speleotrove.com/decimal/
-__libmpdec_version__ = "2.4.1" # compatible libmpdec version
+__libmpdec_version__ = "2.4.2" # compatible libmpdec version
 
 import math as _math
 import numbers as _numbers
@@ -1010,6 +1010,56 @@ class Decimal(object):
         """
         return DecimalTuple(self._sign, tuple(map(int, self._int)), self._exp)
 
+    def as_integer_ratio(self):
+        """Express a finite Decimal instance in the form n / d.
+
+        Returns a pair (n, d) of integers.  When called on an infinity
+        or NaN, raises OverflowError or ValueError respectively.
+
+        >>> Decimal('3.14').as_integer_ratio()
+        (157, 50)
+        >>> Decimal('-123e5').as_integer_ratio()
+        (-12300000, 1)
+        >>> Decimal('0.00').as_integer_ratio()
+        (0, 1)
+
+        """
+        if self._is_special:
+            if self.is_nan():
+                raise ValueError("cannot convert NaN to integer ratio")
+            else:
+                raise OverflowError("cannot convert Infinity to integer ratio")
+
+        if not self:
+            return 0, 1
+
+        # Find n, d in lowest terms such that abs(self) == n / d;
+        # we'll deal with the sign later.
+        n = int(self._int)
+        if self._exp >= 0:
+            # self is an integer.
+            n, d = n * 10**self._exp, 1
+        else:
+            # Find d2, d5 such that abs(self) = n / (2**d2 * 5**d5).
+            d5 = -self._exp
+            while d5 > 0 and n % 5 == 0:
+                n //= 5
+                d5 -= 1
+
+            # (n & -n).bit_length() - 1 counts trailing zeros in binary
+            # representation of n (provided n is nonzero).
+            d2 = -self._exp
+            shift2 = min((n & -n).bit_length() - 1, d2)
+            if shift2:
+                n >>= shift2
+                d2 -= shift2
+
+            d = 5**d5 << d2
+
+        if self._sign:
+            n = -n
+        return n, d
+
     def __repr__(self):
         """Represents the number as an instance of Decimal."""
         # Invariant:  eval(repr(d)) == d
diff --git a/Lib/_pyio.py b/Lib/_pyio.py
index 0d98b74476..40df79d345 100644
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -161,6 +161,8 @@ def open(file, mode="r", buffering=-1, encoding=None, errors=None,
     opened in a text mode, and for bytes a BytesIO can be used like a file
     opened in a binary mode.
     """
+    if not isinstance(file, int):
+        file = os.fspath(file)
     if not isinstance(file, (str, bytes, int)):
         raise TypeError("invalid file: %r" % file)
     if not isinstance(mode, str):
@@ -182,8 +184,8 @@ def open(file, mode="r", buffering=-1, encoding=None, errors=None,
     text = "t" in modes
     binary = "b" in modes
     if "U" in modes:
-        if creating or writing or appending:
-            raise ValueError("can't use U and writing mode at once")
+        if creating or writing or appending or updating:
+            raise ValueError("mode U cannot be combined with 'x', 'w', 'a', or '+'")
         import warnings
         warnings.warn("'U' mode is deprecated",
                       DeprecationWarning, 2)
@@ -1516,7 +1518,7 @@ class FileIO(RawIOBase):
         if self._fd >= 0 and self._closefd and not self.closed:
             import warnings
             warnings.warn('unclosed file %r' % (self,), ResourceWarning,
-                          stacklevel=2)
+                          stacklevel=2, source=self)
             self.close()
 
     def __getstate__(self):
diff --git a/Lib/_strptime.py b/Lib/_strptime.py
index f84227be49..fe9436115a 100644
--- a/Lib/_strptime.py
+++ b/Lib/_strptime.py
@@ -199,12 +199,15 @@ class TimeRE(dict):
             'f': r"(?P<f>[0-9]{1,6})",
             'H': r"(?P<H>2[0-3]|[0-1]\d|\d)",
             'I': r"(?P<I>1[0-2]|0[1-9]|[1-9])",
+            'G': r"(?P<G>\d\d\d\d)",
             'j': r"(?P<j>36[0-6]|3[0-5]\d|[1-2]\d\d|0[1-9]\d|00[1-9]|[1-9]\d|0[1-9]|[1-9])",
             'm': r"(?P<m>1[0-2]|0[1-9]|[1-9])",
             'M': r"(?P<M>[0-5]\d|\d)",
             'S': r"(?P<S>6[0-1]|[0-5]\d|\d)",
             'U': r"(?P<U>5[0-3]|[0-4]\d|\d)",
             'w': r"(?P<w>[0-6])",
+            'u': r"(?P<u>[1-7])",
+            'V': r"(?P<V>5[0-3]|0[1-9]|[1-4]\d|\d)",
             # W is set below by using 'U'
             'y': r"(?P<y>\d\d)",
             #XXX: Does 'Y' need to worry about having less or more than
@@ -299,6 +302,22 @@ def _calc_julian_from_U_or_W(year, week_of_year, day_of_week, week_starts_Mon):
         return 1 + days_to_week + day_of_week
 
 
+def _calc_julian_from_V(iso_year, iso_week, iso_weekday):
+    """Calculate the Julian day based on the ISO 8601 year, week, and weekday.
+    ISO weeks start on Mondays, with week 01 being the week containing 4 Jan.
+    ISO week days range from 1 (Monday) to 7 (Sunday).
+    """
+    correction = datetime_date(iso_year, 1, 4).isoweekday() + 3
+    ordinal = (iso_week * 7) + iso_weekday - correction
+    # ordinal may be negative or 0 now, which means the date is in the previous
+    # calendar year
+    if ordinal < 1:
+        ordinal += datetime_date(iso_year, 1, 1).toordinal()
+        iso_year -= 1
+        ordinal -= datetime_date(iso_year, 1, 1).toordinal()
+    return iso_year, ordinal
+
+
 def _strptime(data_string, format="%a %b %d %H:%M:%S %Y"):
     """Return a 2-tuple consisting of a time struct and an int containing
     the number of microseconds based on the input string and the
@@ -345,15 +364,15 @@ def _strptime(data_string, format="%a %b %d %H:%M:%S %Y"):
         raise ValueError("unconverted data remains: %s" %
                           data_string[found.end():])
 
-    year = None
+    iso_year = year = None
     month = day = 1
     hour = minute = second = fraction = 0
     tz = -1
     tzoffset = None
     # Default to -1 to signify that values not known; not critical to have,
     # though
-    week_of_year = -1
-    week_of_year_start = -1
+    iso_week = week_of_year = None
+    week_of_year_start = None
     # weekday and julian defaulted to None so as to signal need to calculate
     # values
     weekday = julian = None
@@ -375,6 +394,8 @@ def _strptime(data_string, format="%a %b %d %H:%M:%S %Y"):
                 year += 1900
         elif group_key == 'Y':
             year = int(found_dict['Y'])
+        elif group_key == 'G':
+            iso_year = int(found_dict['G'])
         elif group_key == 'm':
             month = int(found_dict['m'])
         elif group_key == 'B':
@@ -420,6 +441,9 @@ def _strptime(data_string, format="%a %b %d %H:%M:%S %Y"):
                 weekday = 6
             else:
                 weekday -= 1
+        elif group_key == 'u':
+            weekday = int(found_dict['u'])
+            weekday -= 1
         elif group_key == 'j':
             julian = int(found_dict['j'])
         elif group_key in ('U', 'W'):
@@ -430,6 +454,8 @@ def _strptime(data_string, format="%a %b %d %H:%M:%S %Y"):
             else:
                 # W starts week on Monday.
                 week_of_year_start = 0
+        elif group_key == 'V':
+            iso_week = int(found_dict['V'])
         elif group_key == 'z':
             z = found_dict['z']
             tzoffset = int(z[1:3]) * 60 + int(z[3:5])
@@ -450,32 +476,61 @@ def _strptime(data_string, format="%a %b %d %H:%M:%S %Y"):
                     else:
                         tz = value
                         break
+    # Deal with the cases where ambiguities arize
+    # don't assume default values for ISO week/year
+    if year is None and iso_year is not None:
+        if iso_week is None or weekday is None:
+            raise ValueError("ISO year directive '%G' must be used with "
+                             "the ISO week directive '%V' and a weekday "
+                             "directive ('%A', '%a', '%w', or '%u').")
+        if julian is not None:
+            raise ValueError("Day of the year directive '%j' is not "
+                             "compatible with ISO year directive '%G'. "
+                             "Use '%Y' instead.")
+    elif week_of_year is None and iso_week is not None:
+        if weekday is None:
+            raise ValueError("ISO week directive '%V' must be used with "
+                             "the ISO year directive '%G' and a weekday "
+                             "directive ('%A', '%a', '%w', or '%u').")
+        else:
+            raise ValueError("ISO week directive '%V' is incompatible with "
+                             "the year directive '%Y'. Use the ISO year '%G' "
+                             "instead.")
+
     leap_year_fix = False
     if year is None and month == 2 and day == 29:
         year = 1904  # 1904 is first leap year of 20th century
         leap_year_fix = True
     elif year is None:
         year = 1900
+
+
     # If we know the week of the year and what day of that week, we can figure
     # out the Julian day of the year.
-    if julian is None and week_of_year != -1 and weekday is not None:
-        week_starts_Mon = True if week_of_year_start == 0 else False
-        julian = _calc_julian_from_U_or_W(year, week_of_year, weekday,
-                                            week_starts_Mon)
-        if julian <= 0:
+    if julian is None and weekday is not None:
+        if week_of_year is not None:
+            week_starts_Mon = True if week_of_year_start == 0 else False
+            julian = _calc_julian_from_U_or_W(year, week_of_year, weekday,
+                                                week_starts_Mon)
+        elif iso_year is not None and iso_week is not None:
+            year, julian = _calc_julian_from_V(iso_year, iso_week, weekday + 1)
+        if julian is not None and julian <= 0:
             year -= 1
             yday = 366 if calendar.isleap(year) else 365
             julian += yday
-    # Cannot pre-calculate datetime_date() since can change in Julian
-    # calculation and thus could have different value for the day of the week
-    # calculation.
+
     if julian is None:
+        # Cannot pre-calculate datetime_date() since can change in Julian
+        # calculation and thus could have different value for the day of
+        # the week calculation.
         # Need to add 1 to result since first day of the year is 1, not 0.
         julian = datetime_date(year, month, day).toordinal() - \
                   datetime_date(year, 1, 1).toordinal() + 1
-    else:  # Assume that if they bothered to include Julian day it will
-           # be accurate.
-        datetime_result = datetime_date.fromordinal((julian - 1) + datetime_date(year, 1, 1).toordinal())
+    else:  # Assume that if they bothered to include Julian day (or if it was
+           # calculated above with year/week/weekday) it will be accurate.
+        datetime_result = datetime_date.fromordinal(
+                            (julian - 1) +
+                            datetime_date(year, 1, 1).toordinal())
         year = datetime_result.year
         month = datetime_result.month
         day = datetime_result.day
diff --git a/Lib/aifc.py b/Lib/aifc.py
index 7ebdbeb68c..692d0bfd27 100644
--- a/Lib/aifc.py
+++ b/Lib/aifc.py
@@ -257,6 +257,15 @@ from collections import namedtuple
 _aifc_params = namedtuple('_aifc_params',
                           'nchannels sampwidth framerate nframes comptype compname')
 
+_aifc_params.nchannels.__doc__ = 'Number of audio channels (1 for mono, 2 for stereo)'
+_aifc_params.sampwidth.__doc__ = 'Sample width in bytes'
+_aifc_params.framerate.__doc__ = 'Sampling frequency'
+_aifc_params.nframes.__doc__ = 'Number of audio frames'
+_aifc_params.comptype.__doc__ = 'Compression type ("NONE" for AIFF files)'
+_aifc_params.compname.__doc__ = ("""\
+A human-readable version of the compression type
+('not compressed' for AIFF files)""")
+
 
 class Aifc_read:
     # Variables used in this class:
diff --git a/Lib/argparse.py b/Lib/argparse.py
index 9a067196da..209b4e99c1 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -118,10 +118,16 @@ class _AttributeHolder(object):
     def __repr__(self):
         type_name = type(self).__name__
         arg_strings = []
+        star_args = {}
         for arg in self._get_args():
             arg_strings.append(repr(arg))
         for name, value in self._get_kwargs():
-            arg_strings.append('%s=%r' % (name, value))
+            if name.isidentifier():
+                arg_strings.append('%s=%r' % (name, value))
+            else:
+                star_args[name] = value
+        if star_args:
+            arg_strings.append('**%s' % repr(star_args))
         return '%s(%s)' % (type_name, ', '.join(arg_strings))
 
     def _get_kwargs(self):
@@ -204,8 +210,6 @@ class HelpFormatter(object):
             if self.parent is not None:
                 self.formatter._indent()
             join = self.formatter._join_parts
-            for func, args in self.items:
-                func(*args)
             item_help = join([func(*args) for func, args in self.items])
             if self.parent is not None:
                 self.formatter._dedent()
diff --git a/Lib/ast.py b/Lib/ast.py
index 017047275b..156a1f2773 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -35,6 +35,8 @@ def parse(source, filename='<unknown>', mode='exec'):
     return compile(source, filename, mode, PyCF_ONLY_AST)
 
 
+_NUM_TYPES = (int, float, complex)
+
 def literal_eval(node_or_string):
     """
     Safely evaluate an expression node or a string containing a Python
@@ -47,7 +49,9 @@ def literal_eval(node_or_string):
     if isinstance(node_or_string, Expression):
         node_or_string = node_or_string.body
     def _convert(node):
-        if isinstance(node, (Str, Bytes)):
+        if isinstance(node, Constant):
+            return node.value
+        elif isinstance(node, (Str, Bytes)):
             return node.s
         elif isinstance(node, Num):
             return node.n
@@ -62,24 +66,21 @@ def literal_eval(node_or_string):
                         in zip(node.keys, node.values))
         elif isinstance(node, NameConstant):
             return node.value
-        elif isinstance(node, UnaryOp) and \
-             isinstance(node.op, (UAdd, USub)) and \
-             isinstance(node.operand, (Num, UnaryOp, BinOp)):
+        elif isinstance(node, UnaryOp) and isinstance(node.op, (UAdd, USub)):
             operand = _convert(node.operand)
-            if isinstance(node.op, UAdd):
-                return + operand
-            else:
-                return - operand
-        elif isinstance(node, BinOp) and \
-             isinstance(node.op, (Add, Sub)) and \
-             isinstance(node.right, (Num, UnaryOp, BinOp)) and \
-             isinstance(node.left, (Num, UnaryOp, BinOp)):
+            if isinstance(operand, _NUM_TYPES):
+                if isinstance(node.op, UAdd):
+                    return + operand
+                else:
+                    return - operand
+        elif isinstance(node, BinOp) and isinstance(node.op, (Add, Sub)):
             left = _convert(node.left)
             right = _convert(node.right)
-            if isinstance(node.op, Add):
-                return left + right
-            else:
-                return left - right
+            if isinstance(left, _NUM_TYPES) and isinstance(right, _NUM_TYPES):
+                if isinstance(node.op, Add):
+                    return left + right
+                else:
+                    return left - right
         raise ValueError('malformed node or string: ' + repr(node))
     return _convert(node_or_string)
 
@@ -196,12 +197,19 @@ def get_docstring(node, clean=True):
     """
     if not isinstance(node, (AsyncFunctionDef, FunctionDef, ClassDef, Module)):
         raise TypeError("%r can't have docstrings" % node.__class__.__name__)
-    if node.body and isinstance(node.body[0], Expr) and \
-       isinstance(node.body[0].value, Str):
-        if clean:
-            import inspect
-            return inspect.cleandoc(node.body[0].value.s)
-        return node.body[0].value.s
+    if not(node.body and isinstance(node.body[0], Expr)):
+        return
+    node = node.body[0].value
+    if isinstance(node, Str):
+        text = node.s
+    elif isinstance(node, Constant) and isinstance(node.value, str):
+        text = node.value
+    else:
+        return
+    if clean:
+        import inspect
+        text = inspect.cleandoc(text)
+    return text
 
 
 def walk(node):
diff --git a/Lib/asynchat.py b/Lib/asynchat.py
index f728d1b470..fc1146adbb 100644
--- a/Lib/asynchat.py
+++ b/Lib/asynchat.py
@@ -285,35 +285,6 @@ class simple_producer:
             return result
 
 
-class fifo:
-    def __init__(self, list=None):
-        import warnings
-        warnings.warn('fifo class will be removed in Python 3.6',
-                      DeprecationWarning, stacklevel=2)
-        if not list:
-            self.list = deque()
-        else:
-            self.list = deque(list)
-
-    def __len__(self):
-        return len(self.list)
-
-    def is_empty(self):
-        return not self.list
-
-    def first(self):
-        return self.list[0]
-
-    def push(self, data):
-        self.list.append(data)
-
-    def pop(self):
-        if self.list:
-            return (1, self.list.popleft())
-        else:
-            return (0, None)
-
-
 # Given 'haystack', see if any prefix of 'needle' is at its end.  This
 # assumes an exact match has already been checked.  Return the number of
 # characters matched.
diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index 172a463ef8..f55a36e082 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -426,7 +426,8 @@ class BaseEventLoop(events.AbstractEventLoop):
     if compat.PY34:
         def __del__(self):
             if not self.is_closed():
-                warnings.warn("unclosed event loop %r" % self, ResourceWarning)
+                warnings.warn("unclosed event loop %r" % self, ResourceWarning,
+                              source=self)
                 if not self.is_running():
                     self.close()
 
diff --git a/Lib/asyncio/base_subprocess.py b/Lib/asyncio/base_subprocess.py
index 8fc253c18e..fb8c2ba72f 100644
--- a/Lib/asyncio/base_subprocess.py
+++ b/Lib/asyncio/base_subprocess.py
@@ -122,7 +122,8 @@ class BaseSubprocessTransport(transports.SubprocessTransport):
     if compat.PY34:
         def __del__(self):
             if not self._closed:
-                warnings.warn("unclosed transport %r" % self, ResourceWarning)
+                warnings.warn("unclosed transport %r" % self, ResourceWarning,
+                              source=self)
                 self.close()
 
     def get_pid(self):
diff --git a/Lib/asyncio/proactor_events.py b/Lib/asyncio/proactor_events.py
index 3ac314c0cc..4b6067aede 100644
--- a/Lib/asyncio/proactor_events.py
+++ b/Lib/asyncio/proactor_events.py
@@ -86,7 +86,8 @@ class _ProactorBasePipeTransport(transports._FlowControlMixin,
     if compat.PY34:
         def __del__(self):
             if self._sock is not None:
-                warnings.warn("unclosed transport %r" % self, ResourceWarning)
+                warnings.warn("unclosed transport %r" % self, ResourceWarning,
+                              source=self)
                 self.close()
 
     def _fatal_error(self, exc, message='Fatal error on pipe transport'):
diff --git a/Lib/asyncio/selector_events.py b/Lib/asyncio/selector_events.py
index fb7ab2108e..7ae532d005 100644
--- a/Lib/asyncio/selector_events.py
+++ b/Lib/asyncio/selector_events.py
@@ -577,7 +577,8 @@ class _SelectorTransport(transports._FlowControlMixin,
     if compat.PY34:
         def __del__(self):
             if self._sock is not None:
-                warnings.warn("unclosed transport %r" % self, ResourceWarning)
+                warnings.warn("unclosed transport %r" % self, ResourceWarning,
+                              source=self)
                 self._sock.close()
 
     def _fatal_error(self, exc, message='Fatal error on transport'):
diff --git a/Lib/asyncio/sslproto.py b/Lib/asyncio/sslproto.py
index f58b5ac502..79b201c910 100644
--- a/Lib/asyncio/sslproto.py
+++ b/Lib/asyncio/sslproto.py
@@ -324,7 +324,8 @@ class _SSLProtocolTransport(transports._FlowControlMixin,
     if compat.PY34:
         def __del__(self):
             if not self._closed:
-                warnings.warn("unclosed transport %r" % self, ResourceWarning)
+                warnings.warn("unclosed transport %r" % self, ResourceWarning,
+                              source=self)
                 self.close()
 
     def pause_reading(self):
diff --git a/Lib/asyncio/unix_events.py b/Lib/asyncio/unix_events.py
index d712749ee5..ce49c4f37a 100644
--- a/Lib/asyncio/unix_events.py
+++ b/Lib/asyncio/unix_events.py
@@ -381,7 +381,8 @@ class _UnixReadPipeTransport(transports.ReadTransport):
     if compat.PY34:
         def __del__(self):
             if self._pipe is not None:
-                warnings.warn("unclosed transport %r" % self, ResourceWarning)
+                warnings.warn("unclosed transport %r" % self, ResourceWarning,
+                              source=self)
                 self._pipe.close()
 
     def _fatal_error(self, exc, message='Fatal error on pipe transport'):
@@ -573,7 +574,8 @@ class _UnixWritePipeTransport(transports._FlowControlMixin,
     if compat.PY34:
         def __del__(self):
             if self._pipe is not None:
-                warnings.warn("unclosed transport %r" % self, ResourceWarning)
+                warnings.warn("unclosed transport %r" % self, ResourceWarning,
+                              source=self)
                 self._pipe.close()
 
     def abort(self):
diff --git a/Lib/asyncio/windows_utils.py b/Lib/asyncio/windows_utils.py
index 870cd13abe..7c63fb904b 100644
--- a/Lib/asyncio/windows_utils.py
+++ b/Lib/asyncio/windows_utils.py
@@ -159,7 +159,8 @@ class PipeHandle:
 
     def __del__(self):
         if self._handle is not None:
-            warnings.warn("unclosed %r" % self, ResourceWarning)
+            warnings.warn("unclosed %r" % self, ResourceWarning,
+                          source=self)
             self.close()
 
     def __enter__(self):
diff --git a/Lib/asyncore.py b/Lib/asyncore.py
index 3b51f0f337..4b046d67e3 100644
--- a/Lib/asyncore.py
+++ b/Lib/asyncore.py
@@ -595,7 +595,8 @@ if os.name == 'posix':
 
         def __del__(self):
             if self.fd >= 0:
-                warnings.warn("unclosed file %r" % self, ResourceWarning)
+                warnings.warn("unclosed file %r" % self, ResourceWarning,
+                              source=self)
             self.close()
 
         def recv(self, *args):
diff --git a/Lib/base64.py b/Lib/base64.py
index adaec1de61..67e54f021a 100755
--- a/Lib/base64.py
+++ b/Lib/base64.py
@@ -55,8 +55,7 @@ def b64encode(s, altchars=None):
     alternative alphabet for the '+' and '/' characters.  This allows an
     application to e.g. generate url or filesystem safe Base64 strings.
     """
-    # Strip off the trailing newline
-    encoded = binascii.b2a_base64(s)[:-1]
+    encoded = binascii.b2a_base64(s, newline=False)
     if altchars is not None:
         assert len(altchars) == 2, repr(altchars)
         return encoded.translate(bytes.maketrans(b'+/', altchars))
diff --git a/Lib/calendar.py b/Lib/calendar.py
index 5244b8d1ee..85baf2ee4a 100644
--- a/Lib/calendar.py
+++ b/Lib/calendar.py
@@ -12,7 +12,9 @@ import locale as _locale
 __all__ = ["IllegalMonthError", "IllegalWeekdayError", "setfirstweekday",
            "firstweekday", "isleap", "leapdays", "weekday", "monthrange",
            "monthcalendar", "prmonth", "month", "prcal", "calendar",
-           "timegm", "month_name", "month_abbr", "day_name", "day_abbr"]
+           "timegm", "month_name", "month_abbr", "day_name", "day_abbr",
+           "Calendar", "TextCalendar", "HTMLCalendar", "LocaleTextCalendar",
+           "LocaleHTMLCalendar", "weekheader"]
 
 # Exception raised for bad input (with string parameter for details)
 error = ValueError
@@ -605,51 +607,63 @@ def timegm(tuple):
 
 
 def main(args):
-    import optparse
-    parser = optparse.OptionParser(usage="usage: %prog [options] [year [month]]")
-    parser.add_option(
+    import argparse
+    parser = argparse.ArgumentParser()
+    textgroup = parser.add_argument_group('text only arguments')
+    htmlgroup = parser.add_argument_group('html only arguments')
+    textgroup.add_argument(
         "-w", "--width",
-        dest="width", type="int", default=2,
-        help="width of date column (default 2, text only)"
+        type=int, default=2,
+        help="width of date column (default 2)"
     )
-    parser.add_option(
+    textgroup.add_argument(
         "-l", "--lines",
-        dest="lines", type="int", default=1,
-        help="number of lines for each week (default 1, text only)"
+        type=int, default=1,
+        help="number of lines for each week (default 1)"
     )
-    parser.add_option(
+    textgroup.add_argument(
         "-s", "--spacing",
-        dest="spacing", type="int", default=6,
-        help="spacing between months (default 6, text only)"
+        type=int, default=6,
+        help="spacing between months (default 6)"
     )
-    parser.add_option(
+    textgroup.add_argument(
         "-m", "--months",
-        dest="months", type="int", default=3,
-        help="months per row (default 3, text only)"
+        type=int, default=3,
+        help="months per row (default 3)"
     )
-    parser.add_option(
+    htmlgroup.add_argument(
         "-c", "--css",
-        dest="css", default="calendar.css",
-        help="CSS to use for page (html only)"
+        default="calendar.css",
+        help="CSS to use for page"
     )
-    parser.add_option(
+    parser.add_argument(
         "-L", "--locale",
-        dest="locale", default=None,
+        default=None,
         help="locale to be used from month and weekday names"
     )
-    parser.add_option(
+    parser.add_argument(
         "-e", "--encoding",
-        dest="encoding", default=None,
-        help="Encoding to use for output."
+        default=None,
+        help="encoding to use for output"
     )
-    parser.add_option(
+    parser.add_argument(
         "-t", "--type",
-        dest="type", default="text",
+        default="text",
         choices=("text", "html"),
         help="output type (text or html)"
     )
+    parser.add_argument(
+        "year",
+        nargs='?', type=int,
+        help="year number (1-9999)"
+    )
+    parser.add_argument(
+        "month",
+        nargs='?', type=int,
+        help="month number (1-12, text only)"
+    )
 
-    (options, args) = parser.parse_args(args)
+    options = parser.parse_args(args[1:])
 
     if options.locale and not options.encoding:
         parser.error("if --locale is specified --encoding is required")
@@ -667,10 +681,10 @@ def main(args):
             encoding = sys.getdefaultencoding()
         optdict = dict(encoding=encoding, css=options.css)
         write = sys.stdout.buffer.write
-        if len(args) == 1:
+        if options.year is None:
             write(cal.formatyearpage(datetime.date.today().year, **optdict))
-        elif len(args) == 2:
-            write(cal.formatyearpage(int(args[1]), **optdict))
+        elif options.month is None:
+            write(cal.formatyearpage(options.year, **optdict))
         else:
             parser.error("incorrect number of arguments")
             sys.exit(1)
@@ -680,18 +694,15 @@ def main(args):
         else:
             cal = TextCalendar()
         optdict = dict(w=options.width, l=options.lines)
-        if len(args) != 3:
+        if options.month is None:
             optdict["c"] = options.spacing
             optdict["m"] = options.months
-        if len(args) == 1:
+        if options.year is None:
             result = cal.formatyear(datetime.date.today().year, **optdict)
-        elif len(args) == 2:
-            result = cal.formatyear(int(args[1]), **optdict)
-        elif len(args) == 3:
-            result = cal.formatmonth(int(args[1]), int(args[2]), **optdict)
+        elif options.month is None:
+            result = cal.formatyear(options.year, **optdict)
         else:
-            parser.error("incorrect number of arguments")
-            sys.exit(1)
+            result = cal.formatmonth(options.year, options.month, **optdict)
         write = sys.stdout.write
         if options.encoding:
             result = result.encode(options.encoding)
diff --git a/Lib/cgi.py b/Lib/cgi.py
index 189c6d5b4a..233a496e81 100755
--- a/Lib/cgi.py
+++ b/Lib/cgi.py
@@ -45,7 +45,7 @@ import tempfile
 
 __all__ = ["MiniFieldStorage", "FieldStorage",
            "parse", "parse_qs", "parse_qsl", "parse_multipart",
-           "parse_header", "print_exception", "print_environ",
+           "parse_header", "test", "print_exception", "print_environ",
            "print_form", "print_directory", "print_arguments",
            "print_environ_usage", "escape"]
 
diff --git a/Lib/collections/__init__.py b/Lib/collections/__init__.py
index ebe8ee7a83..b9419506e9 100644
--- a/Lib/collections/__init__.py
+++ b/Lib/collections/__init__.py
@@ -842,7 +842,7 @@ class Counter(dict):
 
 
 ########################################################################
-###  ChainMap (helper for configparser and string.Template)
+###  ChainMap
 ########################################################################
 
 class ChainMap(MutableMapping):
@@ -969,7 +969,7 @@ class UserDict(MutableMapping):
             dict = kwargs.pop('dict')
             import warnings
             warnings.warn("Passing 'dict' as keyword argument is deprecated",
-                          PendingDeprecationWarning, stacklevel=2)
+                          DeprecationWarning, stacklevel=2)
         else:
             dict = None
         self.data = {}
diff --git a/Lib/compileall.py b/Lib/compileall.py
index 0cc0c1d530..67c5f5ac72 100644
--- a/Lib/compileall.py
+++ b/Lib/compileall.py
@@ -68,7 +68,7 @@ def compile_dir(dir, maxlevels=10, ddir=None, force=False, rx=None,
     """
     files = _walk_dir(dir, quiet=quiet, maxlevels=maxlevels,
                       ddir=ddir)
-    success = 1
+    success = True
     if workers is not None and workers != 1 and ProcessPoolExecutor is not None:
         if workers < 0:
             raise ValueError('workers must be greater or equal to 0')
@@ -81,12 +81,12 @@ def compile_dir(dir, maxlevels=10, ddir=None, force=False, rx=None,
                                            legacy=legacy,
                                            optimize=optimize),
                                    files)
-            success = min(results, default=1)
+            success = min(results, default=True)
     else:
         for file in files:
             if not compile_file(file, ddir, force, rx, quiet,
                                 legacy, optimize):
-                success = 0
+                success = False
     return success
 
 def compile_file(fullname, ddir=None, force=False, rx=None, quiet=0,
@@ -104,7 +104,7 @@ def compile_file(fullname, ddir=None, force=False, rx=None, quiet=0,
     legacy:    if True, produce legacy pyc paths instead of PEP 3147 paths
     optimize:  optimization level or -1 for level of the interpreter
     """
-    success = 1
+    success = True
     name = os.path.basename(fullname)
     if ddir is not None:
         dfile = os.path.join(ddir, name)
@@ -144,7 +144,7 @@ def compile_file(fullname, ddir=None, force=False, rx=None, quiet=0,
                 ok = py_compile.compile(fullname, cfile, dfile, True,
                                         optimize=optimize)
             except py_compile.PyCompileError as err:
-                success = 0
+                success = False
                 if quiet >= 2:
                     return success
                 elif quiet:
@@ -157,7 +157,7 @@ def compile_file(fullname, ddir=None, force=False, rx=None, quiet=0,
                 msg = msg.decode(sys.stdout.encoding)
                 print(msg)
             except (SyntaxError, UnicodeError, OSError) as e:
-                success = 0
+                success = False
                 if quiet >= 2:
                     return success
                 elif quiet:
@@ -167,7 +167,7 @@ def compile_file(fullname, ddir=None, force=False, rx=None, quiet=0,
                 print(e.__class__.__name__ + ':', e)
             else:
                 if ok == 0:
-                    success = 0
+                    success = False
     return success
 
 def compile_path(skip_curdir=1, maxlevels=0, force=False, quiet=0,
@@ -183,7 +183,7 @@ def compile_path(skip_curdir=1, maxlevels=0, force=False, quiet=0,
     legacy: as for compile_dir() (default False)
     optimize: as for compile_dir() (default -1)
     """
-    success = 1
+    success = True
     for dir in sys.path:
         if (not dir or dir == os.curdir) and skip_curdir:
             if quiet < 2:
diff --git a/Lib/contextlib.py b/Lib/contextlib.py
index 5377987ddf..6cf112af0d 100644
--- a/Lib/contextlib.py
+++ b/Lib/contextlib.py
@@ -1,11 +1,34 @@
 """Utilities for with-statement contexts.  See PEP 343."""
-
+import abc
 import sys
 from collections import deque
 from functools import wraps
 
-__all__ = ["contextmanager", "closing", "ContextDecorator", "ExitStack",
-           "redirect_stdout", "redirect_stderr", "suppress"]
+__all__ = ["contextmanager", "closing", "AbstractContextManager",
+           "ContextDecorator", "ExitStack", "redirect_stdout",
+           "redirect_stderr", "suppress"]
+
+
+class AbstractContextManager(abc.ABC):
+
+    """An abstract base class for context managers."""
+
+    def __enter__(self):
+        """Return `self` upon entering the runtime context."""
+        return self
+
+    @abc.abstractmethod
+    def __exit__(self, exc_type, exc_value, traceback):
+        """Raise any exception triggered within the runtime context."""
+        return None
+
+    @classmethod
+    def __subclasshook__(cls, C):
+        if cls is AbstractContextManager:
+            if (any("__enter__" in B.__dict__ for B in C.__mro__) and
+                any("__exit__" in B.__dict__ for B in C.__mro__)):
+                return True
+        return NotImplemented
 
 
 class ContextDecorator(object):
@@ -31,7 +54,7 @@ class ContextDecorator(object):
         return inner
 
 
-class _GeneratorContextManager(ContextDecorator):
+class _GeneratorContextManager(ContextDecorator, AbstractContextManager):
     """Helper for @contextmanager decorator."""
 
     def __init__(self, func, args, kwds):
@@ -134,7 +157,7 @@ def contextmanager(func):
     return helper
 
 
-class closing(object):
+class closing(AbstractContextManager):
     """Context to automatically close something at the end of a block.
 
     Code like this:
@@ -159,7 +182,7 @@ class closing(object):
         self.thing.close()
 
 
-class _RedirectStream:
+class _RedirectStream(AbstractContextManager):
 
     _stream = None
 
@@ -199,7 +222,7 @@ class redirect_stderr(_RedirectStream):
     _stream = "stderr"
 
 
-class suppress:
+class suppress(AbstractContextManager):
     """Context manager to suppress specified exceptions
 
     After the exception is suppressed, execution proceeds with the next
@@ -230,7 +253,7 @@ class suppress:
 
 
 # Inspired by discussions on http://bugs.python.org/issue13585
-class ExitStack(object):
+class ExitStack(AbstractContextManager):
     """Context manager for dynamic management of a stack of exit callbacks
 
     For example:
@@ -309,9 +332,6 @@ class ExitStack(object):
         """Immediately unwind the context stack"""
         self.__exit__(None, None, None)
 
-    def __enter__(self):
-        return self
-
     def __exit__(self, *exc_details):
         received_exc = exc_details[0] is not None
 
diff --git a/Lib/copy.py b/Lib/copy.py
index 972b94ab49..f86040a33c 100644
--- a/Lib/copy.py
+++ b/Lib/copy.py
@@ -51,7 +51,6 @@ __getstate__() and __setstate__().  See the documentation for module
 import types
 import weakref
 from copyreg import dispatch_table
-import builtins
 
 class Error(Exception):
     pass
@@ -102,37 +101,33 @@ def copy(x):
             else:
                 raise Error("un(shallow)copyable object of type %s" % cls)
 
-    return _reconstruct(x, rv, 0)
+    if isinstance(rv, str):
+        return x
+    return _reconstruct(x, None, *rv)
 
 
 _copy_dispatch = d = {}
 
 def _copy_immutable(x):
     return x
-for t in (type(None), int, float, bool, str, tuple,
-          bytes, frozenset, type, range,
-          types.BuiltinFunctionType, type(Ellipsis),
+for t in (type(None), int, float, bool, complex, str, tuple,
+          bytes, frozenset, type, range, slice,
+          types.BuiltinFunctionType, type(Ellipsis), type(NotImplemented),
           types.FunctionType, weakref.ref):
     d[t] = _copy_immutable
 t = getattr(types, "CodeType", None)
 if t is not None:
     d[t] = _copy_immutable
-for name in ("complex", "unicode"):
-    t = getattr(builtins, name, None)
-    if t is not None:
-        d[t] = _copy_immutable
-
-def _copy_with_constructor(x):
-    return type(x)(x)
-for t in (list, dict, set):
-    d[t] = _copy_with_constructor
-
-def _copy_with_copy_method(x):
-    return x.copy()
+
+d[list] = list.copy
+d[dict] = dict.copy
+d[set] = set.copy
+d[bytearray] = bytearray.copy
+
 if PyStringMap is not None:
-    d[PyStringMap] = _copy_with_copy_method
+    d[PyStringMap] = PyStringMap.copy
 
-del d
+del d, t
 
 def deepcopy(x, memo=None, _nil=[]):
     """Deep copy operation on arbitrary Python objects.
@@ -179,7 +174,10 @@ def deepcopy(x, memo=None, _nil=[]):
                         else:
                             raise Error(
                                 "un(deep)copyable object of type %s" % cls)
-                y = _reconstruct(x, rv, 1, memo)
+                if isinstance(rv, str):
+                    y = x
+                else:
+                    y = _reconstruct(x, memo, *rv)
 
     # If is its own copy, don't memoize.
     if y is not x:
@@ -193,13 +191,11 @@ def _deepcopy_atomic(x, memo):
     return x
 d[type(None)] = _deepcopy_atomic
 d[type(Ellipsis)] = _deepcopy_atomic
+d[type(NotImplemented)] = _deepcopy_atomic
 d[int] = _deepcopy_atomic
 d[float] = _deepcopy_atomic
 d[bool] = _deepcopy_atomic
-try:
-    d[complex] = _deepcopy_atomic
-except NameError:
-    pass
+d[complex] = _deepcopy_atomic
 d[bytes] = _deepcopy_atomic
 d[str] = _deepcopy_atomic
 try:
@@ -211,15 +207,16 @@ d[types.BuiltinFunctionType] = _deepcopy_atomic
 d[types.FunctionType] = _deepcopy_atomic
 d[weakref.ref] = _deepcopy_atomic
 
-def _deepcopy_list(x, memo):
+def _deepcopy_list(x, memo, deepcopy=deepcopy):
     y = []
     memo[id(x)] = y
+    append = y.append
     for a in x:
-        y.append(deepcopy(a, memo))
+        append(deepcopy(a, memo))
     return y
 d[list] = _deepcopy_list
 
-def _deepcopy_tuple(x, memo):
+def _deepcopy_tuple(x, memo, deepcopy=deepcopy):
     y = [deepcopy(a, memo) for a in x]
     # We're not going to put the tuple in the memo, but it's still important we
     # check for it, in case the tuple contains recursive mutable structures.
@@ -236,7 +233,7 @@ def _deepcopy_tuple(x, memo):
     return y
 d[tuple] = _deepcopy_tuple
 
-def _deepcopy_dict(x, memo):
+def _deepcopy_dict(x, memo, deepcopy=deepcopy):
     y = {}
     memo[id(x)] = y
     for key, value in x.items():
@@ -248,7 +245,9 @@ if PyStringMap is not None:
 
 def _deepcopy_method(x, memo): # Copy instance methods
     return type(x)(x.__func__, deepcopy(x.__self__, memo))
-_deepcopy_dispatch[types.MethodType] = _deepcopy_method
+d[types.MethodType] = _deepcopy_method
+
+del d
 
 def _keep_alive(x, memo):
     """Keeps a reference to the object x in the memo.
@@ -266,31 +265,15 @@ def _keep_alive(x, memo):
         # aha, this is the first one :-)
         memo[id(memo)]=[x]
 
-def _reconstruct(x, info, deep, memo=None):
-    if isinstance(info, str):
-        return x
-    assert isinstance(info, tuple)
-    if memo is None:
-        memo = {}
-    n = len(info)
-    assert n in (2, 3, 4, 5)
-    callable, args = info[:2]
-    if n > 2:
-        state = info[2]
-    else:
-        state = None
-    if n > 3:
-        listiter = info[3]
-    else:
-        listiter = None
-    if n > 4:
-        dictiter = info[4]
-    else:
-        dictiter = None
+def _reconstruct(x, memo, func, args,
+                 state=None, listiter=None, dictiter=None,
+                 deepcopy=deepcopy):
+    deep = memo is not None
+    if deep and args:
+        args = (deepcopy(arg, memo) for arg in args)
+    y = func(*args)
     if deep:
-        args = deepcopy(args, memo)
-    y = callable(*args)
-    memo[id(x)] = y
+        memo[id(x)] = y
 
     if state is not None:
         if deep:
@@ -309,22 +292,22 @@ def _reconstruct(x, info, deep, memo=None):
                     setattr(y, key, value)
 
     if listiter is not None:
-        for item in listiter:
-            if deep:
+        if deep:
+            for item in listiter:
                 item = deepcopy(item, memo)
-            y.append(item)
+                y.append(item)
+        else:
+            for item in listiter:
+                y.append(item)
     if dictiter is not None:
-        for key, value in dictiter:
-            if deep:
+        if deep:
+            for key, value in dictiter:
                 key = deepcopy(key, memo)
                 value = deepcopy(value, memo)
-            y[key] = value
+                y[key] = value
+        else:
+            for key, value in dictiter:
+                y[key] = value
     return y
 
-del d
-
-del types
-
-# Helper for instance creation without calling __init__
-class _EmptyClass:
-    pass
+del types, weakref, PyStringMap
diff --git a/Lib/crypt.py b/Lib/crypt.py
index 49ab96e140..fbc5f4cc35 100644
--- a/Lib/crypt.py
+++ b/Lib/crypt.py
@@ -54,9 +54,8 @@ METHOD_SHA256 = _Method('SHA256', '5', 16, 63)
 METHOD_SHA512 = _Method('SHA512', '6', 16, 106)
 
 methods = []
-for _method in (METHOD_SHA512, METHOD_SHA256, METHOD_MD5):
+for _method in (METHOD_SHA512, METHOD_SHA256, METHOD_MD5, METHOD_CRYPT):
     _result = crypt('', _method)
     if _result and len(_result) == _method.total_size:
         methods.append(_method)
-methods.append(METHOD_CRYPT)
 del _result, _method
diff --git a/Lib/csv.py b/Lib/csv.py
index ca40e5e0ef..90461dbe1e 100644
--- a/Lib/csv.py
+++ b/Lib/csv.py
@@ -13,11 +13,12 @@ from _csv import Dialect as _Dialect
 
 from io import StringIO
 
-__all__ = [ "QUOTE_MINIMAL", "QUOTE_ALL", "QUOTE_NONNUMERIC", "QUOTE_NONE",
-            "Error", "Dialect", "__doc__", "excel", "excel_tab",
-            "field_size_limit", "reader", "writer",
-            "register_dialect", "get_dialect", "list_dialects", "Sniffer",
-            "unregister_dialect", "__version__", "DictReader", "DictWriter" ]
+__all__ = ["QUOTE_MINIMAL", "QUOTE_ALL", "QUOTE_NONNUMERIC", "QUOTE_NONE",
+           "Error", "Dialect", "__doc__", "excel", "excel_tab",
+           "field_size_limit", "reader", "writer",
+           "register_dialect", "get_dialect", "list_dialects", "Sniffer",
+           "unregister_dialect", "__version__", "DictReader", "DictWriter",
+           "unix_dialect"]
 
 class Dialect:
     """Describe a CSV dialect.
diff --git a/Lib/ctypes/test/test_bitfields.py b/Lib/ctypes/test/test_bitfields.py
index b39d82cc0b..0eb09fb4bf 100644
--- a/Lib/ctypes/test/test_bitfields.py
+++ b/Lib/ctypes/test/test_bitfields.py
@@ -3,7 +3,6 @@ from ctypes.test import need_symbol
 import unittest
 import os
 
-import ctypes
 import _ctypes_test
 
 class BITS(Structure):
diff --git a/Lib/ctypes/test/test_objects.py b/Lib/ctypes/test/test_objects.py
index ef7b20b000..19e3dc1f2d 100644
--- a/Lib/ctypes/test/test_objects.py
+++ b/Lib/ctypes/test/test_objects.py
@@ -54,7 +54,7 @@ of 'x' ('_b_base_' is either None, or the root object owning the memory block):
 
 '''
 
-import unittest, doctest, sys
+import unittest, doctest
 
 import ctypes.test.test_objects
 
diff --git a/Lib/ctypes/test/test_parameters.py b/Lib/ctypes/test/test_parameters.py
index e56bccf999..363f58612d 100644
--- a/Lib/ctypes/test/test_parameters.py
+++ b/Lib/ctypes/test/test_parameters.py
@@ -1,4 +1,4 @@
-import unittest, sys
+import unittest
 from ctypes.test import need_symbol
 
 class SimpleTypesTestCase(unittest.TestCase):
@@ -49,7 +49,7 @@ class SimpleTypesTestCase(unittest.TestCase):
 
     # XXX Replace by c_char_p tests
     def test_cstrings(self):
-        from ctypes import c_char_p, byref
+        from ctypes import c_char_p
 
         # c_char_p.from_param on a Python String packs the string
         # into a cparam object
@@ -68,7 +68,7 @@ class SimpleTypesTestCase(unittest.TestCase):
 
     @need_symbol('c_wchar_p')
     def test_cw_strings(self):
-        from ctypes import byref, c_wchar_p
+        from ctypes import c_wchar_p
 
         c_wchar_p.from_param("123")
 
@@ -98,7 +98,7 @@ class SimpleTypesTestCase(unittest.TestCase):
     def test_byref_pointer(self):
         # The from_param class method of POINTER(typ) classes accepts what is
         # returned by byref(obj), it type(obj) == typ
-        from ctypes import c_short, c_uint, c_int, c_long, pointer, POINTER, byref
+        from ctypes import c_short, c_uint, c_int, c_long, POINTER, byref
         LPINT = POINTER(c_int)
 
         LPINT.from_param(byref(c_int(42)))
diff --git a/Lib/ctypes/test/test_pep3118.py b/Lib/ctypes/test/test_pep3118.py
index 32f802c861..d68397ea80 100644
--- a/Lib/ctypes/test/test_pep3118.py
+++ b/Lib/ctypes/test/test_pep3118.py
@@ -1,6 +1,6 @@
 import unittest
 from ctypes import *
-import re, struct, sys
+import re, sys
 
 if sys.byteorder == "little":
     THIS_ENDIAN = "<"
diff --git a/Lib/ctypes/test/test_returnfuncptrs.py b/Lib/ctypes/test/test_returnfuncptrs.py
index 93eba6bb76..1974f40df6 100644
--- a/Lib/ctypes/test/test_returnfuncptrs.py
+++ b/Lib/ctypes/test/test_returnfuncptrs.py
@@ -1,6 +1,5 @@
 import unittest
 from ctypes import *
-import os
 
 import _ctypes_test
 
diff --git a/Lib/ctypes/test/test_sizes.py b/Lib/ctypes/test/test_sizes.py
index f9b5e97260..4ceacbc290 100644
--- a/Lib/ctypes/test/test_sizes.py
+++ b/Lib/ctypes/test/test_sizes.py
@@ -2,7 +2,6 @@
 
 from ctypes import *
 
-import sys
 import unittest
 
 
diff --git a/Lib/ctypes/test/test_structures.py b/Lib/ctypes/test/test_structures.py
index 84d456c3cc..736679f630 100644
--- a/Lib/ctypes/test/test_structures.py
+++ b/Lib/ctypes/test/test_structures.py
@@ -320,17 +320,14 @@ class StructureTestCase(unittest.TestCase):
 
         cls, msg = self.get_except(Person, b"Someone", (1, 2))
         self.assertEqual(cls, RuntimeError)
-        self.assertEqual(msg,
-                             "(Phone) <class 'TypeError'>: "
-                             "expected bytes, int found")
+        self.assertRegex(msg,
+                             r"\(Phone\) <class 'TypeError' at 0x.+>: "
+                             r"expected bytes, int found")
 
         cls, msg = self.get_except(Person, b"Someone", (b"a", b"b", b"c"))
         self.assertEqual(cls, RuntimeError)
-        if issubclass(Exception, object):
-            self.assertEqual(msg,
-                                 "(Phone) <class 'TypeError'>: too many initializers")
-        else:
-            self.assertEqual(msg, "(Phone) TypeError: too many initializers")
+        self.assertRegex(msg,
+                             r"\(Phone\) <class 'TypeError' at 0x.+>: too many initializers")
 
     def test_huge_field_name(self):
         # issue12881: segfault with large structure field names
diff --git a/Lib/ctypes/test/test_values.py b/Lib/ctypes/test/test_values.py
index 5a3a47f968..e71b48020f 100644
--- a/Lib/ctypes/test/test_values.py
+++ b/Lib/ctypes/test/test_values.py
@@ -79,9 +79,9 @@ class PythonValuesTestCase(unittest.TestCase):
                 continue
             items.append((entry.name.decode("ascii"), entry.size))
 
-        expected = [("__hello__", 161),
-                    ("__phello__", -161),
-                    ("__phello__.spam", 161),
+        expected = [("__hello__", 139),
+                    ("__phello__", -139),
+                    ("__phello__.spam", 139),
                     ]
         self.assertEqual(items, expected, "PyImport_FrozenModules example "
             "in Doc/library/ctypes.rst may be out of date")
diff --git a/Lib/ctypes/util.py b/Lib/ctypes/util.py
index 8ff4aff0ca..b89c315726 100644
--- a/Lib/ctypes/util.py
+++ b/Lib/ctypes/util.py
@@ -222,8 +222,8 @@ elif os.name == "posix":
             abi_type = mach_map.get(machine, 'libc6')
 
             # XXX assuming GLIBC's ldconfig (with option -p)
-            regex = os.fsencode(
-                '\s+(lib%s\.[^\s]+)\s+\(%s' % (re.escape(name), abi_type))
+            regex = r'\s+(lib%s\.[^\s]+)\s+\(%s'
+            regex = os.fsencode(regex % (re.escape(name), abi_type))
             try:
                 with subprocess.Popen(['/sbin/ldconfig', '-p'],
                                       stdin=subprocess.DEVNULL,
diff --git a/Lib/datetime.py b/Lib/datetime.py
index 2f9421829e..b1321a34e3 100644
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -152,12 +152,26 @@ def _build_struct_time(y, m, d, hh, mm, ss, dstflag):
     dnum = _days_before_month(y, m) + d
     return _time.struct_time((y, m, d, hh, mm, ss, wday, dnum, dstflag))
 
-def _format_time(hh, mm, ss, us):
-    # Skip trailing microseconds when us==0.
-    result = "%02d:%02d:%02d" % (hh, mm, ss)
-    if us:
-        result += ".%06d" % us
-    return result
+def _format_time(hh, mm, ss, us, timespec='auto'):
+    specs = {
+        'hours': '{:02d}',
+        'minutes': '{:02d}:{:02d}',
+        'seconds': '{:02d}:{:02d}:{:02d}',
+        'milliseconds': '{:02d}:{:02d}:{:02d}.{:03d}',
+        'microseconds': '{:02d}:{:02d}:{:02d}.{:06d}'
+    }
+
+    if timespec == 'auto':
+        # Skip trailing microseconds when us==0.
+        timespec = 'microseconds' if us else 'seconds'
+    elif timespec == 'milliseconds':
+        us //= 1000
+    try:
+        fmt = specs[timespec]
+    except KeyError:
+        raise ValueError('Unknown timespec value')
+    else:
+        return fmt.format(hh, mm, ss, us)
 
 # Correctly substitute for %z and %Z escapes in strftime formats.
 def _wrap_strftime(object, format, timetuple):
@@ -240,7 +254,7 @@ def _check_utc_offset(name, offset):
         raise ValueError("tzinfo.%s() must return a whole number "
                          "of minutes, got %s" % (name, offset))
     if not -timedelta(1) < offset < timedelta(1):
-        raise ValueError("%s()=%s, must be must be strictly between "
+        raise ValueError("%s()=%s, must be strictly between "
                          "-timedelta(hours=24) and timedelta(hours=24)" %
                          (name, offset))
 
@@ -316,6 +330,7 @@ def _divide_and_round(a, b):
 
     return q
 
+
 class timedelta:
     """Represent the difference between two datetime objects.
 
@@ -1193,14 +1208,17 @@ class time:
             s = s[:-1] + ", tzinfo=%r" % self._tzinfo + ")"
         return s
 
-    def isoformat(self):
+    def isoformat(self, timespec='auto'):
         """Return the time formatted according to ISO.
 
-        This is 'HH:MM:SS.mmmmmm+zz:zz', or 'HH:MM:SS+zz:zz' if
-        self.microsecond == 0.
+        The full format is 'HH:MM:SS.mmmmmm+zz:zz'. By default, the fractional
+        part is omitted if self.microsecond == 0.
+
+        The optional argument timespec specifies the number of additional
+        terms of the time to include.
         """
         s = _format_time(self._hour, self._minute, self._second,
-                         self._microsecond)
+                          self._microsecond, timespec)
         tz = self._tzstr()
         if tz:
             s += tz
@@ -1549,21 +1567,25 @@ class datetime(date):
             self._hour, self._minute, self._second,
             self._year)
 
-    def isoformat(self, sep='T'):
+    def isoformat(self, sep='T', timespec='auto'):
         """Return the time formatted according to ISO.
 
-        This is 'YYYY-MM-DD HH:MM:SS.mmmmmm', or 'YYYY-MM-DD HH:MM:SS' if
-        self.microsecond == 0.
+        The full format looks like 'YYYY-MM-DD HH:MM:SS.mmmmmm'.
+        By default, the fractional part is omitted if self.microsecond == 0.
 
         If self.tzinfo is not None, the UTC offset is also attached, giving
-        'YYYY-MM-DD HH:MM:SS.mmmmmm+HH:MM' or 'YYYY-MM-DD HH:MM:SS+HH:MM'.
+        giving a full format of 'YYYY-MM-DD HH:MM:SS.mmmmmm+HH:MM'.
 
         Optional argument sep specifies the separator between date and
         time, default 'T'.
+
+        The optional argument timespec specifies the number of additional
+        terms of the time to include.
         """
         s = ("%04d-%02d-%02d%c" % (self._year, self._month, self._day, sep) +
              _format_time(self._hour, self._minute, self._second,
-                          self._microsecond))
+                          self._microsecond, timespec))
+
         off = self.utcoffset()
         if off is not None:
             if off.days < 0:
@@ -1913,6 +1935,8 @@ class timezone(tzinfo):
 
     @staticmethod
     def _name_from_offset(delta):
+        if not delta:
+            return 'UTC'
         if delta < timedelta(0):
             sign = '-'
             delta = -delta
diff --git a/Lib/dis.py b/Lib/dis.py
index f7e3c7f8d7..59886f1e37 100644
--- a/Lib/dis.py
+++ b/Lib/dis.py
@@ -163,6 +163,15 @@ def show_code(co, *, file=None):
 _Instruction = collections.namedtuple("_Instruction",
      "opname opcode arg argval argrepr offset starts_line is_jump_target")
 
+_Instruction.opname.__doc__ = "Human readable name for operation"
+_Instruction.opcode.__doc__ = "Numeric code for operation"
+_Instruction.arg.__doc__ = "Numeric argument to operation (if any), otherwise None"
+_Instruction.argval.__doc__ = "Resolved arg value (if known), otherwise same as arg"
+_Instruction.argrepr.__doc__ = "Human readable description of operation argument"
+_Instruction.offset.__doc__ = "Start index of operation within bytecode sequence"
+_Instruction.starts_line.__doc__ = "Line started by this opcode (if any), otherwise None"
+_Instruction.is_jump_target.__doc__ = "True if other code jumps to here, otherwise False"
+
 class Instruction(_Instruction):
     """Details for a bytecode operation
 
@@ -276,7 +285,6 @@ def _get_instructions_bytes(code, varnames=None, names=None, constants=None,
     """
     labels = findlabels(code)
     starts_line = None
-    free = None
     for offset, op, arg in _unpack_opargs(code):
         if linestarts is not None:
             starts_line = linestarts.get(offset, None)
@@ -296,7 +304,7 @@ def _get_instructions_bytes(code, varnames=None, names=None, constants=None,
             elif op in hasname:
                 argval, argrepr = _get_name_info(arg, names)
             elif op in hasjrel:
-                argval = offset + 3 + arg
+                argval = offset + 2 + arg
                 argrepr = "to " + repr(argval)
             elif op in haslocal:
                 argval, argrepr = _get_name_info(arg, varnames)
@@ -343,23 +351,15 @@ def _disassemble_str(source, *, file=None):
 disco = disassemble                     # XXX For backwards compatibility
 
 def _unpack_opargs(code):
-    # enumerate() is not an option, since we sometimes process
-    # multiple elements on a single pass through the loop
     extended_arg = 0
-    n = len(code)
-    i = 0
-    while i < n:
+    for i in range(0, len(code), 2):
         op = code[i]
-        offset = i
-        i = i+1
-        arg = None
         if op >= HAVE_ARGUMENT:
-            arg = code[i] + code[i+1]*256 + extended_arg
-            extended_arg = 0
-            i = i+2
-            if op == EXTENDED_ARG:
-                extended_arg = arg*65536
-        yield (offset, op, arg)
+            arg = code[i+1] | extended_arg
+            extended_arg = (arg << 8) if op == EXTENDED_ARG else 0
+        else:
+            arg = None
+        yield (i, op, arg)
 
 def findlabels(code):
     """Detect all offsets in a byte code which are jump targets.
@@ -370,14 +370,14 @@ def findlabels(code):
     labels = []
     for offset, op, arg in _unpack_opargs(code):
         if arg is not None:
-            label = -1
             if op in hasjrel:
-                label = offset + 3 + arg
+                label = offset + 2 + arg
             elif op in hasjabs:
                 label = arg
-            if label >= 0:
-                if label not in labels:
-                    labels.append(label)
+            else:
+                continue
+            if label not in labels:
+                labels.append(label)
     return labels
 
 def findlinestarts(code):
@@ -386,8 +386,8 @@ def findlinestarts(code):
     Generate pairs (offset, lineno) as described in Python/compile.c.
 
     """
-    byte_increments = list(code.co_lnotab[0::2])
-    line_increments = list(code.co_lnotab[1::2])
+    byte_increments = code.co_lnotab[0::2]
+    line_increments = code.co_lnotab[1::2]
 
     lastlineno = None
     lineno = code.co_firstlineno
@@ -398,6 +398,9 @@ def findlinestarts(code):
                 yield (addr, lineno)
                 lastlineno = lineno
             addr += byte_incr
+        if line_incr >= 0x80:
+            # line_increments is an array of 8-bit signed integers
+            line_incr -= 0x100
         lineno += line_incr
     if lineno != lastlineno:
         yield (addr, lineno)
diff --git a/Lib/distutils/command/bdist_msi.py b/Lib/distutils/command/bdist_msi.py
index b3cfe9ceff..f6c21aee44 100644
--- a/Lib/distutils/command/bdist_msi.py
+++ b/Lib/distutils/command/bdist_msi.py
@@ -199,7 +199,7 @@ class bdist_msi(Command):
             target_version = self.target_version
             if not target_version:
                 assert self.skip_build, "Should have already checked this"
-                target_version = sys.version[0:3]
+                target_version = '%d.%d' % sys.version_info[:2]
             plat_specifier = ".%s-%s" % (self.plat_name, target_version)
             build = self.get_finalized_command('build')
             build.build_lib = os.path.join(build.build_base,
diff --git a/Lib/distutils/command/bdist_wininst.py b/Lib/distutils/command/bdist_wininst.py
index 0c0e2c1a26..d3e1d3af22 100644
--- a/Lib/distutils/command/bdist_wininst.py
+++ b/Lib/distutils/command/bdist_wininst.py
@@ -141,7 +141,7 @@ class bdist_wininst(Command):
             target_version = self.target_version
             if not target_version:
                 assert self.skip_build, "Should have already checked this"
-                target_version = sys.version[0:3]
+                target_version = '%d.%d' % sys.version_info[:2]
             plat_specifier = ".%s-%s" % (self.plat_name, target_version)
             build = self.get_finalized_command('build')
             build.build_lib = os.path.join(build.build_base,
diff --git a/Lib/distutils/command/build.py b/Lib/distutils/command/build.py
index 337dd0bfc1..c6f52e61e1 100644
--- a/Lib/distutils/command/build.py
+++ b/Lib/distutils/command/build.py
@@ -81,7 +81,7 @@ class build(Command):
                             "--plat-name only supported on Windows (try "
                             "using './configure --help' on your platform)")
 
-        plat_specifier = ".%s-%s" % (self.plat_name, sys.version[0:3])
+        plat_specifier = ".%s-%d.%d" % (self.plat_name, *sys.version_info[:2])
 
         # Make it so Python 2.x and Python 2.x with --with-pydebug don't
         # share the same build directories. Doing so confuses the build
@@ -114,7 +114,7 @@ class build(Command):
                                            'temp' + plat_specifier)
         if self.build_scripts is None:
             self.build_scripts = os.path.join(self.build_base,
-                                              'scripts-' + sys.version[0:3])
+                                              'scripts-%d.%d' % sys.version_info[:2])
 
         if self.executable is None:
             self.executable = os.path.normpath(sys.executable)
diff --git a/Lib/distutils/command/config.py b/Lib/distutils/command/config.py
index 847e858160..b1fd09e016 100644
--- a/Lib/distutils/command/config.py
+++ b/Lib/distutils/command/config.py
@@ -9,7 +9,7 @@ configure-like tasks: "try to compile this C code", or "figure out where
 this header file lives".
 """
 
-import sys, os, re
+import os, re
 
 from distutils.core import Command
 from distutils.errors import DistutilsExecError
diff --git a/Lib/distutils/command/install.py b/Lib/distutils/command/install.py
index 67db007a02..9474e9c599 100644
--- a/Lib/distutils/command/install.py
+++ b/Lib/distutils/command/install.py
@@ -290,8 +290,8 @@ class install(Command):
                             'dist_version': self.distribution.get_version(),
                             'dist_fullname': self.distribution.get_fullname(),
                             'py_version': py_version,
-                            'py_version_short': py_version[0:3],
-                            'py_version_nodot': py_version[0] + py_version[2],
+                            'py_version_short': '%d.%d' % sys.version_info[:2],
+                            'py_version_nodot': '%d%d' % sys.version_info[:2],
                             'sys_prefix': prefix,
                             'prefix': prefix,
                             'sys_exec_prefix': exec_prefix,
diff --git a/Lib/distutils/command/install_egg_info.py b/Lib/distutils/command/install_egg_info.py
index c2a7d649c0..0ddc7367cc 100644
--- a/Lib/distutils/command/install_egg_info.py
+++ b/Lib/distutils/command/install_egg_info.py
@@ -21,10 +21,10 @@ class install_egg_info(Command):
 
     def finalize_options(self):
         self.set_undefined_options('install_lib',('install_dir','install_dir'))
-        basename = "%s-%s-py%s.egg-info" % (
+        basename = "%s-%s-py%d.%d.egg-info" % (
             to_filename(safe_name(self.distribution.get_name())),
             to_filename(safe_version(self.distribution.get_version())),
-            sys.version[:3]
+            *sys.version_info[:2]
         )
         self.target = os.path.join(self.install_dir, basename)
         self.outputs = [self.target]
diff --git a/Lib/distutils/command/register.py b/Lib/distutils/command/register.py
index b49f86fe58..a3e0893a0b 100644
--- a/Lib/distutils/command/register.py
+++ b/Lib/distutils/command/register.py
@@ -5,7 +5,7 @@ Implements the Distutils 'register' command (register with the repository).
 
 # created 2002/10/21, Richard Jones
 
-import os, string, getpass
+import getpass
 import io
 import urllib.parse, urllib.request
 from warnings import warn
diff --git a/Lib/distutils/command/sdist.py b/Lib/distutils/command/sdist.py
index 7ea3d5fa27..35a06eb09b 100644
--- a/Lib/distutils/command/sdist.py
+++ b/Lib/distutils/command/sdist.py
@@ -3,7 +3,6 @@
 Implements the Distutils 'sdist' command (create a source distribution)."""
 
 import os
-import string
 import sys
 from types import *
 from glob import glob
diff --git a/Lib/distutils/core.py b/Lib/distutils/core.py
index f05b34b295..d603d4a45a 100644
--- a/Lib/distutils/core.py
+++ b/Lib/distutils/core.py
@@ -204,16 +204,15 @@ def run_setup (script_name, script_args=None, stop_after="run"):
     global _setup_stop_after, _setup_distribution
     _setup_stop_after = stop_after
 
-    save_argv = sys.argv
+    save_argv = sys.argv.copy()
     g = {'__file__': script_name}
-    l = {}
     try:
         try:
             sys.argv[0] = script_name
             if script_args is not None:
                 sys.argv[1:] = script_args
             with open(script_name, 'rb') as f:
-                exec(f.read(), g, l)
+                exec(f.read(), g)
         finally:
             sys.argv = save_argv
             _setup_stop_after = None
diff --git a/Lib/distutils/dist.py b/Lib/distutils/dist.py
index ffb33ff645..62a24516cf 100644
--- a/Lib/distutils/dist.py
+++ b/Lib/distutils/dist.py
@@ -1018,8 +1018,7 @@ class DistributionMetadata:
                          "maintainer", "maintainer_email", "url",
                          "license", "description", "long_description",
                          "keywords", "platforms", "fullname", "contact",
-                         "contact_email", "license", "classifiers",
-                         "download_url",
+                         "contact_email", "classifiers", "download_url",
                          # PEP 314
                          "provides", "requires", "obsoletes",
                          )
diff --git a/Lib/distutils/extension.py b/Lib/distutils/extension.py
index 7efbb74f89..c507da360a 100644
--- a/Lib/distutils/extension.py
+++ b/Lib/distutils/extension.py
@@ -4,7 +4,6 @@ Provides the Extension class, used to describe C/C++ extension
 modules in setup scripts."""
 
 import os
-import sys
 import warnings
 
 # This class is really only used by the "build_ext" command, so it might
diff --git a/Lib/distutils/sysconfig.py b/Lib/distutils/sysconfig.py
index 573724ddd7..f205dcadeb 100644
--- a/Lib/distutils/sysconfig.py
+++ b/Lib/distutils/sysconfig.py
@@ -70,7 +70,7 @@ def get_python_version():
     leaving off the patchlevel.  Sample return values could be '1.5'
     or '2.2'.
     """
-    return sys.version[:3]
+    return '%d.%d' % sys.version_info[:2]
 
 
 def get_python_inc(plat_specific=0, prefix=None):
@@ -415,38 +415,11 @@ _config_vars = None
 
 def _init_posix():
     """Initialize the module as appropriate for POSIX systems."""
-    g = {}
-    # load the installed Makefile:
-    try:
-        filename = get_makefile_filename()
-        parse_makefile(filename, g)
-    except OSError as msg:
-        my_msg = "invalid Python installation: unable to open %s" % filename
-        if hasattr(msg, "strerror"):
-            my_msg = my_msg + " (%s)" % msg.strerror
-
-        raise DistutilsPlatformError(my_msg)
-
-    # load the installed pyconfig.h:
-    try:
-        filename = get_config_h_filename()
-        with open(filename) as file:
-            parse_config_h(file, g)
-    except OSError as msg:
-        my_msg = "invalid Python installation: unable to open %s" % filename
-        if hasattr(msg, "strerror"):
-            my_msg = my_msg + " (%s)" % msg.strerror
-
-        raise DistutilsPlatformError(my_msg)
-
-    # On AIX, there are wrong paths to the linker scripts in the Makefile
-    # -- these paths are relative to the Python source, but when installed
-    # the scripts are in another directory.
-    if python_build:
-        g['LDSHARED'] = g['BLDSHARED']
-
+    # _sysconfigdata is generated at build time, see the sysconfig module
+    from _sysconfigdata import build_time_vars
     global _config_vars
-    _config_vars = g
+    _config_vars = {}
+    _config_vars.update(build_time_vars)
 
 
 def _init_nt():
diff --git a/Lib/distutils/tests/test_bdist_rpm.py b/Lib/distutils/tests/test_bdist_rpm.py
index 25c14abd32..c1a2a041ee 100644
--- a/Lib/distutils/tests/test_bdist_rpm.py
+++ b/Lib/distutils/tests/test_bdist_rpm.py
@@ -3,16 +3,12 @@
 import unittest
 import sys
 import os
-import tempfile
-import shutil
 from test.support import run_unittest
 
 from distutils.core import Distribution
 from distutils.command.bdist_rpm import bdist_rpm
 from distutils.tests import support
 from distutils.spawn import find_executable
-from distutils import spawn
-from distutils.errors import DistutilsExecError
 
 SETUP_PY = """\
 from distutils.core import setup
diff --git a/Lib/distutils/tests/test_build.py b/Lib/distutils/tests/test_build.py
index 3391f36d4b..b020a5ba35 100644
--- a/Lib/distutils/tests/test_build.py
+++ b/Lib/distutils/tests/test_build.py
@@ -27,7 +27,7 @@ class BuildTestCase(support.TempdirManager,
         # build_platlib is 'build/lib.platform-x.x[-pydebug]'
         # examples:
         #   build/lib.macosx-10.3-i386-2.7
-        plat_spec = '.%s-%s' % (cmd.plat_name, sys.version[0:3])
+        plat_spec = '.%s-%d.%d' % (cmd.plat_name, *sys.version_info[:2])
         if hasattr(sys, 'gettotalrefcount'):
             self.assertTrue(cmd.build_platlib.endswith('-pydebug'))
             plat_spec += '-pydebug'
@@ -42,7 +42,8 @@ class BuildTestCase(support.TempdirManager,
         self.assertEqual(cmd.build_temp, wanted)
 
         # build_scripts is build/scripts-x.x
-        wanted = os.path.join(cmd.build_base, 'scripts-' +  sys.version[0:3])
+        wanted = os.path.join(cmd.build_base,
+                              'scripts-%d.%d' % sys.version_info[:2])
         self.assertEqual(cmd.build_scripts, wanted)
 
         # executable is os.path.normpath(sys.executable)
diff --git a/Lib/distutils/tests/test_build_ext.py b/Lib/distutils/tests/test_build_ext.py
index 8f62b1a848..55db5a878b 100644
--- a/Lib/distutils/tests/test_build_ext.py
+++ b/Lib/distutils/tests/test_build_ext.py
@@ -166,7 +166,6 @@ class BuildExtTestCase(TempdirManager,
         cmd = self.build_ext(dist)
         cmd.finalize_options()
 
-        from distutils import sysconfig
         py_include = sysconfig.get_python_inc()
         self.assertIn(py_include, cmd.include_dirs)
 
diff --git a/Lib/distutils/tests/test_clean.py b/Lib/distutils/tests/test_clean.py
index b64f300a04..c605afd860 100644
--- a/Lib/distutils/tests/test_clean.py
+++ b/Lib/distutils/tests/test_clean.py
@@ -1,8 +1,6 @@
 """Tests for distutils.command.clean."""
-import sys
 import os
 import unittest
-import getpass
 
 from distutils.command.clean import clean
 from distutils.tests import support
diff --git a/Lib/distutils/tests/test_config.py b/Lib/distutils/tests/test_config.py
index 4de825a81e..d91dedd3a8 100644
--- a/Lib/distutils/tests/test_config.py
+++ b/Lib/distutils/tests/test_config.py
@@ -1,8 +1,6 @@
 """Tests for distutils.pypirc.pypirc."""
-import sys
 import os
 import unittest
-import tempfile
 
 from distutils.core import PyPIRCCommand
 from distutils.core import Distribution
diff --git a/Lib/distutils/tests/test_core.py b/Lib/distutils/tests/test_core.py
index 654227ca18..27ce7324af 100644
--- a/Lib/distutils/tests/test_core.py
+++ b/Lib/distutils/tests/test_core.py
@@ -29,6 +29,21 @@ from distutils.core import setup
 setup()
 """
 
+setup_does_nothing = """\
+from distutils.core import setup
+setup()
+"""
+
+
+setup_defines_subclass = """\
+from distutils.core import setup
+from distutils.command.install import install as _install
+
+class install(_install):
+    sub_commands = _install.sub_commands + ['cmd']
+
+setup(cmdclass={'install': install})
+"""
 
 class CoreTestCase(support.EnvironGuard, unittest.TestCase):
 
@@ -67,6 +82,21 @@ class CoreTestCase(support.EnvironGuard, unittest.TestCase):
         distutils.core.run_setup(
             self.write_setup(setup_using___file__))
 
+    def test_run_setup_preserves_sys_argv(self):
+        # Make sure run_setup does not clobber sys.argv
+        argv_copy = sys.argv.copy()
+        distutils.core.run_setup(
+            self.write_setup(setup_does_nothing))
+        self.assertEqual(sys.argv, argv_copy)
+
+    def test_run_setup_defines_subclass(self):
+        # Make sure the script can use __file__; if that's missing, the test
+        # setup.py script will raise NameError.
+        dist = distutils.core.run_setup(
+            self.write_setup(setup_defines_subclass))
+        install = dist.get_command_obj('install')
+        self.assertIn('cmd', install.sub_commands)
+
     def test_run_setup_uses_current_dir(self):
         # This tests that the setup script is run with the current directory
         # as its own current directory; this was temporarily broken by a
diff --git a/Lib/distutils/tests/test_cygwinccompiler.py b/Lib/distutils/tests/test_cygwinccompiler.py
index 856921679d..9dc869de4c 100644
--- a/Lib/distutils/tests/test_cygwinccompiler.py
+++ b/Lib/distutils/tests/test_cygwinccompiler.py
@@ -3,11 +3,10 @@ import unittest
 import sys
 import os
 from io import BytesIO
-import subprocess
 from test.support import run_unittest
 
 from distutils import cygwinccompiler
-from distutils.cygwinccompiler import (CygwinCCompiler, check_config_h,
+from distutils.cygwinccompiler import (check_config_h,
                                        CONFIG_H_OK, CONFIG_H_NOTOK,
                                        CONFIG_H_UNCERTAIN, get_versions,
                                        get_msvcr)
diff --git a/Lib/distutils/tests/test_dep_util.py b/Lib/distutils/tests/test_dep_util.py
index 3e1c366892..c6fae39cfb 100644
--- a/Lib/distutils/tests/test_dep_util.py
+++ b/Lib/distutils/tests/test_dep_util.py
@@ -1,7 +1,6 @@
 """Tests for distutils.dep_util."""
 import unittest
 import os
-import time
 
 from distutils.dep_util import newer, newer_pairwise, newer_group
 from distutils.errors import DistutilsFileError
diff --git a/Lib/distutils/tests/test_file_util.py b/Lib/distutils/tests/test_file_util.py
index a6d04f065d..03040afc79 100644
--- a/Lib/distutils/tests/test_file_util.py
+++ b/Lib/distutils/tests/test_file_util.py
@@ -1,7 +1,6 @@
 """Tests for distutils.file_util."""
 import unittest
 import os
-import shutil
 import errno
 from unittest.mock import patch
 
diff --git a/Lib/distutils/tests/test_install_data.py b/Lib/distutils/tests/test_install_data.py
index 4d8c00acb9..32ab296a32 100644
--- a/Lib/distutils/tests/test_install_data.py
+++ b/Lib/distutils/tests/test_install_data.py
@@ -1,8 +1,6 @@
 """Tests for distutils.command.install_data."""
-import sys
 import os
 import unittest
-import getpass
 
 from distutils.command.install_data import install_data
 from distutils.tests import support
diff --git a/Lib/distutils/tests/test_install_headers.py b/Lib/distutils/tests/test_install_headers.py
index d953157bb7..2217b321e6 100644
--- a/Lib/distutils/tests/test_install_headers.py
+++ b/Lib/distutils/tests/test_install_headers.py
@@ -1,8 +1,6 @@
 """Tests for distutils.command.install_headers."""
-import sys
 import os
 import unittest
-import getpass
 
 from distutils.command.install_headers import install_headers
 from distutils.tests import support
diff --git a/Lib/distutils/tests/test_spawn.py b/Lib/distutils/tests/test_spawn.py
index 6c7eb20c47..f507ef7750 100644
--- a/Lib/distutils/tests/test_spawn.py
+++ b/Lib/distutils/tests/test_spawn.py
@@ -1,11 +1,10 @@
 """Tests for distutils.spawn."""
 import unittest
 import os
-import time
-from test.support import captured_stdout, run_unittest
+from test.support import run_unittest
 
 from distutils.spawn import _nt_quote_args
-from distutils.spawn import spawn, find_executable
+from distutils.spawn import spawn
 from distutils.errors import DistutilsExecError
 from distutils.tests import support
 
diff --git a/Lib/distutils/tests/test_unixccompiler.py b/Lib/distutils/tests/test_unixccompiler.py
index e171ee9c4d..efba27e1c8 100644
--- a/Lib/distutils/tests/test_unixccompiler.py
+++ b/Lib/distutils/tests/test_unixccompiler.py
@@ -1,5 +1,4 @@
 """Tests for distutils.unixccompiler."""
-import os
 import sys
 import unittest
 from test.support import EnvironmentVarGuard, run_unittest
diff --git a/Lib/distutils/text_file.py b/Lib/distutils/text_file.py
index 478336f0d2..93abad38f4 100644
--- a/Lib/distutils/text_file.py
+++ b/Lib/distutils/text_file.py
@@ -4,7 +4,7 @@ provides the TextFile class, which gives an interface to text files
 that (optionally) takes care of stripping comments, ignoring blank
 lines, and joining lines with backslashes."""
 
-import sys, os, io
+import sys, io
 
 
 class TextFile:
diff --git a/Lib/distutils/util.py b/Lib/distutils/util.py
index e423325de4..fdcf6fabae 100644
--- a/Lib/distutils/util.py
+++ b/Lib/distutils/util.py
@@ -7,8 +7,8 @@ one of the other *util.py modules.
 import os
 import re
 import importlib.util
-import sys
 import string
+import sys
 from distutils.errors import DistutilsPlatformError
 from distutils.dep_util import newer
 from distutils.spawn import spawn
@@ -350,6 +350,11 @@ def byte_compile (py_files,
     generated in indirect mode; unless you know what you're doing, leave
     it set to None.
     """
+
+    # Late import to fix a bootstrap issue: _posixsubprocess is built by
+    # setup.py, but setup.py uses distutils.
+    import subprocess
+
     # nothing is done if sys.dont_write_bytecode is True
     if sys.dont_write_bytecode:
         raise DistutilsByteCompileError('byte-compiling is disabled.')
@@ -412,11 +417,9 @@ byte_compile(files, optimize=%r, force=%r,
 
             script.close()
 
-        cmd = [sys.executable, script_name]
-        if optimize == 1:
-            cmd.insert(1, "-O")
-        elif optimize == 2:
-            cmd.insert(1, "-OO")
+        cmd = [sys.executable]
+        cmd.extend(subprocess._optim_args_from_interpreter_flags())
+        cmd.append(script_name)
         spawn(cmd, dry_run=dry_run)
         execute(os.remove, (script_name,), "removing %s" % script_name,
                 dry_run=dry_run)
diff --git a/Lib/doctest.py b/Lib/doctest.py
index 38fdd80b4a..5630220c5f 100644
--- a/Lib/doctest.py
+++ b/Lib/doctest.py
@@ -381,12 +381,15 @@ class _OutputRedirectingPdb(pdb.Pdb):
             sys.stdout = save_stdout
 
 # [XX] Normalize with respect to os.path.pardir?
-def _module_relative_path(module, path):
+def _module_relative_path(module, test_path):
     if not inspect.ismodule(module):
         raise TypeError('Expected a module: %r' % module)
-    if path.startswith('/'):
+    if test_path.startswith('/'):
         raise ValueError('Module-relative files may not have absolute paths')
 
+    # Normalize the path. On Windows, replace "/" with "\".
+    test_path = os.path.join(*(test_path.split('/')))
+
     # Find the base directory for the path.
     if hasattr(module, '__file__'):
         # A normal module/package
@@ -398,13 +401,19 @@ def _module_relative_path(module, path):
         else:
             basedir = os.curdir
     else:
+        if hasattr(module, '__path__'):
+            for directory in module.__path__:
+                fullpath = os.path.join(directory, test_path)
+                if os.path.exists(fullpath):
+                    return fullpath
+
         # A module w/o __file__ (this includes builtins)
         raise ValueError("Can't resolve paths relative to the module "
                          "%r (it has no __file__)"
                          % module.__name__)
 
-    # Combine the base directory and the path.
-    return os.path.join(basedir, *(path.split('/')))
+    # Combine the base directory and the test path.
+    return os.path.join(basedir, test_path)
 
 ######################################################################
 ## 2. Example & DocTest
diff --git a/Lib/enum.py b/Lib/enum.py
index b8787d19b8..99db9e6b7f 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -1,8 +1,14 @@
 import sys
-from collections import OrderedDict
 from types import MappingProxyType, DynamicClassAttribute
 
-__all__ = ['Enum', 'IntEnum', 'unique']
+# try _collections first to reduce startup cost
+try:
+    from _collections import OrderedDict
+except ImportError:
+    from collections import OrderedDict
+
+
+__all__ = ['EnumMeta', 'Enum', 'IntEnum', 'unique']
 
 
 def _is_descriptor(obj):
@@ -544,8 +550,14 @@ class Enum(metaclass=EnumMeta):
             source = vars(source)
         else:
             source = module_globals
-        members = {name: value for name, value in source.items()
-                if filter(name)}
+        # We use an OrderedDict of sorted source keys so that the
+        # _value2member_map is populated in the same order every time
+        # for a consistent reverse mapping of number to name when there
+        # are multiple names for the same number rather than varying
+        # between runs due to hash randomization of the module dictionary.
+        members = OrderedDict((name, source[name])
+                              for name in sorted(source.keys())
+                              if filter(name))
         cls = cls(name, members, module=module)
         cls.__reduce_ex__ = _reduce_ex_by_name
         module_globals.update(cls.__members__)
diff --git a/Lib/fileinput.py b/Lib/fileinput.py
index d2b52066d9..721fe9c961 100644
--- a/Lib/fileinput.py
+++ b/Lib/fileinput.py
@@ -75,13 +75,11 @@ XXX Possible additions:
 import sys, os
 
 __all__ = ["input", "close", "nextfile", "filename", "lineno", "filelineno",
-           "isfirstline", "isstdin", "FileInput"]
+           "fileno", "isfirstline", "isstdin", "FileInput", "hook_compressed",
+           "hook_encoded"]
 
 _state = None
 
-# No longer used
-DEFAULT_BUFSIZE = 8*1024
-
 def input(files=None, inplace=False, backup="", bufsize=0,
           mode="r", openhook=None):
     """Return an instance of the FileInput class, which can be iterated.
@@ -201,6 +199,10 @@ class FileInput:
         self._files = files
         self._inplace = inplace
         self._backup = backup
+        if bufsize:
+            import warnings
+            warnings.warn('bufsize is deprecated and ignored',
+                          DeprecationWarning, stacklevel=2)
         self._savestdout = None
         self._output = None
         self._filename = None
@@ -398,9 +400,9 @@ def hook_compressed(filename, mode):
         return open(filename, mode)
 
 
-def hook_encoded(encoding):
+def hook_encoded(encoding, errors=None):
     def openhook(filename, mode):
-        return open(filename, mode, encoding=encoding)
+        return open(filename, mode, encoding=encoding, errors=errors)
     return openhook
 
 
diff --git a/Lib/fractions.py b/Lib/fractions.py
index 60b0728807..64d746b842 100644
--- a/Lib/fractions.py
+++ b/Lib/fractions.py
@@ -125,17 +125,9 @@ class Fraction(numbers.Rational):
                 self._denominator = numerator.denominator
                 return self
 
-            elif isinstance(numerator, float):
-                # Exact conversion from float
-                value = Fraction.from_float(numerator)
-                self._numerator = value._numerator
-                self._denominator = value._denominator
-                return self
-
-            elif isinstance(numerator, Decimal):
-                value = Fraction.from_decimal(numerator)
-                self._numerator = value._numerator
-                self._denominator = value._denominator
+            elif isinstance(numerator, (float, Decimal)):
+                # Exact conversion
+                self._numerator, self._denominator = numerator.as_integer_ratio()
                 return self
 
             elif isinstance(numerator, str):
@@ -210,10 +202,6 @@ class Fraction(numbers.Rational):
         elif not isinstance(f, float):
             raise TypeError("%s.from_float() only takes floats, not %r (%s)" %
                             (cls.__name__, f, type(f).__name__))
-        if math.isnan(f):
-            raise ValueError("Cannot convert %r to %s." % (f, cls.__name__))
-        if math.isinf(f):
-            raise OverflowError("Cannot convert %r to %s." % (f, cls.__name__))
         return cls(*f.as_integer_ratio())
 
     @classmethod
@@ -226,19 +214,7 @@ class Fraction(numbers.Rational):
             raise TypeError(
                 "%s.from_decimal() only takes Decimals, not %r (%s)" %
                 (cls.__name__, dec, type(dec).__name__))
-        if dec.is_infinite():
-            raise OverflowError(
-                "Cannot convert %s to %s." % (dec, cls.__name__))
-        if dec.is_nan():
-            raise ValueError("Cannot convert %s to %s." % (dec, cls.__name__))
-        sign, digits, exp = dec.as_tuple()
-        digits = int(''.join(map(str, digits)))
-        if sign:
-            digits = -digits
-        if exp >= 0:
-            return cls(digits * 10 ** exp)
-        else:
-            return cls(digits, 10 ** -exp)
+        return cls(*dec.as_integer_ratio())
 
     def limit_denominator(self, max_denominator=1000000):
         """Closest Fraction to self with denominator at most max_denominator.
diff --git a/Lib/ftplib.py b/Lib/ftplib.py
index c416d8562b..2ab1d568d7 100644
--- a/Lib/ftplib.py
+++ b/Lib/ftplib.py
@@ -36,13 +36,12 @@ python ftplib.py -d localhost -l -p -l
 # Modified by Giampaolo Rodola' to add TLS support.
 #
 
-import os
 import sys
 import socket
-import warnings
 from socket import _GLOBAL_DEFAULT_TIMEOUT
 
-__all__ = ["FTP"]
+__all__ = ["FTP", "error_reply", "error_temp", "error_perm", "error_proto",
+           "all_errors"]
 
 # Magic number from <socket.h>
 MSG_OOB = 0x1                           # Process data out of band
diff --git a/Lib/http/client.py b/Lib/http/client.py
index 350313e87b..763e1ef4f6 100644
--- a/Lib/http/client.py
+++ b/Lib/http/client.py
@@ -420,6 +420,7 @@ class HTTPResponse(io.BufferedIOBase):
             self.fp.flush()
 
     def readable(self):
+        """Always returns True"""
         return True
 
     # End of "raw stream" methods
@@ -467,6 +468,10 @@ class HTTPResponse(io.BufferedIOBase):
             return s
 
     def readinto(self, b):
+        """Read up to len(b) bytes into bytearray b and return the number
+        of bytes read.
+        """
+
         if self.fp is None:
             return 0
 
@@ -706,6 +711,17 @@ class HTTPResponse(io.BufferedIOBase):
         return self.fp.fileno()
 
     def getheader(self, name, default=None):
+        '''Returns the value of the header matching *name*.
+
+        If there are multiple matching headers, the values are
+        combined into a single string separated by commas and spaces.
+
+        If no matching header is found, returns *default* or None if
+        the *default* is not specified.
+
+        If the headers are unknown, raises http.client.ResponseNotReady.
+
+        '''
         if self.headers is None:
             raise ResponseNotReady()
         headers = self.headers.get_all(name) or default
@@ -728,12 +744,45 @@ class HTTPResponse(io.BufferedIOBase):
     # For compatibility with old-style urllib responses.
 
     def info(self):
+        '''Returns an instance of the class mimetools.Message containing
+        meta-information associated with the URL.
+
+        When the method is HTTP, these headers are those returned by
+        the server at the head of the retrieved HTML page (including
+        Content-Length and Content-Type).
+
+        When the method is FTP, a Content-Length header will be
+        present if (as is now usual) the server passed back a file
+        length in response to the FTP retrieval request. A
+        Content-Type header will be present if the MIME type can be
+        guessed.
+
+        When the method is local-file, returned headers will include
+        a Date representing the file's last-modified time, a
+        Content-Length giving file size, and a Content-Type
+        containing a guess at the file's type. See also the
+        description of the mimetools module.
+
+        '''
         return self.headers
 
     def geturl(self):
+        '''Return the real URL of the page.
+
+        In some cases, the HTTP server redirects a client to another
+        URL. The urlopen() function handles this transparently, but in
+        some cases the caller needs to know which URL the client was
+        redirected to. The geturl() method can be used to get at this
+        redirected URL.
+
+        '''
         return self.url
 
     def getcode(self):
+        '''Return the HTTP status code that was sent with the response,
+        or None if the URL is not an HTTP URL.
+
+        '''
         return self.status
 
 class HTTPConnection:
diff --git a/Lib/http/server.py b/Lib/http/server.py
index 00620d1f85..e12e45bfc3 100644
--- a/Lib/http/server.py
+++ b/Lib/http/server.py
@@ -87,6 +87,7 @@ __all__ = [
     "SimpleHTTPRequestHandler", "CGIHTTPRequestHandler",
 ]
 
+import email.utils
 import html
 import http.client
 import io
@@ -126,9 +127,6 @@ DEFAULT_ERROR_MESSAGE = """\
 
 DEFAULT_ERROR_CONTENT_TYPE = "text/html;charset=utf-8"
 
-def _quote_html(html):
-    return html.replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;")
-
 class HTTPServer(socketserver.TCPServer):
 
     allow_reuse_address = 1    # Seems to make sense in testing environment
@@ -136,7 +134,7 @@ class HTTPServer(socketserver.TCPServer):
     def server_bind(self):
         """Override server_bind to store the server name."""
         socketserver.TCPServer.server_bind(self)
-        host, port = self.socket.getsockname()[:2]
+        host, port = self.server_address[:2]
         self.server_name = socket.getfqdn(host)
         self.server_port = port
 
@@ -282,12 +280,9 @@ class BaseHTTPRequestHandler(socketserver.StreamRequestHandler):
         words = requestline.split()
         if len(words) == 3:
             command, path, version = words
-            if version[:5] != 'HTTP/':
-                self.send_error(
-                    HTTPStatus.BAD_REQUEST,
-                    "Bad request version (%r)" % version)
-                return False
             try:
+                if version[:5] != 'HTTP/':
+                    raise ValueError
                 base_version_number = version.split('/', 1)[1]
                 version_number = base_version_number.split(".")
                 # RFC 2145 section 3.1 says there can be only one "." and
@@ -309,7 +304,7 @@ class BaseHTTPRequestHandler(socketserver.StreamRequestHandler):
             if version_number >= (2, 0):
                 self.send_error(
                     HTTPStatus.HTTP_VERSION_NOT_SUPPORTED,
-                    "Invalid HTTP Version (%s)" % base_version_number)
+                    "Invalid HTTP version (%s)" % base_version_number)
                 return False
         elif len(words) == 2:
             command, path = words
@@ -332,10 +327,11 @@ class BaseHTTPRequestHandler(socketserver.StreamRequestHandler):
         try:
             self.headers = http.client.parse_headers(self.rfile,
                                                      _class=self.MessageClass)
-        except http.client.LineTooLong:
+        except http.client.LineTooLong as err:
             self.send_error(
-                HTTPStatus.BAD_REQUEST,
-                "Line too long")
+                HTTPStatus.REQUEST_HEADER_FIELDS_TOO_LARGE,
+                "Line too long",
+                str(err))
             return False
         except http.client.HTTPException as err:
             self.send_error(
@@ -465,8 +461,8 @@ class BaseHTTPRequestHandler(socketserver.StreamRequestHandler):
             # (see bug #1100201)
             content = (self.error_message_format % {
                 'code': code,
-                'message': _quote_html(message),
-                'explain': _quote_html(explain)
+                'message': html.escape(message, quote=False),
+                'explain': html.escape(explain, quote=False)
             })
             body = content.encode('UTF-8', 'replace')
             self.send_header("Content-Type", self.error_content_type)
@@ -491,12 +487,12 @@ class BaseHTTPRequestHandler(socketserver.StreamRequestHandler):
 
     def send_response_only(self, code, message=None):
         """Send the response header only."""
-        if message is None:
-            if code in self.responses:
-                message = self.responses[code][0]
-            else:
-                message = ''
         if self.request_version != 'HTTP/0.9':
+            if message is None:
+                if code in self.responses:
+                    message = self.responses[code][0]
+                else:
+                    message = ''
             if not hasattr(self, '_headers_buffer'):
                 self._headers_buffer = []
             self._headers_buffer.append(("%s %d %s\r\n" %
@@ -583,12 +579,7 @@ class BaseHTTPRequestHandler(socketserver.StreamRequestHandler):
         """Return the current date and time formatted for a message header."""
         if timestamp is None:
             timestamp = time.time()
-        year, month, day, hh, mm, ss, wd, y, z = time.gmtime(timestamp)
-        s = "%s, %02d %3s %4d %02d:%02d:%02d GMT" % (
-                self.weekdayname[wd],
-                day, self.monthname[month], year,
-                hh, mm, ss)
-        return s
+        return email.utils.formatdate(timestamp, usegmt=True)
 
     def log_date_time_string(self):
         """Return the current time formatted for logging."""
@@ -726,7 +717,7 @@ class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):
                                                errors='surrogatepass')
         except UnicodeDecodeError:
             displaypath = urllib.parse.unquote(path)
-        displaypath = html.escape(displaypath)
+        displaypath = html.escape(displaypath, quote=False)
         enc = sys.getfilesystemencoding()
         title = 'Directory listing for %s' % displaypath
         r.append('<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" '
@@ -750,7 +741,7 @@ class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):
             r.append('<li><a href="%s">%s</a></li>'
                     % (urllib.parse.quote(linkname,
                                           errors='surrogatepass'),
-                       html.escape(displayname)))
+                       html.escape(displayname, quote=False)))
         r.append('</ul>\n<hr>\n</body>\n</html>\n')
         encoded = '\n'.join(r).encode(enc, 'surrogateescape')
         f = io.BytesIO()
@@ -1191,16 +1182,15 @@ def test(HandlerClass=BaseHTTPRequestHandler,
     server_address = (bind, port)
 
     HandlerClass.protocol_version = protocol
-    httpd = ServerClass(server_address, HandlerClass)
-
-    sa = httpd.socket.getsockname()
-    print("Serving HTTP on", sa[0], "port", sa[1], "...")
-    try:
-        httpd.serve_forever()
-    except KeyboardInterrupt:
-        print("\nKeyboard interrupt received, exiting.")
-        httpd.server_close()
-        sys.exit(0)
+    with ServerClass(server_address, HandlerClass) as httpd:
+        sa = httpd.socket.getsockname()
+        serve_message = "Serving HTTP on {host} port {port} (http://{host}:{port}/) ..."
+        print(serve_message.format(host=sa[0], port=sa[1]))
+        try:
+            httpd.serve_forever()
+        except KeyboardInterrupt:
+            print("\nKeyboard interrupt received, exiting.")
+            sys.exit(0)
 
 if __name__ == '__main__':
     parser = argparse.ArgumentParser()
diff --git a/Lib/idlelib/NEWS.txt b/Lib/idlelib/NEWS.txt
index 1168e45c25..9901280d16 100644
--- a/Lib/idlelib/NEWS.txt
+++ b/Lib/idlelib/NEWS.txt
@@ -1,11 +1,11 @@
-What's New in IDLE 3.5.2?
-=========================
-*Release date: 2016-06-30?*
+What's New in IDLE 3.6.0?
+===========================
+*Release date: 2016-09-??*
 
 - Issue #24759: Make clear in idlelib.idle_test.__init__ that the directory
   is a private implementation of test.test_idle and tool for maintainers.
 
-- Issue #27196: Stop 'ThemeChangef' warnings when running IDLE tests.
+- Issue #27196: Stop 'ThemeChanged' warnings when running IDLE tests.
   These persisted after other warnings were suppressed in #20567.
   Apply Serhiy Storchaka's update_idletasks solution to four test files.
   Record this additional advice in idle_test/README.txt
@@ -13,9 +13,26 @@ What's New in IDLE 3.5.2?
 - Issue #20567: Revise idle_test/README.txt with advice about avoiding
   tk warning messages from tests.  Apply advice to several IDLE tests.
 
+- Issue # 24225: Update idlelib/README.txt with new file names
+  and event handlers.
+
+- Issue #27156: Remove obsolete code not used by IDLE.  Replacements:
+  1. help.txt, replaced by help.html, is out-of-date and should not be used.
+  Its dedicated viewer has be replaced by the html viewer in help.py.
+  2. 'import idlever; I = idlever.IDLE_VERSION' is the same as
+  'import sys; I = version[:version.index(' ')]'
+  3. After 'ob = stackviewer.VariablesTreeItem(*args)',
+  'ob.keys()' == 'list(ob.object.keys).
+  4. In macosc, runningAsOSXAPP == isAquaTk; idCarbonAquaTk == isCarbonTk
+
 - Issue #27117: Make colorizer htest and turtledemo work with dark themes.
   Move code for configuring text widget colors to a new function.
 
+- Issue #24225: Rename many idlelib/*.py and idle_test/test_*.py files.
+  Edit files to replace old names with new names when the old name
+  referred to the module rather than the class it contained.
+  See the issue and IDLE section in What's New in 3.6 for more.
+
 - Issue #26673: When tk reports font size as 0, change to size 10.
   Such fonts on Linux prevented the configuration dialog from opening.
 
@@ -28,8 +45,8 @@ What's New in IDLE 3.5.2?
 - Issue #18410: Add test for IDLE's search dialog.
   Original patch by Westley Martínez.
 
-- Issue #21703: Add test for undo delegator.
-  Original patch by Saimadhav Heblikar .
+- Issue #21703: Add test for undo delegator.  Patch mostly by
+  Saimadhav Heblikar .
 
 - Issue #27044: Add ConfigDialog.remove_var_callbacks to stop memory leaks.
 
@@ -48,11 +65,6 @@ What's New in IDLE 3.5.2?
   MARK in README.txt and open this and NEWS.txt with 'ascii'.
   Re-encode CREDITS.txt to utf-8 and open it with 'utf-8'.
 
-
-What's New in IDLE 3.5.1?
-=========================
-*Release date: 2015-12-06*
-
 - Issue 15348: Stop the debugger engine (normally in a user process)
   before closing the debugger window (running in the IDLE process).
   This prevents the RuntimeErrors that were being caught and ignored.
@@ -330,6 +342,11 @@ What's New in IDLE 3.1b1?
 - Use of 'filter' in keybindingDialog.py was causing custom key assignment to
   fail.  Patch 5707 amaury.forgeotdarc.
 
+
+What's New in IDLE 3.1a1?
+=========================
+*Release date: 07-Mar-09*
+
 - Issue #4815: Offer conversion to UTF-8 if source files have
   no encoding declaration and are not encoded in UTF-8.
 
@@ -369,6 +386,11 @@ What's New in IDLE 2.7? (UNRELEASED, but merged into 3.1 releases above.)
 
 - Issue #3549: On MacOS the preferences menu was not present
 
+
+What's New in IDLE 3.0?
+=======================
+*Release date: 03-Dec-2008*
+
 - IDLE would print a "Unhandled server exception!" message when internal
   debugging is enabled.
 
diff --git a/Lib/idlelib/README.txt b/Lib/idlelib/README.txt
index 7bf74c0fc4..e1d682e276 100644
--- a/Lib/idlelib/README.txt
+++ b/Lib/idlelib/README.txt
@@ -29,61 +29,61 @@ idle.pyw
 
 Implementation
 --------------
-AutoComplete.py   # Complete attribute names or filenames.
-AutoCompleteWindow.py  # Display completions.
-AutoExpand.py     # Expand word with previous word in file.
-Bindings.py       # Define most of IDLE menu.
-CallTipWindow.py  # Display calltip.
-CallTips.py       # Create calltip text.
-ClassBrowser.py   # Create module browser window.
-CodeContext.py    # Show compound statement headers otherwise not visible.
-ColorDelegator.py # Colorize text (nim).
-Debugger.py       # Debug code run from editor; show window.
-Delegator.py      # Define base class for delegators (nim).
-EditorWindow.py   # Define most of editor and utility functions.
-FileList.py       # Open files and manage list of open windows (nim).
-FormatParagraph.py# Re-wrap multiline strings and comments.
-GrepDialog.py     # Find all occurrences of pattern in multiple files.
-HyperParser.py    # Parse code around a given index.
-IOBinding.py      # Open, read, and write files
-IdleHistory.py    # Get previous or next user input in shell (nim)
-MultiCall.py      # Wrap tk widget to allow multiple calls per event (nim).
-MultiStatusBar.py # Define status bar for windows (nim).
-ObjectBrowser.py  # Define class used in StackViewer (nim).
-OutputWindow.py   # Create window for grep output.
-ParenMatch.py     # Match fenceposts: (), [], and {}.
-PathBrowser.py    # Create path browser window.
-Percolator.py     # Manage delegator stack (nim).
-PyParse.py        # Give information on code indentation
-PyShell.py        # Start IDLE, manage shell, complete editor window
-RemoteDebugger.py # Debug code run in remote process.
-RemoteObjectBrowser.py # Communicate objects between processes with rpc (nim).
-ReplaceDialog.py  # Search and replace pattern in text.
-RstripExtension.py# Strip trailing whitespace
-ScriptBinding.py  # Check and run user code.
-ScrolledList.py   # Define ScrolledList widget for IDLE (nim).
-SearchDialog.py   # Search for pattern in text.
-SearchDialogBase.py  # Define base for search, replace, and grep dialogs.
-SearchEngine.py   # Define engine for all 3 search dialogs.
-StackViewer.py    # View stack after exception.
-TreeWidget.py     # Define tree widger, used in browsers (nim).
-UndoDelegator.py  # Manage undo stack.
-WidgetRedirector.py # Intercept widget subcommands (for percolator) (nim).
-WindowList.py     # Manage window list and define listed top level.
-ZoomHeight.py     # Zoom window to full height of screen.
-aboutDialog.py    # Display About IDLE dialog.
-configDialog.py   # Display user configuration dialogs.
-configHandler.py  # Load, fetch, and save configuration (nim).
-configHelpSourceEdit.py  # Specify help source.
-configSectionNameDialog.py  # Spefify user config section name
-dynOptionMenuWidget.py  # define mutable OptionMenu widget (nim).
+autocomplete.py   # Complete attribute names or filenames.
+autocomplete_w.py # Display completions.
+autoexpand.py     # Expand word with previous word in file.
+browser.py        # Create module browser window.
+calltip_w.py      # Display calltip.
+calltips.py       # Create calltip text.
+codecontext.py    # Show compound statement headers otherwise not visible.
+colorizer.py      # Colorize text (nim)
+config.py         # Load, fetch, and save configuration (nim).
+configdialog.py   # Display user configuration dialogs.
+config_help.py    # Specify help source in configdialog.
+config_key.py     # Change keybindings.
+config_sec.py     # Spefify user config section name
+dynoption.py      # Define mutable OptionMenu widget (nim).
+debugobj.py       # Define class used in stackviewer.
+debugobj_r.py     # Communicate objects between processes with rpc (nim).
+debugger.py       # Debug code run from shell or editor; show window.
+debugger_r.py     # Debug code run in remote process.
+delegator.py      # Define base class for delegators (nim).
+editor.py         # Define most of editor and utility functions.
+filelist.py       # Open files and manage list of open windows (nim).
+grep.py           # Find all occurrences of pattern in multiple files.
 help.py           # Display IDLE's html doc.
-keybindingDialog.py  # Change keybindings.
-macosxSupport.py  # Help IDLE run on Macs (nim).
+help_about.py     # Display About IDLE dialog.
+history.py        # Get previous or next user input in shell (nim)
+hyperparser.py    # Parse code around a given index.
+iomenu.py         # Open, read, and write files
+macosx.py         # Help IDLE run on Macs (nim).
+mainmenu.py       # Define most of IDLE menu.
+multicall.py      # Wrap tk widget to allow multiple calls per event (nim).
+outwin.py         # Create window for grep output.
+paragraph.py      # Re-wrap multiline strings and comments.
+parenmatch.py     # Match fenceposts: (), [], and {}.
+pathbrowser.py    # Create path browser window.
+percolator.py     # Manage delegator stack (nim).
+pyparse.py        # Give information on code indentation
+pyshell.py        # Start IDLE, manage shell, complete editor window
+redirector.py     # Intercept widget subcommands (for percolator) (nim).
+replace.py        # Search and replace pattern in text.
 rpc.py            # Commuicate between idle and user processes (nim).
+rstrip.py         # Strip trailing whitespace.
 run.py            # Manage user code execution subprocess.
+runscript.py      # Check and run user code.
+scrolledlist.py   # Define scrolledlist widget for IDLE (nim).
+search.py         # Search for pattern in text.
+searchbase.py     # Define base for search, replace, and grep dialogs.
+searchengine.py   # Define engine for all 3 search dialogs.
+stackviewer.py    # View stack after exception.
+statusbar.py      # Define status bar for windows (nim).
 tabbedpages.py    # Define tabbed pages widget (nim).
-textView.py       # Define read-only text widget (nim).
+textview.py       # Define read-only text widget (nim).
+tree.py           # Define tree widger, used in browsers (nim).
+undo.py           # Manage undo stack.
+windows.py        # Manage window list and define listed top level.
+zoomheight.py     # Zoom window to full height of screen.
 
 Configuration
 -------------
@@ -104,126 +104,128 @@ help.html    # copy of idle.html in docs, displayed by IDLE Help
 
 Subdirectories
 --------------
-Icons  # small image files
-idle_test  # files for human test and automated unit tests
+Icons        # small image files
+idle_test    # files for human test and automated unit tests
 
 Unused and Deprecated files and objects (nim)
 ---------------------------------------------
-EditorWindow.py: Helpdialog and helpDialog
-ToolTip.py: unused.
-help.txt
-idlever.py
+tooltip.py # unused
+
 
 
 IDLE MENUS
-Top level items and most submenu items are defined in Bindings.
+Top level items and most submenu items are defined in mainmenu.
 Extenstions add submenu items when active.  The names given are
 found, quoted, in one of these modules, paired with a '<<pseudoevent>>'.
 Each pseudoevent is bound to an event handler.  Some event handlers
 call another function that does the actual work.  The annotations below
 are intended to at least give the module where the actual work is done.
+'eEW' = editor.EditorWindow
 
-File  # IOBindig except as noted
-  New File
-  Open...  # IOBinding.open
-  Open Module
+File
+  New File         # eEW.new_callback
+  Open...          # iomenu.open
+  Open Module      # eEw.open_module
   Recent Files
-  Class Browser  # Class Browser
-  Path Browser  # Path Browser
+  Class Browser    # eEW.open_class_browser, browser.ClassBrowser
+  Path Browser     # eEW.open_path_browser, pathbrowser
   ---
-  Save  # IDBinding.save
-  Save As...  # IOBinding.save_as
-  Save Copy As...  # IOBindling.save_a_copy
+  Save             # iomenu.save
+  Save As...       # iomenu.save_as
+  Save Copy As...  # iomenu.save_a_copy
   ---
-  Print Window  # IOBinding.print_window
+  Print Window     # iomenu.print_window
   ---
-  Close
-  Exit
+  Close            # eEW.close_event
+  Exit             # flist.close_all_callback (bound in eEW)
 
 Edit
-  Undo  # undoDelegator
-  Redo  # undoDelegator
-  ---
-  Cut
-  Copy
-  Paste
-  Select All
-  ---  # Next 5 items use SearchEngine; dialogs use SearchDialogBase
-  Find  # Search Dialog
-  Find Again
-  Find Selection
-  Find in Files...  # GrepDialog
-  Replace...  # ReplaceDialog
-  Go to Line
-  Show Completions  # AutoComplete extension and AutoCompleteWidow (&HP)
-  Expand Word  # AutoExpand extension
-  Show call tip  # Calltips extension and CalltipWindow (& Hyperparser)
-  Show surrounding parens  # ParenMatch (& Hyperparser)
-
-Shell  # PyShell
-  View Last Restart  # PyShell.?
-  Restart Shell  # PyShell.?
+  Undo             # undodelegator
+  Redo             # undodelegator
+  ---              # eEW.right_menu_event
+  Cut              # eEW.cut
+  Copy             # eEW.copy
+  Paste            # eEW.past
+  Select All       # eEW.select_all (+ see eEW.remove_selection)
+  ---              # Next 5 items use searchengine; dialogs use searchbase
+  Find             # eEW.find_event, search.SearchDialog.find
+  Find Again       # eEW.find_again_event, sSD.find_again
+  Find Selection   # eEW.find_selection_event, sSD.find_selection
+  Find in Files... # eEW.find_in_files_event, grep
+  Replace...       # eEW.replace_event, replace.ReplaceDialog.replace
+  Go to Line       # eEW.goto_line_event
+  Show Completions # autocomplete extension and autocompleteWidow (&HP)
+  Expand Word      # autoexpand extension
+  Show call tip    # Calltips extension and CalltipWindow (& Hyperparser)
+  Show surrounding parens  # parenmatch (& Hyperparser)
+
+Shell  # pyshell
+  View Last Restart# pyshell.?
+  Restart Shell    # pyshell.?
 
 Debug (Shell only)
   Go to File/Line
-  Debugger  # Debugger, RemoteDebugger
-  Stack Viewer  # StackViewer
-  Auto-open Stack Viewer  # StackViewer
+  debugger         # debugger, debugger_r
+  Stack Viewer     # stackviewer
+  Auto-open Stack Viewer  # stackviewer
 
 Format (Editor only)
-  Indent Region
-  Dedent Region
-  Comment Out Region
-  Uncomment Region
-  Tabify Region
-  Untabify Region
-  Toggle Tabs
-  New Indent Width
-  Format Paragraph  # FormatParagraph extension
+  Indent Region    # eEW.indent_region_event
+  Dedent Region    # eEW.dedent_region_event
+  Comment Out Reg. # eEW.comment_region_event
+  Uncomment Region # eEW.uncomment_region_event
+  Tabify Region    # eEW.tabify_region_event
+  Untabify Region  # eEW.untabify_region_event
+  Toggle Tabs      # eEW.toggle_tabs_event
+  New Indent Width # eEW.change_indentwidth_event
+  Format Paragraph # paragraph extension
   ---
-  Strip tailing whitespace  # RstripExtension extension
+  Strip tailing whitespace  # rstrip extension
 
 Run (Editor only)
-  Python Shell  # PyShell
+  Python Shell     # pyshell
   ---
-  Check Module  # ScriptBinding
-  Run Module  # ScriptBinding
+  Check Module     # runscript
+  Run Module       # runscript
 
 Options
-  Configure IDLE  # configDialog
+  Configure IDLE   # eEW.config_dialog, configdialog
     (tabs in the dialog)
-    Font tab  # onfig-main.def
-    Highlight tab  # configSectionNameDialog, config-highlight.def
-    Keys tab  # keybindingDialog, configSectionNameDialog, onfig-keus.def
-    General tab  # configHelpSourceEdit, config-main.def
-  Configure Extensions  # configDialog
-    Xyz tab  # xyz.py, config-extensions.def
+    Font tab       # config-main.def
+    Highlight tab  # config_sec, config-highlight.def
+    Keys tab       # config_key, configconfig_secg-keus.def
+    General tab    # config_help, config-main.def
+    Extensions tab # config-extensions.def, corresponding .py
   ---
-  Code Context (editor only)  # CodeContext extension
+  Code Context (ed)# codecontext extension
 
 Window
-  Zoomheight  # ZoomHeight extension
+  Zoomheight       # zoomheight extension
   ---
-  <open windows>  # WindowList
+  <open windows>   # windows
 
 Help
-  About IDLE  # aboutDialog
+  About IDLE       # eEW.about_dialog, help_about.AboutDialog 
   ---
-  IDLE Help  # help
-  Python Doc
-  Turtle Demo
+  IDLE Help        # eEW.help_dialog, helpshow_idlehelp
+  Python Doc       # eEW.python_docs
+  Turtle Demo      # eEW.open_turtle_demo
   ---
   <other help sources>
 
 <Context Menu> (right click)
-Defined in EditorWindow, PyShell, Output
-   Cut
-   Copy
-   Paste
-   ---
-   Go to file/line (shell and output only)
-   Set Breakpoint (editor only)
-   Clear Breakpoint (editor only)
- Defined in Debugger
-   Go to source line
-   Show stack frame
+  Defined in editor, PyShelpyshellut
+    Cut
+    Copy
+    Paste
+    ---
+    Go to file/line (shell and output only)
+    Set Breakpoint (editor only)
+    Clear Breakpoint (editor only)
+  Defined in debugger
+    Go to source line
+    Show stack frame
+
+<No menu>
+Center Insert      # eEW.center_insert_event
+   
diff --git a/Lib/idlelib/__main__.py b/Lib/idlelib/__main__.py
index 2edf5f7dc1..6349ec75c6 100644
--- a/Lib/idlelib/__main__.py
+++ b/Lib/idlelib/__main__.py
@@ -3,6 +3,6 @@ IDLE main entry point
 
 Run IDLE as python -m idlelib
 """
-import idlelib.PyShell
-idlelib.PyShell.main()
+import idlelib.pyshell
+idlelib.pyshell.main()
 # This file does not work for 2.7; See issue 24212.
diff --git a/Lib/idlelib/AutoComplete.py b/Lib/idlelib/autocomplete.py
index ff085d5c70..5ba8dc5dd5 100644
--- a/Lib/idlelib/AutoComplete.py
+++ b/Lib/idlelib/autocomplete.py
@@ -1,4 +1,4 @@
-"""AutoComplete.py - An IDLE extension for automatically completing names.
+"""autocomplete.py - An IDLE extension for automatically completing names.
 
 This extension can complete either attribute names or file names. It can pop
 a window with all available names, for the user to select from.
@@ -7,7 +7,7 @@ import os
 import sys
 import string
 
-from idlelib.configHandler import idleConf
+from idlelib.config import idleConf
 
 # This string includes all chars that may be in an identifier
 ID_CHARS = string.ascii_letters + string.digits + "_"
@@ -15,8 +15,8 @@ ID_CHARS = string.ascii_letters + string.digits + "_"
 # These constants represent the two different types of completions
 COMPLETE_ATTRIBUTES, COMPLETE_FILES = range(1, 2+1)
 
-from idlelib import AutoCompleteWindow
-from idlelib.HyperParser import HyperParser
+from idlelib import autocomplete_w
+from idlelib.hyperparser import HyperParser
 
 import __main__
 
@@ -49,7 +49,7 @@ class AutoComplete:
         self._delayed_completion_index = None
 
     def _make_autocomplete_window(self):
-        return AutoCompleteWindow.AutoCompleteWindow(self.text)
+        return autocomplete_w.AutoCompleteWindow(self.text)
 
     def _remove_autocomplete_window(self, event=None):
         if self.autocompletewindow:
diff --git a/Lib/idlelib/AutoCompleteWindow.py b/Lib/idlelib/autocomplete_w.py
index 2ee6878396..c66b3dfff0 100644
--- a/Lib/idlelib/AutoCompleteWindow.py
+++ b/Lib/idlelib/autocomplete_w.py
@@ -1,9 +1,9 @@
 """
-An auto-completion window for IDLE, used by the AutoComplete extension
+An auto-completion window for IDLE, used by the autocomplete extension
 """
 from tkinter import *
-from idlelib.MultiCall import MC_SHIFT
-from idlelib.AutoComplete import COMPLETE_FILES, COMPLETE_ATTRIBUTES
+from idlelib.multicall import MC_SHIFT
+from idlelib.autocomplete import COMPLETE_FILES, COMPLETE_ATTRIBUTES
 
 HIDE_VIRTUAL_EVENT_NAME = "<<autocompletewindow-hide>>"
 HIDE_SEQUENCES = ("<FocusOut>", "<ButtonPress>")
@@ -34,8 +34,8 @@ class AutoCompleteWindow:
         self.completions = None
         # A list with more completions, or None
         self.morecompletions = None
-        # The completion mode. Either AutoComplete.COMPLETE_ATTRIBUTES or
-        # AutoComplete.COMPLETE_FILES
+        # The completion mode. Either autocomplete.COMPLETE_ATTRIBUTES or
+        # autocomplete.COMPLETE_FILES
         self.mode = None
         # The current completion start, on the text box (a string)
         self.start = None
diff --git a/Lib/idlelib/AutoExpand.py b/Lib/idlelib/autoexpand.py
index 7059054281..7059054281 100644
--- a/Lib/idlelib/AutoExpand.py
+++ b/Lib/idlelib/autoexpand.py
diff --git a/Lib/idlelib/ClassBrowser.py b/Lib/idlelib/browser.py
index d09c52fe4d..9968333c24 100644
--- a/Lib/idlelib/ClassBrowser.py
+++ b/Lib/idlelib/browser.py
@@ -14,13 +14,13 @@ import os
 import sys
 import pyclbr
 
-from idlelib import PyShell
-from idlelib.WindowList import ListedToplevel
-from idlelib.TreeWidget import TreeNode, TreeItem, ScrolledCanvas
-from idlelib.configHandler import idleConf
+from idlelib import pyshell
+from idlelib.windows import ListedToplevel
+from idlelib.tree import TreeNode, TreeItem, ScrolledCanvas
+from idlelib.config import idleConf
 
 file_open = None  # Method...Item and Class...Item use this.
-# Normally PyShell.flist.open, but there is no PyShell.flist for htest.
+# Normally pyshell.flist.open, but there is no pyshell.flist for htest.
 
 class ClassBrowser:
 
@@ -32,7 +32,7 @@ class ClassBrowser:
         """
         global file_open
         if not _htest:
-            file_open = PyShell.flist.open
+            file_open = pyshell.flist.open
         self.name = name
         self.file = os.path.join(path[0], self.name + ".py")
         self._htest = _htest
@@ -95,7 +95,7 @@ class ModuleBrowserTreeItem(TreeItem):
             return
         if not os.path.exists(self.file):
             return
-        PyShell.flist.open(self.file)
+        pyshell.flist.open(self.file)
 
     def IsExpandable(self):
         return os.path.normcase(self.file[-3:]) == ".py"
@@ -226,7 +226,7 @@ def _class_browser(parent): #Wrapper for htest
             file = sys.argv[0]
     dir, file = os.path.split(file)
     name = os.path.splitext(file)[0]
-    flist = PyShell.PyShellFileList(parent)
+    flist = pyshell.PyShellFileList(parent)
     global file_open
     file_open = flist.open
     ClassBrowser(flist, name, [dir], _htest=True)
diff --git a/Lib/idlelib/CallTipWindow.py b/Lib/idlelib/calltip_w.py
index 8e68a76b2a..9f6cdc1771 100644
--- a/Lib/idlelib/CallTipWindow.py
+++ b/Lib/idlelib/calltip_w.py
@@ -1,7 +1,7 @@
 """A CallTip window class for Tkinter/IDLE.
 
-After ToolTip.py, which uses ideas gleaned from PySol
-Used by the CallTips IDLE extension.
+After tooltip.py, which uses ideas gleaned from PySol
+Used by the calltips IDLE extension.
 """
 from tkinter import Toplevel, Label, LEFT, SOLID, TclError
 
diff --git a/Lib/idlelib/CallTips.py b/Lib/idlelib/calltips.py
index 81bd5f1890..3a9b1c6776 100644
--- a/Lib/idlelib/CallTips.py
+++ b/Lib/idlelib/calltips.py
@@ -1,4 +1,4 @@
-"""CallTips.py - An IDLE Extension to Jog Your Memory
+"""calltips.py - An IDLE Extension to Jog Your Memory
 
 Call Tips are floating windows which display function, class, and method
 parameter and docstring information when you type an opening parenthesis, and
@@ -12,8 +12,8 @@ import sys
 import textwrap
 import types
 
-from idlelib import CallTipWindow
-from idlelib.HyperParser import HyperParser
+from idlelib import calltip_w
+from idlelib.hyperparser import HyperParser
 
 class CallTips:
 
@@ -37,7 +37,7 @@ class CallTips:
 
     def _make_tk_calltip_window(self):
         # See __init__ for usage
-        return CallTipWindow.CallTip(self.text)
+        return calltip_w.CallTip(self.text)
 
     def _remove_calltip_window(self, event=None):
         if self.active_calltip:
diff --git a/Lib/idlelib/CodeContext.py b/Lib/idlelib/codecontext.py
index 7d25adaa4c..2a21a1f84a 100644
--- a/Lib/idlelib/CodeContext.py
+++ b/Lib/idlelib/codecontext.py
@@ -1,11 +1,11 @@
-"""CodeContext - Extension to display the block context above the edit window
+"""codecontext - Extension to display the block context above the edit window
 
 Once code has scrolled off the top of a window, it can be difficult to
 determine which block you are in.  This extension implements a pane at the top
 of each IDLE edit window which provides block structure hints.  These hints are
 the lines which contain the block opening keywords, e.g. 'if', for the
 enclosing block.  The number of hint lines is determined by the numlines
-variable in the CodeContext section of config-extensions.def. Lines which do
+variable in the codecontext section of config-extensions.def. Lines which do
 not open blocks are not shown in the context hints pane.
 
 """
@@ -13,7 +13,7 @@ import tkinter
 from tkinter.constants import TOP, LEFT, X, W, SUNKEN
 import re
 from sys import maxsize as INFINITY
-from idlelib.configHandler import idleConf
+from idlelib.config import idleConf
 
 BLOCKOPENERS = {"class", "def", "elif", "else", "except", "finally", "for",
                     "if", "try", "while", "with"}
diff --git a/Lib/idlelib/ColorDelegator.py b/Lib/idlelib/colorizer.py
index 02eac47068..ec84b81a72 100644
--- a/Lib/idlelib/ColorDelegator.py
+++ b/Lib/idlelib/colorizer.py
@@ -3,8 +3,8 @@ import re
 import keyword
 import builtins
 from tkinter import TkVersion
-from idlelib.Delegator import Delegator
-from idlelib.configHandler import idleConf
+from idlelib.delegator import Delegator
+from idlelib.config import idleConf
 
 DEBUG = False
 
@@ -259,7 +259,7 @@ class ColorDelegator(Delegator):
 
 def _color_delegator(parent):  # htest #
     from tkinter import Toplevel, Text
-    from idlelib.Percolator import Percolator
+    from idlelib.percolator import Percolator
 
     top = Toplevel(parent)
     top.title("Test ColorDelegator")
diff --git a/Lib/idlelib/configHandler.py b/Lib/idlelib/config.py
index 8ac1f6097a..b9e1c6df00 100644
--- a/Lib/idlelib/configHandler.py
+++ b/Lib/idlelib/config.py
@@ -7,7 +7,7 @@ duplicate the defaults will be removed from the user's configuration files,
 and if a file becomes empty, it will be deleted.
 
 The contents of the user files may be altered using the Options/Configure IDLE
-menu to access the configuration GUI (configDialog.py), or manually.
+menu to access the configuration GUI (configdialog.py), or manually.
 
 Throughout this module there is an emphasis on returning useable defaults
 when a problem occurs in returning a requested configuration value back to
@@ -230,7 +230,7 @@ class IdleConf:
                 return self.userCfg[configType].Get(section, option,
                                                     type=type, raw=raw)
         except ValueError:
-            warning = ('\n Warning: configHandler.py - IdleConf.GetOption -\n'
+            warning = ('\n Warning: config.py - IdleConf.GetOption -\n'
                        ' invalid %r value for configuration option %r\n'
                        ' from section %r: %r' %
                        (type, option, section,
@@ -247,7 +247,7 @@ class IdleConf:
             pass
         #returning default, print warning
         if warn_on_default:
-            warning = ('\n Warning: configHandler.py - IdleConf.GetOption -\n'
+            warning = ('\n Warning: config.py - IdleConf.GetOption -\n'
                        ' problem retrieving configuration option %r\n'
                        ' from section %r.\n'
                        ' returning default value: %r' %
@@ -358,7 +358,7 @@ class IdleConf:
         for element in theme:
             if not cfgParser.has_option(themeName, element):
                 # Print warning that will return a default color
-                warning = ('\n Warning: configHandler.IdleConf.GetThemeDict'
+                warning = ('\n Warning: config.IdleConf.GetThemeDict'
                            ' -\n problem retrieving theme element %r'
                            '\n from theme %r.\n'
                            ' returning default color: %r' %
@@ -644,7 +644,7 @@ class IdleConf:
                 if binding:
                     keyBindings[event] = binding
                 else: #we are going to return a default, print warning
-                    warning=('\n Warning: configHandler.py - IdleConf.GetCoreKeys'
+                    warning=('\n Warning: config.py - IdleConf.GetCoreKeys'
                                ' -\n problem retrieving key binding for event %r'
                                '\n from key set %r.\n'
                                ' returning default value: %r' %
diff --git a/Lib/idlelib/configHelpSourceEdit.py b/Lib/idlelib/config_help.py
index cde8118fe6..cde8118fe6 100644
--- a/Lib/idlelib/configHelpSourceEdit.py
+++ b/Lib/idlelib/config_help.py
diff --git a/Lib/idlelib/keybindingDialog.py b/Lib/idlelib/config_key.py
index e6438bfc39..e6438bfc39 100644
--- a/Lib/idlelib/keybindingDialog.py
+++ b/Lib/idlelib/config_key.py
diff --git a/Lib/idlelib/configSectionNameDialog.py b/Lib/idlelib/config_sec.py
index 5137836981..7b59124507 100644
--- a/Lib/idlelib/configSectionNameDialog.py
+++ b/Lib/idlelib/config_sec.py
@@ -1,7 +1,7 @@
 """
 Dialog that allows user to specify a new config file section name.
 Used to get new highlight theme and keybinding set names.
-The 'return value' for the dialog, used two placed in configDialog.py,
+The 'return value' for the dialog, used two placed in configdialog.py,
 is the .result attribute set in the Ok and Cancel methods.
 """
 from tkinter import *
diff --git a/Lib/idlelib/configDialog.py b/Lib/idlelib/configdialog.py
index b7022537e6..b58806e38c 100644
--- a/Lib/idlelib/configDialog.py
+++ b/Lib/idlelib/configdialog.py
@@ -14,14 +14,14 @@ import tkinter.messagebox as tkMessageBox
 import tkinter.colorchooser as tkColorChooser
 import tkinter.font as tkFont
 
-from idlelib.configHandler import idleConf
-from idlelib.dynOptionMenuWidget import DynOptionMenu
-from idlelib.keybindingDialog import GetKeysDialog
-from idlelib.configSectionNameDialog import GetCfgSectionNameDialog
-from idlelib.configHelpSourceEdit import GetHelpSourceDialog
+from idlelib.config import idleConf
+from idlelib.dynoption import DynOptionMenu
+from idlelib.config_key import GetKeysDialog
+from idlelib.config_sec import GetCfgSectionNameDialog
+from idlelib.config_help import GetHelpSourceDialog
 from idlelib.tabbedpages import TabbedPageSet
-from idlelib.textView import view_text
-from idlelib import macosxSupport
+from idlelib.textview import view_text
+from idlelib import macosx
 
 class ConfigDialog(Toplevel):
 
@@ -91,7 +91,7 @@ class ConfigDialog(Toplevel):
         self.create_action_buttons().pack(side=BOTTOM)
 
     def create_action_buttons(self):
-        if macosxSupport.isAquaTk():
+        if macosx.isAquaTk():
             # Changing the default padding on OSX results in unreadable
             # text in the buttons
             paddingArgs = {}
diff --git a/Lib/idlelib/Debugger.py b/Lib/idlelib/debugger.py
index d5e217dde9..9af626cca9 100644
--- a/Lib/idlelib/Debugger.py
+++ b/Lib/idlelib/debugger.py
@@ -1,9 +1,9 @@
 import os
 import bdb
 from tkinter import *
-from idlelib.WindowList import ListedToplevel
-from idlelib.ScrolledList import ScrolledList
-from idlelib import macosxSupport
+from idlelib.windows import ListedToplevel
+from idlelib.scrolledlist import ScrolledList
+from idlelib import macosx
 
 
 class Idb(bdb.Bdb):
@@ -34,8 +34,10 @@ class Idb(bdb.Bdb):
             return True
         else:
             prev_frame = frame.f_back
-            if prev_frame.f_code.co_filename.count('Debugger.py'):
-                # (that test will catch both Debugger.py and RemoteDebugger.py)
+            prev_name = prev_frame.f_code.co_filename
+            if 'idlelib' in prev_name and 'debugger' in prev_name:
+                # catch both idlelib/debugger.py and idlelib/debugger_r.py
+                # on both posix and windows
                 return False
             return self.in_rpc_code(prev_frame)
 
@@ -370,7 +372,7 @@ class Debugger:
 class StackViewer(ScrolledList):
 
     def __init__(self, master, flist, gui):
-        if macosxSupport.isAquaTk():
+        if macosx.isAquaTk():
             # At least on with the stock AquaTk version on OSX 10.4 you'll
             # get a shaking GUI that eventually kills IDLE if the width
             # argument is specified.
@@ -502,7 +504,7 @@ class NamespaceViewer:
             #
             # There is also an obscure bug in sorted(dict) where the
             # interpreter gets into a loop requesting non-existing dict[0],
-            # dict[1], dict[2], etc from the RemoteDebugger.DictProxy.
+            # dict[1], dict[2], etc from the debugger_r.DictProxy.
             ###
             keys_list = dict.keys()
             names = sorted(keys_list)
diff --git a/Lib/idlelib/RemoteDebugger.py b/Lib/idlelib/debugger_r.py
index be2262f080..bc971276de 100644
--- a/Lib/idlelib/RemoteDebugger.py
+++ b/Lib/idlelib/debugger_r.py
@@ -21,7 +21,7 @@ barrier, in particular frame and traceback objects.
 """
 
 import types
-from idlelib import Debugger
+from idlelib import debugger
 
 debugging = 0
 
@@ -187,7 +187,7 @@ def start_debugger(rpchandler, gui_adap_oid):
 
     """
     gui_proxy = GUIProxy(rpchandler, gui_adap_oid)
-    idb = Debugger.Idb(gui_proxy)
+    idb = debugger.Idb(gui_proxy)
     idb_adap = IdbAdapter(idb)
     rpchandler.register(idb_adap_oid, idb_adap)
     return idb_adap_oid
@@ -362,7 +362,7 @@ def start_remote_debugger(rpcclt, pyshell):
     idb_adap_oid = rpcclt.remotecall("exec", "start_the_debugger",\
                                    (gui_adap_oid,), {})
     idb_proxy = IdbProxy(rpcclt, pyshell, idb_adap_oid)
-    gui = Debugger.Debugger(pyshell, idb_proxy)
+    gui = debugger.Debugger(pyshell, idb_proxy)
     gui_adap = GUIAdapter(rpcclt, gui)
     rpcclt.register(gui_adap_oid, gui_adap)
     return gui
@@ -373,7 +373,7 @@ def close_remote_debugger(rpcclt):
     Request that the RPCServer shut down the subprocess debugger and link.
     Unregister the GUIAdapter, which will cause a GC on the Idle process
     debugger and RPC link objects.  (The second reference to the debugger GUI
-    is deleted in PyShell.close_remote_debugger().)
+    is deleted in pyshell.close_remote_debugger().)
 
     """
     close_subprocess_debugger(rpcclt)
diff --git a/Lib/idlelib/ObjectBrowser.py b/Lib/idlelib/debugobj.py
index 7b57aa4c68..4016c032d4 100644
--- a/Lib/idlelib/ObjectBrowser.py
+++ b/Lib/idlelib/debugobj.py
@@ -11,7 +11,7 @@
 
 import re
 
-from idlelib.TreeWidget import TreeItem, TreeNode, ScrolledCanvas
+from idlelib.tree import TreeItem, TreeNode, ScrolledCanvas
 
 from reprlib import Repr
 
@@ -126,7 +126,7 @@ def _object_browser(parent):
     import sys
     from tkinter import Tk
     root = Tk()
-    root.title("Test ObjectBrowser")
+    root.title("Test debug object browser")
     width, height, x, y = list(map(int, re.split('[x+]', parent.geometry())))
     root.geometry("+%d+%d"%(x, y + 150))
     root.configure(bd=0, bg="yellow")
diff --git a/Lib/idlelib/RemoteObjectBrowser.py b/Lib/idlelib/debugobj_r.py
index 8031aaeaf1..8031aaeaf1 100644
--- a/Lib/idlelib/RemoteObjectBrowser.py
+++ b/Lib/idlelib/debugobj_r.py
diff --git a/Lib/idlelib/Delegator.py b/Lib/idlelib/delegator.py
index dc2a1aaeea..dc2a1aaeea 100644
--- a/Lib/idlelib/Delegator.py
+++ b/Lib/idlelib/delegator.py
diff --git a/Lib/idlelib/dynOptionMenuWidget.py b/Lib/idlelib/dynoption.py
index 515b4bafc2..515b4bafc2 100644
--- a/Lib/idlelib/dynOptionMenuWidget.py
+++ b/Lib/idlelib/dynoption.py
diff --git a/Lib/idlelib/EditorWindow.py b/Lib/idlelib/editor.py
index 9944da3e70..b214c6ab9b 100644
--- a/Lib/idlelib/EditorWindow.py
+++ b/Lib/idlelib/editor.py
@@ -12,15 +12,15 @@ import tkinter.messagebox as tkMessageBox
 import traceback
 import webbrowser
 
-from idlelib.MultiCall import MultiCallCreator
-from idlelib import WindowList
-from idlelib import SearchDialog
-from idlelib import GrepDialog
-from idlelib import ReplaceDialog
-from idlelib import PyParse
-from idlelib.configHandler import idleConf
-from idlelib import aboutDialog, textView, configDialog
-from idlelib import macosxSupport
+from idlelib.multicall import MultiCallCreator
+from idlelib import windows
+from idlelib import search
+from idlelib import grep
+from idlelib import replace
+from idlelib import pyparse
+from idlelib.config import idleConf
+from idlelib import help_about, textview, configdialog
+from idlelib import macosx
 from idlelib import help
 
 # The default tab setting for a Text widget, in average-width characters.
@@ -40,62 +40,14 @@ def _sphinx_version():
     return release
 
 
-class HelpDialog(object):
-
-    def __init__(self):
-        self.parent = None      # parent of help window
-        self.dlg = None         # the help window iteself
-
-    def display(self, parent, near=None):
-        """ Display the help dialog.
-
-            parent - parent widget for the help window
-
-            near - a Toplevel widget (e.g. EditorWindow or PyShell)
-                   to use as a reference for placing the help window
-        """
-        import warnings as w
-        w.warn("EditorWindow.HelpDialog is no longer used by Idle.\n"
-               "It will be removed in 3.6 or later.\n"
-               "It has been replaced by private help.HelpWindow\n",
-               DeprecationWarning, stacklevel=2)
-        if self.dlg is None:
-            self.show_dialog(parent)
-        if near:
-            self.nearwindow(near)
-
-    def show_dialog(self, parent):
-        self.parent = parent
-        fn=os.path.join(os.path.abspath(os.path.dirname(__file__)),'help.txt')
-        self.dlg = dlg = textView.view_file(parent,'Help',fn, modal=False)
-        dlg.bind('<Destroy>', self.destroy, '+')
-
-    def nearwindow(self, near):
-        # Place the help dialog near the window specified by parent.
-        # Note - this may not reposition the window in Metacity
-        #  if "/apps/metacity/general/disable_workarounds" is enabled
-        dlg = self.dlg
-        geom = (near.winfo_rootx() + 10, near.winfo_rooty() + 10)
-        dlg.withdraw()
-        dlg.geometry("=+%d+%d" % geom)
-        dlg.deiconify()
-        dlg.lift()
-
-    def destroy(self, ev=None):
-        self.dlg = None
-        self.parent = None
-
-helpDialog = HelpDialog()  # singleton instance, no longer used
-
-
 class EditorWindow(object):
-    from idlelib.Percolator import Percolator
-    from idlelib.ColorDelegator import ColorDelegator, color_config
-    from idlelib.UndoDelegator import UndoDelegator
-    from idlelib.IOBinding import IOBinding, filesystemencoding, encoding
-    from idlelib import Bindings
+    from idlelib.percolator import Percolator
+    from idlelib.colorizer import ColorDelegator, color_config
+    from idlelib.undo import UndoDelegator
+    from idlelib.iomenu import IOBinding, filesystemencoding, encoding
+    from idlelib import mainmenu
     from tkinter import Toplevel
-    from idlelib.MultiStatusBar import MultiStatusBar
+    from idlelib.statusbar import MultiStatusBar
 
     help_url = None
 
@@ -136,11 +88,11 @@ class EditorWindow(object):
         except AttributeError:
             sys.ps1 = '>>> '
         self.menubar = Menu(root)
-        self.top = top = WindowList.ListedToplevel(root, menu=self.menubar)
+        self.top = top = windows.ListedToplevel(root, menu=self.menubar)
         if flist:
             self.tkinter_vars = flist.vars
             #self.top.instance_dict makes flist.inversedict available to
-            #configDialog.py so it can access all EditorWindow instances
+            #configdialog.py so it can access all EditorWindow instances
             self.top.instance_dict = flist.inversedict
         else:
             self.tkinter_vars = {}  # keys: Tkinter event names
@@ -173,7 +125,7 @@ class EditorWindow(object):
 
         self.top.protocol("WM_DELETE_WINDOW", self.close)
         self.top.bind("<<close-window>>", self.close_event)
-        if macosxSupport.isAquaTk():
+        if macosx.isAquaTk():
             # Command-W on editorwindows doesn't work without this.
             text.bind('<<close-window>>', self.close_event)
             # Some OS X systems have only one mouse button, so use
@@ -309,7 +261,7 @@ class EditorWindow(object):
                 menu.add_separator()
                 end = end + 1
             self.wmenu_end = end
-            WindowList.register_callback(self.postwindowsmenu)
+            windows.register_callback(self.postwindowsmenu)
 
         # Some abstractions so IDLE extensions are cross-IDE
         self.askyesno = tkMessageBox.askyesno
@@ -418,7 +370,7 @@ class EditorWindow(object):
             underline, label = prepstr(label)
             menudict[name] = menu = Menu(mbar, name=name, tearoff=0)
             mbar.add_cascade(label=label, menu=menu, underline=underline)
-        if macosxSupport.isCarbonTk():
+        if macosx.isCarbonTk():
             # Insert the application menu
             menudict['application'] = menu = Menu(mbar, name='apple',
                                                   tearoff=0)
@@ -439,7 +391,7 @@ class EditorWindow(object):
             end = -1
         if end > self.wmenu_end:
             menu.delete(self.wmenu_end+1, end)
-        WindowList.add_windows_to_menu(menu)
+        windows.add_windows_to_menu(menu)
 
     rmenu = None
 
@@ -507,17 +459,17 @@ class EditorWindow(object):
 
     def about_dialog(self, event=None):
         "Handle Help 'About IDLE' event."
-        # Synchronize with macosxSupport.overrideRootMenu.about_dialog.
-        aboutDialog.AboutDialog(self.top,'About IDLE')
+        # Synchronize with macosx.overrideRootMenu.about_dialog.
+        help_about.AboutDialog(self.top,'About IDLE')
 
     def config_dialog(self, event=None):
         "Handle Options 'Configure IDLE' event."
-        # Synchronize with macosxSupport.overrideRootMenu.config_dialog.
-        configDialog.ConfigDialog(self.top,'Settings')
+        # Synchronize with macosx.overrideRootMenu.config_dialog.
+        configdialog.ConfigDialog(self.top,'Settings')
 
     def help_dialog(self, event=None):
         "Handle Help 'IDLE Help' event."
-        # Synchronize with macosxSupport.overrideRootMenu.help_dialog.
+        # Synchronize with macosx.overrideRootMenu.help_dialog.
         if self.root:
             parent = self.root
         else:
@@ -590,23 +542,23 @@ class EditorWindow(object):
         return "break"
 
     def find_event(self, event):
-        SearchDialog.find(self.text)
+        search.find(self.text)
         return "break"
 
     def find_again_event(self, event):
-        SearchDialog.find_again(self.text)
+        search.find_again(self.text)
         return "break"
 
     def find_selection_event(self, event):
-        SearchDialog.find_selection(self.text)
+        search.find_selection(self.text)
         return "break"
 
     def find_in_files_event(self, event):
-        GrepDialog.grep(self.text, self.io, self.flist)
+        grep.grep(self.text, self.io, self.flist)
         return "break"
 
     def replace_event(self, event):
-        ReplaceDialog.replace(self.text)
+        replace.replace(self.text)
         return "break"
 
     def goto_line_event(self, event):
@@ -673,12 +625,12 @@ class EditorWindow(object):
                 return
         head, tail = os.path.split(filename)
         base, ext = os.path.splitext(tail)
-        from idlelib import ClassBrowser
-        ClassBrowser.ClassBrowser(self.flist, base, [head])
+        from idlelib import browser
+        browser.ClassBrowser(self.flist, base, [head])
 
     def open_path_browser(self, event=None):
-        from idlelib import PathBrowser
-        PathBrowser.PathBrowser(self.flist)
+        from idlelib import pathbrowser
+        pathbrowser.PathBrowser(self.flist)
 
     def open_turtle_demo(self, event = None):
         import subprocess
@@ -739,7 +691,7 @@ class EditorWindow(object):
 
     def ResetColorizer(self):
         "Update the color theme"
-        # Called from self.filename_change_hook and from configDialog.py
+        # Called from self.filename_change_hook and from configdialog.py
         self._rmcolorizer()
         self._addcolorizer()
         EditorWindow.color_config(self.text)
@@ -759,14 +711,14 @@ class EditorWindow(object):
 
     def ResetFont(self):
         "Update the text widgets' font if it is changed"
-        # Called from configDialog.py
+        # Called from configdialog.py
 
         self.text['font'] = idleConf.GetFont(self.root, 'main','EditorWindow')
 
     def RemoveKeybindings(self):
         "Remove the keybindings before they are changed."
-        # Called from configDialog.py
-        self.Bindings.default_keydefs = keydefs = idleConf.GetCurrentKeySet()
+        # Called from configdialog.py
+        self.mainmenu.default_keydefs = keydefs = idleConf.GetCurrentKeySet()
         for event, keylist in keydefs.items():
             self.text.event_delete(event, *keylist)
         for extensionName in self.get_standard_extension_names():
@@ -777,8 +729,8 @@ class EditorWindow(object):
 
     def ApplyKeybindings(self):
         "Update the keybindings after they are changed"
-        # Called from configDialog.py
-        self.Bindings.default_keydefs = keydefs = idleConf.GetCurrentKeySet()
+        # Called from configdialog.py
+        self.mainmenu.default_keydefs = keydefs = idleConf.GetCurrentKeySet()
         self.apply_bindings()
         for extensionName in self.get_standard_extension_names():
             xkeydefs = idleConf.GetExtensionBindings(extensionName)
@@ -786,7 +738,7 @@ class EditorWindow(object):
                 self.apply_bindings(xkeydefs)
         #update menu accelerators
         menuEventDict = {}
-        for menu in self.Bindings.menudefs:
+        for menu in self.mainmenu.menudefs:
             menuEventDict[menu[0]] = {}
             for item in menu[1]:
                 if item:
@@ -813,7 +765,7 @@ class EditorWindow(object):
 
     def set_notabs_indentwidth(self):
         "Update the indentwidth if changed and not using tabs in this window"
-        # Called from configDialog.py
+        # Called from configdialog.py
         if not self.usetabs:
             self.indentwidth = idleConf.GetOption('main', 'Indent','num-spaces',
                                                   type='int')
@@ -993,7 +945,7 @@ class EditorWindow(object):
     def _close(self):
         if self.io.filename:
             self.update_recent_files_list(new_file=self.io.filename)
-        WindowList.unregister_callback(self.postwindowsmenu)
+        windows.unregister_callback(self.postwindowsmenu)
         self.unload_extensions()
         self.io.close()
         self.io = None
@@ -1031,12 +983,25 @@ class EditorWindow(object):
     def get_standard_extension_names(self):
         return idleConf.GetExtensions(editor_only=True)
 
+    extfiles = {  # map config-extension section names to new file names
+        'AutoComplete': 'autocomplete',
+        'AutoExpand': 'autoexpand',
+        'CallTips': 'calltips',
+        'CodeContext': 'codecontext',
+        'FormatParagraph': 'paragraph',
+        'ParenMatch': 'parenmatch',
+        'RstripExtension': 'rstrip',
+        'ScriptBinding': 'runscript',
+        'ZoomHeight': 'zoomheight',
+        }
+
     def load_extension(self, name):
+        fname = self.extfiles.get(name, name)
         try:
             try:
-                mod = importlib.import_module('.' + name, package=__package__)
+                mod = importlib.import_module('.' + fname, package=__package__)
             except (ImportError, TypeError):
-                mod = importlib.import_module(name)
+                mod = importlib.import_module(fname)
         except ImportError:
             print("\nFailed to import extension: ", name)
             raise
@@ -1060,7 +1025,7 @@ class EditorWindow(object):
 
     def apply_bindings(self, keydefs=None):
         if keydefs is None:
-            keydefs = self.Bindings.default_keydefs
+            keydefs = self.mainmenu.default_keydefs
         text = self.text
         text.keydefs = keydefs
         for event, keylist in keydefs.items():
@@ -1073,9 +1038,9 @@ class EditorWindow(object):
         Menus that are absent or None in self.menudict are ignored.
         """
         if menudefs is None:
-            menudefs = self.Bindings.menudefs
+            menudefs = self.mainmenu.menudefs
         if keydefs is None:
-            keydefs = self.Bindings.default_keydefs
+            keydefs = self.mainmenu.default_keydefs
         menudict = self.menudict
         text = self.text
         for mname, entrylist in menudefs:
@@ -1302,7 +1267,7 @@ class EditorWindow(object):
             # adjust indentation for continuations and block
             # open/close first need to find the last stmt
             lno = index2line(text.index('insert'))
-            y = PyParse.Parser(self.indentwidth, self.tabwidth)
+            y = pyparse.Parser(self.indentwidth, self.tabwidth)
             if not self.context_use_ps1:
                 for context in self.num_context_lines:
                     startat = max(lno - context, 1)
@@ -1326,22 +1291,22 @@ class EditorWindow(object):
                 y.set_lo(0)
 
             c = y.get_continuation_type()
-            if c != PyParse.C_NONE:
+            if c != pyparse.C_NONE:
                 # The current stmt hasn't ended yet.
-                if c == PyParse.C_STRING_FIRST_LINE:
+                if c == pyparse.C_STRING_FIRST_LINE:
                     # after the first line of a string; do not indent at all
                     pass
-                elif c == PyParse.C_STRING_NEXT_LINES:
+                elif c == pyparse.C_STRING_NEXT_LINES:
                     # inside a string which started before this line;
                     # just mimic the current indent
                     text.insert("insert", indent)
-                elif c == PyParse.C_BRACKET:
+                elif c == pyparse.C_BRACKET:
                     # line up with the first (if any) element of the
                     # last open bracket structure; else indent one
                     # level beyond the indent of the line with the
                     # last open bracket
                     self.reindent_to(y.compute_bracket_indent())
-                elif c == PyParse.C_BACKSLASH:
+                elif c == pyparse.C_BACKSLASH:
                     # if more than one line in this stmt already, just
                     # mimic the current indent; else if initial line
                     # has a start on an assignment stmt, indent to
@@ -1644,7 +1609,7 @@ def get_accelerator(keydefs, eventname):
     keylist = keydefs.get(eventname)
     # issue10940: temporary workaround to prevent hang with OS X Cocoa Tk 8.5
     # if not keylist:
-    if (not keylist) or (macosxSupport.isCocoaTk() and eventname in {
+    if (not keylist) or (macosx.isCocoaTk() and eventname in {
                             "<<open-module>>",
                             "<<goto-line>>",
                             "<<change-indentwidth>>"}):
@@ -1679,7 +1644,7 @@ def _editor_window(parent):  # htest #
         filename = sys.argv[1]
     else:
         filename = None
-    macosxSupport.setupApp(root, None)
+    macosx.setupApp(root, None)
     edit = EditorWindow(root=root, filename=filename)
     edit.text.bind("<<close-all-windows>>", edit.close_event)
     # Does not stop error, neither does following
diff --git a/Lib/idlelib/FileList.py b/Lib/idlelib/filelist.py
index a9989a8624..b5af90ccaf 100644
--- a/Lib/idlelib/FileList.py
+++ b/Lib/idlelib/filelist.py
@@ -6,7 +6,7 @@ import tkinter.messagebox as tkMessageBox
 class FileList:
 
     # N.B. this import overridden in PyShellFileList.
-    from idlelib.EditorWindow import EditorWindow
+    from idlelib.editor import EditorWindow
 
     def __init__(self, root):
         self.root = root
@@ -111,7 +111,7 @@ class FileList:
 
 
 def _test():
-    from idlelib.EditorWindow import fixwordbreaks
+    from idlelib.editor import fixwordbreaks
     import sys
     root = Tk()
     fixwordbreaks(root)
diff --git a/Lib/idlelib/GrepDialog.py b/Lib/idlelib/grep.py
index 721b231a9e..28132a8917 100644
--- a/Lib/idlelib/GrepDialog.py
+++ b/Lib/idlelib/grep.py
@@ -4,14 +4,14 @@ import re  # for htest
 import sys
 from tkinter import StringVar, BooleanVar, Checkbutton  # for GrepDialog
 from tkinter import Tk, Text, Button, SEL, END  # for htest
-from idlelib import SearchEngine
-from idlelib.SearchDialogBase import SearchDialogBase
+from idlelib import searchengine
+from idlelib.searchbase import SearchDialogBase
 # Importing OutputWindow fails due to import loop
 # EditorWindow -> GrepDialop -> OutputWindow -> EditorWindow
 
 def grep(text, io=None, flist=None):
     root = text._root()
-    engine = SearchEngine.get(root)
+    engine = searchengine.get(root)
     if not hasattr(engine, "_grepdialog"):
         engine._grepdialog = GrepDialog(root, engine, flist)
     dialog = engine._grepdialog
@@ -67,7 +67,7 @@ class GrepDialog(SearchDialogBase):
         if not path:
             self.top.bell()
             return
-        from idlelib.OutputWindow import OutputWindow  # leave here!
+        from idlelib.outwin import OutputWindow  # leave here!
         save = sys.stdout
         try:
             sys.stdout = OutputWindow(self.flist)
@@ -131,7 +131,7 @@ class GrepDialog(SearchDialogBase):
 
 
 def _grep_dialog(parent):  # htest #
-    from idlelib.PyShell import PyShellFileList
+    from idlelib.pyshell import PyShellFileList
     root = Tk()
     root.title("Test GrepDialog")
     width, height, x, y = list(map(int, re.split('[x+]', parent.geometry())))
diff --git a/Lib/idlelib/help.py b/Lib/idlelib/help.py
index d0c59c5fcf..00930151dc 100644
--- a/Lib/idlelib/help.py
+++ b/Lib/idlelib/help.py
@@ -4,7 +4,7 @@ Contents are subject to revision at any time, without notice.
 
 Help => About IDLE: diplay About Idle dialog
 
-<to be moved here from aboutDialog.py>
+<to be moved here from help_about.py>
 
 
 Help => IDLE Help: Display help.html with proper formatting.
@@ -25,10 +25,10 @@ copy_strip - Copy idle.html to help.html, rstripping each line.
 show_idlehelp - Create HelpWindow.  Called in EditorWindow.help_dialog.
 """
 from html.parser import HTMLParser
-from os.path import abspath, dirname, isdir, isfile, join
-from tkinter import Tk, Toplevel, Frame, Text, Scrollbar, Menu, Menubutton
+from os.path import abspath, dirname, isfile, join
+from tkinter import Toplevel, Frame, Text, Scrollbar, Menu, Menubutton
 from tkinter import font as tkfont
-from idlelib.configHandler import idleConf
+from idlelib.config import idleConf
 
 use_ttk = False # until available to import
 if use_ttk:
diff --git a/Lib/idlelib/help.txt b/Lib/idlelib/help.txt
deleted file mode 100644
index 89fbe0b41e..0000000000
--- a/Lib/idlelib/help.txt
+++ /dev/null
@@ -1,372 +0,0 @@
-This file, idlelib/help.txt is out-of-date and no longer used by Idle.
-It is deprecated and will be removed in the future, possibly in 3.6
-----------------------------------------------------------------------
-
-[See the end of this file for ** TIPS ** on using IDLE !!]
-
-IDLE is the Python IDE built with the tkinter GUI toolkit.
-
-IDLE has the following features:
--coded in 100% pure Python, using the tkinter GUI toolkit
--cross-platform: works on Windows, Unix, and OS X
--multi-window text editor with multiple undo, Python colorizing, smart indent,
-call tips, and many other features
--Python shell window (a.k.a interactive interpreter)
--debugger (not complete, but you can set breakpoints, view and step)
-
-Menus:
-
-IDLE has two window types the Shell window and the Editor window. It is
-possible to have multiple editor windows simultaneously. IDLE's
-menus dynamically change based on which window is currently selected. Each menu
-documented below indicates which window type it is associated with. 
-
-File Menu (Shell and Editor):
-
-        New File         -- Create a new file editing window
-        Open...          -- Open an existing file
-        Open Module...   -- Open an existing module (searches sys.path)
-        Recent Files...  -- Open a list of recent files
-        Class Browser    -- Show classes and methods in current file
-        Path Browser     -- Show sys.path directories, modules, classes,
-                            and methods
-        ---
-        Save             -- Save current window to the associated file (unsaved
-                            windows have a * before and after the window title)
-
-        Save As...       -- Save current window to new file, which becomes
-                            the associated file
-        Save Copy As...  -- Save current window to different file
-                            without changing the associated file
-        ---
-        Print Window     -- Print the current window
-        ---
-        Close            -- Close current window (asks to save if unsaved)
-        Exit             -- Close all windows, quit (asks to save if unsaved)
-
-Edit Menu (Shell and Editor):
-
-        Undo             -- Undo last change to current window
-                            (a maximum of 1000 changes may be undone)
-        Redo             -- Redo last undone change to current window
-        ---
-        Cut              -- Copy a selection into system-wide clipboard,
-                            then delete the selection
-        Copy             -- Copy selection into system-wide clipboard
-        Paste            -- Insert system-wide clipboard into window
-        Select All       -- Select the entire contents of the edit buffer
-        ---
-        Find...          -- Open a search dialog box with many options
-        Find Again       -- Repeat last search
-        Find Selection   -- Search for the string in the selection
-        Find in Files... -- Open a search dialog box for searching files
-        Replace...       -- Open a search-and-replace dialog box
-        Go to Line       -- Ask for a line number and show that line
-        Expand Word      -- Expand the word you have typed to match another
-                            word in the same buffer; repeat to get a
-                            different expansion
-        Show Calltip     -- After an unclosed parenthesis for a function, open
-                            a small window with function parameter hints
-        Show Parens      -- Highlight the surrounding parenthesis
-        Show Completions -- Open a scroll window allowing selection keywords
-                            and attributes. (see '*TIPS*', below)
-
-Format Menu (Editor window only):
-
-        Indent Region       -- Shift selected lines right by the indent width
-                               (default 4 spaces)
-        Dedent Region       -- Shift selected lines left by the indent width
-                               (default 4 spaces)
-        Comment Out Region  -- Insert ## in front of selected lines
-        Uncomment Region    -- Remove leading # or ## from selected lines
-        Tabify Region       -- Turns *leading* stretches of spaces into tabs.
-                (Note: We recommend using 4 space blocks to indent Python code.)
-        Untabify Region     -- Turn *all* tabs into the corrent number of spaces
-        Toggle tabs         -- Open a dialog to switch between indenting with
-                               spaces and tabs.
-        New Indent Width... -- Open a dialog to change indent width.  The
-                               accepted default by the Python community is 4
-                               spaces.
-        Format Paragraph    -- Reformat the current blank-line-separated
-                               paragraph. All lines in the paragraph will be
-                               formatted to less than 80 columns.
-        ---
-        Strip trailing whitespace -- Removed any space characters after the end
-                                     of the last non-space character
-
-Run Menu (Editor window only):
-
-        Python Shell -- Open or wake up the Python shell window
-        ---
-        Check Module -- Check the syntax of the module currently open in the
-                        Editor window.  If the module has not been saved IDLE
-                        will prompt the user to save the code.
-        Run Module   -- Restart the shell to clean the environment, then
-                        execute the currently open module. If the module has
-                        not been saved IDLE will prompt the user to save the
-                        code.
-
-Shell Menu (Shell window only):
-
-        View Last Restart -- Scroll the shell window to the last Shell restart
-        Restart Shell     -- Restart the shell to clean the environment
-
-Debug Menu (Shell window only):
-
-        Go to File/Line   -- Look around the insert point for a filename
-                             and line number, open the file, and show the line.
-                             Useful to view the source lines referenced in an
-                             exception traceback.  Available in the context
-                             menu of the Shell window.
-        Debugger (toggle) -- This feature is not complete and considered
-                             experimental. Run commands in the shell under the
-                             debugger.
-        Stack Viewer      -- Show the stack traceback of the last exception
-        Auto-open Stack Viewer (toggle) -- Toggle automatically opening the
-                                           stack viewer on unhandled
-                                           exception
-
-Options Menu (Shell and Editor):
-
-        Configure IDLE -- Open a configuration dialog.  Fonts, indentation,
-                          keybindings, and color themes may be altered.
-                          Startup Preferences may be set, and additional Help
-                          sources can be specified.  On OS X, open the
-                          configuration dialog by selecting Preferences
-                          in the application menu.
-
-        ---
-        Code Context (toggle) -- Open a pane at the top of the edit window
-                                 which shows the block context of the section
-                                 of code which is scrolling off the top or the
-                                 window. This is not present in the Shell
-                                 window only the Editor window.
-
-Window Menu (Shell and Editor):
-
-        Zoom Height -- Toggles the window between normal size (40x80 initial
-        setting) and maximum height.  The initial size is in the Configure
-        IDLE dialog under the general tab.
-        ---
-        The rest of this menu lists the names of all open windows;
-        select one to bring it to the foreground (deiconifying it if
-        necessary).
-
-Help Menu:
-
-        About IDLE  -- Version, copyright, license, credits
-        ---
-        IDLE Help   -- Display this file which is a help file for IDLE
-                       detailing the menu options, basic editing and navigation,
-                       and other tips.
-        Python Docs -- Access local Python documentation, if
-                       installed.  Or will start a web browser and open
-                       docs.python.org showing the latest Python documentation.
-        ---
-        Additional help sources may be added here with the Configure IDLE
-        dialog under the General tab.
-
-Editor context menu (Right-click / Control-click on OS X in Edit window):
-
-        Cut              -- Copy a selection into system-wide clipboard,
-                            then delete the selection
-        Copy             -- Copy selection into system-wide clipboard
-        Paste            -- Insert system-wide clipboard into window
-        Set Breakpoint   -- Sets a breakpoint. Breakpoints are only enabled
-                            when the debugger is open.
-        Clear Breakpoint -- Clears the breakpoint on that line
-
-Shell context menu (Right-click / Control-click on OS X in Shell window):
-
-        Cut              -- Copy a selection into system-wide clipboard,
-                            then delete the selection
-        Copy             -- Copy selection into system-wide clipboard
-        Paste            -- Insert system-wide clipboard into window
-        ---
-        Go to file/line  -- Same as in Debug menu
-
-
-** TIPS **
-==========
-
-Additional Help Sources:
-
-        Windows users can Google on zopeshelf.chm to access Zope help files in
-        the Windows help format.  The Additional Help Sources feature of the
-        configuration GUI supports .chm, along with any other filetypes
-        supported by your browser.  Supply a Menu Item title, and enter the
-        location in the Help File Path slot of the New Help Source dialog.  Use
-        http:// and/or www. to identify external URLs, or download the file and
-        browse for its path on your machine using the Browse button.
-
-        All users can access the extensive sources of help, including
-        tutorials, available at docs.python.org.  Selected URLs can be added
-        or removed from the Help menu at any time using Configure IDLE.
-
-Basic editing and navigation:
-
-        Backspace deletes char to the left; DEL deletes char to the right.
-        Control-backspace deletes word left, Control-DEL deletes word right.
-        Arrow keys and Page Up/Down move around.
-        Control-left/right Arrow moves by words in a strange but useful way.
-        Home/End go to begin/end of line.
-        Control-Home/End go to begin/end of file.
-        Some useful Emacs bindings are inherited from Tcl/Tk:
-                Control-a     beginning of line
-                Control-e     end of line
-                Control-k     kill line (but doesn't put it in clipboard)
-                Control-l     center window around the insertion point
-        Standard keybindings (like Control-c to copy and Control-v to
-        paste) may work.  Keybindings are selected in the Configure IDLE
-        dialog.
-
-Automatic indentation:
-
-        After a block-opening statement, the next line is indented by 4 spaces
-        (in the Python Shell window by one tab).  After certain keywords
-        (break, return etc.) the next line is dedented.  In leading
-        indentation, Backspace deletes up to 4 spaces if they are there.  Tab
-        inserts spaces (in the Python Shell window one tab), number depends on
-        Indent Width. Currently tabs are restricted to four spaces due
-        to Tcl/Tk limitations.
-
-        See also the indent/dedent region commands in the edit menu.
-
-Completions:
-
-        Completions are supplied for functions, classes, and attributes of
-        classes, both built-in and user-defined.  Completions are also provided
-        for filenames.
-
-        The AutoCompleteWindow (ACW) will open after a predefined delay
-        (default is two seconds) after a '.' or (in a string) an os.sep is
-        typed.  If after one of those characters (plus zero or more other
-        characters) a tab is typed the ACW will open immediately if a possible
-        continuation is found.
-
-        If there is only one possible completion for the characters entered, a
-        tab will supply that completion without opening the ACW.
-
-        'Show Completions' will force open a completions window, by default the
-        Control-space keys will open a completions window.  In an empty
-        string, this will contain the files in the current directory.  On a
-        blank line, it will contain the built-in and user-defined functions and
-        classes in the current name spaces, plus any modules imported.  If some
-        characters have been entered, the ACW will attempt to be more specific.
-
-        If string of characters is typed, the ACW selection will jump to the
-        entry most closely matching those characters. Entering a tab will cause
-        the longest non-ambiguous match to be entered in the Edit window or
-        Shell.  Two tabs in a row will supply the current ACW selection, as
-        will return or a double click.  Cursor keys, Page Up/Down, mouse
-        selection, and the scroll wheel all operate on the ACW.
-
-        "Hidden" attributes can be accessed by typing the beginning of hidden
-        name after a '.',  e.g. '_'.  This allows access to modules with
-        '__all__' set, or to class-private attributes.
-
-        Completions and the 'Expand Word' facility can save a lot of typing!
-
-        Completions are currently limited to those in the namespaces.  Names in
-        an Editor window which are not via __main__ or sys.modules will not be
-        found.  Run the module once with your imports to correct this
-        situation.  Note that IDLE itself places quite a few modules in
-        sys.modules, so much can be found by default, e.g. the re module.
-
-        If you don't like the ACW popping up unbidden, simply make the delay
-        longer or disable the extension.  Or another option is the delay could
-        be set to zero. Another alternative to preventing ACW popups is to
-        disable the call tips extension.
-
-Python Shell window:
-
-        Control-c interrupts executing command.
-        Control-d sends end-of-file; closes window if typed at >>> prompt.
-        Alt-/ expand word is also useful to reduce typing.
-
-    Command history:
-
-        Alt-p retrieves previous command matching what you have typed. On OS X
-        use Control-p.
-        Alt-n retrieves next. On OS X use Control-n.
-        Return while cursor is on a previous command retrieves that command.
-
-    Syntax colors:
-
-        The coloring is applied in a background "thread", so you may
-        occasionally see uncolorized text.  To change the color
-        scheme, use the Configure IDLE / Highlighting dialog.
-
-    Python default syntax colors:
-
-        Keywords        orange
-        Builtins        royal purple
-        Strings         green
-        Comments        red
-        Definitions     blue
-
-    Shell default colors:
-
-        Console output  brown
-        stdout          blue
-        stderr          red
-        stdin           black
-
-Other preferences:
-
-        The font preferences, highlighting, keys, and general preferences can
-        be changed via the Configure IDLE menu option.  Be sure to note that
-        keys can be user defined, IDLE ships with four built in key sets. In
-        addition a user can create a custom key set in the Configure IDLE
-        dialog under the keys tab.
-
-Command line usage:
-
-        Enter idle -h at the command prompt to get a usage message.
-
-        idle.py [-c command] [-d] [-e] [-s] [-t title] [arg] ...
-
-        -c command  run this command
-        -d          enable debugger
-        -e          edit mode; arguments are files to be edited
-        -s          run $IDLESTARTUP or $PYTHONSTARTUP first
-        -t title    set title of shell window
-
-        If there are arguments:
-        1. If -e is used, arguments are files opened for editing and sys.argv
-           reflects the arguments passed to IDLE itself.
-        2. Otherwise, if -c is used, all arguments are placed in
-           sys.argv[1:...], with sys.argv[0] set to -c.
-        3. Otherwise, if neither -e nor -c is used, the first argument is a
-           script which is executed with the remaining arguments in
-           sys.argv[1:...]  and sys.argv[0] set to the script name.  If the
-           script name is -, no script is executed but an interactive Python
-           session is started; the arguments are still available in sys.argv.
-
-Running without a subprocess: (DEPRECATED in Python 3.4 see Issue 16123)
-
-        If IDLE is started with the -n command line switch it will run in a
-        single process and will not create the subprocess which runs the RPC
-        Python execution server.  This can be useful if Python cannot create
-        the subprocess or the RPC socket interface on your platform.  However,
-        in this mode user code is not isolated from IDLE itself.  Also, the
-        environment is not restarted when Run/Run Module (F5) is selected.  If
-        your code has been modified, you must reload() the affected modules and
-        re-import any specific items (e.g. from foo import baz) if the changes
-        are to take effect.  For these reasons, it is preferable to run IDLE
-        with the default subprocess if at all possible.
-
-Extensions:
-
-        IDLE contains an extension facility.  See the beginning of
-        config-extensions.def in the idlelib directory for further information.
-        The default extensions are currently:
-
-                FormatParagraph
-                AutoExpand
-                ZoomHeight
-                ScriptBinding
-                CallTips
-                ParenMatch
-                AutoComplete
-                CodeContext
diff --git a/Lib/idlelib/aboutDialog.py b/Lib/idlelib/help_about.py
index 3112e6a3da..4b6c528950 100644
--- a/Lib/idlelib/aboutDialog.py
+++ b/Lib/idlelib/help_about.py
@@ -5,7 +5,7 @@
 import os
 from sys import version
 from tkinter import *
-from idlelib import textView
+from idlelib import textview
 
 class AboutDialog(Toplevel):
     """Modal about dialog for idle
@@ -135,11 +135,11 @@ class AboutDialog(Toplevel):
     def display_printer_text(self, title, printer):
         printer._Printer__setup()
         text = '\n'.join(printer._Printer__lines)
-        textView.view_text(self, title, text)
+        textview.view_text(self, title, text)
 
     def display_file_text(self, title, filename, encoding=None):
         fn = os.path.join(os.path.abspath(os.path.dirname(__file__)), filename)
-        textView.view_file(self, title, fn, encoding)
+        textview.view_file(self, title, fn, encoding)
 
     def Ok(self, event=None):
         self.destroy()
diff --git a/Lib/idlelib/IdleHistory.py b/Lib/idlelib/history.py
index 078af29053..6068d4f9fa 100644
--- a/Lib/idlelib/IdleHistory.py
+++ b/Lib/idlelib/history.py
@@ -1,11 +1,11 @@
 "Implement Idle Shell history mechanism with History class"
 
-from idlelib.configHandler import idleConf
+from idlelib.config import idleConf
 
 class History:
     ''' Implement Idle Shell history mechanism.
 
-    store - Store source statement (called from PyShell.resetoutput).
+    store - Store source statement (called from pyshell.resetoutput).
     fetch - Fetch stored statement matching prefix already entered.
     history_next - Bound to <<history-next>> event (default Alt-N).
     history_prev - Bound to <<history-prev>> event (default Alt-P).
diff --git a/Lib/idlelib/HyperParser.py b/Lib/idlelib/hyperparser.py
index 77cb057ce2..f904a39e24 100644
--- a/Lib/idlelib/HyperParser.py
+++ b/Lib/idlelib/hyperparser.py
@@ -7,7 +7,7 @@ the structure of code.
 
 import string
 from keyword import iskeyword
-from idlelib import PyParse
+from idlelib import pyparse
 
 
 # all ASCII chars that may be in an identifier
@@ -30,7 +30,7 @@ class HyperParser:
         self.editwin = editwin
         self.text = text = editwin.text
 
-        parser = PyParse.Parser(editwin.indentwidth, editwin.tabwidth)
+        parser = pyparse.Parser(editwin.indentwidth, editwin.tabwidth)
 
         def index2line(index):
             return int(float(index))
diff --git a/Lib/idlelib/idle.py b/Lib/idlelib/idle.py
index a249557dd1..c01cf992cc 100644
--- a/Lib/idlelib/idle.py
+++ b/Lib/idlelib/idle.py
@@ -7,5 +7,5 @@ import sys
 idlelib_dir = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 sys.path.insert(0, idlelib_dir)
 
-import idlelib.PyShell
-idlelib.PyShell.main()
+import idlelib.pyshell
+idlelib.pyshell.main()
diff --git a/Lib/idlelib/idle.pyw b/Lib/idlelib/idle.pyw
index 142cb322ac..e73c049b70 100644
--- a/Lib/idlelib/idle.pyw
+++ b/Lib/idlelib/idle.pyw
@@ -1,10 +1,10 @@
 try:
-    import idlelib.PyShell
+    import idlelib.pyshell
 except ImportError:
-    # IDLE is not installed, but maybe PyShell is on sys.path:
-    from . import PyShell
+    # IDLE is not installed, but maybe pyshell is on sys.path:
+    from . import pyshell
     import os
-    idledir = os.path.dirname(os.path.abspath(PyShell.__file__))
+    idledir = os.path.dirname(os.path.abspath(pyshell.__file__))
     if idledir != os.getcwd():
         # We're not in the IDLE directory, help the subprocess find run.py
         pypath = os.environ.get('PYTHONPATH', '')
@@ -12,6 +12,6 @@ except ImportError:
             os.environ['PYTHONPATH'] = pypath + ':' + idledir
         else:
             os.environ['PYTHONPATH'] = idledir
-    PyShell.main()
+    pyshell.main()
 else:
-    idlelib.PyShell.main()
+    idlelib.pyshell.main()
diff --git a/Lib/idlelib/idle_test/htest.py b/Lib/idlelib/idle_test/htest.py
index 58e62cb4e2..686ccc5fd5 100644
--- a/Lib/idlelib/idle_test/htest.py
+++ b/Lib/idlelib/idle_test/htest.py
@@ -59,19 +59,19 @@ msg: master window hints about testing the widget.
 
 
 Modules and classes not being tested at the moment:
-PyShell.PyShellEditorWindow
-Debugger.Debugger
-AutoCompleteWindow.AutoCompleteWindow
-OutputWindow.OutputWindow (indirectly being tested with grep test)
+pyshell.PyShellEditorWindow
+debugger.Debugger
+autocomplete_w.AutoCompleteWindow
+outwin.OutputWindow (indirectly being tested with grep test)
 '''
 
 from importlib import import_module
-from idlelib.macosxSupport import _initializeTkVariantTests
+from idlelib.macosx import _init_tk_type
 import tkinter as tk
 
 AboutDialog_spec = {
-    'file': 'aboutDialog',
-    'kwds': {'title': 'aboutDialog test',
+    'file': 'help_about',
+    'kwds': {'title': 'help_about test',
              '_htest': True,
              },
     'msg': "Test every button. Ensure Python, TK and IDLE versions "
@@ -79,14 +79,14 @@ AboutDialog_spec = {
     }
 
 _calltip_window_spec = {
-    'file': 'CallTipWindow',
+    'file': 'calltip_w',
     'kwds': {},
     'msg': "Typing '(' should display a calltip.\n"
            "Typing ') should hide the calltip.\n"
     }
 
 _class_browser_spec = {
-    'file': 'ClassBrowser',
+    'file': 'browser',
     'kwds': {},
     'msg': "Inspect names of module, class(with superclass if "
            "applicable), methods and functions.\nToggle nested items.\n"
@@ -95,7 +95,7 @@ _class_browser_spec = {
     }
 
 _color_delegator_spec = {
-    'file': 'ColorDelegator',
+    'file': 'colorizer',
     'kwds': {},
     'msg': "The text is sample Python code.\n"
            "Ensure components like comments, keywords, builtins,\n"
@@ -104,7 +104,7 @@ _color_delegator_spec = {
     }
 
 ConfigDialog_spec = {
-    'file': 'configDialog',
+    'file': 'configdialog',
     'kwds': {'title': 'ConfigDialogTest',
              '_htest': True,},
     'msg': "IDLE preferences dialog.\n"
@@ -121,7 +121,7 @@ ConfigDialog_spec = {
 
 # TODO Improve message
 _dyn_option_menu_spec = {
-    'file': 'dynOptionMenuWidget',
+    'file': 'dynoption',
     'kwds': {},
     'msg': "Select one of the many options in the 'old option set'.\n"
            "Click the button to change the option set.\n"
@@ -130,14 +130,14 @@ _dyn_option_menu_spec = {
 
 # TODO edit wrapper
 _editor_window_spec = {
-   'file': 'EditorWindow',
+   'file': 'editor',
     'kwds': {},
     'msg': "Test editor functions of interest.\n"
            "Best to close editor first."
     }
 
 GetCfgSectionNameDialog_spec = {
-    'file': 'configSectionNameDialog',
+    'file': 'config_sec',
     'kwds': {'title':'Get Name',
              'message':'Enter something',
              'used_names': {'abc'},
@@ -149,7 +149,7 @@ GetCfgSectionNameDialog_spec = {
     }
 
 GetHelpSourceDialog_spec = {
-    'file': 'configHelpSourceEdit',
+    'file': 'config_help',
     'kwds': {'title': 'Get helpsource',
              '_htest': True},
     'msg': "Enter menu item name and help file path\n "
@@ -162,7 +162,7 @@ GetHelpSourceDialog_spec = {
 
 # Update once issue21519 is resolved.
 GetKeysDialog_spec = {
-    'file': 'keybindingDialog',
+    'file': 'config_key',
     'kwds': {'title': 'Test keybindings',
              'action': 'find-again',
              'currentKeySequences': [''] ,
@@ -177,7 +177,7 @@ GetKeysDialog_spec = {
     }
 
 _grep_dialog_spec = {
-    'file': 'GrepDialog',
+    'file': 'grep',
     'kwds': {},
     'msg': "Click the 'Show GrepDialog' button.\n"
            "Test the various 'Find-in-files' functions.\n"
@@ -187,7 +187,7 @@ _grep_dialog_spec = {
     }
 
 _io_binding_spec = {
-    'file': 'IOBinding',
+    'file': 'iomenu',
     'kwds': {},
     'msg': "Test the following bindings.\n"
            "<Control-o> to open file from dialog.\n"
@@ -200,7 +200,7 @@ _io_binding_spec = {
     }
 
 _multi_call_spec = {
-    'file': 'MultiCall',
+    'file': 'multicall',
     'kwds': {},
     'msg': "The following actions should trigger a print to console or IDLE"
            " Shell.\nEntering and leaving the text area, key entry, "
@@ -210,14 +210,14 @@ _multi_call_spec = {
     }
 
 _multistatus_bar_spec = {
-    'file': 'MultiStatusBar',
+    'file': 'statusbar',
     'kwds': {},
     'msg': "Ensure presence of multi-status bar below text area.\n"
            "Click 'Update Status' to change the multi-status text"
     }
 
 _object_browser_spec = {
-    'file': 'ObjectBrowser',
+    'file': 'debugobj',
     'kwds': {},
     'msg': "Double click on items upto the lowest level.\n"
            "Attributes of the objects and related information "
@@ -225,7 +225,7 @@ _object_browser_spec = {
     }
 
 _path_browser_spec = {
-    'file': 'PathBrowser',
+    'file': 'pathbrowser',
     'kwds': {},
     'msg': "Test for correct display of all paths in sys.path.\n"
            "Toggle nested items upto the lowest level.\n"
@@ -234,7 +234,7 @@ _path_browser_spec = {
     }
 
 _percolator_spec = {
-    'file': 'Percolator',
+    'file': 'percolator',
     'kwds': {},
     'msg': "There are two tracers which can be toggled using a checkbox.\n"
            "Toggling a tracer 'on' by checking it should print tracer"
@@ -245,7 +245,7 @@ _percolator_spec = {
     }
 
 _replace_dialog_spec = {
-    'file': 'ReplaceDialog',
+    'file': 'replace',
     'kwds': {},
     'msg': "Click the 'Replace' button.\n"
            "Test various replace options in the 'Replace dialog'.\n"
@@ -253,7 +253,7 @@ _replace_dialog_spec = {
     }
 
 _search_dialog_spec = {
-    'file': 'SearchDialog',
+    'file': 'search',
     'kwds': {},
     'msg': "Click the 'Search' button.\n"
            "Test various search options in the 'Search dialog'.\n"
@@ -261,7 +261,7 @@ _search_dialog_spec = {
     }
 
 _scrolled_list_spec = {
-    'file': 'ScrolledList',
+    'file': 'scrolledlist',
     'kwds': {},
     'msg': "You should see a scrollable list of items\n"
            "Selecting (clicking) or double clicking an item "
@@ -277,7 +277,7 @@ show_idlehelp_spec = {
     }
 
 _stack_viewer_spec = {
-    'file': 'StackViewer',
+    'file': 'stackviewer',
     'kwds': {},
     'msg': "A stacktrace for a NameError exception.\n"
            "Expand 'idlelib ...' and '<locals>'.\n"
@@ -295,8 +295,8 @@ _tabbed_pages_spec = {
     }
 
 TextViewer_spec = {
-    'file': 'textView',
-    'kwds': {'title': 'Test textView',
+    'file': 'textview',
+    'kwds': {'title': 'Test textview',
              'text':'The quick brown fox jumps over the lazy dog.\n'*35,
              '_htest': True},
     'msg': "Test for read-only property of text.\n"
@@ -304,21 +304,21 @@ TextViewer_spec = {
      }
 
 _tooltip_spec = {
-    'file': 'ToolTip',
+    'file': 'tooltip',
     'kwds': {},
     'msg': "Place mouse cursor over both the buttons\n"
            "A tooltip should appear with some text."
     }
 
 _tree_widget_spec = {
-    'file': 'TreeWidget',
+    'file': 'tree',
     'kwds': {},
     'msg': "The canvas is scrollable.\n"
            "Click on folders upto to the lowest level."
     }
 
 _undo_delegator_spec = {
-    'file': 'UndoDelegator',
+    'file': 'undo',
     'kwds': {},
     'msg': "Click [Undo] to undo any action.\n"
            "Click [Redo] to redo any action.\n"
@@ -327,7 +327,7 @@ _undo_delegator_spec = {
     }
 
 _widget_redirector_spec = {
-    'file': 'WidgetRedirector',
+    'file': 'redirector',
     'kwds': {},
     'msg': "Every text insert should be printed to the console."
            "or the IDLE shell."
@@ -337,7 +337,7 @@ def run(*tests):
     root = tk.Tk()
     root.title('IDLE htest')
     root.resizable(0, 0)
-    _initializeTkVariantTests(root)
+    _init_tk_type(root)
 
     # a scrollable Label like constant width text widget.
     frameLabel = tk.Frame(root, padx=10)
diff --git a/Lib/idlelib/idle_test/mock_idle.py b/Lib/idlelib/idle_test/mock_idle.py
index 1672a3413e..c7b49ef02b 100644
--- a/Lib/idlelib/idle_test/mock_idle.py
+++ b/Lib/idlelib/idle_test/mock_idle.py
@@ -33,7 +33,7 @@ class Func:
 
 
 class Editor:
-    '''Minimally imitate EditorWindow.EditorWindow class.
+    '''Minimally imitate editor.EditorWindow class.
     '''
     def __init__(self, flist=None, filename=None, key=None, root=None):
         self.text = Text()
@@ -46,7 +46,7 @@ class Editor:
 
 
 class UndoDelegator:
-    '''Minimally imitate UndoDelegator,UndoDelegator class.
+    '''Minimally imitate undo.UndoDelegator class.
     '''
     # A real undo block is only needed for user interaction.
     def undo_block_start(*args):
diff --git a/Lib/idlelib/idle_test/test_autocomplete.py b/Lib/idlelib/idle_test/test_autocomplete.py
index e4493d1205..496a41dbe7 100644
--- a/Lib/idlelib/idle_test/test_autocomplete.py
+++ b/Lib/idlelib/idle_test/test_autocomplete.py
@@ -2,9 +2,9 @@ import unittest
 from test.support import requires
 from tkinter import Tk, Text
 
-import idlelib.AutoComplete as ac
-import idlelib.AutoCompleteWindow as acw
-import idlelib.macosxSupport as mac
+import idlelib.autocomplete as ac
+import idlelib.autocomplete_w as acw
+import idlelib.macosx as mac
 from idlelib.idle_test.mock_idle import Func
 from idlelib.idle_test.mock_tk import Event
 
diff --git a/Lib/idlelib/idle_test/test_autoexpand.py b/Lib/idlelib/idle_test/test_autoexpand.py
index d2a3156dca..5d234dd862 100644
--- a/Lib/idlelib/idle_test/test_autoexpand.py
+++ b/Lib/idlelib/idle_test/test_autoexpand.py
@@ -1,9 +1,9 @@
-"""Unit tests for idlelib.AutoExpand"""
+"""Unit tests for idlelib.autoexpand"""
 import unittest
 from test.support import requires
 from tkinter import Text, Tk
 #from idlelib.idle_test.mock_tk import Text
-from idlelib.AutoExpand import AutoExpand
+from idlelib.autoexpand import AutoExpand
 
 
 class Dummy_Editwin:
diff --git a/Lib/idlelib/idle_test/test_calltips.py b/Lib/idlelib/idle_test/test_calltips.py
index b2a733cc0d..0b11602ca9 100644
--- a/Lib/idlelib/idle_test/test_calltips.py
+++ b/Lib/idlelib/idle_test/test_calltips.py
@@ -1,5 +1,5 @@
 import unittest
-import idlelib.CallTips as ct
+import idlelib.calltips as ct
 import textwrap
 import types
 
diff --git a/Lib/idlelib/idle_test/test_config_help.py b/Lib/idlelib/idle_test/test_config_help.py
index 664f8edc62..b89b4e3ca1 100644
--- a/Lib/idlelib/idle_test/test_config_help.py
+++ b/Lib/idlelib/idle_test/test_config_help.py
@@ -1,7 +1,7 @@
-"""Unittests for idlelib.configHelpSourceEdit"""
+"""Unittests for idlelib.config_help.py"""
 import unittest
 from idlelib.idle_test.mock_tk import Var, Mbox, Entry
-from idlelib import configHelpSourceEdit as help_dialog_module
+from idlelib import config_help as help_dialog_module
 
 help_dialog = help_dialog_module.GetHelpSourceDialog
 
diff --git a/Lib/idlelib/idle_test/test_config_name.py b/Lib/idlelib/idle_test/test_config_sec.py
index 40e72b9551..a98b484bf7 100644
--- a/Lib/idlelib/idle_test/test_config_name.py
+++ b/Lib/idlelib/idle_test/test_config_sec.py
@@ -1,7 +1,7 @@
-"""Unit tests for idlelib.configSectionNameDialog"""
+"""Unit tests for idlelib.config_sec"""
 import unittest
 from idlelib.idle_test.mock_tk import Var, Mbox
-from idlelib import configSectionNameDialog as name_dialog_module
+from idlelib import config_sec as name_dialog_module
 
 name_dialog = name_dialog_module.GetCfgSectionNameDialog
 
diff --git a/Lib/idlelib/idle_test/test_configdialog.py b/Lib/idlelib/idle_test/test_configdialog.py
index b063601b27..1801a7d6c2 100644
--- a/Lib/idlelib/idle_test/test_configdialog.py
+++ b/Lib/idlelib/idle_test/test_configdialog.py
@@ -1,21 +1,19 @@
-'''Test idlelib.configDialog.
+'''Test idlelib.configdialog.
 
 Coverage: 46% just by creating dialog.
 The other half is code for working with user customizations.
 '''
-from idlelib.configDialog import ConfigDialog  # always test import
+from idlelib.configdialog import ConfigDialog  # always test import
 from test.support import requires
 requires('gui')
 from tkinter import Tk
 import unittest
-from idlelib import macosxSupport as macosx
 
 class ConfigDialogTest(unittest.TestCase):
 
     @classmethod
     def setUpClass(cls):
         cls.root = Tk()
-        macosx._initializeTkVariantTests(cls.root)
 
     @classmethod
     def tearDownClass(cls):
diff --git a/Lib/idlelib/idle_test/test_delegator.py b/Lib/idlelib/idle_test/test_delegator.py
index 1f0baa9c0d..85624fbc12 100644
--- a/Lib/idlelib/idle_test/test_delegator.py
+++ b/Lib/idlelib/idle_test/test_delegator.py
@@ -1,5 +1,5 @@
 import unittest
-from idlelib.Delegator import Delegator
+from idlelib.delegator import Delegator
 
 class DelegatorTest(unittest.TestCase):
 
diff --git a/Lib/idlelib/idle_test/test_editor.py b/Lib/idlelib/idle_test/test_editor.py
index a31d26d25d..e9d29d45b8 100644
--- a/Lib/idlelib/idle_test/test_editor.py
+++ b/Lib/idlelib/idle_test/test_editor.py
@@ -1,6 +1,6 @@
 import unittest
 from tkinter import Tk, Text
-from idlelib.EditorWindow import EditorWindow
+from idlelib.editor import EditorWindow
 from test.support import requires
 
 class Editor_func_test(unittest.TestCase):
diff --git a/Lib/idlelib/idle_test/test_grep.py b/Lib/idlelib/idle_test/test_grep.py
index 0d8ff0d9f1..6b54c13131 100644
--- a/Lib/idlelib/idle_test/test_grep.py
+++ b/Lib/idlelib/idle_test/test_grep.py
@@ -1,5 +1,5 @@
 """ !Changing this line will break Test_findfile.test_found!
-Non-gui unit tests for idlelib.GrepDialog methods.
+Non-gui unit tests for grep.GrepDialog methods.
 dummy_command calls grep_it calls findfiles.
 An exception raised in one method will fail callers.
 Otherwise, tests are mostly independent.
@@ -8,7 +8,7 @@ Otherwise, tests are mostly independent.
 import unittest
 from test.support import captured_stdout
 from idlelib.idle_test.mock_tk import Var
-from idlelib.GrepDialog import GrepDialog
+from idlelib.grep import GrepDialog
 import re
 
 class Dummy_searchengine:
@@ -72,7 +72,7 @@ class Grep_itTest(unittest.TestCase):
         self.assertTrue(lines[4].startswith('(Hint:'))
 
 class Default_commandTest(unittest.TestCase):
-    # To write this, mode OutputWindow import to top of GrepDialog
+    # To write this, move outwin import to top of GrepDialog
     # so it can be replaced by captured_stdout in class setup/teardown.
     pass
 
diff --git a/Lib/idlelib/idle_test/test_idlehistory.py b/Lib/idlelib/idle_test/test_history.py
index d7c3d70393..6e8269c5f5 100644
--- a/Lib/idlelib/idle_test/test_idlehistory.py
+++ b/Lib/idlelib/idle_test/test_history.py
@@ -4,8 +4,8 @@ from test.support import requires
 import tkinter as tk
 from tkinter import Text as tkText
 from idlelib.idle_test.mock_tk import Text as mkText
-from idlelib.IdleHistory import History
-from idlelib.configHandler import idleConf
+from idlelib.history import History
+from idlelib.config import idleConf
 
 line1 = 'a = 7'
 line2 = 'b = a'
diff --git a/Lib/idlelib/idle_test/test_hyperparser.py b/Lib/idlelib/idle_test/test_hyperparser.py
index edfc783fe8..067e5b19e8 100644
--- a/Lib/idlelib/idle_test/test_hyperparser.py
+++ b/Lib/idlelib/idle_test/test_hyperparser.py
@@ -1,9 +1,9 @@
-"""Unittest for idlelib.HyperParser"""
+"""Unittest for idlelib.hyperparser.py."""
 import unittest
 from test.support import requires
 from tkinter import Tk, Text
-from idlelib.EditorWindow import EditorWindow
-from idlelib.HyperParser import HyperParser
+from idlelib.editor import EditorWindow
+from idlelib.hyperparser import HyperParser
 
 class DummyEditwin:
     def __init__(self, text):
diff --git a/Lib/idlelib/idle_test/test_io.py b/Lib/idlelib/idle_test/test_iomenu.py
index e0e3b985e2..f8ff1127c3 100644
--- a/Lib/idlelib/idle_test/test_io.py
+++ b/Lib/idlelib/idle_test/test_iomenu.py
@@ -1,6 +1,6 @@
 import unittest
 import io
-from idlelib.PyShell import PseudoInputFile, PseudoOutputFile
+from idlelib.pyshell import PseudoInputFile, PseudoOutputFile
 
 
 class S(str):
diff --git a/Lib/idlelib/idle_test/test_macosx.py b/Lib/idlelib/idle_test/test_macosx.py
new file mode 100644
index 0000000000..0f90fb65f1
--- /dev/null
+++ b/Lib/idlelib/idle_test/test_macosx.py
@@ -0,0 +1,69 @@
+'''Test idlelib.macosx.py
+'''
+from idlelib import macosx
+from test.support import requires
+import sys
+import tkinter as tk
+import unittest
+import unittest.mock as mock
+
+MAC = sys.platform == 'darwin'
+mactypes = {'carbon', 'cocoa', 'xquartz'}
+nontypes = {'other'}
+alltypes = mactypes | nontypes
+
+
+class InitTktypeTest(unittest.TestCase):
+    "Test _init_tk_type."
+
+    @classmethod
+    def setUpClass(cls):
+        requires('gui')
+        cls.root = tk.Tk()
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.root.update_idletasks()
+        cls.root.destroy()
+        del cls.root
+
+    def test_init_sets_tktype(self):
+        "Test that _init_tk_type sets _tk_type according to platform."
+        for root in (None, self.root):
+            with self.subTest(root=root):
+                macosx._tk_type == None
+                macosx._init_tk_type(root)
+                self.assertIn(macosx._tk_type,
+                              mactypes if MAC else nontypes)
+
+
+class IsTypeTkTest(unittest.TestCase):
+    "Test each of the four isTypeTk predecates."
+    isfuncs = ((macosx.isAquaTk, ('carbon', 'cocoa')),
+               (macosx.isCarbonTk, ('carbon')),
+               (macosx.isCocoaTk, ('cocoa')),
+               (macosx.isXQuartz, ('xquartz')),
+               )
+
+    @mock.patch('idlelib.macosx._init_tk_type')
+    def test_is_calls_init(self, mockinit):
+        "Test that each isTypeTk calls _init_tk_type when _tk_type is None."
+        macosx._tk_type = None
+        for func, whentrue in self.isfuncs:
+            with self.subTest(func=func):
+                func()
+                self.assertTrue(mockinit.called)
+                mockinit.reset_mock()
+
+    def test_isfuncs(self):
+        "Test that each isTypeTk return correct bool."
+        for func, whentrue in self.isfuncs:
+            for tktype in alltypes:
+                with self.subTest(func=func, whentrue=whentrue, tktype=tktype):
+                    macosx._tk_type = tktype
+                    (self.assertTrue if tktype in whentrue else self.assertFalse)\
+                                     (func())
+
+
+if __name__ == '__main__':
+    unittest.main(verbosity=2)
diff --git a/Lib/idlelib/idle_test/test_formatparagraph.py b/Lib/idlelib/idle_test/test_paragraph.py
index e5561d84a6..4741eb87be 100644
--- a/Lib/idlelib/idle_test/test_formatparagraph.py
+++ b/Lib/idlelib/idle_test/test_paragraph.py
@@ -1,7 +1,7 @@
-# Test the functions and main class method of FormatParagraph.py
+# Test the functions and main class method of paragraph.py
 import unittest
-from idlelib import FormatParagraph as fp
-from idlelib.EditorWindow import EditorWindow
+from idlelib import paragraph as fp
+from idlelib.editor import EditorWindow
 from tkinter import Tk, Text
 from test.support import requires
 
@@ -38,7 +38,7 @@ class Is_Get_Test(unittest.TestCase):
 
 
 class FindTest(unittest.TestCase):
-    """Test the find_paragraph function in FormatParagraph.
+    """Test the find_paragraph function in paragraph module.
 
     Using the runcase() function, find_paragraph() is called with 'mark' set at
     multiple indexes before and inside the test paragraph.
diff --git a/Lib/idlelib/idle_test/test_parenmatch.py b/Lib/idlelib/idle_test/test_parenmatch.py
index 95cc22cf68..d467a9a97a 100644
--- a/Lib/idlelib/idle_test/test_parenmatch.py
+++ b/Lib/idlelib/idle_test/test_parenmatch.py
@@ -1,4 +1,4 @@
-'''Test idlelib.ParenMatch.
+'''Test idlelib.parenmatch.
 
 This must currently be a gui test because ParenMatch methods use
 several text methods not defined on idlelib.idle_test.mock_tk.Text.
@@ -9,7 +9,7 @@ requires('gui')
 import unittest
 from unittest.mock import Mock
 from tkinter import Tk, Text
-from idlelib.ParenMatch import ParenMatch
+from idlelib.parenmatch import ParenMatch
 
 class DummyEditwin:
     def __init__(self, text):
diff --git a/Lib/idlelib/idle_test/test_pathbrowser.py b/Lib/idlelib/idle_test/test_pathbrowser.py
index afb886fa33..813cbcc631 100644
--- a/Lib/idlelib/idle_test/test_pathbrowser.py
+++ b/Lib/idlelib/idle_test/test_pathbrowser.py
@@ -2,13 +2,13 @@ import unittest
 import os
 import sys
 import idlelib
-from idlelib import PathBrowser
+from idlelib import pathbrowser
 
 class PathBrowserTest(unittest.TestCase):
 
     def test_DirBrowserTreeItem(self):
         # Issue16226 - make sure that getting a sublist works
-        d = PathBrowser.DirBrowserTreeItem('')
+        d = pathbrowser.DirBrowserTreeItem('')
         d.GetSubList()
         self.assertEqual('', d.GetText())
 
@@ -17,11 +17,11 @@ class PathBrowserTest(unittest.TestCase):
         self.assertEqual(d.ispackagedir(dir + '/Icons'), False)
 
     def test_PathBrowserTreeItem(self):
-        p = PathBrowser.PathBrowserTreeItem()
+        p = pathbrowser.PathBrowserTreeItem()
         self.assertEqual(p.GetText(), 'sys.path')
         sub = p.GetSubList()
         self.assertEqual(len(sub), len(sys.path))
-        self.assertEqual(type(sub[0]), PathBrowser.DirBrowserTreeItem)
+        self.assertEqual(type(sub[0]), pathbrowser.DirBrowserTreeItem)
 
 if __name__ == '__main__':
     unittest.main(verbosity=2, exit=False)
diff --git a/Lib/idlelib/idle_test/test_percolator.py b/Lib/idlelib/idle_test/test_percolator.py
index 4c0a7ad2bd..573b9a1e8e 100644
--- a/Lib/idlelib/idle_test/test_percolator.py
+++ b/Lib/idlelib/idle_test/test_percolator.py
@@ -1,10 +1,10 @@
-'''Test Percolator'''
+'''Test percolator.py.'''
 from test.support import requires
 requires('gui')
 
 import unittest
 from tkinter import Text, Tk, END
-from idlelib.Percolator import Percolator, Delegator
+from idlelib.percolator import Percolator, Delegator
 
 
 class MyFilter(Delegator):
diff --git a/Lib/idlelib/idle_test/test_widgetredir.py b/Lib/idlelib/idle_test/test_redirector.py
index c68dfcc412..c8dd1184c4 100644
--- a/Lib/idlelib/idle_test/test_widgetredir.py
+++ b/Lib/idlelib/idle_test/test_redirector.py
@@ -1,4 +1,4 @@
-'''Test idlelib.WidgetRedirector.
+'''Test idlelib.redirector.
 
 100% coverage
 '''
@@ -6,7 +6,7 @@ from test.support import requires
 import unittest
 from idlelib.idle_test.mock_idle import Func
 from tkinter import Tk, Text, TclError
-from idlelib.WidgetRedirector import WidgetRedirector
+from idlelib.redirector import WidgetRedirector
 
 
 class InitCloseTest(unittest.TestCase):
@@ -118,6 +118,5 @@ class WidgetRedirectorTest(unittest.TestCase):
         self.assertEqual(self.root.call(self.text._w, 'insert', 'boo'), '')
 
 
-
 if __name__ == '__main__':
     unittest.main(verbosity=2)
diff --git a/Lib/idlelib/idle_test/test_replacedialog.py b/Lib/idlelib/idle_test/test_replace.py
index ff44820809..a9f3e15f25 100644
--- a/Lib/idlelib/idle_test/test_replacedialog.py
+++ b/Lib/idlelib/idle_test/test_replace.py
@@ -1,4 +1,4 @@
-"""Unittest for idlelib.ReplaceDialog"""
+"""Unittest for idlelib.replace.py"""
 from test.support import requires
 requires('gui')
 
@@ -6,8 +6,8 @@ import unittest
 from unittest.mock import Mock
 from tkinter import Tk, Text
 from idlelib.idle_test.mock_tk import Mbox
-import idlelib.SearchEngine as se
-import idlelib.ReplaceDialog as rd
+import idlelib.searchengine as se
+import idlelib.replace as rd
 
 orig_mbox = se.tkMessageBox
 showerror = Mbox.showerror
diff --git a/Lib/idlelib/idle_test/test_rstrip.py b/Lib/idlelib/idle_test/test_rstrip.py
index 1c90b93d21..130e6be257 100644
--- a/Lib/idlelib/idle_test/test_rstrip.py
+++ b/Lib/idlelib/idle_test/test_rstrip.py
@@ -1,5 +1,5 @@
 import unittest
-import idlelib.RstripExtension as rs
+import idlelib.rstrip as rs
 from idlelib.idle_test.mock_idle import Editor
 
 class rstripTest(unittest.TestCase):
@@ -21,7 +21,7 @@ class rstripTest(unittest.TestCase):
     def test_rstrip_multiple(self):
         editor = Editor()
         #  Uncomment following to verify that test passes with real widgets.
-##        from idlelib.EditorWindow import EditorWindow as Editor
+##        from idlelib.editor import EditorWindow as Editor
 ##        from tkinter import Tk
 ##        editor = Editor(root=Tk())
         text = editor.text
diff --git a/Lib/idlelib/idle_test/test_searchdialog.py b/Lib/idlelib/idle_test/test_search.py
index 190c866a18..0735d84356 100644
--- a/Lib/idlelib/idle_test/test_searchdialog.py
+++ b/Lib/idlelib/idle_test/test_search.py
@@ -1,4 +1,4 @@
-"""Test SearchDialog class in SearchDialogue.py"""
+"""Test SearchDialog class in idlelib.search.py"""
 
 # Does not currently test the event handler wrappers.
 # A usage test should simulate clicks and check hilighting.
@@ -11,8 +11,8 @@ requires('gui')
 import unittest
 import tkinter as tk
 from tkinter import BooleanVar
-import idlelib.SearchEngine as se
-import idlelib.SearchDialog as sd
+import idlelib.searchengine as se
+import idlelib.search as sd
 
 
 class SearchDialogTest(unittest.TestCase):
diff --git a/Lib/idlelib/idle_test/test_searchdialogbase.py b/Lib/idlelib/idle_test/test_searchbase.py
index 8036b918c5..5ff9476c87 100644
--- a/Lib/idlelib/idle_test/test_searchdialogbase.py
+++ b/Lib/idlelib/idle_test/test_searchbase.py
@@ -1,4 +1,4 @@
-'''Unittests for idlelib/SearchDialogBase.py
+'''Unittests for idlelib/searchbase.py
 
 Coverage: 99%. The only thing not covered is inconsequential --
 testing skipping of suite when self.needwrapbutton is false.
@@ -7,8 +7,8 @@ testing skipping of suite when self.needwrapbutton is false.
 import unittest
 from test.support import requires
 from tkinter import Tk, Toplevel, Frame ##, BooleanVar, StringVar
-from idlelib import SearchEngine as se
-from idlelib import SearchDialogBase as sdb
+from idlelib import searchengine as se
+from idlelib import searchbase as sdb
 from idlelib.idle_test.mock_idle import Func
 ## from idlelib.idle_test.mock_tk import Var
 
diff --git a/Lib/idlelib/idle_test/test_searchengine.py b/Lib/idlelib/idle_test/test_searchengine.py
index edbd558133..7e6f8b71a8 100644
--- a/Lib/idlelib/idle_test/test_searchengine.py
+++ b/Lib/idlelib/idle_test/test_searchengine.py
@@ -1,4 +1,4 @@
-'''Test functions and SearchEngine class in SearchEngine.py.'''
+'''Test functions and SearchEngine class in idlelib.searchengine.py.'''
 
 # With mock replacements, the module does not use any gui widgets.
 # The use of tk.Text is avoided (for now, until mock Text is improved)
@@ -10,7 +10,7 @@ import unittest
 # from test.support import requires
 from tkinter import  BooleanVar, StringVar, TclError  # ,Tk, Text
 import tkinter.messagebox as tkMessageBox
-from idlelib import SearchEngine as se
+from idlelib import searchengine as se
 from idlelib.idle_test.mock_tk import Var, Mbox
 from idlelib.idle_test.mock_tk import Text as mockText
 
diff --git a/Lib/idlelib/idle_test/test_textview.py b/Lib/idlelib/idle_test/test_textview.py
index 02d1472240..4c70ebb905 100644
--- a/Lib/idlelib/idle_test/test_textview.py
+++ b/Lib/idlelib/idle_test/test_textview.py
@@ -1,4 +1,4 @@
-'''Test idlelib.textView.
+'''Test idlelib.textview.
 
 Since all methods and functions create (or destroy) a TextViewer, which
 is a widget containing multiple widgets, all tests must be gui tests.
@@ -13,7 +13,7 @@ requires('gui')
 import unittest
 import os
 from tkinter import Tk
-from idlelib import textView as tv
+from idlelib import textview as tv
 from idlelib.idle_test.mock_idle import Func
 from idlelib.idle_test.mock_tk import Mbox
 
diff --git a/Lib/idlelib/idle_test/test_undodelegator.py b/Lib/idlelib/idle_test/test_undo.py
index 2b83c991e2..80f1b8071e 100644
--- a/Lib/idlelib/idle_test/test_undodelegator.py
+++ b/Lib/idlelib/idle_test/test_undo.py
@@ -1,4 +1,4 @@
-"""Unittest for UndoDelegator in idlelib.UndoDelegator.
+"""Unittest for UndoDelegator in idlelib.undo.py.
 
 Coverage about 80% (retest).
 """
@@ -8,8 +8,8 @@ requires('gui')
 import unittest
 from unittest.mock import Mock
 from tkinter import Text, Tk
-from idlelib.UndoDelegator import UndoDelegator
-from idlelib.Percolator import Percolator
+from idlelib.undo import UndoDelegator
+from idlelib.percolator import Percolator
 
 
 class UndoDelegatorTest(unittest.TestCase):
diff --git a/Lib/idlelib/idle_test/test_warning.py b/Lib/idlelib/idle_test/test_warning.py
index 18627ddd23..f3269f195a 100644
--- a/Lib/idlelib/idle_test/test_warning.py
+++ b/Lib/idlelib/idle_test/test_warning.py
@@ -1,4 +1,4 @@
-'''Test warnings replacement in PyShell.py and run.py.
+'''Test warnings replacement in pyshell.py and run.py.
 
 This file could be expanded to include traceback overrides
 (in same two modules). If so, change name.
@@ -17,9 +17,9 @@ showwarning = warnings.showwarning
 running_in_idle = 'idle' in showwarning.__name__
 
 from idlelib import run
-from idlelib import PyShell as shell
+from idlelib import pyshell as shell
 
-# The following was generated from PyShell.idle_formatwarning
+# The following was generated from pyshell.idle_formatwarning
 # and checked as matching expectation.
 idlemsg = '''
 Warning (from warnings module):
diff --git a/Lib/idlelib/idlever.py b/Lib/idlelib/idlever.py
deleted file mode 100644
index 3e9f69a3e3..0000000000
--- a/Lib/idlelib/idlever.py
+++ /dev/null
@@ -1,12 +0,0 @@
-"""
-The separate Idle version was eliminated years ago;
-idlelib.idlever is no longer used by Idle
-and will be removed in 3.6 or later.  Use
-    from sys import version
-    IDLE_VERSION = version[:version.index(' ')]
-"""
-# Kept for now only for possible existing extension use
-import warnings as w
-w.warn(__doc__, DeprecationWarning, stacklevel=2)
-from sys import version
-IDLE_VERSION = version[:version.index(' ')]
diff --git a/Lib/idlelib/IOBinding.py b/Lib/idlelib/iomenu.py
index 84f39a2fee..f6a7f1489f 100644
--- a/Lib/idlelib/IOBinding.py
+++ b/Lib/idlelib/iomenu.py
@@ -10,7 +10,7 @@ import tkinter.filedialog as tkFileDialog
 import tkinter.messagebox as tkMessageBox
 from tkinter.simpledialog import askstring
 
-from idlelib.configHandler import idleConf
+from idlelib.config import idleConf
 
 
 # Try setting the locale, so that we can find out
@@ -107,6 +107,9 @@ def coding_spec(data):
 
 
 class IOBinding:
+# One instance per editor Window so methods know which to save, close.
+# Open returns focus to self.editwin if aborted.
+# EditorWindow.open_module, others, belong here.
 
     def __init__(self, editwin):
         self.editwin = editwin
diff --git a/Lib/idlelib/macosxSupport.py b/Lib/idlelib/macosx.py
index b96bae1d55..4e4dcd6ae7 100644
--- a/Lib/idlelib/macosxSupport.py
+++ b/Lib/idlelib/macosx.py
@@ -3,28 +3,18 @@ A number of functions that enhance IDLE on Mac OSX.
 """
 import sys
 import tkinter
-from os import path
 import warnings
 
-def runningAsOSXApp():
-    warnings.warn("runningAsOSXApp() is deprecated, use isAquaTk()",
-                        DeprecationWarning, stacklevel=2)
-    return isAquaTk()
-
-def isCarbonAquaTk(root):
-    warnings.warn("isCarbonAquaTk(root) is deprecated, use isCarbonTk()",
-                        DeprecationWarning, stacklevel=2)
-    return isCarbonTk()
-
 _tk_type = None
 
-def _initializeTkVariantTests(root):
+def _init_tk_type(idleroot=None):
     """
     Initializes OS X Tk variant values for
     isAquaTk(), isCarbonTk(), isCocoaTk(), and isXQuartz().
     """
     global _tk_type
     if sys.platform == 'darwin':
+        root = idleroot or tkinter.Tk()
         ws = root.tk.call('tk', 'windowingsystem')
         if 'x11' in ws:
             _tk_type = "xquartz"
@@ -34,6 +24,8 @@ def _initializeTkVariantTests(root):
             _tk_type = "cocoa"
         else:
             _tk_type = "carbon"
+        if not idleroot:
+            root.destroy
     else:
         _tk_type = "other"
 
@@ -41,7 +33,8 @@ def isAquaTk():
     """
     Returns True if IDLE is using a native OS X Tk (Cocoa or Carbon).
     """
-    assert _tk_type is not None
+    if not _tk_type:
+        _init_tk_type()
     return _tk_type == "cocoa" or _tk_type == "carbon"
 
 def isCarbonTk():
@@ -49,21 +42,24 @@ def isCarbonTk():
     Returns True if IDLE is using a Carbon Aqua Tk (instead of the
     newer Cocoa Aqua Tk).
     """
-    assert _tk_type is not None
+    if not _tk_type:
+        _init_tk_type()
     return _tk_type == "carbon"
 
 def isCocoaTk():
     """
     Returns True if IDLE is using a Cocoa Aqua Tk.
     """
-    assert _tk_type is not None
+    if not _tk_type:
+        _init_tk_type()
     return _tk_type == "cocoa"
 
 def isXQuartz():
     """
     Returns True if IDLE is using an OS X X11 Tk.
     """
-    assert _tk_type is not None
+    if not _tk_type:
+        _init_tk_type()
     return _tk_type == "xquartz"
 
 def tkVersionWarning(root):
@@ -124,23 +120,23 @@ def overrideRootMenu(root, flist):
     # Due to a (mis-)feature of TkAqua the user will also see an empty Help
     # menu.
     from tkinter import Menu
-    from idlelib import Bindings
-    from idlelib import WindowList
+    from idlelib import mainmenu
+    from idlelib import windows
 
-    closeItem = Bindings.menudefs[0][1][-2]
+    closeItem = mainmenu.menudefs[0][1][-2]
 
     # Remove the last 3 items of the file menu: a separator, close window and
     # quit. Close window will be reinserted just above the save item, where
     # it should be according to the HIG. Quit is in the application menu.
-    del Bindings.menudefs[0][1][-3:]
-    Bindings.menudefs[0][1].insert(6, closeItem)
+    del mainmenu.menudefs[0][1][-3:]
+    mainmenu.menudefs[0][1].insert(6, closeItem)
 
     # Remove the 'About' entry from the help menu, it is in the application
     # menu
-    del Bindings.menudefs[-1][1][0:2]
+    del mainmenu.menudefs[-1][1][0:2]
     # Remove the 'Configure Idle' entry from the options menu, it is in the
     # application menu as 'Preferences'
-    del Bindings.menudefs[-2][1][0]
+    del mainmenu.menudefs[-2][1][0]
     menubar = Menu(root)
     root.configure(menu=menubar)
     menudict = {}
@@ -155,30 +151,30 @@ def overrideRootMenu(root, flist):
 
         if end > 0:
             menu.delete(0, end)
-        WindowList.add_windows_to_menu(menu)
-    WindowList.register_callback(postwindowsmenu)
+        windows.add_windows_to_menu(menu)
+    windows.register_callback(postwindowsmenu)
 
     def about_dialog(event=None):
         "Handle Help 'About IDLE' event."
-        # Synchronize with EditorWindow.EditorWindow.about_dialog.
-        from idlelib import aboutDialog
-        aboutDialog.AboutDialog(root, 'About IDLE')
+        # Synchronize with editor.EditorWindow.about_dialog.
+        from idlelib import help_about
+        help_about.AboutDialog(root, 'About IDLE')
 
     def config_dialog(event=None):
         "Handle Options 'Configure IDLE' event."
-        # Synchronize with EditorWindow.EditorWindow.config_dialog.
-        from idlelib import configDialog
+        # Synchronize with editor.EditorWindow.config_dialog.
+        from idlelib import configdialog
 
         # Ensure that the root object has an instance_dict attribute,
         # mirrors code in EditorWindow (although that sets the attribute
         # on an EditorWindow instance that is then passed as the first
         # argument to ConfigDialog)
         root.instance_dict = flist.inversedict
-        configDialog.ConfigDialog(root, 'Settings')
+        configdialog.ConfigDialog(root, 'Settings')
 
     def help_dialog(event=None):
         "Handle Help 'IDLE Help' event."
-        # Synchronize with EditorWindow.EditorWindow.help_dialog.
+        # Synchronize with editor.EditorWindow.help_dialog.
         from idlelib import help
         help.show_idlehelp(root)
 
@@ -198,7 +194,7 @@ def overrideRootMenu(root, flist):
         menudict['application'] = menu = Menu(menubar, name='apple',
                                               tearoff=0)
         menubar.add_cascade(label='IDLE', menu=menu)
-        Bindings.menudefs.insert(0,
+        mainmenu.menudefs.insert(0,
             ('application', [
                 ('About IDLE', '<<about-idle>>'),
                     None,
@@ -206,7 +202,7 @@ def overrideRootMenu(root, flist):
         tkversion = root.tk.eval('info patchlevel')
         if tuple(map(int, tkversion.split('.'))) < (8, 4, 14):
             # for earlier AquaTk versions, supply a Preferences menu item
-            Bindings.menudefs[0][1].append(
+            mainmenu.menudefs[0][1].append(
                     ('_Preferences....', '<<open-config-dialog>>'),
                 )
     if isCocoaTk():
@@ -215,12 +211,22 @@ def overrideRootMenu(root, flist):
         # replace default "Help" item in Help menu
         root.createcommand('::tk::mac::ShowHelp', help_dialog)
         # remove redundant "IDLE Help" from menu
-        del Bindings.menudefs[-1][1][0]
+        del mainmenu.menudefs[-1][1][0]
+
+def fixb2context(root):
+    '''Removed bad AquaTk Button-2 (right) and Paste bindings.
+
+    They prevent context menu access and seem to be gone in AquaTk8.6.
+    See issue #24801.
+    '''
+    root.unbind_class('Text', '<B2>')
+    root.unbind_class('Text', '<B2-Motion>')
+    root.unbind_class('Text', '<<PasteSelection>>')
 
 def setupApp(root, flist):
     """
     Perform initial OS X customizations if needed.
-    Called from PyShell.main() after initial calls to Tk()
+    Called from pyshell.main() after initial calls to Tk()
 
     There are currently three major versions of Tk in use on OS X:
         1. Aqua Cocoa Tk (native default since OS X 10.6)
@@ -233,8 +239,9 @@ def setupApp(root, flist):
     isAquaTk(), isCarbonTk(), isCocoaTk(), isXQuartz() functions which
     are initialized here as well.
     """
-    _initializeTkVariantTests(root)
+    _init_tk_type(root)
     if isAquaTk():
         hideTkConsole(root)
         overrideRootMenu(root, flist)
         addOpenEventSupport(root, flist)
+        fixb2context()
diff --git a/Lib/idlelib/Bindings.py b/Lib/idlelib/mainmenu.py
index ab25ff18b6..965ada3081 100644
--- a/Lib/idlelib/Bindings.py
+++ b/Lib/idlelib/mainmenu.py
@@ -10,9 +10,9 @@ windows.
 """
 from importlib.util import find_spec
 
-from idlelib.configHandler import idleConf
+from idlelib.config import idleConf
 
-#   Warning: menudefs is altered in macosxSupport.overrideRootMenu()
+#   Warning: menudefs is altered in macosx.overrideRootMenu()
 #   after it is determined that an OS X Aqua Tk is in use,
 #   which cannot be done until after Tk() is first called.
 #   Do not alter the 'file', 'options', or 'help' cascades here
diff --git a/Lib/idlelib/MultiCall.py b/Lib/idlelib/multicall.py
index 8462854921..8462854921 100644
--- a/Lib/idlelib/MultiCall.py
+++ b/Lib/idlelib/multicall.py
diff --git a/Lib/idlelib/OutputWindow.py b/Lib/idlelib/outwin.py
index e614f9b2bb..b3bc786151 100644
--- a/Lib/idlelib/OutputWindow.py
+++ b/Lib/idlelib/outwin.py
@@ -1,8 +1,8 @@
 from tkinter import *
-from idlelib.EditorWindow import EditorWindow
+from idlelib.editor import EditorWindow
 import re
 import tkinter.messagebox as tkMessageBox
-from idlelib import IOBinding
+from idlelib import iomenu
 
 class OutputWindow(EditorWindow):
 
@@ -36,7 +36,7 @@ class OutputWindow(EditorWindow):
 
     def write(self, s, tags=(), mark="insert"):
         if isinstance(s, (bytes, bytes)):
-            s = s.decode(IOBinding.encoding, "replace")
+            s = s.decode(iomenu.encoding, "replace")
         self.text.insert(mark, s, tags)
         self.text.see(mark)
         self.text.update()
diff --git a/Lib/idlelib/FormatParagraph.py b/Lib/idlelib/paragraph.py
index 7a9d185042..0323b53d86 100644
--- a/Lib/idlelib/FormatParagraph.py
+++ b/Lib/idlelib/paragraph.py
@@ -16,7 +16,7 @@ Known problems with comment reformatting:
 """
 
 import re
-from idlelib.configHandler import idleConf
+from idlelib.config import idleConf
 
 class FormatParagraph:
 
@@ -191,5 +191,5 @@ def get_comment_header(line):
 
 if __name__ == "__main__":
     import unittest
-    unittest.main('idlelib.idle_test.test_formatparagraph',
+    unittest.main('idlelib.idle_test.test_paragraph',
             verbosity=2, exit=False)
diff --git a/Lib/idlelib/ParenMatch.py b/Lib/idlelib/parenmatch.py
index 19bad8ce38..e98fac1952 100644
--- a/Lib/idlelib/ParenMatch.py
+++ b/Lib/idlelib/parenmatch.py
@@ -5,8 +5,8 @@ paren.  Paren here is used generically; the matching applies to
 parentheses, square brackets, and curly braces.
 """
 
-from idlelib.HyperParser import HyperParser
-from idlelib.configHandler import idleConf
+from idlelib.hyperparser import HyperParser
+from idlelib.config import idleConf
 
 _openers = {')':'(',']':'[','}':'{'}
 CHECK_DELAY = 100 # miliseconds
diff --git a/Lib/idlelib/PathBrowser.py b/Lib/idlelib/pathbrowser.py
index 9ab7632f4d..966af4b259 100644
--- a/Lib/idlelib/PathBrowser.py
+++ b/Lib/idlelib/pathbrowser.py
@@ -2,9 +2,9 @@ import os
 import sys
 import importlib.machinery
 
-from idlelib.TreeWidget import TreeItem
-from idlelib.ClassBrowser import ClassBrowser, ModuleBrowserTreeItem
-from idlelib.PyShell import PyShellFileList
+from idlelib.tree import TreeItem
+from idlelib.browser import ClassBrowser, ModuleBrowserTreeItem
+from idlelib.pyshell import PyShellFileList
 
 
 class PathBrowser(ClassBrowser):
diff --git a/Lib/idlelib/Percolator.py b/Lib/idlelib/percolator.py
index b8be2aa746..227144581b 100644
--- a/Lib/idlelib/Percolator.py
+++ b/Lib/idlelib/percolator.py
@@ -1,5 +1,5 @@
-from idlelib.WidgetRedirector import WidgetRedirector
-from idlelib.Delegator import Delegator
+from idlelib.redirector import WidgetRedirector
+from idlelib.delegator import Delegator
 
 
 class Percolator:
diff --git a/Lib/idlelib/PyParse.py b/Lib/idlelib/pyparse.py
index 9ccbb25076..9ccbb25076 100644
--- a/Lib/idlelib/PyParse.py
+++ b/Lib/idlelib/pyparse.py
diff --git a/Lib/idlelib/PyShell.py b/Lib/idlelib/pyshell.py
index 1bcc9b6814..9fc46caa63 100755
--- a/Lib/idlelib/PyShell.py
+++ b/Lib/idlelib/pyshell.py
@@ -24,16 +24,16 @@ except ImportError:
     sys.exit(1)
 import tkinter.messagebox as tkMessageBox
 
-from idlelib.EditorWindow import EditorWindow, fixwordbreaks
-from idlelib.FileList import FileList
-from idlelib.ColorDelegator import ColorDelegator
-from idlelib.UndoDelegator import UndoDelegator
-from idlelib.OutputWindow import OutputWindow
-from idlelib.configHandler import idleConf
+from idlelib.editor import EditorWindow, fixwordbreaks
+from idlelib.filelist import FileList
+from idlelib.colorizer import ColorDelegator
+from idlelib.undo import UndoDelegator
+from idlelib.outwin import OutputWindow
+from idlelib.config import idleConf
 from idlelib import rpc
-from idlelib import Debugger
-from idlelib import RemoteDebugger
-from idlelib import macosxSupport
+from idlelib import debugger
+from idlelib import debugger_r
+from idlelib import macosx
 
 HOST = '127.0.0.1' # python execution server on localhost loopback
 PORT = 0  # someday pass in host, port for remote debug capability
@@ -410,7 +410,7 @@ class ModifiedInterpreter(InteractiveInterpreter):
         # run from the IDLE source directory.
         del_exitf = idleConf.GetOption('main', 'General', 'delete-exitfunc',
                                        default=False, type='bool')
-        if __name__ == 'idlelib.PyShell':
+        if __name__ == 'idlelib.pyshell':
             command = "__import__('idlelib.run').run.main(%r)" % (del_exitf,)
         else:
             command = "__import__('run').main(%r)" % (del_exitf,)
@@ -468,7 +468,7 @@ class ModifiedInterpreter(InteractiveInterpreter):
         if debug:
             try:
                 # Only close subprocess debugger, don't unregister gui_adap!
-                RemoteDebugger.close_subprocess_debugger(self.rpcclt)
+                debugger_r.close_subprocess_debugger(self.rpcclt)
             except:
                 pass
         # Kill subprocess, spawn a new one, accept connection.
@@ -497,7 +497,7 @@ class ModifiedInterpreter(InteractiveInterpreter):
         # restart subprocess debugger
         if debug:
             # Restarted debugger connects to current instance of debug GUI
-            RemoteDebugger.restart_subprocess_debugger(self.rpcclt)
+            debugger_r.restart_subprocess_debugger(self.rpcclt)
             # reload remote debugger breakpoints for all PyShellEditWindows
             debug.load_breakpoints()
         self.compile.compiler.flags = self.original_compiler_flags
@@ -578,7 +578,7 @@ class ModifiedInterpreter(InteractiveInterpreter):
                 if self.tkconsole.getvar("<<toggle-jit-stack-viewer>>"):
                     self.remote_stack_viewer()
             elif how == "ERROR":
-                errmsg = "PyShell.ModifiedInterpreter: Subprocess ERROR:\n"
+                errmsg = "pyshell.ModifiedInterpreter: Subprocess ERROR:\n"
                 print(errmsg, what, file=sys.__stderr__)
                 print(errmsg, what, file=console)
             # we received a response to the currently active seq number:
@@ -613,13 +613,13 @@ class ModifiedInterpreter(InteractiveInterpreter):
         return
 
     def remote_stack_viewer(self):
-        from idlelib import RemoteObjectBrowser
+        from idlelib import debugobj_r
         oid = self.rpcclt.remotequeue("exec", "stackviewer", ("flist",), {})
         if oid is None:
             self.tkconsole.root.bell()
             return
-        item = RemoteObjectBrowser.StubObjectTreeItem(self.rpcclt, oid)
-        from idlelib.TreeWidget import ScrolledCanvas, TreeNode
+        item = debugobj_r.StubObjectTreeItem(self.rpcclt, oid)
+        from idlelib.tree import ScrolledCanvas, TreeNode
         top = Toplevel(self.tkconsole.root)
         theme = idleConf.CurrentTheme()
         background = idleConf.GetHighlight(theme, 'normal')['background']
@@ -662,9 +662,9 @@ class ModifiedInterpreter(InteractiveInterpreter):
         # at the moment, InteractiveInterpreter expects str
         assert isinstance(source, str)
         #if isinstance(source, str):
-        #    from idlelib import IOBinding
+        #    from idlelib import iomenu
         #    try:
-        #        source = source.encode(IOBinding.encoding)
+        #        source = source.encode(iomenu.encoding)
         #    except UnicodeError:
         #        self.tkconsole.resetoutput()
         #        self.write("Unsupported characters in input\n")
@@ -850,7 +850,7 @@ class PyShell(OutputWindow):
 
 
     # New classes
-    from idlelib.IdleHistory import History
+    from idlelib.history import History
 
     def __init__(self, flist=None):
         if use_subprocess:
@@ -888,11 +888,11 @@ class PyShell(OutputWindow):
         self.save_stdout = sys.stdout
         self.save_stderr = sys.stderr
         self.save_stdin = sys.stdin
-        from idlelib import IOBinding
-        self.stdin = PseudoInputFile(self, "stdin", IOBinding.encoding)
-        self.stdout = PseudoOutputFile(self, "stdout", IOBinding.encoding)
-        self.stderr = PseudoOutputFile(self, "stderr", IOBinding.encoding)
-        self.console = PseudoOutputFile(self, "console", IOBinding.encoding)
+        from idlelib import iomenu
+        self.stdin = PseudoInputFile(self, "stdin", iomenu.encoding)
+        self.stdout = PseudoOutputFile(self, "stdout", iomenu.encoding)
+        self.stderr = PseudoOutputFile(self, "stderr", iomenu.encoding)
+        self.console = PseudoOutputFile(self, "console", iomenu.encoding)
         if not use_subprocess:
             sys.stdout = self.stdout
             sys.stderr = self.stderr
@@ -900,7 +900,7 @@ class PyShell(OutputWindow):
         try:
             # page help() text to shell.
             import pydoc # import must be done here to capture i/o rebinding.
-            # XXX KBK 27Dec07 use a textView someday, but must work w/o subproc
+            # XXX KBK 27Dec07 use TextViewer someday, but must work w/o subproc
             pydoc.pager = pydoc.plainpager
         except:
             sys.stderr = sys.__stderr__
@@ -954,7 +954,7 @@ class PyShell(OutputWindow):
             self.interp.setdebugger(None)
             db.close()
             if self.interp.rpcclt:
-                RemoteDebugger.close_remote_debugger(self.interp.rpcclt)
+                debugger_r.close_remote_debugger(self.interp.rpcclt)
             self.resetoutput()
             self.console.write("[DEBUG OFF]\n")
             sys.ps1 = ">>> "
@@ -963,10 +963,10 @@ class PyShell(OutputWindow):
 
     def open_debugger(self):
         if self.interp.rpcclt:
-            dbg_gui = RemoteDebugger.start_remote_debugger(self.interp.rpcclt,
+            dbg_gui = debugger_r.start_remote_debugger(self.interp.rpcclt,
                                                            self)
         else:
-            dbg_gui = Debugger.Debugger(self)
+            dbg_gui = debugger.Debugger(self)
         self.interp.setdebugger(dbg_gui)
         dbg_gui.load_breakpoints()
         sys.ps1 = "[DEBUG ON]\n>>> "
@@ -1241,7 +1241,7 @@ class PyShell(OutputWindow):
                 "(sys.last_traceback is not defined)",
                 parent=self.text)
             return
-        from idlelib.StackViewer import StackBrowser
+        from idlelib.stackviewer import StackBrowser
         StackBrowser(self.root, self.flist)
 
     def view_restart_mark(self, event=None):
@@ -1546,15 +1546,7 @@ def main():
     fixwordbreaks(root)
     root.withdraw()
     flist = PyShellFileList(root)
-    macosxSupport.setupApp(root, flist)
-
-    if macosxSupport.isAquaTk():
-        # There are some screwed up <2> class bindings for text
-        # widgets defined in Tk which we need to do away with.
-        # See issue #24801.
-        root.unbind_class('Text', '<B2>')
-        root.unbind_class('Text', '<B2-Motion>')
-        root.unbind_class('Text', '<<PasteSelection>>')
+    macosx.setupApp(root, flist)
 
     if enable_edit:
         if not (cmd or script):
@@ -1569,7 +1561,7 @@ def main():
         shell = flist.open_shell()
         if not shell:
             return # couldn't open shell
-        if macosxSupport.isAquaTk() and flist.dict:
+        if macosx.isAquaTk() and flist.dict:
             # On OSX: when the user has double-clicked on a file that causes
             # IDLE to be launched the shell window will open just in front of
             # the file she wants to see. Lower the interpreter window when
@@ -1603,7 +1595,7 @@ def main():
         # check for problematic OS X Tk versions and print a warning
         # message in the IDLE shell window; this is less intrusive
         # than always opening a separate window.
-        tkversionwarning = macosxSupport.tkVersionWarning(root)
+        tkversionwarning = macosx.tkVersionWarning(root)
         if tkversionwarning:
             shell.interp.runcommand("print('%s')" % tkversionwarning)
 
@@ -1613,7 +1605,7 @@ def main():
     capture_warnings(False)
 
 if __name__ == "__main__":
-    sys.modules['PyShell'] = sys.modules['__main__']
+    sys.modules['pyshell'] = sys.modules['__main__']
     main()
 
 capture_warnings(False)  # Make sure turned off; see issue 18081
diff --git a/Lib/idlelib/WidgetRedirector.py b/Lib/idlelib/redirector.py
index b66be9e721..5ca7a2d5ff 100644
--- a/Lib/idlelib/WidgetRedirector.py
+++ b/Lib/idlelib/redirector.py
@@ -104,7 +104,7 @@ class WidgetRedirector:
 
         Note that if a registered function is called, the operation is not
         passed through to Tk.  Apply the function returned by self.register()
-        to *args to accomplish that.  For an example, see ColorDelegator.py.
+        to *args to accomplish that.  For an example, see colorizer.py.
 
         '''
         m = self._operations.get(operation)
diff --git a/Lib/idlelib/ReplaceDialog.py b/Lib/idlelib/replace.py
index f2ea22e7f7..589b814192 100644
--- a/Lib/idlelib/ReplaceDialog.py
+++ b/Lib/idlelib/replace.py
@@ -5,8 +5,8 @@ replace+find.
 """
 from tkinter import *
 
-from idlelib import SearchEngine
-from idlelib.SearchDialogBase import SearchDialogBase
+from idlelib import searchengine
+from idlelib.searchbase import SearchDialogBase
 import re
 
 
@@ -14,7 +14,7 @@ def replace(text):
     """Returns a singleton ReplaceDialog instance.The single dialog
      saves user entries and preferences across instances."""
     root = text._root()
-    engine = SearchEngine.get(root)
+    engine = searchengine.get(root)
     if not hasattr(engine, "_replacedialog"):
         engine._replacedialog = ReplaceDialog(root, engine)
     dialog = engine._replacedialog
@@ -164,7 +164,7 @@ class ReplaceDialog(SearchDialogBase):
             pos = None
         if not pos:
             first = last = pos = text.index("insert")
-        line, col = SearchEngine.get_line_col(pos)
+        line, col = searchengine.get_line_col(pos)
         chars = text.get("%d.0" % line, "%d.0" % (line+1))
         m = prog.match(chars, col)
         if not prog:
diff --git a/Lib/idlelib/RstripExtension.py b/Lib/idlelib/rstrip.py
index 2ce3c7eafe..2ce3c7eafe 100644
--- a/Lib/idlelib/RstripExtension.py
+++ b/Lib/idlelib/rstrip.py
diff --git a/Lib/idlelib/run.py b/Lib/idlelib/run.py
index 595e7bc3aa..eb34944eb3 100644
--- a/Lib/idlelib/run.py
+++ b/Lib/idlelib/run.py
@@ -7,15 +7,15 @@ import threading
 import queue
 import tkinter
 
-from idlelib import CallTips
-from idlelib import AutoComplete
+from idlelib import calltips
+from idlelib import autocomplete
 
-from idlelib import RemoteDebugger
-from idlelib import RemoteObjectBrowser
-from idlelib import StackViewer
+from idlelib import debugger_r
+from idlelib import debugobj_r
+from idlelib import stackviewer
 from idlelib import rpc
-from idlelib import PyShell
-from idlelib import IOBinding
+from idlelib import pyshell
+from idlelib import iomenu
 
 import __main__
 
@@ -32,7 +32,7 @@ def idle_showwarning_subproc(
     if file is None:
         file = sys.stderr
     try:
-        file.write(PyShell.idle_formatwarning(
+        file.write(pyshell.idle_formatwarning(
                 message, category, filename, lineno, line))
     except IOError:
         pass # the file (probably stderr) is invalid - this warning gets lost.
@@ -82,7 +82,7 @@ def main(del_exitfunc=False):
     MyHandler object.  That reference is saved as attribute rpchandler of the
     Executive instance.  The Executive methods have access to the reference and
     can pass it on to entities that they command
-    (e.g. RemoteDebugger.Debugger.start_debugger()).  The latter, in turn, can
+    (e.g. debugger_r.Debugger.start_debugger()).  The latter, in turn, can
     call MyHandler(SocketIO) register/unregister methods via the reference to
     register and unregister themselves.
 
@@ -204,7 +204,7 @@ def print_exception():
             tbe = traceback.extract_tb(tb)
             print('Traceback (most recent call last):', file=efile)
             exclude = ("run.py", "rpc.py", "threading.py", "queue.py",
-                       "RemoteDebugger.py", "bdb.py")
+                       "debugger_r.py", "bdb.py")
             cleanup_traceback(tbe, exclude)
             traceback.print_list(tbe, file=efile)
         lines = traceback.format_exception_only(typ, exc)
@@ -298,12 +298,12 @@ class MyHandler(rpc.RPCHandler):
         executive = Executive(self)
         self.register("exec", executive)
         self.console = self.get_remote_proxy("console")
-        sys.stdin = PyShell.PseudoInputFile(self.console, "stdin",
-                IOBinding.encoding)
-        sys.stdout = PyShell.PseudoOutputFile(self.console, "stdout",
-                IOBinding.encoding)
-        sys.stderr = PyShell.PseudoOutputFile(self.console, "stderr",
-                IOBinding.encoding)
+        sys.stdin = pyshell.PseudoInputFile(self.console, "stdin",
+                iomenu.encoding)
+        sys.stdout = pyshell.PseudoOutputFile(self.console, "stdout",
+                iomenu.encoding)
+        sys.stderr = pyshell.PseudoOutputFile(self.console, "stderr",
+                iomenu.encoding)
 
         sys.displayhook = rpc.displayhook
         # page help() text to shell.
@@ -339,8 +339,8 @@ class Executive(object):
     def __init__(self, rpchandler):
         self.rpchandler = rpchandler
         self.locals = __main__.__dict__
-        self.calltip = CallTips.CallTips()
-        self.autocomplete = AutoComplete.AutoComplete()
+        self.calltip = calltips.CallTips()
+        self.autocomplete = autocomplete.AutoComplete()
 
     def runcode(self, code):
         global interruptable
@@ -372,7 +372,7 @@ class Executive(object):
             thread.interrupt_main()
 
     def start_the_debugger(self, gui_adap_oid):
-        return RemoteDebugger.start_debugger(self.rpchandler, gui_adap_oid)
+        return debugger_r.start_debugger(self.rpchandler, gui_adap_oid)
 
     def stop_the_debugger(self, idb_adap_oid):
         "Unregister the Idb Adapter.  Link objects and Idb then subject to GC"
@@ -396,7 +396,7 @@ class Executive(object):
             tb = tb.tb_next
         sys.last_type = typ
         sys.last_value = val
-        item = StackViewer.StackTreeItem(flist, tb)
-        return RemoteObjectBrowser.remote_object_tree_item(item)
+        item = stackviewer.StackTreeItem(flist, tb)
+        return debugobj_r.remote_object_tree_item(item)
 
 capture_warnings(False)  # Make sure turned off; see issue 18081
diff --git a/Lib/idlelib/ScriptBinding.py b/Lib/idlelib/runscript.py
index 5cb818d833..7e7524a3c4 100644
--- a/Lib/idlelib/ScriptBinding.py
+++ b/Lib/idlelib/runscript.py
@@ -21,10 +21,10 @@ import os
 import tabnanny
 import tokenize
 import tkinter.messagebox as tkMessageBox
-from idlelib import PyShell
+from idlelib import pyshell
 
-from idlelib.configHandler import idleConf
-from idlelib import macosxSupport
+from idlelib.config import idleConf
+from idlelib import macosx
 
 indent_message = """Error: Inconsistent indentation detected!
 
@@ -46,12 +46,12 @@ class ScriptBinding:
 
     def __init__(self, editwin):
         self.editwin = editwin
-        # Provide instance variables referenced by Debugger
+        # Provide instance variables referenced by debugger
         # XXX This should be done differently
         self.flist = self.editwin.flist
         self.root = self.editwin.root
 
-        if macosxSupport.isCocoaTk():
+        if macosx.isCocoaTk():
             self.editwin.text_frame.bind('<<run-module-event-2>>', self._run_module_event)
 
     def check_module_event(self, event):
@@ -112,7 +112,7 @@ class ScriptBinding:
             shell.set_warning_stream(saved_stream)
 
     def run_module_event(self, event):
-        if macosxSupport.isCocoaTk():
+        if macosx.isCocoaTk():
             # Tk-Cocoa in MacOSX is broken until at least
             # Tk 8.5.9, and without this rather
             # crude workaround IDLE would hang when a user
@@ -142,7 +142,7 @@ class ScriptBinding:
         if not self.tabnanny(filename):
             return 'break'
         interp = self.shell.interp
-        if PyShell.use_subprocess:
+        if pyshell.use_subprocess:
             interp.restart_subprocess(with_cwd=False, filename=
                         self.editwin._filename_to_unicode(filename))
         dirname = os.path.dirname(filename)
@@ -161,7 +161,7 @@ class ScriptBinding:
         interp.prepend_syspath(filename)
         # XXX KBK 03Jul04 When run w/o subprocess, runtime warnings still
         #         go to __stderr__.  With subprocess, they go to the shell.
-        #         Need to change streams in PyShell.ModifiedInterpreter.
+        #         Need to change streams in pyshell.ModifiedInterpreter.
         interp.runcode(code)
         return 'break'
 
diff --git a/Lib/idlelib/ScrolledList.py b/Lib/idlelib/scrolledlist.py
index 53576b5f82..80df0f8132 100644
--- a/Lib/idlelib/ScrolledList.py
+++ b/Lib/idlelib/scrolledlist.py
@@ -1,5 +1,5 @@
 from tkinter import *
-from idlelib import macosxSupport
+from idlelib import macosx
 
 class ScrolledList:
 
@@ -23,7 +23,7 @@ class ScrolledList:
         # Bind events to the list box
         listbox.bind("<ButtonRelease-1>", self.click_event)
         listbox.bind("<Double-ButtonRelease-1>", self.double_click_event)
-        if macosxSupport.isAquaTk():
+        if macosx.isAquaTk():
             listbox.bind("<ButtonPress-2>", self.popup_event)
             listbox.bind("<Control-Button-1>", self.popup_event)
         else:
diff --git a/Lib/idlelib/SearchDialog.py b/Lib/idlelib/search.py
index 765d53fe92..a609fd9583 100644
--- a/Lib/idlelib/SearchDialog.py
+++ b/Lib/idlelib/search.py
@@ -1,12 +1,12 @@
 from tkinter import *
 
-from idlelib import SearchEngine
-from idlelib.SearchDialogBase import SearchDialogBase
+from idlelib import searchengine
+from idlelib.searchbase import SearchDialogBase
 
 def _setup(text):
     "Create or find the singleton SearchDialog instance."
     root = text._root()
-    engine = SearchEngine.get(root)
+    engine = searchengine.get(root)
     if not hasattr(engine, "_searchdialog"):
         engine._searchdialog = SearchDialog(root, engine)
     return engine._searchdialog
diff --git a/Lib/idlelib/SearchDialogBase.py b/Lib/idlelib/searchbase.py
index 5fa84e238b..9206bf5051 100644
--- a/Lib/idlelib/SearchDialogBase.py
+++ b/Lib/idlelib/searchbase.py
@@ -125,7 +125,7 @@ class SearchDialogBase:
     def create_option_buttons(self):
         '''Return (filled frame, options) for testing.
 
-        Options is a list of SearchEngine booleanvar, label pairs.
+        Options is a list of searchengine booleanvar, label pairs.
         A gridded frame from make_frame is filled with a Checkbutton
         for each pair, bound to the var, with the corresponding label.
         '''
diff --git a/Lib/idlelib/SearchEngine.py b/Lib/idlelib/searchengine.py
index 37883bf687..2e3700ece3 100644
--- a/Lib/idlelib/SearchEngine.py
+++ b/Lib/idlelib/searchengine.py
@@ -57,7 +57,7 @@ class SearchEngine:
 
     def setcookedpat(self, pat):
         "Set pattern after escaping if re."
-        # called only in SearchDialog.py: 66
+        # called only in search.py: 66
         if self.isre():
             pat = re.escape(pat)
         self.setpat(pat)
diff --git a/Lib/idlelib/StackViewer.py b/Lib/idlelib/stackviewer.py
index ccc755ce31..87c964e7af 100644
--- a/Lib/idlelib/StackViewer.py
+++ b/Lib/idlelib/stackviewer.py
@@ -4,9 +4,9 @@ import linecache
 import re
 import tkinter as tk
 
-from idlelib.TreeWidget import TreeNode, TreeItem, ScrolledCanvas
-from idlelib.ObjectBrowser import ObjectTreeItem, make_objecttreeitem
-from idlelib.PyShell import PyShellFileList
+from idlelib.tree import TreeNode, TreeItem, ScrolledCanvas
+from idlelib.debugobj import ObjectTreeItem, make_objecttreeitem
+from idlelib.pyshell import PyShellFileList
 
 def StackBrowser(root, flist=None, tb=None, top=None):
     if top is None:
@@ -120,9 +120,6 @@ class VariablesTreeItem(ObjectTreeItem):
             sublist.append(item)
         return sublist
 
-    def keys(self):  # unused, left for possible 3rd party use
-        return list(self.object.keys())
-
 def _stack_viewer(parent):
     root = tk.Tk()
     root.title("Test StackViewer")
diff --git a/Lib/idlelib/MultiStatusBar.py b/Lib/idlelib/statusbar.py
index e82ba9ab2f..e82ba9ab2f 100644
--- a/Lib/idlelib/MultiStatusBar.py
+++ b/Lib/idlelib/statusbar.py
diff --git a/Lib/idlelib/textView.py b/Lib/idlelib/textview.py
index 01b2d8f4ab..01b2d8f4ab 100644
--- a/Lib/idlelib/textView.py
+++ b/Lib/idlelib/textview.py
diff --git a/Lib/idlelib/ToolTip.py b/Lib/idlelib/tooltip.py
index 964107e117..c3eafed9d5 100644
--- a/Lib/idlelib/ToolTip.py
+++ b/Lib/idlelib/tooltip.py
@@ -1,4 +1,4 @@
-# general purpose 'tooltip' routines - currently unused in idlefork
+# general purpose 'tooltip' routines - currently unused in idlelib
 # (although the 'calltips' extension is partly based on this code)
 # may be useful for some purposes in (or almost in ;) the current project scope
 # Ideas gleaned from PySol
@@ -76,7 +76,7 @@ class ListboxToolTip(ToolTipBase):
         for item in self.items:
             listbox.insert(END, item)
 
-def _tooltip(parent):
+def _tooltip(parent):  # htest #
     root = Tk()
     root.title("Test tooltip")
     width, height, x, y = list(map(int, re.split('[x+]', parent.geometry())))
diff --git a/Lib/idlelib/TreeWidget.py b/Lib/idlelib/tree.py
index a19578fdcb..08cc6370dd 100644
--- a/Lib/idlelib/TreeWidget.py
+++ b/Lib/idlelib/tree.py
@@ -17,8 +17,8 @@
 import os
 from tkinter import *
 
-from idlelib import ZoomHeight
-from idlelib.configHandler import idleConf
+from idlelib import zoomheight
+from idlelib.config import idleConf
 
 ICONDIR = "Icons"
 
@@ -445,7 +445,7 @@ class ScrolledCanvas:
         self.canvas.yview_scroll(1, "unit")
         return "break"
     def zoom_height(self, event):
-        ZoomHeight.zoom_height(self.master)
+        zoomheight.zoom_height(self.master)
         return "break"
 
 
diff --git a/Lib/idlelib/UndoDelegator.py b/Lib/idlelib/undo.py
index 1c2502d818..3e94b69bbe 100644
--- a/Lib/idlelib/UndoDelegator.py
+++ b/Lib/idlelib/undo.py
@@ -1,7 +1,7 @@
 import string
 from tkinter import *
 
-from idlelib.Delegator import Delegator
+from idlelib.delegator import Delegator
 
 #$ event <<redo>>
 #$ win <Control-y>
@@ -340,7 +340,7 @@ class CommandSequence(Command):
 def _undo_delegator(parent):  # htest #
     import re
     import tkinter as tk
-    from idlelib.Percolator import Percolator
+    from idlelib.percolator import Percolator
     undowin = tk.Toplevel()
     undowin.title("Test UndoDelegator")
     width, height, x, y = list(map(int, re.split('[x+]', parent.geometry())))
diff --git a/Lib/idlelib/WindowList.py b/Lib/idlelib/windows.py
index bc74348f56..bc74348f56 100644
--- a/Lib/idlelib/WindowList.py
+++ b/Lib/idlelib/windows.py
diff --git a/Lib/idlelib/ZoomHeight.py b/Lib/idlelib/zoomheight.py
index a5d679e499..0016e9de5f 100644
--- a/Lib/idlelib/ZoomHeight.py
+++ b/Lib/idlelib/zoomheight.py
@@ -3,7 +3,7 @@
 import re
 import sys
 
-from idlelib import macosxSupport
+from idlelib import macosx
 
 class ZoomHeight:
 
@@ -32,7 +32,7 @@ def zoom_height(top):
         newy = 0
         newheight = newheight - 72
 
-    elif macosxSupport.isAquaTk():
+    elif macosx.isAquaTk():
         # The '88' below is a magic number that avoids placing the bottom
         # of the window below the panel on my machine. I don't know how
         # to calculate the correct value for this with tkinter.
diff --git a/Lib/imaplib.py b/Lib/imaplib.py
index 4e8a4bb6fa..a63ba8dbe0 100644
--- a/Lib/imaplib.py
+++ b/Lib/imaplib.py
@@ -111,7 +111,15 @@ InternalDate = re.compile(br'.*INTERNALDATE "'
 # Literal is no longer used; kept for backward compatibility.
 Literal = re.compile(br'.*{(?P<size>\d+)}$', re.ASCII)
 MapCRLF = re.compile(br'\r\n|\r|\n')
-Response_code = re.compile(br'\[(?P<type>[A-Z-]+)( (?P<data>[^\]]*))?\]')
+# We no longer exclude the ']' character from the data portion of the response
+# code, even though it violates the RFC.  Popular IMAP servers such as Gmail
+# allow flags with ']', and there are programs (including imaplib!) that can
+# produce them.  The problem with this is if the 'text' portion of the response
+# includes a ']' we'll parse the response wrong (which is the point of the RFC
+# restriction).  However, that seems less likely to be a problem in practice
+# than being unable to correctly parse flags that include ']' chars, which
+# was reported as a real-world problem in issue #21815.
+Response_code = re.compile(br'\[(?P<type>[A-Z-]+)( (?P<data>.*))?\]')
 Untagged_response = re.compile(br'\* (?P<type>[A-Z-]+)( (?P<data>.*))?')
 # Untagged_status is no longer used; kept for backward compatibility
 Untagged_status = re.compile(
diff --git a/Lib/imp.py b/Lib/imp.py
index f6fff44201..b33995267b 100644
--- a/Lib/imp.py
+++ b/Lib/imp.py
@@ -30,7 +30,7 @@ import warnings
 
 warnings.warn("the imp module is deprecated in favour of importlib; "
               "see the module's documentation for alternative uses",
-              PendingDeprecationWarning, stacklevel=2)
+              DeprecationWarning, stacklevel=2)
 
 # DEPRECATED
 SEARCH_ERROR = 0
diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py
index 9eecbfe967..afc31ee5e8 100644
--- a/Lib/importlib/_bootstrap.py
+++ b/Lib/importlib/_bootstrap.py
@@ -878,13 +878,20 @@ def _find_spec_legacy(finder, name, path):
 
 def _find_spec(name, path, target=None):
     """Find a module's loader."""
-    if sys.meta_path is not None and not sys.meta_path:
+    meta_path = sys.meta_path
+    if meta_path is None:
+        # PyImport_Cleanup() is running or has been called.
+        raise ImportError("sys.meta_path is None, Python is likely "
+                          "shutting down")
+
+    if not meta_path:
         _warnings.warn('sys.meta_path is empty', ImportWarning)
+
     # We check sys.modules here for the reload case.  While a passed-in
     # target will usually indicate a reload there is no guarantee, whereas
     # sys.modules provides one.
     is_reload = name in sys.modules
-    for finder in sys.meta_path:
+    for finder in meta_path:
         with _ImportLockContext():
             try:
                 find_spec = finder.find_spec
@@ -925,6 +932,9 @@ def _sanity_check(name, package, level):
     if level > 0:
         if not isinstance(package, str):
             raise TypeError('__package__ not set to a string')
+        elif not package:
+            raise ImportError('attempted relative import with no known parent '
+                              'package')
         elif package not in sys.modules:
             msg = ('Parent module {!r} not loaded, cannot perform relative '
                    'import')
@@ -1033,7 +1043,19 @@ def _calc___package__(globals):
 
     """
     package = globals.get('__package__')
-    if package is None:
+    spec = globals.get('__spec__')
+    if package is not None:
+        if spec is not None and package != spec.parent:
+            _warnings.warn("__package__ != __spec__.parent "
+                           f"({package!r} != {spec.parent!r})",
+                           ImportWarning, stacklevel=3)
+        return package
+    elif spec is not None:
+        return spec.parent
+    else:
+        _warnings.warn("can't resolve package from __spec__ or __package__, "
+                       "falling back on __name__ and __path__",
+                       ImportWarning, stacklevel=3)
         package = globals['__name__']
         if '__path__' not in globals:
             package = package.rpartition('.')[0]
diff --git a/Lib/importlib/_bootstrap_external.py b/Lib/importlib/_bootstrap_external.py
index 9788828688..034b783990 100644
--- a/Lib/importlib/_bootstrap_external.py
+++ b/Lib/importlib/_bootstrap_external.py
@@ -223,6 +223,9 @@ _code_type = type(_write_atomic.__code__)
 #     Python 3.5b1  3330 (PEP 448: Additional Unpacking Generalizations)
 #     Python 3.5b2  3340 (fix dictionary display evaluation order #11205)
 #     Python 3.5b2  3350 (add GET_YIELD_FROM_ITER opcode #24400)
+#     Python 3.6a0  3360 (add FORMAT_VALUE opcode #25483
+#     Python 3.6a0  3361 (lineno delta of code.co_lnotab becomes signed)
+#     Python 3.6a0  3370 (16 bit wordcode)
 #
 # MAGIC must change whenever the bytecode emitted by the compiler may no
 # longer be understood by older implementations of the eval loop (usually
@@ -231,7 +234,7 @@ _code_type = type(_write_atomic.__code__)
 # Whenever MAGIC_NUMBER is changed, the ranges in the magic_values array
 # in PC/launcher.c must also be updated.
 
-MAGIC_NUMBER = (3350).to_bytes(2, 'little') + b'\r\n'
+MAGIC_NUMBER = (3370).to_bytes(2, 'little') + b'\r\n'
 _RAW_MAGIC_NUMBER = int.from_bytes(MAGIC_NUMBER, 'little')  # For import.c
 
 _PYCACHE = '__pycache__'
@@ -363,14 +366,6 @@ def _calc_mode(path):
     return mode
 
 
-def _verbose_message(message, *args, verbosity=1):
-    """Print the message to stderr if -v/PYTHONVERBOSE is turned on."""
-    if sys.flags.verbose >= verbosity:
-        if not message.startswith(('#', 'import ')):
-            message = '# ' + message
-        print(message.format(*args), file=sys.stderr)
-
-
 def _check_name(method):
     """Decorator to verify that the module being requested matches the one the
     loader can handle.
@@ -440,15 +435,15 @@ def _validate_bytecode_header(data, source_stats=None, name=None, path=None):
     raw_size = data[8:12]
     if magic != MAGIC_NUMBER:
         message = 'bad magic number in {!r}: {!r}'.format(name, magic)
-        _verbose_message('{}', message)
+        _bootstrap._verbose_message('{}', message)
         raise ImportError(message, **exc_details)
     elif len(raw_timestamp) != 4:
         message = 'reached EOF while reading timestamp in {!r}'.format(name)
-        _verbose_message('{}', message)
+        _bootstrap._verbose_message('{}', message)
         raise EOFError(message)
     elif len(raw_size) != 4:
         message = 'reached EOF while reading size of source in {!r}'.format(name)
-        _verbose_message('{}', message)
+        _bootstrap._verbose_message('{}', message)
         raise EOFError(message)
     if source_stats is not None:
         try:
@@ -458,7 +453,7 @@ def _validate_bytecode_header(data, source_stats=None, name=None, path=None):
         else:
             if _r_long(raw_timestamp) != source_mtime:
                 message = 'bytecode is stale for {!r}'.format(name)
-                _verbose_message('{}', message)
+                _bootstrap._verbose_message('{}', message)
                 raise ImportError(message, **exc_details)
         try:
             source_size = source_stats['size'] & 0xFFFFFFFF
@@ -475,7 +470,7 @@ def _compile_bytecode(data, name=None, bytecode_path=None, source_path=None):
     """Compile bytecode as returned by _validate_bytecode_header()."""
     code = marshal.loads(data)
     if isinstance(code, _code_type):
-        _verbose_message('code object from {!r}', bytecode_path)
+        _bootstrap._verbose_message('code object from {!r}', bytecode_path)
         if source_path is not None:
             _imp._fix_co_filename(code, source_path)
         return code
@@ -602,7 +597,7 @@ class WindowsRegistryFinder:
         else:
             registry_key = cls.REGISTRY_KEY
         key = registry_key.format(fullname=fullname,
-                                  sys_version=sys.version[:3])
+                                  sys_version='%d.%d' % sys.version_info[:2])
         try:
             with cls._open_registry(key) as hkey:
                 filepath = _winreg.QueryValue(hkey, '')
@@ -665,6 +660,7 @@ class _LoaderBasics:
         _bootstrap._call_with_frames_removed(exec, code, module.__dict__)
 
     def load_module(self, fullname):
+        """This module is deprecated."""
         return _bootstrap._load_module_shim(self, fullname)
 
 
@@ -758,21 +754,21 @@ class SourceLoader(_LoaderBasics):
                     except (ImportError, EOFError):
                         pass
                     else:
-                        _verbose_message('{} matches {}', bytecode_path,
-                                        source_path)
+                        _bootstrap._verbose_message('{} matches {}', bytecode_path,
+                                                    source_path)
                         return _compile_bytecode(bytes_data, name=fullname,
                                                  bytecode_path=bytecode_path,
                                                  source_path=source_path)
         source_bytes = self.get_data(source_path)
         code_object = self.source_to_code(source_bytes, source_path)
-        _verbose_message('code object from {}', source_path)
+        _bootstrap._verbose_message('code object from {}', source_path)
         if (not sys.dont_write_bytecode and bytecode_path is not None and
                 source_mtime is not None):
             data = _code_to_bytecode(code_object, source_mtime,
                     len(source_bytes))
             try:
                 self._cache_bytecode(source_path, bytecode_path, data)
-                _verbose_message('wrote {!r}', bytecode_path)
+                _bootstrap._verbose_message('wrote {!r}', bytecode_path)
             except NotImplementedError:
                 pass
         return code_object
@@ -852,14 +848,16 @@ class SourceFileLoader(FileLoader, SourceLoader):
             except OSError as exc:
                 # Could be a permission error, read-only filesystem: just forget
                 # about writing the data.
-                _verbose_message('could not create {!r}: {!r}', parent, exc)
+                _bootstrap._verbose_message('could not create {!r}: {!r}',
+                                            parent, exc)
                 return
         try:
             _write_atomic(path, data, _mode)
-            _verbose_message('created {!r}', path)
+            _bootstrap._verbose_message('created {!r}', path)
         except OSError as exc:
             # Same as above: just don't write the bytecode.
-            _verbose_message('could not create {!r}: {!r}', path, exc)
+            _bootstrap._verbose_message('could not create {!r}: {!r}', path,
+                                        exc)
 
 
 class SourcelessFileLoader(FileLoader, _LoaderBasics):
@@ -904,14 +902,14 @@ class ExtensionFileLoader(FileLoader, _LoaderBasics):
         """Create an unitialized extension module"""
         module = _bootstrap._call_with_frames_removed(
             _imp.create_dynamic, spec)
-        _verbose_message('extension module {!r} loaded from {!r}',
+        _bootstrap._verbose_message('extension module {!r} loaded from {!r}',
                          spec.name, self.path)
         return module
 
     def exec_module(self, module):
         """Initialize an extension module"""
         _bootstrap._call_with_frames_removed(_imp.exec_dynamic, module)
-        _verbose_message('extension module {!r} executed from {!r}',
+        _bootstrap._verbose_message('extension module {!r} executed from {!r}',
                          self.name, self.path)
 
     def is_package(self, fullname):
@@ -977,6 +975,9 @@ class _NamespacePath:
     def __iter__(self):
         return iter(self._recalculate())
 
+    def __setitem__(self, index, path):
+        self._path[index] = path
+
     def __len__(self):
         return len(self._recalculate())
 
@@ -1026,7 +1027,8 @@ class _NamespaceLoader:
 
         """
         # The import system never calls this method.
-        _verbose_message('namespace module loaded with path {!r}', self._path)
+        _bootstrap._verbose_message('namespace module loaded with path {!r}',
+                                    self._path)
         return _bootstrap._load_module_shim(self, fullname)
 
 
@@ -1246,12 +1248,13 @@ class FileFinder:
         # Check for a file w/ a proper suffix exists.
         for suffix, loader_class in self._loaders:
             full_path = _path_join(self.path, tail_module + suffix)
-            _verbose_message('trying {}'.format(full_path), verbosity=2)
+            _bootstrap._verbose_message('trying {}', full_path, verbosity=2)
             if cache_module + suffix in cache:
                 if _path_isfile(full_path):
-                    return self._get_spec(loader_class, fullname, full_path, None, target)
+                    return self._get_spec(loader_class, fullname, full_path,
+                                          None, target)
         if is_namespace:
-            _verbose_message('possible namespace for {}'.format(base_path))
+            _bootstrap._verbose_message('possible namespace for {}', base_path)
             spec = _bootstrap.ModuleSpec(fullname, None)
             spec.submodule_search_locations = [base_path]
             return spec
diff --git a/Lib/importlib/util.py b/Lib/importlib/util.py
index 4525b3f78e..af781fd4cd 100644
--- a/Lib/importlib/util.py
+++ b/Lib/importlib/util.py
@@ -22,8 +22,8 @@ def resolve_name(name, package):
     if not name.startswith('.'):
         return name
     elif not package:
-        raise ValueError('{!r} is not a relative name '
-                         '(no leading dot)'.format(name))
+        raise ValueError(f'no package specified for {repr(name)} '
+                         '(required for relative module names)')
     level = 0
     for character in name:
         if character != '.':
diff --git a/Lib/inspect.py b/Lib/inspect.py
index e830eb64ca..45d2110106 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -16,7 +16,7 @@ Here are some of the useful functions provided by this module:
     getmodule() - determine the module that an object came from
     getclasstree() - arrange classes so as to represent their hierarchy
 
-    getargspec(), getargvalues(), getcallargs() - get info about function arguments
+    getargvalues(), getcallargs() - get info about function arguments
     getfullargspec() - same, with support for Python 3 features
     formatargspec(), formatargvalues() - format an argument spec
     getouterframes(), getinnerframes() - get info about frames
@@ -624,23 +624,6 @@ def getfile(object):
     raise TypeError('{!r} is not a module, class, method, '
                     'function, traceback, frame, or code object'.format(object))
 
-ModuleInfo = namedtuple('ModuleInfo', 'name suffix mode module_type')
-
-def getmoduleinfo(path):
-    """Get the module name, suffix, mode, and module type for a given file."""
-    warnings.warn('inspect.getmoduleinfo() is deprecated', DeprecationWarning,
-                  2)
-    with warnings.catch_warnings():
-        warnings.simplefilter('ignore', PendingDeprecationWarning)
-        import imp
-    filename = os.path.basename(path)
-    suffixes = [(-len(suffix), suffix, mode, mtype)
-                    for suffix, mode, mtype in imp.get_suffixes()]
-    suffixes.sort() # try longest suffixes first, in case they overlap
-    for neglen, suffix, mode, mtype in suffixes:
-        if filename[neglen:] == suffix:
-            return ModuleInfo(filename[:neglen], suffix, mode, mtype)
-
 def getmodulename(path):
     """Return the module name for a given file, or None."""
     fname = os.path.basename(path)
@@ -1061,8 +1044,6 @@ def getfullargspec(func):
     'kwonlydefaults' is a dictionary mapping names from kwonlyargs to defaults.
     'annotations' is a dictionary mapping argument names to annotations.
 
-    The first four items in the tuple correspond to getargspec().
-
     This function is deprecated, use inspect.signature() instead.
     """
 
@@ -1173,8 +1154,7 @@ def formatargspec(args, varargs=None, varkw=None, defaults=None,
                   formatvalue=lambda value: '=' + repr(value),
                   formatreturns=lambda text: ' -> ' + text,
                   formatannotation=formatannotation):
-    """Format an argument spec from the values returned by getargspec
-    or getfullargspec.
+    """Format an argument spec from the values returned by getfullargspec.
 
     The first seven arguments are (args, varargs, varkw, defaults,
     kwonlyargs, kwonlydefaults, annotations).  The other five arguments
@@ -2416,6 +2396,20 @@ class Parameter:
         if not isinstance(name, str):
             raise TypeError("name must be a str, not a {!r}".format(name))
 
+        if name[0] == '.' and name[1:].isdigit():
+            # These are implicit arguments generated by comprehensions. In
+            # order to provide a friendlier interface to users, we recast
+            # their name as "implicitN" and treat them as positional-only.
+            # See issue 19611.
+            if kind != _POSITIONAL_OR_KEYWORD:
+                raise ValueError(
+                    'implicit arguments must be passed in as {}'.format(
+                        _POSITIONAL_OR_KEYWORD
+                    )
+                )
+            self._kind = _POSITIONAL_ONLY
+            name = 'implicit{}'.format(name[1:])
+
         if not name.isidentifier():
             raise ValueError('{!r} is not a valid parameter name'.format(name))
 
diff --git a/Lib/json/encoder.py b/Lib/json/encoder.py
index d596489f42..0772bbc06b 100644
--- a/Lib/json/encoder.py
+++ b/Lib/json/encoder.py
@@ -176,7 +176,8 @@ class JSONEncoder(object):
                 return JSONEncoder.default(self, o)
 
         """
-        raise TypeError(repr(o) + " is not JSON serializable")
+        raise TypeError("Object of type '%s' is not JSON serializable" %
+                        o.__class__.__name__)
 
     def encode(self, o):
         """Return a JSON string representation of a Python data structure.
diff --git a/Lib/lib2to3/fixer_util.py b/Lib/lib2to3/fixer_util.py
index 44502bf7bd..babe6cb3f6 100644
--- a/Lib/lib2to3/fixer_util.py
+++ b/Lib/lib2to3/fixer_util.py
@@ -1,8 +1,6 @@
 """Utility functions, node construction macros, etc."""
 # Author: Collin Winter
 
-from itertools import islice
-
 # Local imports
 from .pgen2 import token
 from .pytree import Leaf, Node
diff --git a/Lib/lib2to3/fixes/fix_dict.py b/Lib/lib2to3/fixes/fix_dict.py
index 963f952e0b..d3655c9f1b 100644
--- a/Lib/lib2to3/fixes/fix_dict.py
+++ b/Lib/lib2to3/fixes/fix_dict.py
@@ -30,9 +30,8 @@ as an argument to a function that introspects the argument).
 # Local imports
 from .. import pytree
 from .. import patcomp
-from ..pgen2 import token
 from .. import fixer_base
-from ..fixer_util import Name, Call, LParen, RParen, ArgList, Dot
+from ..fixer_util import Name, Call, Dot
 from .. import fixer_util
 
 
diff --git a/Lib/lib2to3/fixes/fix_exec.py b/Lib/lib2to3/fixes/fix_exec.py
index 2c9b72d542..ab921ee80c 100644
--- a/Lib/lib2to3/fixes/fix_exec.py
+++ b/Lib/lib2to3/fixes/fix_exec.py
@@ -10,7 +10,6 @@ exec code in ns1, ns2 -> exec(code, ns1, ns2)
 """
 
 # Local imports
-from .. import pytree
 from .. import fixer_base
 from ..fixer_util import Comma, Name, Call
 
diff --git a/Lib/lib2to3/fixes/fix_filter.py b/Lib/lib2to3/fixes/fix_filter.py
index 391889f913..bb6718cbf7 100644
--- a/Lib/lib2to3/fixes/fix_filter.py
+++ b/Lib/lib2to3/fixes/fix_filter.py
@@ -14,7 +14,6 @@ Python 2.6 figure it out.
 """
 
 # Local imports
-from ..pgen2 import token
 from .. import fixer_base
 from ..fixer_util import Name, Call, ListComp, in_special_context
 
diff --git a/Lib/lib2to3/fixes/fix_has_key.py b/Lib/lib2to3/fixes/fix_has_key.py
index 18c560fd85..439708c992 100644
--- a/Lib/lib2to3/fixes/fix_has_key.py
+++ b/Lib/lib2to3/fixes/fix_has_key.py
@@ -31,7 +31,6 @@ CAVEATS:
 
 # Local imports
 from .. import pytree
-from ..pgen2 import token
 from .. import fixer_base
 from ..fixer_util import Name, parenthesize
 
diff --git a/Lib/lib2to3/fixes/fix_metaclass.py b/Lib/lib2to3/fixes/fix_metaclass.py
index 46c7aaf1e3..8e34463bd8 100644
--- a/Lib/lib2to3/fixes/fix_metaclass.py
+++ b/Lib/lib2to3/fixes/fix_metaclass.py
@@ -20,7 +20,7 @@
 # Local imports
 from .. import fixer_base
 from ..pygram import token
-from ..fixer_util import Name, syms, Node, Leaf
+from ..fixer_util import syms, Node, Leaf
 
 
 def has_metaclass(parent):
diff --git a/Lib/lib2to3/fixes/fix_nonzero.py b/Lib/lib2to3/fixes/fix_nonzero.py
index ad91a29e43..c2295969a7 100644
--- a/Lib/lib2to3/fixes/fix_nonzero.py
+++ b/Lib/lib2to3/fixes/fix_nonzero.py
@@ -3,7 +3,7 @@
 
 # Local imports
 from .. import fixer_base
-from ..fixer_util import Name, syms
+from ..fixer_util import Name
 
 class FixNonzero(fixer_base.BaseFix):
     BM_compatible = True
diff --git a/Lib/lib2to3/fixes/fix_print.py b/Lib/lib2to3/fixes/fix_print.py
index a1fe2f5c78..8780322265 100644
--- a/Lib/lib2to3/fixes/fix_print.py
+++ b/Lib/lib2to3/fixes/fix_print.py
@@ -18,7 +18,7 @@ from .. import patcomp
 from .. import pytree
 from ..pgen2 import token
 from .. import fixer_base
-from ..fixer_util import Name, Call, Comma, String, is_tuple
+from ..fixer_util import Name, Call, Comma, String
 
 
 parend_expr = patcomp.compile_pattern(
diff --git a/Lib/lib2to3/fixes/fix_types.py b/Lib/lib2to3/fixes/fix_types.py
index db34104785..67bf51f2f5 100644
--- a/Lib/lib2to3/fixes/fix_types.py
+++ b/Lib/lib2to3/fixes/fix_types.py
@@ -20,7 +20,6 @@ There should be another fixer that handles at least the following constants:
 """
 
 # Local imports
-from ..pgen2 import token
 from .. import fixer_base
 from ..fixer_util import Name
 
@@ -42,7 +41,7 @@ _TYPE_MAPPING = {
         'NotImplementedType' : 'type(NotImplemented)',
         'SliceType' : 'slice',
         'StringType': 'bytes', # XXX ?
-        'StringTypes' : 'str', # XXX ?
+        'StringTypes' : '(str,)', # XXX ?
         'TupleType': 'tuple',
         'TypeType' : 'type',
         'UnicodeType': 'str',
diff --git a/Lib/lib2to3/fixes/fix_urllib.py b/Lib/lib2to3/fixes/fix_urllib.py
index 1481cd91e3..5a36049df5 100644
--- a/Lib/lib2to3/fixes/fix_urllib.py
+++ b/Lib/lib2to3/fixes/fix_urllib.py
@@ -6,7 +6,6 @@
 
 # Local imports
 from lib2to3.fixes.fix_imports import alternates, FixImports
-from lib2to3 import fixer_base
 from lib2to3.fixer_util import (Name, Comma, FromImport, Newline,
                                 find_indentation, Node, syms)
 
diff --git a/Lib/lib2to3/refactor.py b/Lib/lib2to3/refactor.py
index 0728083652..b60b9def4d 100644
--- a/Lib/lib2to3/refactor.py
+++ b/Lib/lib2to3/refactor.py
@@ -26,7 +26,6 @@ from itertools import chain
 from .pgen2 import driver, tokenize, token
 from .fixer_util import find_root
 from . import pytree, pygram
-from . import btm_utils as bu
 from . import btm_matcher as bm
 
 
diff --git a/Lib/lib2to3/tests/support.py b/Lib/lib2to3/tests/support.py
index 6f2d214bd4..7153bb6990 100644
--- a/Lib/lib2to3/tests/support.py
+++ b/Lib/lib2to3/tests/support.py
@@ -3,10 +3,8 @@
 
 # Python imports
 import unittest
-import sys
 import os
 import os.path
-import re
 from textwrap import dedent
 
 # Local imports
diff --git a/Lib/lib2to3/tests/test_all_fixers.py b/Lib/lib2to3/tests/test_all_fixers.py
index 15079fe028..c0507cf3fb 100644
--- a/Lib/lib2to3/tests/test_all_fixers.py
+++ b/Lib/lib2to3/tests/test_all_fixers.py
@@ -10,7 +10,6 @@ import unittest
 import test.support
 
 # Local imports
-from lib2to3 import refactor
 from . import support
 
 
diff --git a/Lib/lib2to3/tests/test_fixers.py b/Lib/lib2to3/tests/test_fixers.py
index 06b0033b8f..b97b73ab60 100644
--- a/Lib/lib2to3/tests/test_fixers.py
+++ b/Lib/lib2to3/tests/test_fixers.py
@@ -2,12 +2,11 @@
 
 # Python imports
 import os
-import unittest
 from itertools import chain
 from operator import itemgetter
 
 # Local imports
-from lib2to3 import pygram, pytree, refactor, fixer_util
+from lib2to3 import pygram, fixer_util
 from lib2to3.tests import support
 
 
@@ -3322,6 +3321,10 @@ class Test_types(FixerTestCase):
         a = """type(None)"""
         self.check(b, a)
 
+        b = "types.StringTypes"
+        a = "(str,)"
+        self.check(b, a)
+
 class Test_idioms(FixerTestCase):
     fixer = "idioms"
 
diff --git a/Lib/lib2to3/tests/test_parser.py b/Lib/lib2to3/tests/test_parser.py
index b533c01e28..36eb176e5f 100644
--- a/Lib/lib2to3/tests/test_parser.py
+++ b/Lib/lib2to3/tests/test_parser.py
@@ -10,12 +10,11 @@ from __future__ import with_statement
 
 # Testing imports
 from . import support
-from .support import driver, test_dir
+from .support import driver
 from test.support import verbose
 
 # Python imports
 import os
-import sys
 import unittest
 import warnings
 import subprocess
diff --git a/Lib/lib2to3/tests/test_pytree.py b/Lib/lib2to3/tests/test_pytree.py
index 4d585a8841..a611d1715e 100644
--- a/Lib/lib2to3/tests/test_pytree.py
+++ b/Lib/lib2to3/tests/test_pytree.py
@@ -11,9 +11,6 @@ especially when debugging a test.
 
 from __future__ import with_statement
 
-import sys
-import warnings
-
 # Testing imports
 from . import support
 
diff --git a/Lib/lib2to3/tests/test_refactor.py b/Lib/lib2to3/tests/test_refactor.py
index f30c1e8630..ab5ce72793 100644
--- a/Lib/lib2to3/tests/test_refactor.py
+++ b/Lib/lib2to3/tests/test_refactor.py
@@ -7,18 +7,14 @@ from __future__ import with_statement
 import sys
 import os
 import codecs
-import operator
 import io
 import tempfile
 import shutil
 import unittest
-import warnings
 
 from lib2to3 import refactor, pygram, fixer_base
 from lib2to3.pgen2 import token
 
-from . import support
-
 
 TEST_DATA_DIR = os.path.join(os.path.dirname(__file__), "data")
 FIXER_DIR = os.path.join(TEST_DATA_DIR, "fixers")
diff --git a/Lib/lib2to3/tests/test_util.py b/Lib/lib2to3/tests/test_util.py
index d2be82c4a2..c6c613972d 100644
--- a/Lib/lib2to3/tests/test_util.py
+++ b/Lib/lib2to3/tests/test_util.py
@@ -3,9 +3,6 @@
 # Testing imports
 from . import support
 
-# Python imports
-import os.path
-
 # Local imports
 from lib2to3.pytree import Node, Leaf
 from lib2to3 import fixer_util
diff --git a/Lib/locale.py b/Lib/locale.py
index 6d59cd8bab..4de0090ed9 100644
--- a/Lib/locale.py
+++ b/Lib/locale.py
@@ -302,12 +302,16 @@ def str(val):
 
 def delocalize(string):
     "Parses a string as a normalized number according to the locale settings."
+
+    conv = localeconv()
+
     #First, get rid of the grouping
-    ts = localeconv()['thousands_sep']
+    ts = conv['thousands_sep']
     if ts:
         string = string.replace(ts, '')
+
     #next, replace the decimal point with a dot
-    dd = localeconv()['decimal_point']
+    dd = conv['decimal_point']
     if dd:
         string = string.replace(dd, '.')
     return string
diff --git a/Lib/logging/__init__.py b/Lib/logging/__init__.py
index a7bd890e3c..f941f4884b 100644
--- a/Lib/logging/__init__.py
+++ b/Lib/logging/__init__.py
@@ -33,8 +33,9 @@ __all__ = ['BASIC_FORMAT', 'BufferingFormatter', 'CRITICAL', 'DEBUG', 'ERROR',
            'StreamHandler', 'WARN', 'WARNING', 'addLevelName', 'basicConfig',
            'captureWarnings', 'critical', 'debug', 'disable', 'error',
            'exception', 'fatal', 'getLevelName', 'getLogger', 'getLoggerClass',
-           'info', 'log', 'makeLogRecord', 'setLoggerClass', 'warn', 'warning',
-           'getLogRecordFactory', 'setLogRecordFactory', 'lastResort']
+           'info', 'log', 'makeLogRecord', 'setLoggerClass', 'shutdown',
+           'warn', 'warning', 'getLogRecordFactory', 'setLogRecordFactory',
+           'lastResort', 'raiseExceptions']
 
 try:
     import threading
diff --git a/Lib/logging/handlers.py b/Lib/logging/handlers.py
index c9f8217b06..c0748a8853 100644
--- a/Lib/logging/handlers.py
+++ b/Lib/logging/handlers.py
@@ -440,11 +440,11 @@ class WatchedFileHandler(logging.FileHandler):
             sres = os.fstat(self.stream.fileno())
             self.dev, self.ino = sres[ST_DEV], sres[ST_INO]
 
-    def emit(self, record):
+    def reopenIfNeeded(self):
         """
-        Emit a record.
+        Reopen log file if needed.
 
-        First check if the underlying file has changed, and if it
+        Checks if the underlying file has changed, and if it
         has, close the old stream and reopen the file to get the
         current stream.
         """
@@ -467,6 +467,15 @@ class WatchedFileHandler(logging.FileHandler):
                 # open a new file handle and get new stat info from that fd
                 self.stream = self._open()
                 self._statstream()
+
+    def emit(self, record):
+        """
+        Emit a record.
+
+        If underlying file has changed, reopen the file before emitting the
+        record to it.
+        """
+        self.reopenIfNeeded()
         logging.FileHandler.emit(self, record)
 
 
diff --git a/Lib/mailbox.py b/Lib/mailbox.py
index 0270e25b00..0e23987ce7 100644
--- a/Lib/mailbox.py
+++ b/Lib/mailbox.py
@@ -23,9 +23,10 @@ try:
 except ImportError:
     fcntl = None
 
-__all__ = [ 'Mailbox', 'Maildir', 'mbox', 'MH', 'Babyl', 'MMDF',
-            'Message', 'MaildirMessage', 'mboxMessage', 'MHMessage',
-            'BabylMessage', 'MMDFMessage']
+__all__ = ['Mailbox', 'Maildir', 'mbox', 'MH', 'Babyl', 'MMDF',
+           'Message', 'MaildirMessage', 'mboxMessage', 'MHMessage',
+           'BabylMessage', 'MMDFMessage', 'Error', 'NoSuchMailboxError',
+           'NotEmptyError', 'ExternalClashError', 'FormatError']
 
 linesep = os.linesep.encode('ascii')
 
diff --git a/Lib/mimetypes.py b/Lib/mimetypes.py
index 0be76ad4f7..9a886803dc 100644
--- a/Lib/mimetypes.py
+++ b/Lib/mimetypes.py
@@ -33,8 +33,10 @@ except ImportError:
     _winreg = None
 
 __all__ = [
-    "guess_type","guess_extension","guess_all_extensions",
-    "add_type","read_mime_types","init"
+    "knownfiles", "inited", "MimeTypes",
+    "guess_type", "guess_all_extensions", "guess_extension",
+    "add_type", "init", "read_mime_types",
+    "suffix_map", "encodings_map", "types_map", "common_types"
 ]
 
 knownfiles = [
diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 8103502404..e220315253 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -10,7 +10,7 @@ import types
 import struct
 import warnings
 with warnings.catch_warnings():
-    warnings.simplefilter('ignore', PendingDeprecationWarning)
+    warnings.simplefilter('ignore', DeprecationWarning)
     import imp
 
 LOAD_CONST = dis.opmap['LOAD_CONST']
@@ -336,8 +336,7 @@ class ModuleFinder:
                         fullname = name + "." + sub
                         self._add_badmodule(fullname, caller)
 
-    def scan_opcodes_25(self, co,
-                     unpack = struct.unpack):
+    def scan_opcodes(self, co):
         # Scan the code, and yield 'interesting' opcode combinations
         code = co.co_code
         names = co.co_names
@@ -360,7 +359,7 @@ class ModuleFinder:
 
     def scan_code(self, co, m):
         code = co.co_code
-        scanner = self.scan_opcodes_25
+        scanner = self.scan_opcodes
         for what, args in scanner(co):
             if what == "store":
                 name, = args
diff --git a/Lib/msilib/__init__.py b/Lib/msilib/__init__.py
index 6d0a28f876..823644a006 100644
--- a/Lib/msilib/__init__.py
+++ b/Lib/msilib/__init__.py
@@ -1,7 +1,7 @@
 # Copyright (C) 2005 Martin v. Löwis
 # Licensed to PSF under a Contributor Agreement.
 from _msi import *
-import glob
+import fnmatch
 import os
 import re
 import string
@@ -379,7 +379,13 @@ class Directory:
     def glob(self, pattern, exclude = None):
         """Add a list of files to the current component as specified in the
         glob pattern. Individual files can be excluded in the exclude list."""
-        files = glob.glob1(self.absolute, pattern)
+        try:
+            files = os.listdir(self.absolute)
+        except OSError:
+            return []
+        if pattern[:1] != '.':
+            files = (f for f in files if f[0] != '.')
+        files = fnmatch.filter(files, pattern)
         for f in files:
             if exclude and f in exclude: continue
             self.add_file(f)
diff --git a/Lib/multiprocessing/pool.py b/Lib/multiprocessing/pool.py
index 6d25469e16..ffdf42614d 100644
--- a/Lib/multiprocessing/pool.py
+++ b/Lib/multiprocessing/pool.py
@@ -638,22 +638,26 @@ class MapResult(ApplyResult):
             self._number_left = length//chunksize + bool(length % chunksize)
 
     def _set(self, i, success_result):
+        self._number_left -= 1
         success, result = success_result
-        if success:
+        if success and self._success:
             self._value[i*self._chunksize:(i+1)*self._chunksize] = result
-            self._number_left -= 1
             if self._number_left == 0:
                 if self._callback:
                     self._callback(self._value)
                 del self._cache[self._job]
                 self._event.set()
         else:
-            self._success = False
-            self._value = result
-            if self._error_callback:
-                self._error_callback(self._value)
-            del self._cache[self._job]
-            self._event.set()
+            if not success and self._success:
+                # only store first exception
+                self._success = False
+                self._value = result
+            if self._number_left == 0:
+                # only consider the result ready once all jobs are done
+                if self._error_callback:
+                    self._error_callback(self._value)
+                del self._cache[self._job]
+                self._event.set()
 
 #
 # Class whose instances are returned by `Pool.imap()`
diff --git a/Lib/opcode.py b/Lib/opcode.py
index 4c826a7730..ecc24bb165 100644
--- a/Lib/opcode.py
+++ b/Lib/opcode.py
@@ -34,9 +34,7 @@ hasfree = []
 hasnargs = []
 
 opmap = {}
-opname = [''] * 256
-for op in range(256): opname[op] = '<%r>' % (op,)
-del op
+opname = ['<%r>' % (op,) for op in range(256)]
 
 def def_op(name, op):
     opname[op] = name
@@ -214,4 +212,6 @@ def_op('BUILD_MAP_UNPACK_WITH_CALL', 151)
 def_op('BUILD_TUPLE_UNPACK', 152)
 def_op('BUILD_SET_UNPACK', 153)
 
+def_op('FORMAT_VALUE', 155)
+
 del def_op, name_op, jrel_op, jabs_op
diff --git a/Lib/optparse.py b/Lib/optparse.py
index 74b3b36995..e8ac1e156a 100644
--- a/Lib/optparse.py
+++ b/Lib/optparse.py
@@ -38,7 +38,8 @@ __all__ = ['Option',
            'OptionError',
            'OptionConflictError',
            'OptionValueError',
-           'BadOptionError']
+           'BadOptionError',
+           'check_choice']
 
 __copyright__ = """
 Copyright (c) 2001-2006 Gregory P. Ward.  All rights reserved.
diff --git a/Lib/os.py b/Lib/os.py
index b4c651d24d..56a2f7187b 100644
--- a/Lib/os.py
+++ b/Lib/os.py
@@ -22,7 +22,7 @@ and opendir), and leave all pathname manipulation to os.path
 """
 
 #'
-
+import abc
 import sys, errno
 import stat as st
 
@@ -356,6 +356,7 @@ def walk(top, topdown=True, onerror=None, followlinks=False):
 
     dirs = []
     nondirs = []
+    walk_dirs = []
 
     # We may not have read permission for top, in which case we can't
     # get a list of the files the directory contains.  os.walk
@@ -369,42 +370,52 @@ def walk(top, topdown=True, onerror=None, followlinks=False):
             # Note that scandir is global in this module due
             # to earlier import-*.
             scandir_it = scandir(top)
-        entries = list(scandir_it)
     except OSError as error:
         if onerror is not None:
             onerror(error)
         return
 
-    for entry in entries:
-        try:
-            is_dir = entry.is_dir()
-        except OSError:
-            # If is_dir() raises an OSError, consider that the entry is not
-            # a directory, same behaviour than os.path.isdir().
-            is_dir = False
-
-        if is_dir:
-            dirs.append(entry.name)
-        else:
-            nondirs.append(entry.name)
+    with scandir_it:
+        while True:
+            try:
+                try:
+                    entry = next(scandir_it)
+                except StopIteration:
+                    break
+            except OSError as error:
+                if onerror is not None:
+                    onerror(error)
+                return
 
-        if not topdown and is_dir:
-            # Bottom-up: recurse into sub-directory, but exclude symlinks to
-            # directories if followlinks is False
-            if followlinks:
-                walk_into = True
+            try:
+                is_dir = entry.is_dir()
+            except OSError:
+                # If is_dir() raises an OSError, consider that the entry is not
+                # a directory, same behaviour than os.path.isdir().
+                is_dir = False
+
+            if is_dir:
+                dirs.append(entry.name)
             else:
-                try:
-                    is_symlink = entry.is_symlink()
-                except OSError:
-                    # If is_symlink() raises an OSError, consider that the
-                    # entry is not a symbolic link, same behaviour than
-                    # os.path.islink().
-                    is_symlink = False
-                walk_into = not is_symlink
+                nondirs.append(entry.name)
 
-            if walk_into:
-                yield from walk(entry.path, topdown, onerror, followlinks)
+            if not topdown and is_dir:
+                # Bottom-up: recurse into sub-directory, but exclude symlinks to
+                # directories if followlinks is False
+                if followlinks:
+                    walk_into = True
+                else:
+                    try:
+                        is_symlink = entry.is_symlink()
+                    except OSError:
+                        # If is_symlink() raises an OSError, consider that the
+                        # entry is not a symbolic link, same behaviour than
+                        # os.path.islink().
+                        is_symlink = False
+                    walk_into = not is_symlink
+
+                if walk_into:
+                    walk_dirs.append(entry.path)
 
     # Yield before recursion if going top down
     if topdown:
@@ -421,6 +432,9 @@ def walk(top, topdown=True, onerror=None, followlinks=False):
             if followlinks or not islink(new_path):
                 yield from walk(new_path, topdown, onerror, followlinks)
     else:
+        # Recurse into sub-directories
+        for new_path in walk_dirs:
+            yield from walk(new_path, topdown, onerror, followlinks)
         # Yield after recursion if going bottom up
         yield top, dirs, nondirs
 
@@ -467,10 +481,23 @@ class _DummyDirEntry:
         stat = self.stat(follow_symlinks=False)
         return st.S_ISLNK(stat.st_mode)
 
-def _dummy_scandir(dir):
+class _dummy_scandir:
     # listdir-based implementation for bytes patches on Windows
-    for name in listdir(dir):
-        yield _DummyDirEntry(dir, name)
+    def __init__(self, dir):
+        self.dir = dir
+        self.it = iter(listdir(dir))
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        return _DummyDirEntry(self.dir, next(self.it))
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *args):
+        self.it = iter(())
 
 __all__.append("walk")
 
@@ -850,29 +877,35 @@ def _fscodec():
 
     def fsencode(filename):
         """
-        Encode filename to the filesystem encoding with 'surrogateescape' error
-        handler, return bytes unchanged. On Windows, use 'strict' error handler if
-        the file system encoding is 'mbcs' (which is the default encoding).
+        Encode filename (an os.PathLike, bytes, or str) to the filesystem
+        encoding with 'surrogateescape' error handler, return bytes unchanged.
+        On Windows, use 'strict' error handler if the file system encoding is
+        'mbcs' (which is the default encoding).
         """
+        filename = fspath(filename)
         if isinstance(filename, bytes):
             return filename
         elif isinstance(filename, str):
             return filename.encode(encoding, errors)
         else:
-            raise TypeError("expect bytes or str, not %s" % type(filename).__name__)
+            raise TypeError("expected str, bytes or os.PathLike object, not "
+                            + type(filename).__name__)
 
     def fsdecode(filename):
         """
-        Decode filename from the filesystem encoding with 'surrogateescape' error
-        handler, return str unchanged. On Windows, use 'strict' error handler if
-        the file system encoding is 'mbcs' (which is the default encoding).
+        Decode filename (an os.PathLike, bytes, or str) from the filesystem
+        encoding with 'surrogateescape' error handler, return str unchanged. On
+        Windows, use 'strict' error handler if the file system encoding is
+        'mbcs' (which is the default encoding).
         """
+        filename = fspath(filename)
         if isinstance(filename, str):
             return filename
         elif isinstance(filename, bytes):
             return filename.decode(encoding, errors)
         else:
-            raise TypeError("expect bytes or str, not %s" % type(filename).__name__)
+            raise TypeError("expected str, bytes or os.PathLike object, not "
+                            + type(filename).__name__)
 
     return fsencode, fsdecode
 
@@ -1070,3 +1103,40 @@ def fdopen(fd, *args, **kwargs):
         raise TypeError("invalid fd type (%s, expected integer)" % type(fd))
     import io
     return io.open(fd, *args, **kwargs)
+
+# Supply os.fspath() if not defined in C
+if not _exists('fspath'):
+    def fspath(path):
+        """Return the string representation of the path.
+
+        If str or bytes is passed in, it is returned unchanged.
+        """
+        if isinstance(path, (str, bytes)):
+            return path
+
+        # Work from the object's type to match method resolution of other magic
+        # methods.
+        path_type = type(path)
+        try:
+            return path_type.__fspath__(path)
+        except AttributeError:
+            if hasattr(path_type, '__fspath__'):
+                raise
+
+            raise TypeError("expected str, bytes or os.PathLike object, not "
+                            + path_type.__name__)
+
+class PathLike(abc.ABC):
+    """
+    Abstract base class for implementing the file system path protocol.
+    """
+    @abc.abstractmethod
+    def __fspath__(self):
+        """
+        Return the file system path representation of the object.
+        """
+        raise NotImplementedError
+
+    @classmethod
+    def __subclasshook__(cls, subclass):
+        return hasattr(subclass, '__fspath__')
diff --git a/Lib/pickle.py b/Lib/pickle.py
index 7760425e76..963b5950b1 100644
--- a/Lib/pickle.py
+++ b/Lib/pickle.py
@@ -27,6 +27,7 @@ from types import FunctionType
 from copyreg import dispatch_table
 from copyreg import _extension_registry, _inverted_registry, _extension_cache
 from itertools import islice
+from functools import partial
 import sys
 from sys import maxsize
 from struct import pack, unpack
@@ -544,7 +545,7 @@ class _Pickler:
         write = self.write
 
         func_name = getattr(func, "__name__", "")
-        if self.proto >= 4 and func_name == "__newobj_ex__":
+        if self.proto >= 2 and func_name == "__newobj_ex__":
             cls, args, kwargs = args
             if not hasattr(cls, "__new__"):
                 raise PicklingError("args[0] from {} args has no __new__"
@@ -552,10 +553,16 @@ class _Pickler:
             if obj is not None and cls is not obj.__class__:
                 raise PicklingError("args[0] from {} args has the wrong class"
                                     .format(func_name))
-            save(cls)
-            save(args)
-            save(kwargs)
-            write(NEWOBJ_EX)
+            if self.proto >= 4:
+                save(cls)
+                save(args)
+                save(kwargs)
+                write(NEWOBJ_EX)
+            else:
+                func = partial(cls.__new__, cls, *args, **kwargs)
+                save(func)
+                save(())
+                write(REDUCE)
         elif self.proto >= 2 and func_name == "__newobj__":
             # A __reduce__ implementation can direct protocol 2 or newer to
             # use the more efficient NEWOBJ opcode, while still
@@ -1024,7 +1031,7 @@ class _Unpickler:
         self._unframer = _Unframer(self._file_read, self._file_readline)
         self.read = self._unframer.read
         self.readline = self._unframer.readline
-        self.mark = object() # any new unique object
+        self.metastack = []
         self.stack = []
         self.append = self.stack.append
         self.proto = 0
@@ -1040,20 +1047,12 @@ class _Unpickler:
         except _Stop as stopinst:
             return stopinst.value
 
-    # Return largest index k such that self.stack[k] is self.mark.
-    # If the stack doesn't contain a mark, eventually raises IndexError.
-    # This could be sped by maintaining another stack, of indices at which
-    # the mark appears.  For that matter, the latter stack would suffice,
-    # and we wouldn't need to push mark objects on self.stack at all.
-    # Doing so is probably a good thing, though, since if the pickle is
-    # corrupt (or hostile) we may get a clue from finding self.mark embedded
-    # in unpickled objects.
-    def marker(self):
-        stack = self.stack
-        mark = self.mark
-        k = len(stack)-1
-        while stack[k] is not mark: k = k-1
-        return k
+    # Return a list of items pushed in the stack after last MARK instruction.
+    def pop_mark(self):
+        items = self.stack
+        self.stack = self.metastack.pop()
+        self.append = self.stack.append
+        return items
 
     def persistent_load(self, pid):
         raise UnpicklingError("unsupported persistent id encountered")
@@ -1230,8 +1229,8 @@ class _Unpickler:
     dispatch[SHORT_BINUNICODE[0]] = load_short_binunicode
 
     def load_tuple(self):
-        k = self.marker()
-        self.stack[k:] = [tuple(self.stack[k+1:])]
+        items = self.pop_mark()
+        self.append(tuple(items))
     dispatch[TUPLE[0]] = load_tuple
 
     def load_empty_tuple(self):
@@ -1263,21 +1262,20 @@ class _Unpickler:
     dispatch[EMPTY_SET[0]] = load_empty_set
 
     def load_frozenset(self):
-        k = self.marker()
-        self.stack[k:] = [frozenset(self.stack[k+1:])]
+        items = self.pop_mark()
+        self.append(frozenset(items))
     dispatch[FROZENSET[0]] = load_frozenset
 
     def load_list(self):
-        k = self.marker()
-        self.stack[k:] = [self.stack[k+1:]]
+        items = self.pop_mark()
+        self.append(items)
     dispatch[LIST[0]] = load_list
 
     def load_dict(self):
-        k = self.marker()
-        items = self.stack[k+1:]
+        items = self.pop_mark()
         d = {items[i]: items[i+1]
              for i in range(0, len(items), 2)}
-        self.stack[k:] = [d]
+        self.append(d)
     dispatch[DICT[0]] = load_dict
 
     # INST and OBJ differ only in how they get a class object.  It's not
@@ -1285,9 +1283,7 @@ class _Unpickler:
     # previously diverged and grew different bugs.
     # klass is the class to instantiate, and k points to the topmost mark
     # object, following which are the arguments for klass.__init__.
-    def _instantiate(self, klass, k):
-        args = tuple(self.stack[k+1:])
-        del self.stack[k:]
+    def _instantiate(self, klass, args):
         if (args or not isinstance(klass, type) or
             hasattr(klass, "__getinitargs__")):
             try:
@@ -1303,14 +1299,14 @@ class _Unpickler:
         module = self.readline()[:-1].decode("ascii")
         name = self.readline()[:-1].decode("ascii")
         klass = self.find_class(module, name)
-        self._instantiate(klass, self.marker())
+        self._instantiate(klass, self.pop_mark())
     dispatch[INST[0]] = load_inst
 
     def load_obj(self):
         # Stack is ... markobject classobject arg1 arg2 ...
-        k = self.marker()
-        klass = self.stack.pop(k+1)
-        self._instantiate(klass, k)
+        args = self.pop_mark()
+        cls = args.pop(0)
+        self._instantiate(cls, args)
     dispatch[OBJ[0]] = load_obj
 
     def load_newobj(self):
@@ -1395,12 +1391,14 @@ class _Unpickler:
     dispatch[REDUCE[0]] = load_reduce
 
     def load_pop(self):
-        del self.stack[-1]
+        if self.stack:
+            del self.stack[-1]
+        else:
+            self.pop_mark()
     dispatch[POP[0]] = load_pop
 
     def load_pop_mark(self):
-        k = self.marker()
-        del self.stack[k:]
+        self.pop_mark()
     dispatch[POP_MARK[0]] = load_pop_mark
 
     def load_dup(self):
@@ -1456,17 +1454,14 @@ class _Unpickler:
     dispatch[APPEND[0]] = load_append
 
     def load_appends(self):
-        stack = self.stack
-        mark = self.marker()
-        list_obj = stack[mark - 1]
-        items = stack[mark + 1:]
+        items = self.pop_mark()
+        list_obj = self.stack[-1]
         if isinstance(list_obj, list):
             list_obj.extend(items)
         else:
             append = list_obj.append
             for item in items:
                 append(item)
-        del stack[mark:]
     dispatch[APPENDS[0]] = load_appends
 
     def load_setitem(self):
@@ -1478,27 +1473,21 @@ class _Unpickler:
     dispatch[SETITEM[0]] = load_setitem
 
     def load_setitems(self):
-        stack = self.stack
-        mark = self.marker()
-        dict = stack[mark - 1]
-        for i in range(mark + 1, len(stack), 2):
-            dict[stack[i]] = stack[i + 1]
-
-        del stack[mark:]
+        items = self.pop_mark()
+        dict = self.stack[-1]
+        for i in range(0, len(items), 2):
+            dict[items[i]] = items[i + 1]
     dispatch[SETITEMS[0]] = load_setitems
 
     def load_additems(self):
-        stack = self.stack
-        mark = self.marker()
-        set_obj = stack[mark - 1]
-        items = stack[mark + 1:]
+        items = self.pop_mark()
+        set_obj = self.stack[-1]
         if isinstance(set_obj, set):
             set_obj.update(items)
         else:
             add = set_obj.add
             for item in items:
                 add(item)
-        del stack[mark:]
     dispatch[ADDITEMS[0]] = load_additems
 
     def load_build(self):
@@ -1526,7 +1515,9 @@ class _Unpickler:
     dispatch[BUILD[0]] = load_build
 
     def load_mark(self):
-        self.append(self.mark)
+        self.metastack.append(self.stack)
+        self.stack = []
+        self.append = self.stack.append
     dispatch[MARK[0]] = load_mark
 
     def load_stop(self):
diff --git a/Lib/pickletools.py b/Lib/pickletools.py
index 16ae7d56b9..4eefc19fdb 100644
--- a/Lib/pickletools.py
+++ b/Lib/pickletools.py
@@ -2440,6 +2440,7 @@ def dis(pickle, out=None, memo=None, indentlevel=4, annotate=0):
         if opcode.name in ("PUT", "BINPUT", "LONG_BINPUT", "MEMOIZE"):
             if opcode.name == "MEMOIZE":
                 memo_idx = len(memo)
+                markmsg = "(as %d)" % memo_idx
             else:
                 assert arg is not None
                 memo_idx = arg
diff --git a/Lib/pkgutil.py b/Lib/pkgutil.py
index fc4a074f5b..203d515e5e 100644
--- a/Lib/pkgutil.py
+++ b/Lib/pkgutil.py
@@ -180,7 +180,7 @@ iter_importer_modules.register(
 def _import_imp():
     global imp
     with warnings.catch_warnings():
-        warnings.simplefilter('ignore', PendingDeprecationWarning)
+        warnings.simplefilter('ignore', DeprecationWarning)
         imp = importlib.import_module('imp')
 
 class ImpImporter:
diff --git a/Lib/plistlib.py b/Lib/plistlib.py
index b66639ca9e..4f360f3220 100644
--- a/Lib/plistlib.py
+++ b/Lib/plistlib.py
@@ -47,7 +47,7 @@ Parse Plist example:
 """
 __all__ = [
     "readPlist", "writePlist", "readPlistFromBytes", "writePlistToBytes",
-    "Plist", "Data", "Dict", "FMT_XML", "FMT_BINARY",
+    "Plist", "Data", "Dict", "InvalidFileException", "FMT_XML", "FMT_BINARY",
     "load", "dump", "loads", "dumps"
 ]
 
diff --git a/Lib/pyclbr.py b/Lib/pyclbr.py
index 4d40b87f16..d7dba97618 100644
--- a/Lib/pyclbr.py
+++ b/Lib/pyclbr.py
@@ -40,12 +40,10 @@ Instances of this class have the following instance variables:
 """
 
 import io
-import os
 import sys
 import importlib.util
 import tokenize
 from token import NAME, DEDENT, OP
-from operator import itemgetter
 
 __all__ = ["readmodule", "readmodule_ex", "Class", "Function"]
 
@@ -328,6 +326,7 @@ def _getname(g):
 def _main():
     # Main program for testing.
     import os
+    from operator import itemgetter
     mod = sys.argv[1]
     if os.path.exists(mod):
         path = [os.path.dirname(mod)]
diff --git a/Lib/pydoc.py b/Lib/pydoc.py
index 3ca08c9b58..85000fe206 100755..100644
--- a/Lib/pydoc.py
+++ b/Lib/pydoc.py
@@ -209,6 +209,18 @@ def classify_class_attrs(object):
         results.append((name, kind, cls, value))
     return results
 
+def sort_attributes(attrs, object):
+    'Sort the attrs list in-place by _fields and then alphabetically by name'
+    # This allows data descriptors to be ordered according
+    # to a _fields attribute if present.
+    fields = getattr(object, '_fields', [])
+    try:
+        field_order = {name : i-len(fields) for (i, name) in enumerate(fields)}
+    except TypeError:
+        field_order = {}
+    keyfunc = lambda attr: (field_order.get(attr[0], 0), attr[0])
+    attrs.sort(key=keyfunc)
+
 # ----------------------------------------------------- module manipulation
 
 def ispackage(path):
@@ -867,8 +879,7 @@ class HTMLDoc(Doc):
                                                            object.__module__)
             tag += ':<br>\n'
 
-            # Sort attrs by name.
-            attrs.sort(key=lambda t: t[0])
+            sort_attributes(attrs, object)
 
             # Pump out the attrs, segregated by kind.
             attrs = spill('Methods %s' % tag, attrs,
@@ -1286,8 +1297,8 @@ location listed above.
             else:
                 tag = "inherited from %s" % classname(thisclass,
                                                       object.__module__)
-            # Sort attrs by name.
-            attrs.sort()
+
+            sort_attributes(attrs, object)
 
             # Pump out the attrs, segregated by kind.
             attrs = spill("Methods %s:\n" % tag, attrs,
@@ -1900,10 +1911,10 @@ has the same effect as typing a particular string at the help> prompt.
 
     def intro(self):
         self.output.write('''
-Welcome to Python %s's help utility!
+Welcome to Python {0}'s help utility!
 
 If this is your first time using Python, you should definitely check out
-the tutorial on the Internet at http://docs.python.org/%s/tutorial/.
+the tutorial on the Internet at http://docs.python.org/{0}/tutorial/.
 
 Enter the name of any module, keyword, or topic to get help on writing
 Python programs and using Python modules.  To quit this help utility and
@@ -1913,7 +1924,7 @@ To get a list of available modules, keywords, symbols, or topics, type
 "modules", "keywords", "symbols", or "topics".  Each module also comes
 with a one-line summary of what it does; to list the modules whose name
 or summary contain a given string such as "spam", type "modules spam".
-''' % tuple([sys.version[:3]]*2))
+'''.format('%d.%d' % sys.version_info[:2]))
 
     def list(self, items, columns=4, width=80):
         items = list(sorted(items))
diff --git a/Lib/pydoc_data/topics.py b/Lib/pydoc_data/topics.py
index 250bfd331e..a0b071b0c5 100644
--- a/Lib/pydoc_data/topics.py
+++ b/Lib/pydoc_data/topics.py
@@ -1,79 +1,12686 @@
 # -*- coding: utf-8 -*-
-# Autogenerated by Sphinx on Sat Dec  5 17:02:49 2015
-topics = {'assert': u'\nThe "assert" statement\n**********************\n\nAssert statements are a convenient way to insert debugging assertions\ninto a program:\n\n   assert_stmt ::= "assert" expression ["," expression]\n\nThe simple form, "assert expression", is equivalent to\n\n   if __debug__:\n      if not expression: raise AssertionError\n\nThe extended form, "assert expression1, expression2", is equivalent to\n\n   if __debug__:\n      if not expression1: raise AssertionError(expression2)\n\nThese equivalences assume that "__debug__" and "AssertionError" refer\nto the built-in variables with those names.  In the current\nimplementation, the built-in variable "__debug__" is "True" under\nnormal circumstances, "False" when optimization is requested (command\nline option -O).  The current code generator emits no code for an\nassert statement when optimization is requested at compile time.  Note\nthat it is unnecessary to include the source code for the expression\nthat failed in the error message; it will be displayed as part of the\nstack trace.\n\nAssignments to "__debug__" are illegal.  The value for the built-in\nvariable is determined when the interpreter starts.\n',
- 'assignment': u'\nAssignment statements\n*********************\n\nAssignment statements are used to (re)bind names to values and to\nmodify attributes or items of mutable objects:\n\n   assignment_stmt ::= (target_list "=")+ (expression_list | yield_expression)\n   target_list     ::= target ("," target)* [","]\n   target          ::= identifier\n              | "(" target_list ")"\n              | "[" target_list "]"\n              | attributeref\n              | subscription\n              | slicing\n              | "*" target\n\n(See section *Primaries* for the syntax definitions for\n*attributeref*, *subscription*, and *slicing*.)\n\nAn assignment statement evaluates the expression list (remember that\nthis can be a single expression or a comma-separated list, the latter\nyielding a tuple) and assigns the single resulting object to each of\nthe target lists, from left to right.\n\nAssignment is defined recursively depending on the form of the target\n(list). When a target is part of a mutable object (an attribute\nreference, subscription or slicing), the mutable object must\nultimately perform the assignment and decide about its validity, and\nmay raise an exception if the assignment is unacceptable.  The rules\nobserved by various types and the exceptions raised are given with the\ndefinition of the object types (see section *The standard type\nhierarchy*).\n\nAssignment of an object to a target list, optionally enclosed in\nparentheses or square brackets, is recursively defined as follows.\n\n* If the target list is a single target: The object is assigned to\n  that target.\n\n* If the target list is a comma-separated list of targets: The\n  object must be an iterable with the same number of items as there\n  are targets in the target list, and the items are assigned, from\n  left to right, to the corresponding targets.\n\n  * If the target list contains one target prefixed with an\n    asterisk, called a "starred" target: The object must be a sequence\n    with at least as many items as there are targets in the target\n    list, minus one.  The first items of the sequence are assigned,\n    from left to right, to the targets before the starred target.  The\n    final items of the sequence are assigned to the targets after the\n    starred target.  A list of the remaining items in the sequence is\n    then assigned to the starred target (the list can be empty).\n\n  * Else: The object must be a sequence with the same number of\n    items as there are targets in the target list, and the items are\n    assigned, from left to right, to the corresponding targets.\n\nAssignment of an object to a single target is recursively defined as\nfollows.\n\n* If the target is an identifier (name):\n\n  * If the name does not occur in a "global" or "nonlocal" statement\n    in the current code block: the name is bound to the object in the\n    current local namespace.\n\n  * Otherwise: the name is bound to the object in the global\n    namespace or the outer namespace determined by "nonlocal",\n    respectively.\n\n  The name is rebound if it was already bound.  This may cause the\n  reference count for the object previously bound to the name to reach\n  zero, causing the object to be deallocated and its destructor (if it\n  has one) to be called.\n\n* If the target is a target list enclosed in parentheses or in\n  square brackets: The object must be an iterable with the same number\n  of items as there are targets in the target list, and its items are\n  assigned, from left to right, to the corresponding targets.\n\n* If the target is an attribute reference: The primary expression in\n  the reference is evaluated.  It should yield an object with\n  assignable attributes; if this is not the case, "TypeError" is\n  raised.  That object is then asked to assign the assigned object to\n  the given attribute; if it cannot perform the assignment, it raises\n  an exception (usually but not necessarily "AttributeError").\n\n  Note: If the object is a class instance and the attribute reference\n  occurs on both sides of the assignment operator, the RHS expression,\n  "a.x" can access either an instance attribute or (if no instance\n  attribute exists) a class attribute.  The LHS target "a.x" is always\n  set as an instance attribute, creating it if necessary.  Thus, the\n  two occurrences of "a.x" do not necessarily refer to the same\n  attribute: if the RHS expression refers to a class attribute, the\n  LHS creates a new instance attribute as the target of the\n  assignment:\n\n     class Cls:\n         x = 3             # class variable\n     inst = Cls()\n     inst.x = inst.x + 1   # writes inst.x as 4 leaving Cls.x as 3\n\n  This description does not necessarily apply to descriptor\n  attributes, such as properties created with "property()".\n\n* If the target is a subscription: The primary expression in the\n  reference is evaluated.  It should yield either a mutable sequence\n  object (such as a list) or a mapping object (such as a dictionary).\n  Next, the subscript expression is evaluated.\n\n  If the primary is a mutable sequence object (such as a list), the\n  subscript must yield an integer.  If it is negative, the sequence\'s\n  length is added to it.  The resulting value must be a nonnegative\n  integer less than the sequence\'s length, and the sequence is asked\n  to assign the assigned object to its item with that index.  If the\n  index is out of range, "IndexError" is raised (assignment to a\n  subscripted sequence cannot add new items to a list).\n\n  If the primary is a mapping object (such as a dictionary), the\n  subscript must have a type compatible with the mapping\'s key type,\n  and the mapping is then asked to create a key/datum pair which maps\n  the subscript to the assigned object.  This can either replace an\n  existing key/value pair with the same key value, or insert a new\n  key/value pair (if no key with the same value existed).\n\n  For user-defined objects, the "__setitem__()" method is called with\n  appropriate arguments.\n\n* If the target is a slicing: The primary expression in the\n  reference is evaluated.  It should yield a mutable sequence object\n  (such as a list).  The assigned object should be a sequence object\n  of the same type.  Next, the lower and upper bound expressions are\n  evaluated, insofar they are present; defaults are zero and the\n  sequence\'s length.  The bounds should evaluate to integers. If\n  either bound is negative, the sequence\'s length is added to it.  The\n  resulting bounds are clipped to lie between zero and the sequence\'s\n  length, inclusive.  Finally, the sequence object is asked to replace\n  the slice with the items of the assigned sequence.  The length of\n  the slice may be different from the length of the assigned sequence,\n  thus changing the length of the target sequence, if the target\n  sequence allows it.\n\n**CPython implementation detail:** In the current implementation, the\nsyntax for targets is taken to be the same as for expressions, and\ninvalid syntax is rejected during the code generation phase, causing\nless detailed error messages.\n\nAlthough the definition of assignment implies that overlaps between\nthe left-hand side and the right-hand side are \'simultanenous\' (for\nexample "a, b = b, a" swaps two variables), overlaps *within* the\ncollection of assigned-to variables occur left-to-right, sometimes\nresulting in confusion.  For instance, the following program prints\n"[0, 2]":\n\n   x = [0, 1]\n   i = 0\n   i, x[i] = 1, 2         # i is updated, then x[i] is updated\n   print(x)\n\nSee also: **PEP 3132** - Extended Iterable Unpacking\n\n     The specification for the "*target" feature.\n\n\nAugmented assignment statements\n===============================\n\nAugmented assignment is the combination, in a single statement, of a\nbinary operation and an assignment statement:\n\n   augmented_assignment_stmt ::= augtarget augop (expression_list | yield_expression)\n   augtarget                 ::= identifier | attributeref | subscription | slicing\n   augop                     ::= "+=" | "-=" | "*=" | "@=" | "/=" | "//=" | "%=" | "**="\n             | ">>=" | "<<=" | "&=" | "^=" | "|="\n\n(See section *Primaries* for the syntax definitions of the last three\nsymbols.)\n\nAn augmented assignment evaluates the target (which, unlike normal\nassignment statements, cannot be an unpacking) and the expression\nlist, performs the binary operation specific to the type of assignment\non the two operands, and assigns the result to the original target.\nThe target is only evaluated once.\n\nAn augmented assignment expression like "x += 1" can be rewritten as\n"x = x + 1" to achieve a similar, but not exactly equal effect. In the\naugmented version, "x" is only evaluated once. Also, when possible,\nthe actual operation is performed *in-place*, meaning that rather than\ncreating a new object and assigning that to the target, the old object\nis modified instead.\n\nUnlike normal assignments, augmented assignments evaluate the left-\nhand side *before* evaluating the right-hand side.  For example, "a[i]\n+= f(x)" first looks-up "a[i]", then it evaluates "f(x)" and performs\nthe addition, and lastly, it writes the result back to "a[i]".\n\nWith the exception of assigning to tuples and multiple targets in a\nsingle statement, the assignment done by augmented assignment\nstatements is handled the same way as normal assignments. Similarly,\nwith the exception of the possible *in-place* behavior, the binary\noperation performed by augmented assignment is the same as the normal\nbinary operations.\n\nFor targets which are attribute references, the same *caveat about\nclass and instance attributes* applies as for regular assignments.\n',
- 'atom-identifiers': u'\nIdentifiers (Names)\n*******************\n\nAn identifier occurring as an atom is a name.  See section\n*Identifiers and keywords* for lexical definition and section *Naming\nand binding* for documentation of naming and binding.\n\nWhen the name is bound to an object, evaluation of the atom yields\nthat object. When a name is not bound, an attempt to evaluate it\nraises a "NameError" exception.\n\n**Private name mangling:** When an identifier that textually occurs in\na class definition begins with two or more underscore characters and\ndoes not end in two or more underscores, it is considered a *private\nname* of that class. Private names are transformed to a longer form\nbefore code is generated for them.  The transformation inserts the\nclass name, with leading underscores removed and a single underscore\ninserted, in front of the name.  For example, the identifier "__spam"\noccurring in a class named "Ham" will be transformed to "_Ham__spam".\nThis transformation is independent of the syntactical context in which\nthe identifier is used.  If the transformed name is extremely long\n(longer than 255 characters), implementation defined truncation may\nhappen. If the class name consists only of underscores, no\ntransformation is done.\n',
- 'atom-literals': u"\nLiterals\n********\n\nPython supports string and bytes literals and various numeric\nliterals:\n\n   literal ::= stringliteral | bytesliteral\n               | integer | floatnumber | imagnumber\n\nEvaluation of a literal yields an object of the given type (string,\nbytes, integer, floating point number, complex number) with the given\nvalue.  The value may be approximated in the case of floating point\nand imaginary (complex) literals.  See section *Literals* for details.\n\nAll literals correspond to immutable data types, and hence the\nobject's identity is less important than its value.  Multiple\nevaluations of literals with the same value (either the same\noccurrence in the program text or a different occurrence) may obtain\nthe same object or a different object with the same value.\n",
- 'attribute-access': u'\nCustomizing attribute access\n****************************\n\nThe following methods can be defined to customize the meaning of\nattribute access (use of, assignment to, or deletion of "x.name") for\nclass instances.\n\nobject.__getattr__(self, name)\n\n   Called when an attribute lookup has not found the attribute in the\n   usual places (i.e. it is not an instance attribute nor is it found\n   in the class tree for "self").  "name" is the attribute name. This\n   method should return the (computed) attribute value or raise an\n   "AttributeError" exception.\n\n   Note that if the attribute is found through the normal mechanism,\n   "__getattr__()" is not called.  (This is an intentional asymmetry\n   between "__getattr__()" and "__setattr__()".) This is done both for\n   efficiency reasons and because otherwise "__getattr__()" would have\n   no way to access other attributes of the instance.  Note that at\n   least for instance variables, you can fake total control by not\n   inserting any values in the instance attribute dictionary (but\n   instead inserting them in another object).  See the\n   "__getattribute__()" method below for a way to actually get total\n   control over attribute access.\n\nobject.__getattribute__(self, name)\n\n   Called unconditionally to implement attribute accesses for\n   instances of the class. If the class also defines "__getattr__()",\n   the latter will not be called unless "__getattribute__()" either\n   calls it explicitly or raises an "AttributeError". This method\n   should return the (computed) attribute value or raise an\n   "AttributeError" exception. In order to avoid infinite recursion in\n   this method, its implementation should always call the base class\n   method with the same name to access any attributes it needs, for\n   example, "object.__getattribute__(self, name)".\n\n   Note: This method may still be bypassed when looking up special\n     methods as the result of implicit invocation via language syntax\n     or built-in functions. See *Special method lookup*.\n\nobject.__setattr__(self, name, value)\n\n   Called when an attribute assignment is attempted.  This is called\n   instead of the normal mechanism (i.e. store the value in the\n   instance dictionary). *name* is the attribute name, *value* is the\n   value to be assigned to it.\n\n   If "__setattr__()" wants to assign to an instance attribute, it\n   should call the base class method with the same name, for example,\n   "object.__setattr__(self, name, value)".\n\nobject.__delattr__(self, name)\n\n   Like "__setattr__()" but for attribute deletion instead of\n   assignment.  This should only be implemented if "del obj.name" is\n   meaningful for the object.\n\nobject.__dir__(self)\n\n   Called when "dir()" is called on the object. A sequence must be\n   returned. "dir()" converts the returned sequence to a list and\n   sorts it.\n\n\nImplementing Descriptors\n========================\n\nThe following methods only apply when an instance of the class\ncontaining the method (a so-called *descriptor* class) appears in an\n*owner* class (the descriptor must be in either the owner\'s class\ndictionary or in the class dictionary for one of its parents).  In the\nexamples below, "the attribute" refers to the attribute whose name is\nthe key of the property in the owner class\' "__dict__".\n\nobject.__get__(self, instance, owner)\n\n   Called to get the attribute of the owner class (class attribute\n   access) or of an instance of that class (instance attribute\n   access). *owner* is always the owner class, while *instance* is the\n   instance that the attribute was accessed through, or "None" when\n   the attribute is accessed through the *owner*.  This method should\n   return the (computed) attribute value or raise an "AttributeError"\n   exception.\n\nobject.__set__(self, instance, value)\n\n   Called to set the attribute on an instance *instance* of the owner\n   class to a new value, *value*.\n\nobject.__delete__(self, instance)\n\n   Called to delete the attribute on an instance *instance* of the\n   owner class.\n\nThe attribute "__objclass__" is interpreted by the "inspect" module as\nspecifying the class where this object was defined (setting this\nappropriately can assist in runtime introspection of dynamic class\nattributes). For callables, it may indicate that an instance of the\ngiven type (or a subclass) is expected or required as the first\npositional argument (for example, CPython sets this attribute for\nunbound methods that are implemented in C).\n\n\nInvoking Descriptors\n====================\n\nIn general, a descriptor is an object attribute with "binding\nbehavior", one whose attribute access has been overridden by methods\nin the descriptor protocol:  "__get__()", "__set__()", and\n"__delete__()". If any of those methods are defined for an object, it\nis said to be a descriptor.\n\nThe default behavior for attribute access is to get, set, or delete\nthe attribute from an object\'s dictionary. For instance, "a.x" has a\nlookup chain starting with "a.__dict__[\'x\']", then\n"type(a).__dict__[\'x\']", and continuing through the base classes of\n"type(a)" excluding metaclasses.\n\nHowever, if the looked-up value is an object defining one of the\ndescriptor methods, then Python may override the default behavior and\ninvoke the descriptor method instead.  Where this occurs in the\nprecedence chain depends on which descriptor methods were defined and\nhow they were called.\n\nThe starting point for descriptor invocation is a binding, "a.x". How\nthe arguments are assembled depends on "a":\n\nDirect Call\n   The simplest and least common call is when user code directly\n   invokes a descriptor method:    "x.__get__(a)".\n\nInstance Binding\n   If binding to an object instance, "a.x" is transformed into the\n   call: "type(a).__dict__[\'x\'].__get__(a, type(a))".\n\nClass Binding\n   If binding to a class, "A.x" is transformed into the call:\n   "A.__dict__[\'x\'].__get__(None, A)".\n\nSuper Binding\n   If "a" is an instance of "super", then the binding "super(B,\n   obj).m()" searches "obj.__class__.__mro__" for the base class "A"\n   immediately preceding "B" and then invokes the descriptor with the\n   call: "A.__dict__[\'m\'].__get__(obj, obj.__class__)".\n\nFor instance bindings, the precedence of descriptor invocation depends\non the which descriptor methods are defined.  A descriptor can define\nany combination of "__get__()", "__set__()" and "__delete__()".  If it\ndoes not define "__get__()", then accessing the attribute will return\nthe descriptor object itself unless there is a value in the object\'s\ninstance dictionary.  If the descriptor defines "__set__()" and/or\n"__delete__()", it is a data descriptor; if it defines neither, it is\na non-data descriptor.  Normally, data descriptors define both\n"__get__()" and "__set__()", while non-data descriptors have just the\n"__get__()" method.  Data descriptors with "__set__()" and "__get__()"\ndefined always override a redefinition in an instance dictionary.  In\ncontrast, non-data descriptors can be overridden by instances.\n\nPython methods (including "staticmethod()" and "classmethod()") are\nimplemented as non-data descriptors.  Accordingly, instances can\nredefine and override methods.  This allows individual instances to\nacquire behaviors that differ from other instances of the same class.\n\nThe "property()" function is implemented as a data descriptor.\nAccordingly, instances cannot override the behavior of a property.\n\n\n__slots__\n=========\n\nBy default, instances of classes have a dictionary for attribute\nstorage.  This wastes space for objects having very few instance\nvariables.  The space consumption can become acute when creating large\nnumbers of instances.\n\nThe default can be overridden by defining *__slots__* in a class\ndefinition. The *__slots__* declaration takes a sequence of instance\nvariables and reserves just enough space in each instance to hold a\nvalue for each variable.  Space is saved because *__dict__* is not\ncreated for each instance.\n\nobject.__slots__\n\n   This class variable can be assigned a string, iterable, or sequence\n   of strings with variable names used by instances.  *__slots__*\n   reserves space for the declared variables and prevents the\n   automatic creation of *__dict__* and *__weakref__* for each\n   instance.\n\n\nNotes on using *__slots__*\n--------------------------\n\n* When inheriting from a class without *__slots__*, the *__dict__*\n  attribute of that class will always be accessible, so a *__slots__*\n  definition in the subclass is meaningless.\n\n* Without a *__dict__* variable, instances cannot be assigned new\n  variables not listed in the *__slots__* definition.  Attempts to\n  assign to an unlisted variable name raises "AttributeError". If\n  dynamic assignment of new variables is desired, then add\n  "\'__dict__\'" to the sequence of strings in the *__slots__*\n  declaration.\n\n* Without a *__weakref__* variable for each instance, classes\n  defining *__slots__* do not support weak references to its\n  instances. If weak reference support is needed, then add\n  "\'__weakref__\'" to the sequence of strings in the *__slots__*\n  declaration.\n\n* *__slots__* are implemented at the class level by creating\n  descriptors (*Implementing Descriptors*) for each variable name.  As\n  a result, class attributes cannot be used to set default values for\n  instance variables defined by *__slots__*; otherwise, the class\n  attribute would overwrite the descriptor assignment.\n\n* The action of a *__slots__* declaration is limited to the class\n  where it is defined.  As a result, subclasses will have a *__dict__*\n  unless they also define *__slots__* (which must only contain names\n  of any *additional* slots).\n\n* If a class defines a slot also defined in a base class, the\n  instance variable defined by the base class slot is inaccessible\n  (except by retrieving its descriptor directly from the base class).\n  This renders the meaning of the program undefined.  In the future, a\n  check may be added to prevent this.\n\n* Nonempty *__slots__* does not work for classes derived from\n  "variable-length" built-in types such as "int", "bytes" and "tuple".\n\n* Any non-string iterable may be assigned to *__slots__*. Mappings\n  may also be used; however, in the future, special meaning may be\n  assigned to the values corresponding to each key.\n\n* *__class__* assignment works only if both classes have the same\n  *__slots__*.\n',
- 'attribute-references': u'\nAttribute references\n********************\n\nAn attribute reference is a primary followed by a period and a name:\n\n   attributeref ::= primary "." identifier\n\nThe primary must evaluate to an object of a type that supports\nattribute references, which most objects do.  This object is then\nasked to produce the attribute whose name is the identifier.  This\nproduction can be customized by overriding the "__getattr__()" method.\nIf this attribute is not available, the exception "AttributeError" is\nraised.  Otherwise, the type and value of the object produced is\ndetermined by the object.  Multiple evaluations of the same attribute\nreference may yield different objects.\n',
- 'augassign': u'\nAugmented assignment statements\n*******************************\n\nAugmented assignment is the combination, in a single statement, of a\nbinary operation and an assignment statement:\n\n   augmented_assignment_stmt ::= augtarget augop (expression_list | yield_expression)\n   augtarget                 ::= identifier | attributeref | subscription | slicing\n   augop                     ::= "+=" | "-=" | "*=" | "@=" | "/=" | "//=" | "%=" | "**="\n             | ">>=" | "<<=" | "&=" | "^=" | "|="\n\n(See section *Primaries* for the syntax definitions of the last three\nsymbols.)\n\nAn augmented assignment evaluates the target (which, unlike normal\nassignment statements, cannot be an unpacking) and the expression\nlist, performs the binary operation specific to the type of assignment\non the two operands, and assigns the result to the original target.\nThe target is only evaluated once.\n\nAn augmented assignment expression like "x += 1" can be rewritten as\n"x = x + 1" to achieve a similar, but not exactly equal effect. In the\naugmented version, "x" is only evaluated once. Also, when possible,\nthe actual operation is performed *in-place*, meaning that rather than\ncreating a new object and assigning that to the target, the old object\nis modified instead.\n\nUnlike normal assignments, augmented assignments evaluate the left-\nhand side *before* evaluating the right-hand side.  For example, "a[i]\n+= f(x)" first looks-up "a[i]", then it evaluates "f(x)" and performs\nthe addition, and lastly, it writes the result back to "a[i]".\n\nWith the exception of assigning to tuples and multiple targets in a\nsingle statement, the assignment done by augmented assignment\nstatements is handled the same way as normal assignments. Similarly,\nwith the exception of the possible *in-place* behavior, the binary\noperation performed by augmented assignment is the same as the normal\nbinary operations.\n\nFor targets which are attribute references, the same *caveat about\nclass and instance attributes* applies as for regular assignments.\n',
- 'binary': u'\nBinary arithmetic operations\n****************************\n\nThe binary arithmetic operations have the conventional priority\nlevels.  Note that some of these operations also apply to certain non-\nnumeric types.  Apart from the power operator, there are only two\nlevels, one for multiplicative operators and one for additive\noperators:\n\n   m_expr ::= u_expr | m_expr "*" u_expr | m_expr "@" m_expr |\n              m_expr "//" u_expr| m_expr "/" u_expr |\n              m_expr "%" u_expr\n   a_expr ::= m_expr | a_expr "+" m_expr | a_expr "-" m_expr\n\nThe "*" (multiplication) operator yields the product of its arguments.\nThe arguments must either both be numbers, or one argument must be an\ninteger and the other must be a sequence. In the former case, the\nnumbers are converted to a common type and then multiplied together.\nIn the latter case, sequence repetition is performed; a negative\nrepetition factor yields an empty sequence.\n\nThe "@" (at) operator is intended to be used for matrix\nmultiplication.  No builtin Python types implement this operator.\n\nNew in version 3.5.\n\nThe "/" (division) and "//" (floor division) operators yield the\nquotient of their arguments.  The numeric arguments are first\nconverted to a common type. Division of integers yields a float, while\nfloor division of integers results in an integer; the result is that\nof mathematical division with the \'floor\' function applied to the\nresult.  Division by zero raises the "ZeroDivisionError" exception.\n\nThe "%" (modulo) operator yields the remainder from the division of\nthe first argument by the second.  The numeric arguments are first\nconverted to a common type.  A zero right argument raises the\n"ZeroDivisionError" exception.  The arguments may be floating point\nnumbers, e.g., "3.14%0.7" equals "0.34" (since "3.14" equals "4*0.7 +\n0.34".)  The modulo operator always yields a result with the same sign\nas its second operand (or zero); the absolute value of the result is\nstrictly smaller than the absolute value of the second operand [1].\n\nThe floor division and modulo operators are connected by the following\nidentity: "x == (x//y)*y + (x%y)".  Floor division and modulo are also\nconnected with the built-in function "divmod()": "divmod(x, y) ==\n(x//y, x%y)". [2].\n\nIn addition to performing the modulo operation on numbers, the "%"\noperator is also overloaded by string objects to perform old-style\nstring formatting (also known as interpolation).  The syntax for\nstring formatting is described in the Python Library Reference,\nsection *printf-style String Formatting*.\n\nThe floor division operator, the modulo operator, and the "divmod()"\nfunction are not defined for complex numbers.  Instead, convert to a\nfloating point number using the "abs()" function if appropriate.\n\nThe "+" (addition) operator yields the sum of its arguments.  The\narguments must either both be numbers or both be sequences of the same\ntype.  In the former case, the numbers are converted to a common type\nand then added together. In the latter case, the sequences are\nconcatenated.\n\nThe "-" (subtraction) operator yields the difference of its arguments.\nThe numeric arguments are first converted to a common type.\n',
- 'bitwise': u'\nBinary bitwise operations\n*************************\n\nEach of the three bitwise operations has a different priority level:\n\n   and_expr ::= shift_expr | and_expr "&" shift_expr\n   xor_expr ::= and_expr | xor_expr "^" and_expr\n   or_expr  ::= xor_expr | or_expr "|" xor_expr\n\nThe "&" operator yields the bitwise AND of its arguments, which must\nbe integers.\n\nThe "^" operator yields the bitwise XOR (exclusive OR) of its\narguments, which must be integers.\n\nThe "|" operator yields the bitwise (inclusive) OR of its arguments,\nwhich must be integers.\n',
- 'bltin-code-objects': u'\nCode Objects\n************\n\nCode objects are used by the implementation to represent "pseudo-\ncompiled" executable Python code such as a function body. They differ\nfrom function objects because they don\'t contain a reference to their\nglobal execution environment.  Code objects are returned by the built-\nin "compile()" function and can be extracted from function objects\nthrough their "__code__" attribute. See also the "code" module.\n\nA code object can be executed or evaluated by passing it (instead of a\nsource string) to the "exec()" or "eval()"  built-in functions.\n\nSee *The standard type hierarchy* for more information.\n',
- 'bltin-ellipsis-object': u'\nThe Ellipsis Object\n*******************\n\nThis object is commonly used by slicing (see *Slicings*).  It supports\nno special operations.  There is exactly one ellipsis object, named\n"Ellipsis" (a built-in name).  "type(Ellipsis)()" produces the\n"Ellipsis" singleton.\n\nIt is written as "Ellipsis" or "...".\n',
- 'bltin-null-object': u'\nThe Null Object\n***************\n\nThis object is returned by functions that don\'t explicitly return a\nvalue.  It supports no special operations.  There is exactly one null\nobject, named "None" (a built-in name).  "type(None)()" produces the\nsame singleton.\n\nIt is written as "None".\n',
- 'bltin-type-objects': u'\nType Objects\n************\n\nType objects represent the various object types.  An object\'s type is\naccessed by the built-in function "type()".  There are no special\noperations on types.  The standard module "types" defines names for\nall standard built-in types.\n\nTypes are written like this: "<class \'int\'>".\n',
- 'booleans': u'\nBoolean operations\n******************\n\n   or_test  ::= and_test | or_test "or" and_test\n   and_test ::= not_test | and_test "and" not_test\n   not_test ::= comparison | "not" not_test\n\nIn the context of Boolean operations, and also when expressions are\nused by control flow statements, the following values are interpreted\nas false: "False", "None", numeric zero of all types, and empty\nstrings and containers (including strings, tuples, lists,\ndictionaries, sets and frozensets).  All other values are interpreted\nas true.  User-defined objects can customize their truth value by\nproviding a "__bool__()" method.\n\nThe operator "not" yields "True" if its argument is false, "False"\notherwise.\n\nThe expression "x and y" first evaluates *x*; if *x* is false, its\nvalue is returned; otherwise, *y* is evaluated and the resulting value\nis returned.\n\nThe expression "x or y" first evaluates *x*; if *x* is true, its value\nis returned; otherwise, *y* is evaluated and the resulting value is\nreturned.\n\n(Note that neither "and" nor "or" restrict the value and type they\nreturn to "False" and "True", but rather return the last evaluated\nargument.  This is sometimes useful, e.g., if "s" is a string that\nshould be replaced by a default value if it is empty, the expression\n"s or \'foo\'" yields the desired value.  Because "not" has to create a\nnew value, it returns a boolean value regardless of the type of its\nargument (for example, "not \'foo\'" produces "False" rather than "\'\'".)\n',
- 'break': u'\nThe "break" statement\n*********************\n\n   break_stmt ::= "break"\n\n"break" may only occur syntactically nested in a "for" or "while"\nloop, but not nested in a function or class definition within that\nloop.\n\nIt terminates the nearest enclosing loop, skipping the optional "else"\nclause if the loop has one.\n\nIf a "for" loop is terminated by "break", the loop control target\nkeeps its current value.\n\nWhen "break" passes control out of a "try" statement with a "finally"\nclause, that "finally" clause is executed before really leaving the\nloop.\n',
- 'callable-types': u'\nEmulating callable objects\n**************************\n\nobject.__call__(self[, args...])\n\n   Called when the instance is "called" as a function; if this method\n   is defined, "x(arg1, arg2, ...)" is a shorthand for\n   "x.__call__(arg1, arg2, ...)".\n',
- 'calls': u'\nCalls\n*****\n\nA call calls a callable object (e.g., a *function*) with a possibly\nempty series of *arguments*:\n\n   call                 ::= primary "(" [argument_list [","] | comprehension] ")"\n   argument_list        ::= positional_arguments ["," keyword_arguments]\n                       ["," "*" expression] ["," keyword_arguments]\n                       ["," "**" expression]\n                     | keyword_arguments ["," "*" expression]\n                       ["," keyword_arguments] ["," "**" expression]\n                     | "*" expression ["," keyword_arguments] ["," "**" expression]\n                     | "**" expression\n   positional_arguments ::= expression ("," expression)*\n   keyword_arguments    ::= keyword_item ("," keyword_item)*\n   keyword_item         ::= identifier "=" expression\n\nAn optional trailing comma may be present after the positional and\nkeyword arguments but does not affect the semantics.\n\nThe primary must evaluate to a callable object (user-defined\nfunctions, built-in functions, methods of built-in objects, class\nobjects, methods of class instances, and all objects having a\n"__call__()" method are callable).  All argument expressions are\nevaluated before the call is attempted.  Please refer to section\n*Function definitions* for the syntax of formal *parameter* lists.\n\nIf keyword arguments are present, they are first converted to\npositional arguments, as follows.  First, a list of unfilled slots is\ncreated for the formal parameters.  If there are N positional\narguments, they are placed in the first N slots.  Next, for each\nkeyword argument, the identifier is used to determine the\ncorresponding slot (if the identifier is the same as the first formal\nparameter name, the first slot is used, and so on).  If the slot is\nalready filled, a "TypeError" exception is raised. Otherwise, the\nvalue of the argument is placed in the slot, filling it (even if the\nexpression is "None", it fills the slot).  When all arguments have\nbeen processed, the slots that are still unfilled are filled with the\ncorresponding default value from the function definition.  (Default\nvalues are calculated, once, when the function is defined; thus, a\nmutable object such as a list or dictionary used as default value will\nbe shared by all calls that don\'t specify an argument value for the\ncorresponding slot; this should usually be avoided.)  If there are any\nunfilled slots for which no default value is specified, a "TypeError"\nexception is raised.  Otherwise, the list of filled slots is used as\nthe argument list for the call.\n\n**CPython implementation detail:** An implementation may provide\nbuilt-in functions whose positional parameters do not have names, even\nif they are \'named\' for the purpose of documentation, and which\ntherefore cannot be supplied by keyword.  In CPython, this is the case\nfor functions implemented in C that use "PyArg_ParseTuple()" to parse\ntheir arguments.\n\nIf there are more positional arguments than there are formal parameter\nslots, a "TypeError" exception is raised, unless a formal parameter\nusing the syntax "*identifier" is present; in this case, that formal\nparameter receives a tuple containing the excess positional arguments\n(or an empty tuple if there were no excess positional arguments).\n\nIf any keyword argument does not correspond to a formal parameter\nname, a "TypeError" exception is raised, unless a formal parameter\nusing the syntax "**identifier" is present; in this case, that formal\nparameter receives a dictionary containing the excess keyword\narguments (using the keywords as keys and the argument values as\ncorresponding values), or a (new) empty dictionary if there were no\nexcess keyword arguments.\n\nIf the syntax "*expression" appears in the function call, "expression"\nmust evaluate to an iterable.  Elements from this iterable are treated\nas if they were additional positional arguments; if there are\npositional arguments *x1*, ..., *xN*, and "expression" evaluates to a\nsequence *y1*, ..., *yM*, this is equivalent to a call with M+N\npositional arguments *x1*, ..., *xN*, *y1*, ..., *yM*.\n\nA consequence of this is that although the "*expression" syntax may\nappear *after* some keyword arguments, it is processed *before* the\nkeyword arguments (and the "**expression" argument, if any -- see\nbelow).  So:\n\n   >>> def f(a, b):\n   ...  print(a, b)\n   ...\n   >>> f(b=1, *(2,))\n   2 1\n   >>> f(a=1, *(2,))\n   Traceback (most recent call last):\n     File "<stdin>", line 1, in ?\n   TypeError: f() got multiple values for keyword argument \'a\'\n   >>> f(1, *(2,))\n   1 2\n\nIt is unusual for both keyword arguments and the "*expression" syntax\nto be used in the same call, so in practice this confusion does not\narise.\n\nIf the syntax "**expression" appears in the function call,\n"expression" must evaluate to a mapping, the contents of which are\ntreated as additional keyword arguments.  In the case of a keyword\nappearing in both "expression" and as an explicit keyword argument, a\n"TypeError" exception is raised.\n\nFormal parameters using the syntax "*identifier" or "**identifier"\ncannot be used as positional argument slots or as keyword argument\nnames.\n\nA call always returns some value, possibly "None", unless it raises an\nexception.  How this value is computed depends on the type of the\ncallable object.\n\nIf it is---\n\na user-defined function:\n   The code block for the function is executed, passing it the\n   argument list.  The first thing the code block will do is bind the\n   formal parameters to the arguments; this is described in section\n   *Function definitions*.  When the code block executes a "return"\n   statement, this specifies the return value of the function call.\n\na built-in function or method:\n   The result is up to the interpreter; see *Built-in Functions* for\n   the descriptions of built-in functions and methods.\n\na class object:\n   A new instance of that class is returned.\n\na class instance method:\n   The corresponding user-defined function is called, with an argument\n   list that is one longer than the argument list of the call: the\n   instance becomes the first argument.\n\na class instance:\n   The class must define a "__call__()" method; the effect is then the\n   same as if that method was called.\n',
- 'class': u'\nClass definitions\n*****************\n\nA class definition defines a class object (see section *The standard\ntype hierarchy*):\n\n   classdef    ::= [decorators] "class" classname [inheritance] ":" suite\n   inheritance ::= "(" [parameter_list] ")"\n   classname   ::= identifier\n\nA class definition is an executable statement.  The inheritance list\nusually gives a list of base classes (see *Customizing class creation*\nfor more advanced uses), so each item in the list should evaluate to a\nclass object which allows subclassing.  Classes without an inheritance\nlist inherit, by default, from the base class "object"; hence,\n\n   class Foo:\n       pass\n\nis equivalent to\n\n   class Foo(object):\n       pass\n\nThe class\'s suite is then executed in a new execution frame (see\n*Naming and binding*), using a newly created local namespace and the\noriginal global namespace. (Usually, the suite contains mostly\nfunction definitions.)  When the class\'s suite finishes execution, its\nexecution frame is discarded but its local namespace is saved. [4] A\nclass object is then created using the inheritance list for the base\nclasses and the saved local namespace for the attribute dictionary.\nThe class name is bound to this class object in the original local\nnamespace.\n\nClass creation can be customized heavily using *metaclasses*.\n\nClasses can also be decorated: just like when decorating functions,\n\n   @f1(arg)\n   @f2\n   class Foo: pass\n\nis equivalent to\n\n   class Foo: pass\n   Foo = f1(arg)(f2(Foo))\n\nThe evaluation rules for the decorator expressions are the same as for\nfunction decorators.  The result must be a class object, which is then\nbound to the class name.\n\n**Programmer\'s note:** Variables defined in the class definition are\nclass attributes; they are shared by instances.  Instance attributes\ncan be set in a method with "self.name = value".  Both class and\ninstance attributes are accessible through the notation ""self.name"",\nand an instance attribute hides a class attribute with the same name\nwhen accessed in this way.  Class attributes can be used as defaults\nfor instance attributes, but using mutable values there can lead to\nunexpected results.  *Descriptors* can be used to create instance\nvariables with different implementation details.\n\nSee also: **PEP 3115** - Metaclasses in Python 3 **PEP 3129** -\n  Class Decorators\n',
- 'comparisons': u'\nComparisons\n***********\n\nUnlike C, all comparison operations in Python have the same priority,\nwhich is lower than that of any arithmetic, shifting or bitwise\noperation.  Also unlike C, expressions like "a < b < c" have the\ninterpretation that is conventional in mathematics:\n\n   comparison    ::= or_expr ( comp_operator or_expr )*\n   comp_operator ::= "<" | ">" | "==" | ">=" | "<=" | "!="\n                     | "is" ["not"] | ["not"] "in"\n\nComparisons yield boolean values: "True" or "False".\n\nComparisons can be chained arbitrarily, e.g., "x < y <= z" is\nequivalent to "x < y and y <= z", except that "y" is evaluated only\nonce (but in both cases "z" is not evaluated at all when "x < y" is\nfound to be false).\n\nFormally, if *a*, *b*, *c*, ..., *y*, *z* are expressions and *op1*,\n*op2*, ..., *opN* are comparison operators, then "a op1 b op2 c ... y\nopN z" is equivalent to "a op1 b and b op2 c and ... y opN z", except\nthat each expression is evaluated at most once.\n\nNote that "a op1 b op2 c" doesn\'t imply any kind of comparison between\n*a* and *c*, so that, e.g., "x < y > z" is perfectly legal (though\nperhaps not pretty).\n\n\nValue comparisons\n=================\n\nThe operators "<", ">", "==", ">=", "<=", and "!=" compare the values\nof two objects.  The objects do not need to have the same type.\n\nChapter *Objects, values and types* states that objects have a value\n(in addition to type and identity).  The value of an object is a\nrather abstract notion in Python: For example, there is no canonical\naccess method for an object\'s value.  Also, there is no requirement\nthat the value of an object should be constructed in a particular way,\ne.g. comprised of all its data attributes. Comparison operators\nimplement a particular notion of what the value of an object is.  One\ncan think of them as defining the value of an object indirectly, by\nmeans of their comparison implementation.\n\nBecause all types are (direct or indirect) subtypes of "object", they\ninherit the default comparison behavior from "object".  Types can\ncustomize their comparison behavior by implementing *rich comparison\nmethods* like "__lt__()", described in *Basic customization*.\n\nThe default behavior for equality comparison ("==" and "!=") is based\non the identity of the objects.  Hence, equality comparison of\ninstances with the same identity results in equality, and equality\ncomparison of instances with different identities results in\ninequality.  A motivation for this default behavior is the desire that\nall objects should be reflexive (i.e. "x is y" implies "x == y").\n\nA default order comparison ("<", ">", "<=", and ">=") is not provided;\nan attempt raises "TypeError".  A motivation for this default behavior\nis the lack of a similar invariant as for equality.\n\nThe behavior of the default equality comparison, that instances with\ndifferent identities are always unequal, may be in contrast to what\ntypes will need that have a sensible definition of object value and\nvalue-based equality.  Such types will need to customize their\ncomparison behavior, and in fact, a number of built-in types have done\nthat.\n\nThe following list describes the comparison behavior of the most\nimportant built-in types.\n\n* Numbers of built-in numeric types (*Numeric Types --- int, float,\n  complex*) and of the standard library types "fractions.Fraction" and\n  "decimal.Decimal" can be compared within and across their types,\n  with the restriction that complex numbers do not support order\n  comparison.  Within the limits of the types involved, they compare\n  mathematically (algorithmically) correct without loss of precision.\n\n  The not-a-number values "float(\'NaN\')" and "Decimal(\'NaN\')" are\n  special.  They are identical to themselves ("x is x" is true) but\n  are not equal to themselves ("x == x" is false).  Additionally,\n  comparing any number to a not-a-number value will return "False".\n  For example, both "3 < float(\'NaN\')" and "float(\'NaN\') < 3" will\n  return "False".\n\n* Binary sequences (instances of "bytes" or "bytearray") can be\n  compared within and across their types.  They compare\n  lexicographically using the numeric values of their elements.\n\n* Strings (instances of "str") compare lexicographically using the\n  numerical Unicode code points (the result of the built-in function\n  "ord()") of their characters. [3]\n\n  Strings and binary sequences cannot be directly compared.\n\n* Sequences (instances of "tuple", "list", or "range") can be\n  compared only within each of their types, with the restriction that\n  ranges do not support order comparison.  Equality comparison across\n  these types results in unequality, and ordering comparison across\n  these types raises "TypeError".\n\n  Sequences compare lexicographically using comparison of\n  corresponding elements, whereby reflexivity of the elements is\n  enforced.\n\n  In enforcing reflexivity of elements, the comparison of collections\n  assumes that for a collection element "x", "x == x" is always true.\n  Based on that assumption, element identity is compared first, and\n  element comparison is performed only for distinct elements.  This\n  approach yields the same result as a strict element comparison\n  would, if the compared elements are reflexive.  For non-reflexive\n  elements, the result is different than for strict element\n  comparison, and may be surprising:  The non-reflexive not-a-number\n  values for example result in the following comparison behavior when\n  used in a list:\n\n     >>> nan = float(\'NaN\')\n     >>> nan is nan\n     True\n     >>> nan == nan\n     False                 <-- the defined non-reflexive behavior of NaN\n     >>> [nan] == [nan]\n     True                  <-- list enforces reflexivity and tests identity first\n\n  Lexicographical comparison between built-in collections works as\n  follows:\n\n  * For two collections to compare equal, they must be of the same\n    type, have the same length, and each pair of corresponding\n    elements must compare equal (for example, "[1,2] == (1,2)" is\n    false because the type is not the same).\n\n  * Collections that support order comparison are ordered the same\n    as their first unequal elements (for example, "[1,2,x] <= [1,2,y]"\n    has the same value as "x <= y").  If a corresponding element does\n    not exist, the shorter collection is ordered first (for example,\n    "[1,2] < [1,2,3]" is true).\n\n* Mappings (instances of "dict") compare equal if and only if they\n  have equal *(key, value)* pairs. Equality comparison of the keys and\n  elements enforces reflexivity.\n\n  Order comparisons ("<", ">", "<=", and ">=") raise "TypeError".\n\n* Sets (instances of "set" or "frozenset") can be compared within\n  and across their types.\n\n  They define order comparison operators to mean subset and superset\n  tests.  Those relations do not define total orderings (for example,\n  the two sets "{1,2}" and "{2,3}" are not equal, nor subsets of one\n  another, nor supersets of one another).  Accordingly, sets are not\n  appropriate arguments for functions which depend on total ordering\n  (for example, "min()", "max()", and "sorted()" produce undefined\n  results given a list of sets as inputs).\n\n  Comparison of sets enforces reflexivity of its elements.\n\n* Most other built-in types have no comparison methods implemented,\n  so they inherit the default comparison behavior.\n\nUser-defined classes that customize their comparison behavior should\nfollow some consistency rules, if possible:\n\n* Equality comparison should be reflexive. In other words, identical\n  objects should compare equal:\n\n     "x is y" implies "x == y"\n\n* Comparison should be symmetric. In other words, the following\n  expressions should have the same result:\n\n     "x == y" and "y == x"\n\n     "x != y" and "y != x"\n\n     "x < y" and "y > x"\n\n     "x <= y" and "y >= x"\n\n* Comparison should be transitive. The following (non-exhaustive)\n  examples illustrate that:\n\n     "x > y and y > z" implies "x > z"\n\n     "x < y and y <= z" implies "x < z"\n\n* Inverse comparison should result in the boolean negation. In other\n  words, the following expressions should have the same result:\n\n     "x == y" and "not x != y"\n\n     "x < y" and "not x >= y" (for total ordering)\n\n     "x > y" and "not x <= y" (for total ordering)\n\n  The last two expressions apply to totally ordered collections (e.g.\n  to sequences, but not to sets or mappings). See also the\n  "total_ordering()" decorator.\n\nPython does not enforce these consistency rules. In fact, the\nnot-a-number values are an example for not following these rules.\n\n\nMembership test operations\n==========================\n\nThe operators "in" and "not in" test for membership.  "x in s"\nevaluates to true if *x* is a member of *s*, and false otherwise.  "x\nnot in s" returns the negation of "x in s".  All built-in sequences\nand set types support this as well as dictionary, for which "in" tests\nwhether the dictionary has a given key. For container types such as\nlist, tuple, set, frozenset, dict, or collections.deque, the\nexpression "x in y" is equivalent to "any(x is e or x == e for e in\ny)".\n\nFor the string and bytes types, "x in y" is true if and only if *x* is\na substring of *y*.  An equivalent test is "y.find(x) != -1".  Empty\nstrings are always considered to be a substring of any other string,\nso """ in "abc"" will return "True".\n\nFor user-defined classes which define the "__contains__()" method, "x\nin y" is true if and only if "y.__contains__(x)" is true.\n\nFor user-defined classes which do not define "__contains__()" but do\ndefine "__iter__()", "x in y" is true if some value "z" with "x == z"\nis produced while iterating over "y".  If an exception is raised\nduring the iteration, it is as if "in" raised that exception.\n\nLastly, the old-style iteration protocol is tried: if a class defines\n"__getitem__()", "x in y" is true if and only if there is a non-\nnegative integer index *i* such that "x == y[i]", and all lower\ninteger indices do not raise "IndexError" exception.  (If any other\nexception is raised, it is as if "in" raised that exception).\n\nThe operator "not in" is defined to have the inverse true value of\n"in".\n\n\nIdentity comparisons\n====================\n\nThe operators "is" and "is not" test for object identity: "x is y" is\ntrue if and only if *x* and *y* are the same object.  "x is not y"\nyields the inverse truth value. [4]\n',
- 'compound': u'\nCompound statements\n*******************\n\nCompound statements contain (groups of) other statements; they affect\nor control the execution of those other statements in some way.  In\ngeneral, compound statements span multiple lines, although in simple\nincarnations a whole compound statement may be contained in one line.\n\nThe "if", "while" and "for" statements implement traditional control\nflow constructs.  "try" specifies exception handlers and/or cleanup\ncode for a group of statements, while the "with" statement allows the\nexecution of initialization and finalization code around a block of\ncode.  Function and class definitions are also syntactically compound\nstatements.\n\nA compound statement consists of one or more \'clauses.\'  A clause\nconsists of a header and a \'suite.\'  The clause headers of a\nparticular compound statement are all at the same indentation level.\nEach clause header begins with a uniquely identifying keyword and ends\nwith a colon.  A suite is a group of statements controlled by a\nclause.  A suite can be one or more semicolon-separated simple\nstatements on the same line as the header, following the header\'s\ncolon, or it can be one or more indented statements on subsequent\nlines.  Only the latter form of a suite can contain nested compound\nstatements; the following is illegal, mostly because it wouldn\'t be\nclear to which "if" clause a following "else" clause would belong:\n\n   if test1: if test2: print(x)\n\nAlso note that the semicolon binds tighter than the colon in this\ncontext, so that in the following example, either all or none of the\n"print()" calls are executed:\n\n   if x < y < z: print(x); print(y); print(z)\n\nSummarizing:\n\n   compound_stmt ::= if_stmt\n                     | while_stmt\n                     | for_stmt\n                     | try_stmt\n                     | with_stmt\n                     | funcdef\n                     | classdef\n                     | async_with_stmt\n                     | async_for_stmt\n                     | async_funcdef\n   suite         ::= stmt_list NEWLINE | NEWLINE INDENT statement+ DEDENT\n   statement     ::= stmt_list NEWLINE | compound_stmt\n   stmt_list     ::= simple_stmt (";" simple_stmt)* [";"]\n\nNote that statements always end in a "NEWLINE" possibly followed by a\n"DEDENT".  Also note that optional continuation clauses always begin\nwith a keyword that cannot start a statement, thus there are no\nambiguities (the \'dangling "else"\' problem is solved in Python by\nrequiring nested "if" statements to be indented).\n\nThe formatting of the grammar rules in the following sections places\neach clause on a separate line for clarity.\n\n\nThe "if" statement\n==================\n\nThe "if" statement is used for conditional execution:\n\n   if_stmt ::= "if" expression ":" suite\n               ( "elif" expression ":" suite )*\n               ["else" ":" suite]\n\nIt selects exactly one of the suites by evaluating the expressions one\nby one until one is found to be true (see section *Boolean operations*\nfor the definition of true and false); then that suite is executed\n(and no other part of the "if" statement is executed or evaluated).\nIf all expressions are false, the suite of the "else" clause, if\npresent, is executed.\n\n\nThe "while" statement\n=====================\n\nThe "while" statement is used for repeated execution as long as an\nexpression is true:\n\n   while_stmt ::= "while" expression ":" suite\n                  ["else" ":" suite]\n\nThis repeatedly tests the expression and, if it is true, executes the\nfirst suite; if the expression is false (which may be the first time\nit is tested) the suite of the "else" clause, if present, is executed\nand the loop terminates.\n\nA "break" statement executed in the first suite terminates the loop\nwithout executing the "else" clause\'s suite.  A "continue" statement\nexecuted in the first suite skips the rest of the suite and goes back\nto testing the expression.\n\n\nThe "for" statement\n===================\n\nThe "for" statement is used to iterate over the elements of a sequence\n(such as a string, tuple or list) or other iterable object:\n\n   for_stmt ::= "for" target_list "in" expression_list ":" suite\n                ["else" ":" suite]\n\nThe expression list is evaluated once; it should yield an iterable\nobject.  An iterator is created for the result of the\n"expression_list".  The suite is then executed once for each item\nprovided by the iterator, in the order returned by the iterator.  Each\nitem in turn is assigned to the target list using the standard rules\nfor assignments (see *Assignment statements*), and then the suite is\nexecuted.  When the items are exhausted (which is immediately when the\nsequence is empty or an iterator raises a "StopIteration" exception),\nthe suite in the "else" clause, if present, is executed, and the loop\nterminates.\n\nA "break" statement executed in the first suite terminates the loop\nwithout executing the "else" clause\'s suite.  A "continue" statement\nexecuted in the first suite skips the rest of the suite and continues\nwith the next item, or with the "else" clause if there is no next\nitem.\n\nThe for-loop makes assignments to the variables(s) in the target list.\nThis overwrites all previous assignments to those variables including\nthose made in the suite of the for-loop:\n\n   for i in range(10):\n       print(i)\n       i = 5             # this will not affect the for-loop\n                         # because i will be overwritten with the next\n                         # index in the range\n\nNames in the target list are not deleted when the loop is finished,\nbut if the sequence is empty, they will not have been assigned to at\nall by the loop.  Hint: the built-in function "range()" returns an\niterator of integers suitable to emulate the effect of Pascal\'s "for i\n:= a to b do"; e.g., "list(range(3))" returns the list "[0, 1, 2]".\n\nNote: There is a subtlety when the sequence is being modified by the\n  loop (this can only occur for mutable sequences, i.e. lists).  An\n  internal counter is used to keep track of which item is used next,\n  and this is incremented on each iteration.  When this counter has\n  reached the length of the sequence the loop terminates.  This means\n  that if the suite deletes the current (or a previous) item from the\n  sequence, the next item will be skipped (since it gets the index of\n  the current item which has already been treated).  Likewise, if the\n  suite inserts an item in the sequence before the current item, the\n  current item will be treated again the next time through the loop.\n  This can lead to nasty bugs that can be avoided by making a\n  temporary copy using a slice of the whole sequence, e.g.,\n\n     for x in a[:]:\n         if x < 0: a.remove(x)\n\n\nThe "try" statement\n===================\n\nThe "try" statement specifies exception handlers and/or cleanup code\nfor a group of statements:\n\n   try_stmt  ::= try1_stmt | try2_stmt\n   try1_stmt ::= "try" ":" suite\n                 ("except" [expression ["as" identifier]] ":" suite)+\n                 ["else" ":" suite]\n                 ["finally" ":" suite]\n   try2_stmt ::= "try" ":" suite\n                 "finally" ":" suite\n\nThe "except" clause(s) specify one or more exception handlers. When no\nexception occurs in the "try" clause, no exception handler is\nexecuted. When an exception occurs in the "try" suite, a search for an\nexception handler is started.  This search inspects the except clauses\nin turn until one is found that matches the exception.  An expression-\nless except clause, if present, must be last; it matches any\nexception.  For an except clause with an expression, that expression\nis evaluated, and the clause matches the exception if the resulting\nobject is "compatible" with the exception.  An object is compatible\nwith an exception if it is the class or a base class of the exception\nobject or a tuple containing an item compatible with the exception.\n\nIf no except clause matches the exception, the search for an exception\nhandler continues in the surrounding code and on the invocation stack.\n[1]\n\nIf the evaluation of an expression in the header of an except clause\nraises an exception, the original search for a handler is canceled and\na search starts for the new exception in the surrounding code and on\nthe call stack (it is treated as if the entire "try" statement raised\nthe exception).\n\nWhen a matching except clause is found, the exception is assigned to\nthe target specified after the "as" keyword in that except clause, if\npresent, and the except clause\'s suite is executed.  All except\nclauses must have an executable block.  When the end of this block is\nreached, execution continues normally after the entire try statement.\n(This means that if two nested handlers exist for the same exception,\nand the exception occurs in the try clause of the inner handler, the\nouter handler will not handle the exception.)\n\nWhen an exception has been assigned using "as target", it is cleared\nat the end of the except clause.  This is as if\n\n   except E as N:\n       foo\n\nwas translated to\n\n   except E as N:\n       try:\n           foo\n       finally:\n           del N\n\nThis means the exception must be assigned to a different name to be\nable to refer to it after the except clause.  Exceptions are cleared\nbecause with the traceback attached to them, they form a reference\ncycle with the stack frame, keeping all locals in that frame alive\nuntil the next garbage collection occurs.\n\nBefore an except clause\'s suite is executed, details about the\nexception are stored in the "sys" module and can be accessed via\n"sys.exc_info()". "sys.exc_info()" returns a 3-tuple consisting of the\nexception class, the exception instance and a traceback object (see\nsection *The standard type hierarchy*) identifying the point in the\nprogram where the exception occurred.  "sys.exc_info()" values are\nrestored to their previous values (before the call) when returning\nfrom a function that handled an exception.\n\nThe optional "else" clause is executed if and when control flows off\nthe end of the "try" clause. [2] Exceptions in the "else" clause are\nnot handled by the preceding "except" clauses.\n\nIf "finally" is present, it specifies a \'cleanup\' handler.  The "try"\nclause is executed, including any "except" and "else" clauses.  If an\nexception occurs in any of the clauses and is not handled, the\nexception is temporarily saved. The "finally" clause is executed.  If\nthere is a saved exception it is re-raised at the end of the "finally"\nclause.  If the "finally" clause raises another exception, the saved\nexception is set as the context of the new exception. If the "finally"\nclause executes a "return" or "break" statement, the saved exception\nis discarded:\n\n   >>> def f():\n   ...     try:\n   ...         1/0\n   ...     finally:\n   ...         return 42\n   ...\n   >>> f()\n   42\n\nThe exception information is not available to the program during\nexecution of the "finally" clause.\n\nWhen a "return", "break" or "continue" statement is executed in the\n"try" suite of a "try"..."finally" statement, the "finally" clause is\nalso executed \'on the way out.\' A "continue" statement is illegal in\nthe "finally" clause. (The reason is a problem with the current\nimplementation --- this restriction may be lifted in the future).\n\nThe return value of a function is determined by the last "return"\nstatement executed.  Since the "finally" clause always executes, a\n"return" statement executed in the "finally" clause will always be the\nlast one executed:\n\n   >>> def foo():\n   ...     try:\n   ...         return \'try\'\n   ...     finally:\n   ...         return \'finally\'\n   ...\n   >>> foo()\n   \'finally\'\n\nAdditional information on exceptions can be found in section\n*Exceptions*, and information on using the "raise" statement to\ngenerate exceptions may be found in section *The raise statement*.\n\n\nThe "with" statement\n====================\n\nThe "with" statement is used to wrap the execution of a block with\nmethods defined by a context manager (see section *With Statement\nContext Managers*). This allows common "try"..."except"..."finally"\nusage patterns to be encapsulated for convenient reuse.\n\n   with_stmt ::= "with" with_item ("," with_item)* ":" suite\n   with_item ::= expression ["as" target]\n\nThe execution of the "with" statement with one "item" proceeds as\nfollows:\n\n1. The context expression (the expression given in the "with_item")\n   is evaluated to obtain a context manager.\n\n2. The context manager\'s "__exit__()" is loaded for later use.\n\n3. The context manager\'s "__enter__()" method is invoked.\n\n4. If a target was included in the "with" statement, the return\n   value from "__enter__()" is assigned to it.\n\n   Note: The "with" statement guarantees that if the "__enter__()"\n     method returns without an error, then "__exit__()" will always be\n     called. Thus, if an error occurs during the assignment to the\n     target list, it will be treated the same as an error occurring\n     within the suite would be. See step 6 below.\n\n5. The suite is executed.\n\n6. The context manager\'s "__exit__()" method is invoked.  If an\n   exception caused the suite to be exited, its type, value, and\n   traceback are passed as arguments to "__exit__()". Otherwise, three\n   "None" arguments are supplied.\n\n   If the suite was exited due to an exception, and the return value\n   from the "__exit__()" method was false, the exception is reraised.\n   If the return value was true, the exception is suppressed, and\n   execution continues with the statement following the "with"\n   statement.\n\n   If the suite was exited for any reason other than an exception, the\n   return value from "__exit__()" is ignored, and execution proceeds\n   at the normal location for the kind of exit that was taken.\n\nWith more than one item, the context managers are processed as if\nmultiple "with" statements were nested:\n\n   with A() as a, B() as b:\n       suite\n\nis equivalent to\n\n   with A() as a:\n       with B() as b:\n           suite\n\nChanged in version 3.1: Support for multiple context expressions.\n\nSee also: **PEP 0343** - The "with" statement\n\n     The specification, background, and examples for the Python "with"\n     statement.\n\n\nFunction definitions\n====================\n\nA function definition defines a user-defined function object (see\nsection *The standard type hierarchy*):\n\n   funcdef        ::= [decorators] "def" funcname "(" [parameter_list] ")" ["->" expression] ":" suite\n   decorators     ::= decorator+\n   decorator      ::= "@" dotted_name ["(" [parameter_list [","]] ")"] NEWLINE\n   dotted_name    ::= identifier ("." identifier)*\n   parameter_list ::= (defparameter ",")*\n                      | "*" [parameter] ("," defparameter)* ["," "**" parameter]\n                      | "**" parameter\n                      | defparameter [","] )\n   parameter      ::= identifier [":" expression]\n   defparameter   ::= parameter ["=" expression]\n   funcname       ::= identifier\n\nA function definition is an executable statement.  Its execution binds\nthe function name in the current local namespace to a function object\n(a wrapper around the executable code for the function).  This\nfunction object contains a reference to the current global namespace\nas the global namespace to be used when the function is called.\n\nThe function definition does not execute the function body; this gets\nexecuted only when the function is called. [3]\n\nA function definition may be wrapped by one or more *decorator*\nexpressions. Decorator expressions are evaluated when the function is\ndefined, in the scope that contains the function definition.  The\nresult must be a callable, which is invoked with the function object\nas the only argument. The returned value is bound to the function name\ninstead of the function object.  Multiple decorators are applied in\nnested fashion. For example, the following code\n\n   @f1(arg)\n   @f2\n   def func(): pass\n\nis equivalent to\n\n   def func(): pass\n   func = f1(arg)(f2(func))\n\nWhen one or more *parameters* have the form *parameter* "="\n*expression*, the function is said to have "default parameter values."\nFor a parameter with a default value, the corresponding *argument* may\nbe omitted from a call, in which case the parameter\'s default value is\nsubstituted.  If a parameter has a default value, all following\nparameters up until the ""*"" must also have a default value --- this\nis a syntactic restriction that is not expressed by the grammar.\n\n**Default parameter values are evaluated from left to right when the\nfunction definition is executed.** This means that the expression is\nevaluated once, when the function is defined, and that the same "pre-\ncomputed" value is used for each call.  This is especially important\nto understand when a default parameter is a mutable object, such as a\nlist or a dictionary: if the function modifies the object (e.g. by\nappending an item to a list), the default value is in effect modified.\nThis is generally not what was intended.  A way around this is to use\n"None" as the default, and explicitly test for it in the body of the\nfunction, e.g.:\n\n   def whats_on_the_telly(penguin=None):\n       if penguin is None:\n           penguin = []\n       penguin.append("property of the zoo")\n       return penguin\n\nFunction call semantics are described in more detail in section\n*Calls*. A function call always assigns values to all parameters\nmentioned in the parameter list, either from position arguments, from\nkeyword arguments, or from default values.  If the form\n""*identifier"" is present, it is initialized to a tuple receiving any\nexcess positional parameters, defaulting to the empty tuple.  If the\nform ""**identifier"" is present, it is initialized to a new\ndictionary receiving any excess keyword arguments, defaulting to a new\nempty dictionary. Parameters after ""*"" or ""*identifier"" are\nkeyword-only parameters and may only be passed used keyword arguments.\n\nParameters may have annotations of the form "": expression"" following\nthe parameter name.  Any parameter may have an annotation even those\nof the form "*identifier" or "**identifier".  Functions may have\n"return" annotation of the form ""-> expression"" after the parameter\nlist.  These annotations can be any valid Python expression and are\nevaluated when the function definition is executed.  Annotations may\nbe evaluated in a different order than they appear in the source code.\nThe presence of annotations does not change the semantics of a\nfunction.  The annotation values are available as values of a\ndictionary keyed by the parameters\' names in the "__annotations__"\nattribute of the function object.\n\nIt is also possible to create anonymous functions (functions not bound\nto a name), for immediate use in expressions.  This uses lambda\nexpressions, described in section *Lambdas*.  Note that the lambda\nexpression is merely a shorthand for a simplified function definition;\na function defined in a ""def"" statement can be passed around or\nassigned to another name just like a function defined by a lambda\nexpression.  The ""def"" form is actually more powerful since it\nallows the execution of multiple statements and annotations.\n\n**Programmer\'s note:** Functions are first-class objects.  A ""def""\nstatement executed inside a function definition defines a local\nfunction that can be returned or passed around.  Free variables used\nin the nested function can access the local variables of the function\ncontaining the def.  See section *Naming and binding* for details.\n\nSee also: **PEP 3107** - Function Annotations\n\n     The original specification for function annotations.\n\n\nClass definitions\n=================\n\nA class definition defines a class object (see section *The standard\ntype hierarchy*):\n\n   classdef    ::= [decorators] "class" classname [inheritance] ":" suite\n   inheritance ::= "(" [parameter_list] ")"\n   classname   ::= identifier\n\nA class definition is an executable statement.  The inheritance list\nusually gives a list of base classes (see *Customizing class creation*\nfor more advanced uses), so each item in the list should evaluate to a\nclass object which allows subclassing.  Classes without an inheritance\nlist inherit, by default, from the base class "object"; hence,\n\n   class Foo:\n       pass\n\nis equivalent to\n\n   class Foo(object):\n       pass\n\nThe class\'s suite is then executed in a new execution frame (see\n*Naming and binding*), using a newly created local namespace and the\noriginal global namespace. (Usually, the suite contains mostly\nfunction definitions.)  When the class\'s suite finishes execution, its\nexecution frame is discarded but its local namespace is saved. [4] A\nclass object is then created using the inheritance list for the base\nclasses and the saved local namespace for the attribute dictionary.\nThe class name is bound to this class object in the original local\nnamespace.\n\nClass creation can be customized heavily using *metaclasses*.\n\nClasses can also be decorated: just like when decorating functions,\n\n   @f1(arg)\n   @f2\n   class Foo: pass\n\nis equivalent to\n\n   class Foo: pass\n   Foo = f1(arg)(f2(Foo))\n\nThe evaluation rules for the decorator expressions are the same as for\nfunction decorators.  The result must be a class object, which is then\nbound to the class name.\n\n**Programmer\'s note:** Variables defined in the class definition are\nclass attributes; they are shared by instances.  Instance attributes\ncan be set in a method with "self.name = value".  Both class and\ninstance attributes are accessible through the notation ""self.name"",\nand an instance attribute hides a class attribute with the same name\nwhen accessed in this way.  Class attributes can be used as defaults\nfor instance attributes, but using mutable values there can lead to\nunexpected results.  *Descriptors* can be used to create instance\nvariables with different implementation details.\n\nSee also: **PEP 3115** - Metaclasses in Python 3 **PEP 3129** -\n  Class Decorators\n\n\nCoroutines\n==========\n\nNew in version 3.5.\n\n\nCoroutine function definition\n-----------------------------\n\n   async_funcdef ::= [decorators] "async" "def" funcname "(" [parameter_list] ")" ["->" expression] ":" suite\n\nExecution of Python coroutines can be suspended and resumed at many\npoints (see *coroutine*).  In the body of a coroutine, any "await" and\n"async" identifiers become reserved keywords; "await" expressions,\n"async for" and "async with" can only be used in coroutine bodies.\n\nFunctions defined with "async def" syntax are always coroutine\nfunctions, even if they do not contain "await" or "async" keywords.\n\nIt is a "SyntaxError" to use "yield" expressions in "async def"\ncoroutines.\n\nAn example of a coroutine function:\n\n   async def func(param1, param2):\n       do_stuff()\n       await some_coroutine()\n\n\nThe "async for" statement\n-------------------------\n\n   async_for_stmt ::= "async" for_stmt\n\nAn *asynchronous iterable* is able to call asynchronous code in its\n*iter* implementation, and *asynchronous iterator* can call\nasynchronous code in its *next* method.\n\nThe "async for" statement allows convenient iteration over\nasynchronous iterators.\n\nThe following code:\n\n   async for TARGET in ITER:\n       BLOCK\n   else:\n       BLOCK2\n\nIs semantically equivalent to:\n\n   iter = (ITER)\n   iter = await type(iter).__aiter__(iter)\n   running = True\n   while running:\n       try:\n           TARGET = await type(iter).__anext__(iter)\n       except StopAsyncIteration:\n           running = False\n       else:\n           BLOCK\n   else:\n       BLOCK2\n\nSee also "__aiter__()" and "__anext__()" for details.\n\nIt is a "SyntaxError" to use "async for" statement outside of an\n"async def" function.\n\n\nThe "async with" statement\n--------------------------\n\n   async_with_stmt ::= "async" with_stmt\n\nAn *asynchronous context manager* is a *context manager* that is able\nto suspend execution in its *enter* and *exit* methods.\n\nThe following code:\n\n   async with EXPR as VAR:\n       BLOCK\n\nIs semantically equivalent to:\n\n   mgr = (EXPR)\n   aexit = type(mgr).__aexit__\n   aenter = type(mgr).__aenter__(mgr)\n   exc = True\n\n   VAR = await aenter\n   try:\n       BLOCK\n   except:\n       if not await aexit(mgr, *sys.exc_info()):\n           raise\n   else:\n       await aexit(mgr, None, None, None)\n\nSee also "__aenter__()" and "__aexit__()" for details.\n\nIt is a "SyntaxError" to use "async with" statement outside of an\n"async def" function.\n\nSee also: **PEP 492** - Coroutines with async and await syntax\n\n-[ Footnotes ]-\n\n[1] The exception is propagated to the invocation stack unless\n    there is a "finally" clause which happens to raise another\n    exception. That new exception causes the old one to be lost.\n\n[2] Currently, control "flows off the end" except in the case of\n    an exception or the execution of a "return", "continue", or\n    "break" statement.\n\n[3] A string literal appearing as the first statement in the\n    function body is transformed into the function\'s "__doc__"\n    attribute and therefore the function\'s *docstring*.\n\n[4] A string literal appearing as the first statement in the class\n    body is transformed into the namespace\'s "__doc__" item and\n    therefore the class\'s *docstring*.\n',
- 'context-managers': u'\nWith Statement Context Managers\n*******************************\n\nA *context manager* is an object that defines the runtime context to\nbe established when executing a "with" statement. The context manager\nhandles the entry into, and the exit from, the desired runtime context\nfor the execution of the block of code.  Context managers are normally\ninvoked using the "with" statement (described in section *The with\nstatement*), but can also be used by directly invoking their methods.\n\nTypical uses of context managers include saving and restoring various\nkinds of global state, locking and unlocking resources, closing opened\nfiles, etc.\n\nFor more information on context managers, see *Context Manager Types*.\n\nobject.__enter__(self)\n\n   Enter the runtime context related to this object. The "with"\n   statement will bind this method\'s return value to the target(s)\n   specified in the "as" clause of the statement, if any.\n\nobject.__exit__(self, exc_type, exc_value, traceback)\n\n   Exit the runtime context related to this object. The parameters\n   describe the exception that caused the context to be exited. If the\n   context was exited without an exception, all three arguments will\n   be "None".\n\n   If an exception is supplied, and the method wishes to suppress the\n   exception (i.e., prevent it from being propagated), it should\n   return a true value. Otherwise, the exception will be processed\n   normally upon exit from this method.\n\n   Note that "__exit__()" methods should not reraise the passed-in\n   exception; this is the caller\'s responsibility.\n\nSee also: **PEP 0343** - The "with" statement\n\n     The specification, background, and examples for the Python "with"\n     statement.\n',
- 'continue': u'\nThe "continue" statement\n************************\n\n   continue_stmt ::= "continue"\n\n"continue" may only occur syntactically nested in a "for" or "while"\nloop, but not nested in a function or class definition or "finally"\nclause within that loop.  It continues with the next cycle of the\nnearest enclosing loop.\n\nWhen "continue" passes control out of a "try" statement with a\n"finally" clause, that "finally" clause is executed before really\nstarting the next loop cycle.\n',
- 'conversions': u'\nArithmetic conversions\n**********************\n\nWhen a description of an arithmetic operator below uses the phrase\n"the numeric arguments are converted to a common type," this means\nthat the operator implementation for built-in types works as follows:\n\n* If either argument is a complex number, the other is converted to\n  complex;\n\n* otherwise, if either argument is a floating point number, the\n  other is converted to floating point;\n\n* otherwise, both must be integers and no conversion is necessary.\n\nSome additional rules apply for certain operators (e.g., a string as a\nleft argument to the \'%\' operator).  Extensions must define their own\nconversion behavior.\n',
- 'customization': u'\nBasic customization\n*******************\n\nobject.__new__(cls[, ...])\n\n   Called to create a new instance of class *cls*.  "__new__()" is a\n   static method (special-cased so you need not declare it as such)\n   that takes the class of which an instance was requested as its\n   first argument.  The remaining arguments are those passed to the\n   object constructor expression (the call to the class).  The return\n   value of "__new__()" should be the new object instance (usually an\n   instance of *cls*).\n\n   Typical implementations create a new instance of the class by\n   invoking the superclass\'s "__new__()" method using\n   "super(currentclass, cls).__new__(cls[, ...])" with appropriate\n   arguments and then modifying the newly-created instance as\n   necessary before returning it.\n\n   If "__new__()" returns an instance of *cls*, then the new\n   instance\'s "__init__()" method will be invoked like\n   "__init__(self[, ...])", where *self* is the new instance and the\n   remaining arguments are the same as were passed to "__new__()".\n\n   If "__new__()" does not return an instance of *cls*, then the new\n   instance\'s "__init__()" method will not be invoked.\n\n   "__new__()" is intended mainly to allow subclasses of immutable\n   types (like int, str, or tuple) to customize instance creation.  It\n   is also commonly overridden in custom metaclasses in order to\n   customize class creation.\n\nobject.__init__(self[, ...])\n\n   Called after the instance has been created (by "__new__()"), but\n   before it is returned to the caller.  The arguments are those\n   passed to the class constructor expression.  If a base class has an\n   "__init__()" method, the derived class\'s "__init__()" method, if\n   any, must explicitly call it to ensure proper initialization of the\n   base class part of the instance; for example:\n   "BaseClass.__init__(self, [args...])".\n\n   Because "__new__()" and "__init__()" work together in constructing\n   objects ("__new__()" to create it, and "__init__()" to customise\n   it), no non-"None" value may be returned by "__init__()"; doing so\n   will cause a "TypeError" to be raised at runtime.\n\nobject.__del__(self)\n\n   Called when the instance is about to be destroyed.  This is also\n   called a destructor.  If a base class has a "__del__()" method, the\n   derived class\'s "__del__()" method, if any, must explicitly call it\n   to ensure proper deletion of the base class part of the instance.\n   Note that it is possible (though not recommended!) for the\n   "__del__()" method to postpone destruction of the instance by\n   creating a new reference to it.  It may then be called at a later\n   time when this new reference is deleted.  It is not guaranteed that\n   "__del__()" methods are called for objects that still exist when\n   the interpreter exits.\n\n   Note: "del x" doesn\'t directly call "x.__del__()" --- the former\n     decrements the reference count for "x" by one, and the latter is\n     only called when "x"\'s reference count reaches zero.  Some common\n     situations that may prevent the reference count of an object from\n     going to zero include: circular references between objects (e.g.,\n     a doubly-linked list or a tree data structure with parent and\n     child pointers); a reference to the object on the stack frame of\n     a function that caught an exception (the traceback stored in\n     "sys.exc_info()[2]" keeps the stack frame alive); or a reference\n     to the object on the stack frame that raised an unhandled\n     exception in interactive mode (the traceback stored in\n     "sys.last_traceback" keeps the stack frame alive).  The first\n     situation can only be remedied by explicitly breaking the cycles;\n     the second can be resolved by freeing the reference to the\n     traceback object when it is no longer useful, and the third can\n     be resolved by storing "None" in "sys.last_traceback". Circular\n     references which are garbage are detected and cleaned up when the\n     cyclic garbage collector is enabled (it\'s on by default). Refer\n     to the documentation for the "gc" module for more information\n     about this topic.\n\n   Warning: Due to the precarious circumstances under which\n     "__del__()" methods are invoked, exceptions that occur during\n     their execution are ignored, and a warning is printed to\n     "sys.stderr" instead. Also, when "__del__()" is invoked in\n     response to a module being deleted (e.g., when execution of the\n     program is done), other globals referenced by the "__del__()"\n     method may already have been deleted or in the process of being\n     torn down (e.g. the import machinery shutting down).  For this\n     reason, "__del__()" methods should do the absolute minimum needed\n     to maintain external invariants.  Starting with version 1.5,\n     Python guarantees that globals whose name begins with a single\n     underscore are deleted from their module before other globals are\n     deleted; if no other references to such globals exist, this may\n     help in assuring that imported modules are still available at the\n     time when the "__del__()" method is called.\n\nobject.__repr__(self)\n\n   Called by the "repr()" built-in function to compute the "official"\n   string representation of an object.  If at all possible, this\n   should look like a valid Python expression that could be used to\n   recreate an object with the same value (given an appropriate\n   environment).  If this is not possible, a string of the form\n   "<...some useful description...>" should be returned. The return\n   value must be a string object. If a class defines "__repr__()" but\n   not "__str__()", then "__repr__()" is also used when an "informal"\n   string representation of instances of that class is required.\n\n   This is typically used for debugging, so it is important that the\n   representation is information-rich and unambiguous.\n\nobject.__str__(self)\n\n   Called by "str(object)" and the built-in functions "format()" and\n   "print()" to compute the "informal" or nicely printable string\n   representation of an object.  The return value must be a *string*\n   object.\n\n   This method differs from "object.__repr__()" in that there is no\n   expectation that "__str__()" return a valid Python expression: a\n   more convenient or concise representation can be used.\n\n   The default implementation defined by the built-in type "object"\n   calls "object.__repr__()".\n\nobject.__bytes__(self)\n\n   Called by "bytes()" to compute a byte-string representation of an\n   object. This should return a "bytes" object.\n\nobject.__format__(self, format_spec)\n\n   Called by the "format()" built-in function (and by extension, the\n   "str.format()" method of class "str") to produce a "formatted"\n   string representation of an object. The "format_spec" argument is a\n   string that contains a description of the formatting options\n   desired. The interpretation of the "format_spec" argument is up to\n   the type implementing "__format__()", however most classes will\n   either delegate formatting to one of the built-in types, or use a\n   similar formatting option syntax.\n\n   See *Format Specification Mini-Language* for a description of the\n   standard formatting syntax.\n\n   The return value must be a string object.\n\n   Changed in version 3.4: The __format__ method of "object" itself\n   raises a "TypeError" if passed any non-empty string.\n\nobject.__lt__(self, other)\nobject.__le__(self, other)\nobject.__eq__(self, other)\nobject.__ne__(self, other)\nobject.__gt__(self, other)\nobject.__ge__(self, other)\n\n   These are the so-called "rich comparison" methods. The\n   correspondence between operator symbols and method names is as\n   follows: "x<y" calls "x.__lt__(y)", "x<=y" calls "x.__le__(y)",\n   "x==y" calls "x.__eq__(y)", "x!=y" calls "x.__ne__(y)", "x>y" calls\n   "x.__gt__(y)", and "x>=y" calls "x.__ge__(y)".\n\n   A rich comparison method may return the singleton "NotImplemented"\n   if it does not implement the operation for a given pair of\n   arguments. By convention, "False" and "True" are returned for a\n   successful comparison. However, these methods can return any value,\n   so if the comparison operator is used in a Boolean context (e.g.,\n   in the condition of an "if" statement), Python will call "bool()"\n   on the value to determine if the result is true or false.\n\n   By default, "__ne__()" delegates to "__eq__()" and inverts the\n   result unless it is "NotImplemented".  There are no other implied\n   relationships among the comparison operators, for example, the\n   truth of "(x<y or x==y)" does not imply "x<=y". To automatically\n   generate ordering operations from a single root operation, see\n   "functools.total_ordering()".\n\n   See the paragraph on "__hash__()" for some important notes on\n   creating *hashable* objects which support custom comparison\n   operations and are usable as dictionary keys.\n\n   There are no swapped-argument versions of these methods (to be used\n   when the left argument does not support the operation but the right\n   argument does); rather, "__lt__()" and "__gt__()" are each other\'s\n   reflection, "__le__()" and "__ge__()" are each other\'s reflection,\n   and "__eq__()" and "__ne__()" are their own reflection. If the\n   operands are of different types, and right operand\'s type is a\n   direct or indirect subclass of the left operand\'s type, the\n   reflected method of the right operand has priority, otherwise the\n   left operand\'s method has priority.  Virtual subclassing is not\n   considered.\n\nobject.__hash__(self)\n\n   Called by built-in function "hash()" and for operations on members\n   of hashed collections including "set", "frozenset", and "dict".\n   "__hash__()" should return an integer.  The only required property\n   is that objects which compare equal have the same hash value; it is\n   advised to somehow mix together (e.g. using exclusive or) the hash\n   values for the components of the object that also play a part in\n   comparison of objects.\n\n   Note: "hash()" truncates the value returned from an object\'s\n     custom "__hash__()" method to the size of a "Py_ssize_t".  This\n     is typically 8 bytes on 64-bit builds and 4 bytes on 32-bit\n     builds. If an object\'s   "__hash__()" must interoperate on builds\n     of different bit sizes, be sure to check the width on all\n     supported builds.  An easy way to do this is with "python -c\n     "import sys; print(sys.hash_info.width)"".\n\n   If a class does not define an "__eq__()" method it should not\n   define a "__hash__()" operation either; if it defines "__eq__()"\n   but not "__hash__()", its instances will not be usable as items in\n   hashable collections.  If a class defines mutable objects and\n   implements an "__eq__()" method, it should not implement\n   "__hash__()", since the implementation of hashable collections\n   requires that a key\'s hash value is immutable (if the object\'s hash\n   value changes, it will be in the wrong hash bucket).\n\n   User-defined classes have "__eq__()" and "__hash__()" methods by\n   default; with them, all objects compare unequal (except with\n   themselves) and "x.__hash__()" returns an appropriate value such\n   that "x == y" implies both that "x is y" and "hash(x) == hash(y)".\n\n   A class that overrides "__eq__()" and does not define "__hash__()"\n   will have its "__hash__()" implicitly set to "None".  When the\n   "__hash__()" method of a class is "None", instances of the class\n   will raise an appropriate "TypeError" when a program attempts to\n   retrieve their hash value, and will also be correctly identified as\n   unhashable when checking "isinstance(obj, collections.Hashable)".\n\n   If a class that overrides "__eq__()" needs to retain the\n   implementation of "__hash__()" from a parent class, the interpreter\n   must be told this explicitly by setting "__hash__ =\n   <ParentClass>.__hash__".\n\n   If a class that does not override "__eq__()" wishes to suppress\n   hash support, it should include "__hash__ = None" in the class\n   definition. A class which defines its own "__hash__()" that\n   explicitly raises a "TypeError" would be incorrectly identified as\n   hashable by an "isinstance(obj, collections.Hashable)" call.\n\n   Note: By default, the "__hash__()" values of str, bytes and\n     datetime objects are "salted" with an unpredictable random value.\n     Although they remain constant within an individual Python\n     process, they are not predictable between repeated invocations of\n     Python.This is intended to provide protection against a denial-\n     of-service caused by carefully-chosen inputs that exploit the\n     worst case performance of a dict insertion, O(n^2) complexity.\n     See http://www.ocert.org/advisories/ocert-2011-003.html for\n     details.Changing hash values affects the iteration order of\n     dicts, sets and other mappings.  Python has never made guarantees\n     about this ordering (and it typically varies between 32-bit and\n     64-bit builds).See also "PYTHONHASHSEED".\n\n   Changed in version 3.3: Hash randomization is enabled by default.\n\nobject.__bool__(self)\n\n   Called to implement truth value testing and the built-in operation\n   "bool()"; should return "False" or "True".  When this method is not\n   defined, "__len__()" is called, if it is defined, and the object is\n   considered true if its result is nonzero.  If a class defines\n   neither "__len__()" nor "__bool__()", all its instances are\n   considered true.\n',
- 'debugger': u'\n"pdb" --- The Python Debugger\n*****************************\n\n**Source code:** Lib/pdb.py\n\n======================================================================\n\nThe module "pdb" defines an interactive source code debugger for\nPython programs.  It supports setting (conditional) breakpoints and\nsingle stepping at the source line level, inspection of stack frames,\nsource code listing, and evaluation of arbitrary Python code in the\ncontext of any stack frame.  It also supports post-mortem debugging\nand can be called under program control.\n\nThe debugger is extensible -- it is actually defined as the class\n"Pdb". This is currently undocumented but easily understood by reading\nthe source.  The extension interface uses the modules "bdb" and "cmd".\n\nThe debugger\'s prompt is "(Pdb)". Typical usage to run a program under\ncontrol of the debugger is:\n\n   >>> import pdb\n   >>> import mymodule\n   >>> pdb.run(\'mymodule.test()\')\n   > <string>(0)?()\n   (Pdb) continue\n   > <string>(1)?()\n   (Pdb) continue\n   NameError: \'spam\'\n   > <string>(1)?()\n   (Pdb)\n\nChanged in version 3.3: Tab-completion via the "readline" module is\navailable for commands and command arguments, e.g. the current global\nand local names are offered as arguments of the "p" command.\n\n"pdb.py" can also be invoked as a script to debug other scripts.  For\nexample:\n\n   python3 -m pdb myscript.py\n\nWhen invoked as a script, pdb will automatically enter post-mortem\ndebugging if the program being debugged exits abnormally.  After post-\nmortem debugging (or after normal exit of the program), pdb will\nrestart the program.  Automatic restarting preserves pdb\'s state (such\nas breakpoints) and in most cases is more useful than quitting the\ndebugger upon program\'s exit.\n\nNew in version 3.2: "pdb.py" now accepts a "-c" option that executes\ncommands as if given in a ".pdbrc" file, see *Debugger Commands*.\n\nThe typical usage to break into the debugger from a running program is\nto insert\n\n   import pdb; pdb.set_trace()\n\nat the location you want to break into the debugger.  You can then\nstep through the code following this statement, and continue running\nwithout the debugger using the "continue" command.\n\nThe typical usage to inspect a crashed program is:\n\n   >>> import pdb\n   >>> import mymodule\n   >>> mymodule.test()\n   Traceback (most recent call last):\n     File "<stdin>", line 1, in ?\n     File "./mymodule.py", line 4, in test\n       test2()\n     File "./mymodule.py", line 3, in test2\n       print(spam)\n   NameError: spam\n   >>> pdb.pm()\n   > ./mymodule.py(3)test2()\n   -> print(spam)\n   (Pdb)\n\nThe module defines the following functions; each enters the debugger\nin a slightly different way:\n\npdb.run(statement, globals=None, locals=None)\n\n   Execute the *statement* (given as a string or a code object) under\n   debugger control.  The debugger prompt appears before any code is\n   executed; you can set breakpoints and type "continue", or you can\n   step through the statement using "step" or "next" (all these\n   commands are explained below).  The optional *globals* and *locals*\n   arguments specify the environment in which the code is executed; by\n   default the dictionary of the module "__main__" is used.  (See the\n   explanation of the built-in "exec()" or "eval()" functions.)\n\npdb.runeval(expression, globals=None, locals=None)\n\n   Evaluate the *expression* (given as a string or a code object)\n   under debugger control.  When "runeval()" returns, it returns the\n   value of the expression.  Otherwise this function is similar to\n   "run()".\n\npdb.runcall(function, *args, **kwds)\n\n   Call the *function* (a function or method object, not a string)\n   with the given arguments.  When "runcall()" returns, it returns\n   whatever the function call returned.  The debugger prompt appears\n   as soon as the function is entered.\n\npdb.set_trace()\n\n   Enter the debugger at the calling stack frame.  This is useful to\n   hard-code a breakpoint at a given point in a program, even if the\n   code is not otherwise being debugged (e.g. when an assertion\n   fails).\n\npdb.post_mortem(traceback=None)\n\n   Enter post-mortem debugging of the given *traceback* object.  If no\n   *traceback* is given, it uses the one of the exception that is\n   currently being handled (an exception must be being handled if the\n   default is to be used).\n\npdb.pm()\n\n   Enter post-mortem debugging of the traceback found in\n   "sys.last_traceback".\n\nThe "run*" functions and "set_trace()" are aliases for instantiating\nthe "Pdb" class and calling the method of the same name.  If you want\nto access further features, you have to do this yourself:\n\nclass class pdb.Pdb(completekey=\'tab\', stdin=None, stdout=None, skip=None, nosigint=False)\n\n   "Pdb" is the debugger class.\n\n   The *completekey*, *stdin* and *stdout* arguments are passed to the\n   underlying "cmd.Cmd" class; see the description there.\n\n   The *skip* argument, if given, must be an iterable of glob-style\n   module name patterns.  The debugger will not step into frames that\n   originate in a module that matches one of these patterns. [1]\n\n   By default, Pdb sets a handler for the SIGINT signal (which is sent\n   when the user presses "Ctrl-C" on the console) when you give a\n   "continue" command. This allows you to break into the debugger\n   again by pressing "Ctrl-C".  If you want Pdb not to touch the\n   SIGINT handler, set *nosigint* tot true.\n\n   Example call to enable tracing with *skip*:\n\n      import pdb; pdb.Pdb(skip=[\'django.*\']).set_trace()\n\n   New in version 3.1: The *skip* argument.\n\n   New in version 3.2: The *nosigint* argument.  Previously, a SIGINT\n   handler was never set by Pdb.\n\n   run(statement, globals=None, locals=None)\n   runeval(expression, globals=None, locals=None)\n   runcall(function, *args, **kwds)\n   set_trace()\n\n      See the documentation for the functions explained above.\n\n\nDebugger Commands\n=================\n\nThe commands recognized by the debugger are listed below.  Most\ncommands can be abbreviated to one or two letters as indicated; e.g.\n"h(elp)" means that either "h" or "help" can be used to enter the help\ncommand (but not "he" or "hel", nor "H" or "Help" or "HELP").\nArguments to commands must be separated by whitespace (spaces or\ntabs).  Optional arguments are enclosed in square brackets ("[]") in\nthe command syntax; the square brackets must not be typed.\nAlternatives in the command syntax are separated by a vertical bar\n("|").\n\nEntering a blank line repeats the last command entered.  Exception: if\nthe last command was a "list" command, the next 11 lines are listed.\n\nCommands that the debugger doesn\'t recognize are assumed to be Python\nstatements and are executed in the context of the program being\ndebugged.  Python statements can also be prefixed with an exclamation\npoint ("!").  This is a powerful way to inspect the program being\ndebugged; it is even possible to change a variable or call a function.\nWhen an exception occurs in such a statement, the exception name is\nprinted but the debugger\'s state is not changed.\n\nThe debugger supports *aliases*.  Aliases can have parameters which\nallows one a certain level of adaptability to the context under\nexamination.\n\nMultiple commands may be entered on a single line, separated by ";;".\n(A single ";" is not used as it is the separator for multiple commands\nin a line that is passed to the Python parser.)  No intelligence is\napplied to separating the commands; the input is split at the first\n";;" pair, even if it is in the middle of a quoted string.\n\nIf a file ".pdbrc" exists in the user\'s home directory or in the\ncurrent directory, it is read in and executed as if it had been typed\nat the debugger prompt.  This is particularly useful for aliases.  If\nboth files exist, the one in the home directory is read first and\naliases defined there can be overridden by the local file.\n\nChanged in version 3.2: ".pdbrc" can now contain commands that\ncontinue debugging, such as "continue" or "next".  Previously, these\ncommands had no effect.\n\nh(elp) [command]\n\n   Without argument, print the list of available commands.  With a\n   *command* as argument, print help about that command.  "help pdb"\n   displays the full documentation (the docstring of the "pdb"\n   module).  Since the *command* argument must be an identifier, "help\n   exec" must be entered to get help on the "!" command.\n\nw(here)\n\n   Print a stack trace, with the most recent frame at the bottom.  An\n   arrow indicates the current frame, which determines the context of\n   most commands.\n\nd(own) [count]\n\n   Move the current frame *count* (default one) levels down in the\n   stack trace (to a newer frame).\n\nu(p) [count]\n\n   Move the current frame *count* (default one) levels up in the stack\n   trace (to an older frame).\n\nb(reak) [([filename:]lineno | function) [, condition]]\n\n   With a *lineno* argument, set a break there in the current file.\n   With a *function* argument, set a break at the first executable\n   statement within that function.  The line number may be prefixed\n   with a filename and a colon, to specify a breakpoint in another\n   file (probably one that hasn\'t been loaded yet).  The file is\n   searched on "sys.path".  Note that each breakpoint is assigned a\n   number to which all the other breakpoint commands refer.\n\n   If a second argument is present, it is an expression which must\n   evaluate to true before the breakpoint is honored.\n\n   Without argument, list all breaks, including for each breakpoint,\n   the number of times that breakpoint has been hit, the current\n   ignore count, and the associated condition if any.\n\ntbreak [([filename:]lineno | function) [, condition]]\n\n   Temporary breakpoint, which is removed automatically when it is\n   first hit. The arguments are the same as for "break".\n\ncl(ear) [filename:lineno | bpnumber [bpnumber ...]]\n\n   With a *filename:lineno* argument, clear all the breakpoints at\n   this line. With a space separated list of breakpoint numbers, clear\n   those breakpoints. Without argument, clear all breaks (but first\n   ask confirmation).\n\ndisable [bpnumber [bpnumber ...]]\n\n   Disable the breakpoints given as a space separated list of\n   breakpoint numbers.  Disabling a breakpoint means it cannot cause\n   the program to stop execution, but unlike clearing a breakpoint, it\n   remains in the list of breakpoints and can be (re-)enabled.\n\nenable [bpnumber [bpnumber ...]]\n\n   Enable the breakpoints specified.\n\nignore bpnumber [count]\n\n   Set the ignore count for the given breakpoint number.  If count is\n   omitted, the ignore count is set to 0.  A breakpoint becomes active\n   when the ignore count is zero.  When non-zero, the count is\n   decremented each time the breakpoint is reached and the breakpoint\n   is not disabled and any associated condition evaluates to true.\n\ncondition bpnumber [condition]\n\n   Set a new *condition* for the breakpoint, an expression which must\n   evaluate to true before the breakpoint is honored.  If *condition*\n   is absent, any existing condition is removed; i.e., the breakpoint\n   is made unconditional.\n\ncommands [bpnumber]\n\n   Specify a list of commands for breakpoint number *bpnumber*.  The\n   commands themselves appear on the following lines.  Type a line\n   containing just "end" to terminate the commands. An example:\n\n      (Pdb) commands 1\n      (com) p some_variable\n      (com) end\n      (Pdb)\n\n   To remove all commands from a breakpoint, type commands and follow\n   it immediately with "end"; that is, give no commands.\n\n   With no *bpnumber* argument, commands refers to the last breakpoint\n   set.\n\n   You can use breakpoint commands to start your program up again.\n   Simply use the continue command, or step, or any other command that\n   resumes execution.\n\n   Specifying any command resuming execution (currently continue,\n   step, next, return, jump, quit and their abbreviations) terminates\n   the command list (as if that command was immediately followed by\n   end). This is because any time you resume execution (even with a\n   simple next or step), you may encounter another breakpoint--which\n   could have its own command list, leading to ambiguities about which\n   list to execute.\n\n   If you use the \'silent\' command in the command list, the usual\n   message about stopping at a breakpoint is not printed.  This may be\n   desirable for breakpoints that are to print a specific message and\n   then continue.  If none of the other commands print anything, you\n   see no sign that the breakpoint was reached.\n\ns(tep)\n\n   Execute the current line, stop at the first possible occasion\n   (either in a function that is called or on the next line in the\n   current function).\n\nn(ext)\n\n   Continue execution until the next line in the current function is\n   reached or it returns.  (The difference between "next" and "step"\n   is that "step" stops inside a called function, while "next"\n   executes called functions at (nearly) full speed, only stopping at\n   the next line in the current function.)\n\nunt(il) [lineno]\n\n   Without argument, continue execution until the line with a number\n   greater than the current one is reached.\n\n   With a line number, continue execution until a line with a number\n   greater or equal to that is reached.  In both cases, also stop when\n   the current frame returns.\n\n   Changed in version 3.2: Allow giving an explicit line number.\n\nr(eturn)\n\n   Continue execution until the current function returns.\n\nc(ont(inue))\n\n   Continue execution, only stop when a breakpoint is encountered.\n\nj(ump) lineno\n\n   Set the next line that will be executed.  Only available in the\n   bottom-most frame.  This lets you jump back and execute code again,\n   or jump forward to skip code that you don\'t want to run.\n\n   It should be noted that not all jumps are allowed -- for instance\n   it is not possible to jump into the middle of a "for" loop or out\n   of a "finally" clause.\n\nl(ist) [first[, last]]\n\n   List source code for the current file.  Without arguments, list 11\n   lines around the current line or continue the previous listing.\n   With "." as argument, list 11 lines around the current line.  With\n   one argument, list 11 lines around at that line.  With two\n   arguments, list the given range; if the second argument is less\n   than the first, it is interpreted as a count.\n\n   The current line in the current frame is indicated by "->".  If an\n   exception is being debugged, the line where the exception was\n   originally raised or propagated is indicated by ">>", if it differs\n   from the current line.\n\n   New in version 3.2: The ">>" marker.\n\nll | longlist\n\n   List all source code for the current function or frame.\n   Interesting lines are marked as for "list".\n\n   New in version 3.2.\n\na(rgs)\n\n   Print the argument list of the current function.\n\np expression\n\n   Evaluate the *expression* in the current context and print its\n   value.\n\n   Note: "print()" can also be used, but is not a debugger command\n     --- this executes the Python "print()" function.\n\npp expression\n\n   Like the "p" command, except the value of the expression is pretty-\n   printed using the "pprint" module.\n\nwhatis expression\n\n   Print the type of the *expression*.\n\nsource expression\n\n   Try to get source code for the given object and display it.\n\n   New in version 3.2.\n\ndisplay [expression]\n\n   Display the value of the expression if it changed, each time\n   execution stops in the current frame.\n\n   Without expression, list all display expressions for the current\n   frame.\n\n   New in version 3.2.\n\nundisplay [expression]\n\n   Do not display the expression any more in the current frame.\n   Without expression, clear all display expressions for the current\n   frame.\n\n   New in version 3.2.\n\ninteract\n\n   Start an interative interpreter (using the "code" module) whose\n   global namespace contains all the (global and local) names found in\n   the current scope.\n\n   New in version 3.2.\n\nalias [name [command]]\n\n   Create an alias called *name* that executes *command*.  The command\n   must *not* be enclosed in quotes.  Replaceable parameters can be\n   indicated by "%1", "%2", and so on, while "%*" is replaced by all\n   the parameters. If no command is given, the current alias for\n   *name* is shown. If no arguments are given, all aliases are listed.\n\n   Aliases may be nested and can contain anything that can be legally\n   typed at the pdb prompt.  Note that internal pdb commands *can* be\n   overridden by aliases.  Such a command is then hidden until the\n   alias is removed.  Aliasing is recursively applied to the first\n   word of the command line; all other words in the line are left\n   alone.\n\n   As an example, here are two useful aliases (especially when placed\n   in the ".pdbrc" file):\n\n      # Print instance variables (usage "pi classInst")\n      alias pi for k in %1.__dict__.keys(): print("%1.",k,"=",%1.__dict__[k])\n      # Print instance variables in self\n      alias ps pi self\n\nunalias name\n\n   Delete the specified alias.\n\n! statement\n\n   Execute the (one-line) *statement* in the context of the current\n   stack frame. The exclamation point can be omitted unless the first\n   word of the statement resembles a debugger command.  To set a\n   global variable, you can prefix the assignment command with a\n   "global" statement on the same line, e.g.:\n\n      (Pdb) global list_options; list_options = [\'-l\']\n      (Pdb)\n\nrun [args ...]\nrestart [args ...]\n\n   Restart the debugged Python program.  If an argument is supplied,\n   it is split with "shlex" and the result is used as the new\n   "sys.argv". History, breakpoints, actions and debugger options are\n   preserved. "restart" is an alias for "run".\n\nq(uit)\n\n   Quit from the debugger.  The program being executed is aborted.\n\n-[ Footnotes ]-\n\n[1] Whether a frame is considered to originate in a certain module\n    is determined by the "__name__" in the frame globals.\n',
- 'del': u'\nThe "del" statement\n*******************\n\n   del_stmt ::= "del" target_list\n\nDeletion is recursively defined very similar to the way assignment is\ndefined. Rather than spelling it out in full details, here are some\nhints.\n\nDeletion of a target list recursively deletes each target, from left\nto right.\n\nDeletion of a name removes the binding of that name from the local or\nglobal namespace, depending on whether the name occurs in a "global"\nstatement in the same code block.  If the name is unbound, a\n"NameError" exception will be raised.\n\nDeletion of attribute references, subscriptions and slicings is passed\nto the primary object involved; deletion of a slicing is in general\nequivalent to assignment of an empty slice of the right type (but even\nthis is determined by the sliced object).\n\nChanged in version 3.2: Previously it was illegal to delete a name\nfrom the local namespace if it occurs as a free variable in a nested\nblock.\n',
- 'dict': u'\nDictionary displays\n*******************\n\nA dictionary display is a possibly empty series of key/datum pairs\nenclosed in curly braces:\n\n   dict_display       ::= "{" [key_datum_list | dict_comprehension] "}"\n   key_datum_list     ::= key_datum ("," key_datum)* [","]\n   key_datum          ::= expression ":" expression\n   dict_comprehension ::= expression ":" expression comp_for\n\nA dictionary display yields a new dictionary object.\n\nIf a comma-separated sequence of key/datum pairs is given, they are\nevaluated from left to right to define the entries of the dictionary:\neach key object is used as a key into the dictionary to store the\ncorresponding datum.  This means that you can specify the same key\nmultiple times in the key/datum list, and the final dictionary\'s value\nfor that key will be the last one given.\n\nA dict comprehension, in contrast to list and set comprehensions,\nneeds two expressions separated with a colon followed by the usual\n"for" and "if" clauses. When the comprehension is run, the resulting\nkey and value elements are inserted in the new dictionary in the order\nthey are produced.\n\nRestrictions on the types of the key values are listed earlier in\nsection *The standard type hierarchy*.  (To summarize, the key type\nshould be *hashable*, which excludes all mutable objects.)  Clashes\nbetween duplicate keys are not detected; the last datum (textually\nrightmost in the display) stored for a given key value prevails.\n',
- 'dynamic-features': u'\nInteraction with dynamic features\n*********************************\n\nName resolution of free variables occurs at runtime, not at compile\ntime. This means that the following code will print 42:\n\n   i = 10\n   def f():\n       print(i)\n   i = 42\n   f()\n\nThere are several cases where Python statements are illegal when used\nin conjunction with nested scopes that contain free variables.\n\nIf a variable is referenced in an enclosing scope, it is illegal to\ndelete the name.  An error will be reported at compile time.\n\nThe "eval()" and "exec()" functions do not have access to the full\nenvironment for resolving names.  Names may be resolved in the local\nand global namespaces of the caller.  Free variables are not resolved\nin the nearest enclosing namespace, but in the global namespace.  [1]\nThe "exec()" and "eval()" functions have optional arguments to\noverride the global and local namespace.  If only one namespace is\nspecified, it is used for both.\n',
- 'else': u'\nThe "if" statement\n******************\n\nThe "if" statement is used for conditional execution:\n\n   if_stmt ::= "if" expression ":" suite\n               ( "elif" expression ":" suite )*\n               ["else" ":" suite]\n\nIt selects exactly one of the suites by evaluating the expressions one\nby one until one is found to be true (see section *Boolean operations*\nfor the definition of true and false); then that suite is executed\n(and no other part of the "if" statement is executed or evaluated).\nIf all expressions are false, the suite of the "else" clause, if\npresent, is executed.\n',
- 'exceptions': u'\nExceptions\n**********\n\nExceptions are a means of breaking out of the normal flow of control\nof a code block in order to handle errors or other exceptional\nconditions.  An exception is *raised* at the point where the error is\ndetected; it may be *handled* by the surrounding code block or by any\ncode block that directly or indirectly invoked the code block where\nthe error occurred.\n\nThe Python interpreter raises an exception when it detects a run-time\nerror (such as division by zero).  A Python program can also\nexplicitly raise an exception with the "raise" statement. Exception\nhandlers are specified with the "try" ... "except" statement.  The\n"finally" clause of such a statement can be used to specify cleanup\ncode which does not handle the exception, but is executed whether an\nexception occurred or not in the preceding code.\n\nPython uses the "termination" model of error handling: an exception\nhandler can find out what happened and continue execution at an outer\nlevel, but it cannot repair the cause of the error and retry the\nfailing operation (except by re-entering the offending piece of code\nfrom the top).\n\nWhen an exception is not handled at all, the interpreter terminates\nexecution of the program, or returns to its interactive main loop.  In\neither case, it prints a stack backtrace, except when the exception is\n"SystemExit".\n\nExceptions are identified by class instances.  The "except" clause is\nselected depending on the class of the instance: it must reference the\nclass of the instance or a base class thereof.  The instance can be\nreceived by the handler and can carry additional information about the\nexceptional condition.\n\nNote: Exception messages are not part of the Python API.  Their\n  contents may change from one version of Python to the next without\n  warning and should not be relied on by code which will run under\n  multiple versions of the interpreter.\n\nSee also the description of the "try" statement in section *The try\nstatement* and "raise" statement in section *The raise statement*.\n\n-[ Footnotes ]-\n\n[1] This limitation occurs because the code that is executed by\n    these operations is not available at the time the module is\n    compiled.\n',
- 'execmodel': u'\nExecution model\n***************\n\n\nStructure of a program\n======================\n\nA Python program is constructed from code blocks. A *block* is a piece\nof Python program text that is executed as a unit. The following are\nblocks: a module, a function body, and a class definition. Each\ncommand typed interactively is a block.  A script file (a file given\nas standard input to the interpreter or specified as a command line\nargument to the interpreter) is a code block.  A script command (a\ncommand specified on the interpreter command line with the \'**-c**\'\noption) is a code block.  The string argument passed to the built-in\nfunctions "eval()" and "exec()" is a code block.\n\nA code block is executed in an *execution frame*.  A frame contains\nsome administrative information (used for debugging) and determines\nwhere and how execution continues after the code block\'s execution has\ncompleted.\n\n\nNaming and binding\n==================\n\n\nBinding of names\n----------------\n\n*Names* refer to objects.  Names are introduced by name binding\noperations.\n\nThe following constructs bind names: formal parameters to functions,\n"import" statements, class and function definitions (these bind the\nclass or function name in the defining block), and targets that are\nidentifiers if occurring in an assignment, "for" loop header, or after\n"as" in a "with" statement or "except" clause. The "import" statement\nof the form "from ... import *" binds all names defined in the\nimported module, except those beginning with an underscore.  This form\nmay only be used at the module level.\n\nA target occurring in a "del" statement is also considered bound for\nthis purpose (though the actual semantics are to unbind the name).\n\nEach assignment or import statement occurs within a block defined by a\nclass or function definition or at the module level (the top-level\ncode block).\n\nIf a name is bound in a block, it is a local variable of that block,\nunless declared as "nonlocal" or "global".  If a name is bound at the\nmodule level, it is a global variable.  (The variables of the module\ncode block are local and global.)  If a variable is used in a code\nblock but not defined there, it is a *free variable*.\n\nEach occurrence of a name in the program text refers to the *binding*\nof that name established by the following name resolution rules.\n\n\nResolution of names\n-------------------\n\nA *scope* defines the visibility of a name within a block.  If a local\nvariable is defined in a block, its scope includes that block.  If the\ndefinition occurs in a function block, the scope extends to any blocks\ncontained within the defining one, unless a contained block introduces\na different binding for the name.\n\nWhen a name is used in a code block, it is resolved using the nearest\nenclosing scope.  The set of all such scopes visible to a code block\nis called the block\'s *environment*.\n\nWhen a name is not found at all, a "NameError" exception is raised. If\nthe current scope is a function scope, and the name refers to a local\nvariable that has not yet been bound to a value at the point where the\nname is used, an "UnboundLocalError" exception is raised.\n"UnboundLocalError" is a subclass of "NameError".\n\nIf a name binding operation occurs anywhere within a code block, all\nuses of the name within the block are treated as references to the\ncurrent block.  This can lead to errors when a name is used within a\nblock before it is bound.  This rule is subtle.  Python lacks\ndeclarations and allows name binding operations to occur anywhere\nwithin a code block.  The local variables of a code block can be\ndetermined by scanning the entire text of the block for name binding\noperations.\n\nIf the "global" statement occurs within a block, all uses of the name\nspecified in the statement refer to the binding of that name in the\ntop-level namespace.  Names are resolved in the top-level namespace by\nsearching the global namespace, i.e. the namespace of the module\ncontaining the code block, and the builtins namespace, the namespace\nof the module "builtins".  The global namespace is searched first.  If\nthe name is not found there, the builtins namespace is searched.  The\n"global" statement must precede all uses of the name.\n\nThe "global" statement has the same scope as a name binding operation\nin the same block.  If the nearest enclosing scope for a free variable\ncontains a global statement, the free variable is treated as a global.\n\nThe "nonlocal" statement causes corresponding names to refer to\npreviously bound variables in the nearest enclosing function scope.\n"SyntaxError" is raised at compile time if the given name does not\nexist in any enclosing function scope.\n\nThe namespace for a module is automatically created the first time a\nmodule is imported.  The main module for a script is always called\n"__main__".\n\nClass definition blocks and arguments to "exec()" and "eval()" are\nspecial in the context of name resolution. A class definition is an\nexecutable statement that may use and define names. These references\nfollow the normal rules for name resolution with an exception that\nunbound local variables are looked up in the global namespace. The\nnamespace of the class definition becomes the attribute dictionary of\nthe class. The scope of names defined in a class block is limited to\nthe class block; it does not extend to the code blocks of methods --\nthis includes comprehensions and generator expressions since they are\nimplemented using a function scope.  This means that the following\nwill fail:\n\n   class A:\n       a = 42\n       b = list(a + i for i in range(10))\n\n\nBuiltins and restricted execution\n---------------------------------\n\nThe builtins namespace associated with the execution of a code block\nis actually found by looking up the name "__builtins__" in its global\nnamespace; this should be a dictionary or a module (in the latter case\nthe module\'s dictionary is used).  By default, when in the "__main__"\nmodule, "__builtins__" is the built-in module "builtins"; when in any\nother module, "__builtins__" is an alias for the dictionary of the\n"builtins" module itself.  "__builtins__" can be set to a user-created\ndictionary to create a weak form of restricted execution.\n\n**CPython implementation detail:** Users should not touch\n"__builtins__"; it is strictly an implementation detail.  Users\nwanting to override values in the builtins namespace should "import"\nthe "builtins" module and modify its attributes appropriately.\n\n\nInteraction with dynamic features\n---------------------------------\n\nName resolution of free variables occurs at runtime, not at compile\ntime. This means that the following code will print 42:\n\n   i = 10\n   def f():\n       print(i)\n   i = 42\n   f()\n\nThere are several cases where Python statements are illegal when used\nin conjunction with nested scopes that contain free variables.\n\nIf a variable is referenced in an enclosing scope, it is illegal to\ndelete the name.  An error will be reported at compile time.\n\nThe "eval()" and "exec()" functions do not have access to the full\nenvironment for resolving names.  Names may be resolved in the local\nand global namespaces of the caller.  Free variables are not resolved\nin the nearest enclosing namespace, but in the global namespace.  [1]\nThe "exec()" and "eval()" functions have optional arguments to\noverride the global and local namespace.  If only one namespace is\nspecified, it is used for both.\n\n\nExceptions\n==========\n\nExceptions are a means of breaking out of the normal flow of control\nof a code block in order to handle errors or other exceptional\nconditions.  An exception is *raised* at the point where the error is\ndetected; it may be *handled* by the surrounding code block or by any\ncode block that directly or indirectly invoked the code block where\nthe error occurred.\n\nThe Python interpreter raises an exception when it detects a run-time\nerror (such as division by zero).  A Python program can also\nexplicitly raise an exception with the "raise" statement. Exception\nhandlers are specified with the "try" ... "except" statement.  The\n"finally" clause of such a statement can be used to specify cleanup\ncode which does not handle the exception, but is executed whether an\nexception occurred or not in the preceding code.\n\nPython uses the "termination" model of error handling: an exception\nhandler can find out what happened and continue execution at an outer\nlevel, but it cannot repair the cause of the error and retry the\nfailing operation (except by re-entering the offending piece of code\nfrom the top).\n\nWhen an exception is not handled at all, the interpreter terminates\nexecution of the program, or returns to its interactive main loop.  In\neither case, it prints a stack backtrace, except when the exception is\n"SystemExit".\n\nExceptions are identified by class instances.  The "except" clause is\nselected depending on the class of the instance: it must reference the\nclass of the instance or a base class thereof.  The instance can be\nreceived by the handler and can carry additional information about the\nexceptional condition.\n\nNote: Exception messages are not part of the Python API.  Their\n  contents may change from one version of Python to the next without\n  warning and should not be relied on by code which will run under\n  multiple versions of the interpreter.\n\nSee also the description of the "try" statement in section *The try\nstatement* and "raise" statement in section *The raise statement*.\n\n-[ Footnotes ]-\n\n[1] This limitation occurs because the code that is executed by\n    these operations is not available at the time the module is\n    compiled.\n',
- 'exprlists': u'\nExpression lists\n****************\n\n   expression_list ::= expression ( "," expression )* [","]\n\nAn expression list containing at least one comma yields a tuple.  The\nlength of the tuple is the number of expressions in the list.  The\nexpressions are evaluated from left to right.\n\nThe trailing comma is required only to create a single tuple (a.k.a. a\n*singleton*); it is optional in all other cases.  A single expression\nwithout a trailing comma doesn\'t create a tuple, but rather yields the\nvalue of that expression. (To create an empty tuple, use an empty pair\nof parentheses: "()".)\n',
- 'floating': u'\nFloating point literals\n***********************\n\nFloating point literals are described by the following lexical\ndefinitions:\n\n   floatnumber   ::= pointfloat | exponentfloat\n   pointfloat    ::= [intpart] fraction | intpart "."\n   exponentfloat ::= (intpart | pointfloat) exponent\n   intpart       ::= digit+\n   fraction      ::= "." digit+\n   exponent      ::= ("e" | "E") ["+" | "-"] digit+\n\nNote that the integer and exponent parts are always interpreted using\nradix 10. For example, "077e010" is legal, and denotes the same number\nas "77e10". The allowed range of floating point literals is\nimplementation-dependent. Some examples of floating point literals:\n\n   3.14    10.    .001    1e100    3.14e-10    0e0\n\nNote that numeric literals do not include a sign; a phrase like "-1"\nis actually an expression composed of the unary operator "-" and the\nliteral "1".\n',
- 'for': u'\nThe "for" statement\n*******************\n\nThe "for" statement is used to iterate over the elements of a sequence\n(such as a string, tuple or list) or other iterable object:\n\n   for_stmt ::= "for" target_list "in" expression_list ":" suite\n                ["else" ":" suite]\n\nThe expression list is evaluated once; it should yield an iterable\nobject.  An iterator is created for the result of the\n"expression_list".  The suite is then executed once for each item\nprovided by the iterator, in the order returned by the iterator.  Each\nitem in turn is assigned to the target list using the standard rules\nfor assignments (see *Assignment statements*), and then the suite is\nexecuted.  When the items are exhausted (which is immediately when the\nsequence is empty or an iterator raises a "StopIteration" exception),\nthe suite in the "else" clause, if present, is executed, and the loop\nterminates.\n\nA "break" statement executed in the first suite terminates the loop\nwithout executing the "else" clause\'s suite.  A "continue" statement\nexecuted in the first suite skips the rest of the suite and continues\nwith the next item, or with the "else" clause if there is no next\nitem.\n\nThe for-loop makes assignments to the variables(s) in the target list.\nThis overwrites all previous assignments to those variables including\nthose made in the suite of the for-loop:\n\n   for i in range(10):\n       print(i)\n       i = 5             # this will not affect the for-loop\n                         # because i will be overwritten with the next\n                         # index in the range\n\nNames in the target list are not deleted when the loop is finished,\nbut if the sequence is empty, they will not have been assigned to at\nall by the loop.  Hint: the built-in function "range()" returns an\niterator of integers suitable to emulate the effect of Pascal\'s "for i\n:= a to b do"; e.g., "list(range(3))" returns the list "[0, 1, 2]".\n\nNote: There is a subtlety when the sequence is being modified by the\n  loop (this can only occur for mutable sequences, i.e. lists).  An\n  internal counter is used to keep track of which item is used next,\n  and this is incremented on each iteration.  When this counter has\n  reached the length of the sequence the loop terminates.  This means\n  that if the suite deletes the current (or a previous) item from the\n  sequence, the next item will be skipped (since it gets the index of\n  the current item which has already been treated).  Likewise, if the\n  suite inserts an item in the sequence before the current item, the\n  current item will be treated again the next time through the loop.\n  This can lead to nasty bugs that can be avoided by making a\n  temporary copy using a slice of the whole sequence, e.g.,\n\n     for x in a[:]:\n         if x < 0: a.remove(x)\n',
- 'formatstrings': u'\nFormat String Syntax\n********************\n\nThe "str.format()" method and the "Formatter" class share the same\nsyntax for format strings (although in the case of "Formatter",\nsubclasses can define their own format string syntax).\n\nFormat strings contain "replacement fields" surrounded by curly braces\n"{}". Anything that is not contained in braces is considered literal\ntext, which is copied unchanged to the output.  If you need to include\na brace character in the literal text, it can be escaped by doubling:\n"{{" and "}}".\n\nThe grammar for a replacement field is as follows:\n\n      replacement_field ::= "{" [field_name] ["!" conversion] [":" format_spec] "}"\n      field_name        ::= arg_name ("." attribute_name | "[" element_index "]")*\n      arg_name          ::= [identifier | integer]\n      attribute_name    ::= identifier\n      element_index     ::= integer | index_string\n      index_string      ::= <any source character except "]"> +\n      conversion        ::= "r" | "s" | "a"\n      format_spec       ::= <described in the next section>\n\nIn less formal terms, the replacement field can start with a\n*field_name* that specifies the object whose value is to be formatted\nand inserted into the output instead of the replacement field. The\n*field_name* is optionally followed by a  *conversion* field, which is\npreceded by an exclamation point "\'!\'", and a *format_spec*, which is\npreceded by a colon "\':\'".  These specify a non-default format for the\nreplacement value.\n\nSee also the *Format Specification Mini-Language* section.\n\nThe *field_name* itself begins with an *arg_name* that is either a\nnumber or a keyword.  If it\'s a number, it refers to a positional\nargument, and if it\'s a keyword, it refers to a named keyword\nargument.  If the numerical arg_names in a format string are 0, 1, 2,\n... in sequence, they can all be omitted (not just some) and the\nnumbers 0, 1, 2, ... will be automatically inserted in that order.\nBecause *arg_name* is not quote-delimited, it is not possible to\nspecify arbitrary dictionary keys (e.g., the strings "\'10\'" or\n"\':-]\'") within a format string. The *arg_name* can be followed by any\nnumber of index or attribute expressions. An expression of the form\n"\'.name\'" selects the named attribute using "getattr()", while an\nexpression of the form "\'[index]\'" does an index lookup using\n"__getitem__()".\n\nChanged in version 3.1: The positional argument specifiers can be\nomitted, so "\'{} {}\'" is equivalent to "\'{0} {1}\'".\n\nSome simple format string examples:\n\n   "First, thou shalt count to {0}" # References first positional argument\n   "Bring me a {}"                  # Implicitly references the first positional argument\n   "From {} to {}"                  # Same as "From {0} to {1}"\n   "My quest is {name}"             # References keyword argument \'name\'\n   "Weight in tons {0.weight}"      # \'weight\' attribute of first positional arg\n   "Units destroyed: {players[0]}"  # First element of keyword argument \'players\'.\n\nThe *conversion* field causes a type coercion before formatting.\nNormally, the job of formatting a value is done by the "__format__()"\nmethod of the value itself.  However, in some cases it is desirable to\nforce a type to be formatted as a string, overriding its own\ndefinition of formatting.  By converting the value to a string before\ncalling "__format__()", the normal formatting logic is bypassed.\n\nThree conversion flags are currently supported: "\'!s\'" which calls\n"str()" on the value, "\'!r\'" which calls "repr()" and "\'!a\'" which\ncalls "ascii()".\n\nSome examples:\n\n   "Harold\'s a clever {0!s}"        # Calls str() on the argument first\n   "Bring out the holy {name!r}"    # Calls repr() on the argument first\n   "More {!a}"                      # Calls ascii() on the argument first\n\nThe *format_spec* field contains a specification of how the value\nshould be presented, including such details as field width, alignment,\npadding, decimal precision and so on.  Each value type can define its\nown "formatting mini-language" or interpretation of the *format_spec*.\n\nMost built-in types support a common formatting mini-language, which\nis described in the next section.\n\nA *format_spec* field can also include nested replacement fields\nwithin it. These nested replacement fields can contain only a field\nname; conversion flags and format specifications are not allowed.  The\nreplacement fields within the format_spec are substituted before the\n*format_spec* string is interpreted. This allows the formatting of a\nvalue to be dynamically specified.\n\nSee the *Format examples* section for some examples.\n\n\nFormat Specification Mini-Language\n==================================\n\n"Format specifications" are used within replacement fields contained\nwithin a format string to define how individual values are presented\n(see *Format String Syntax*).  They can also be passed directly to the\nbuilt-in "format()" function.  Each formattable type may define how\nthe format specification is to be interpreted.\n\nMost built-in types implement the following options for format\nspecifications, although some of the formatting options are only\nsupported by the numeric types.\n\nA general convention is that an empty format string ("""") produces\nthe same result as if you had called "str()" on the value. A non-empty\nformat string typically modifies the result.\n\nThe general form of a *standard format specifier* is:\n\n   format_spec ::= [[fill]align][sign][#][0][width][,][.precision][type]\n   fill        ::= <any character>\n   align       ::= "<" | ">" | "=" | "^"\n   sign        ::= "+" | "-" | " "\n   width       ::= integer\n   precision   ::= integer\n   type        ::= "b" | "c" | "d" | "e" | "E" | "f" | "F" | "g" | "G" | "n" | "o" | "s" | "x" | "X" | "%"\n\nIf a valid *align* value is specified, it can be preceded by a *fill*\ncharacter that can be any character and defaults to a space if\nomitted. Note that it is not possible to use "{" and "}" as *fill*\nchar while using the "str.format()" method; this limitation however\ndoesn\'t affect the "format()" function.\n\nThe meaning of the various alignment options is as follows:\n\n   +-----------+------------------------------------------------------------+\n   | Option    | Meaning                                                    |\n   +===========+============================================================+\n   | "\'<\'"     | Forces the field to be left-aligned within the available   |\n   |           | space (this is the default for most objects).              |\n   +-----------+------------------------------------------------------------+\n   | "\'>\'"     | Forces the field to be right-aligned within the available  |\n   |           | space (this is the default for numbers).                   |\n   +-----------+------------------------------------------------------------+\n   | "\'=\'"     | Forces the padding to be placed after the sign (if any)    |\n   |           | but before the digits.  This is used for printing fields   |\n   |           | in the form \'+000000120\'. This alignment option is only    |\n   |           | valid for numeric types.                                   |\n   +-----------+------------------------------------------------------------+\n   | "\'^\'"     | Forces the field to be centered within the available       |\n   |           | space.                                                     |\n   +-----------+------------------------------------------------------------+\n\nNote that unless a minimum field width is defined, the field width\nwill always be the same size as the data to fill it, so that the\nalignment option has no meaning in this case.\n\nThe *sign* option is only valid for number types, and can be one of\nthe following:\n\n   +-----------+------------------------------------------------------------+\n   | Option    | Meaning                                                    |\n   +===========+============================================================+\n   | "\'+\'"     | indicates that a sign should be used for both positive as  |\n   |           | well as negative numbers.                                  |\n   +-----------+------------------------------------------------------------+\n   | "\'-\'"     | indicates that a sign should be used only for negative     |\n   |           | numbers (this is the default behavior).                    |\n   +-----------+------------------------------------------------------------+\n   | space     | indicates that a leading space should be used on positive  |\n   |           | numbers, and a minus sign on negative numbers.             |\n   +-----------+------------------------------------------------------------+\n\nThe "\'#\'" option causes the "alternate form" to be used for the\nconversion.  The alternate form is defined differently for different\ntypes.  This option is only valid for integer, float, complex and\nDecimal types. For integers, when binary, octal, or hexadecimal output\nis used, this option adds the prefix respective "\'0b\'", "\'0o\'", or\n"\'0x\'" to the output value. For floats, complex and Decimal the\nalternate form causes the result of the conversion to always contain a\ndecimal-point character, even if no digits follow it. Normally, a\ndecimal-point character appears in the result of these conversions\nonly if a digit follows it. In addition, for "\'g\'" and "\'G\'"\nconversions, trailing zeros are not removed from the result.\n\nThe "\',\'" option signals the use of a comma for a thousands separator.\nFor a locale aware separator, use the "\'n\'" integer presentation type\ninstead.\n\nChanged in version 3.1: Added the "\',\'" option (see also **PEP 378**).\n\n*width* is a decimal integer defining the minimum field width.  If not\nspecified, then the field width will be determined by the content.\n\nPreceding the *width* field by a zero ("\'0\'") character enables sign-\naware zero-padding for numeric types.  This is equivalent to a *fill*\ncharacter of "\'0\'" with an *alignment* type of "\'=\'".\n\nThe *precision* is a decimal number indicating how many digits should\nbe displayed after the decimal point for a floating point value\nformatted with "\'f\'" and "\'F\'", or before and after the decimal point\nfor a floating point value formatted with "\'g\'" or "\'G\'".  For non-\nnumber types the field indicates the maximum field size - in other\nwords, how many characters will be used from the field content. The\n*precision* is not allowed for integer values.\n\nFinally, the *type* determines how the data should be presented.\n\nThe available string presentation types are:\n\n   +-----------+------------------------------------------------------------+\n   | Type      | Meaning                                                    |\n   +===========+============================================================+\n   | "\'s\'"     | String format. This is the default type for strings and    |\n   |           | may be omitted.                                            |\n   +-----------+------------------------------------------------------------+\n   | None      | The same as "\'s\'".                                         |\n   +-----------+------------------------------------------------------------+\n\nThe available integer presentation types are:\n\n   +-----------+------------------------------------------------------------+\n   | Type      | Meaning                                                    |\n   +===========+============================================================+\n   | "\'b\'"     | Binary format. Outputs the number in base 2.               |\n   +-----------+------------------------------------------------------------+\n   | "\'c\'"     | Character. Converts the integer to the corresponding       |\n   |           | unicode character before printing.                         |\n   +-----------+------------------------------------------------------------+\n   | "\'d\'"     | Decimal Integer. Outputs the number in base 10.            |\n   +-----------+------------------------------------------------------------+\n   | "\'o\'"     | Octal format. Outputs the number in base 8.                |\n   +-----------+------------------------------------------------------------+\n   | "\'x\'"     | Hex format. Outputs the number in base 16, using lower-    |\n   |           | case letters for the digits above 9.                       |\n   +-----------+------------------------------------------------------------+\n   | "\'X\'"     | Hex format. Outputs the number in base 16, using upper-    |\n   |           | case letters for the digits above 9.                       |\n   +-----------+------------------------------------------------------------+\n   | "\'n\'"     | Number. This is the same as "\'d\'", except that it uses the |\n   |           | current locale setting to insert the appropriate number    |\n   |           | separator characters.                                      |\n   +-----------+------------------------------------------------------------+\n   | None      | The same as "\'d\'".                                         |\n   +-----------+------------------------------------------------------------+\n\nIn addition to the above presentation types, integers can be formatted\nwith the floating point presentation types listed below (except "\'n\'"\nand None). When doing so, "float()" is used to convert the integer to\na floating point number before formatting.\n\nThe available presentation types for floating point and decimal values\nare:\n\n   +-----------+------------------------------------------------------------+\n   | Type      | Meaning                                                    |\n   +===========+============================================================+\n   | "\'e\'"     | Exponent notation. Prints the number in scientific         |\n   |           | notation using the letter \'e\' to indicate the exponent.    |\n   |           | The default precision is "6".                              |\n   +-----------+------------------------------------------------------------+\n   | "\'E\'"     | Exponent notation. Same as "\'e\'" except it uses an upper   |\n   |           | case \'E\' as the separator character.                       |\n   +-----------+------------------------------------------------------------+\n   | "\'f\'"     | Fixed point. Displays the number as a fixed-point number.  |\n   |           | The default precision is "6".                              |\n   +-----------+------------------------------------------------------------+\n   | "\'F\'"     | Fixed point. Same as "\'f\'", but converts "nan" to "NAN"    |\n   |           | and "inf" to "INF".                                        |\n   +-----------+------------------------------------------------------------+\n   | "\'g\'"     | General format.  For a given precision "p >= 1", this      |\n   |           | rounds the number to "p" significant digits and then       |\n   |           | formats the result in either fixed-point format or in      |\n   |           | scientific notation, depending on its magnitude.  The      |\n   |           | precise rules are as follows: suppose that the result      |\n   |           | formatted with presentation type "\'e\'" and precision "p-1" |\n   |           | would have exponent "exp".  Then if "-4 <= exp < p", the   |\n   |           | number is formatted with presentation type "\'f\'" and       |\n   |           | precision "p-1-exp".  Otherwise, the number is formatted   |\n   |           | with presentation type "\'e\'" and precision "p-1". In both  |\n   |           | cases insignificant trailing zeros are removed from the    |\n   |           | significand, and the decimal point is also removed if      |\n   |           | there are no remaining digits following it.  Positive and  |\n   |           | negative infinity, positive and negative zero, and nans,   |\n   |           | are formatted as "inf", "-inf", "0", "-0" and "nan"        |\n   |           | respectively, regardless of the precision.  A precision of |\n   |           | "0" is treated as equivalent to a precision of "1". The    |\n   |           | default precision is "6".                                  |\n   +-----------+------------------------------------------------------------+\n   | "\'G\'"     | General format. Same as "\'g\'" except switches to "\'E\'" if  |\n   |           | the number gets too large. The representations of infinity |\n   |           | and NaN are uppercased, too.                               |\n   +-----------+------------------------------------------------------------+\n   | "\'n\'"     | Number. This is the same as "\'g\'", except that it uses the |\n   |           | current locale setting to insert the appropriate number    |\n   |           | separator characters.                                      |\n   +-----------+------------------------------------------------------------+\n   | "\'%\'"     | Percentage. Multiplies the number by 100 and displays in   |\n   |           | fixed ("\'f\'") format, followed by a percent sign.          |\n   +-----------+------------------------------------------------------------+\n   | None      | Similar to "\'g\'", except that fixed-point notation, when   |\n   |           | used, has at least one digit past the decimal point. The   |\n   |           | default precision is as high as needed to represent the    |\n   |           | particular value. The overall effect is to match the       |\n   |           | output of "str()" as altered by the other format           |\n   |           | modifiers.                                                 |\n   +-----------+------------------------------------------------------------+\n\n\nFormat examples\n===============\n\nThis section contains examples of the new format syntax and comparison\nwith the old "%"-formatting.\n\nIn most of the cases the syntax is similar to the old "%"-formatting,\nwith the addition of the "{}" and with ":" used instead of "%". For\nexample, "\'%03.2f\'" can be translated to "\'{:03.2f}\'".\n\nThe new format syntax also supports new and different options, shown\nin the follow examples.\n\nAccessing arguments by position:\n\n   >>> \'{0}, {1}, {2}\'.format(\'a\', \'b\', \'c\')\n   \'a, b, c\'\n   >>> \'{}, {}, {}\'.format(\'a\', \'b\', \'c\')  # 3.1+ only\n   \'a, b, c\'\n   >>> \'{2}, {1}, {0}\'.format(\'a\', \'b\', \'c\')\n   \'c, b, a\'\n   >>> \'{2}, {1}, {0}\'.format(*\'abc\')      # unpacking argument sequence\n   \'c, b, a\'\n   >>> \'{0}{1}{0}\'.format(\'abra\', \'cad\')   # arguments\' indices can be repeated\n   \'abracadabra\'\n\nAccessing arguments by name:\n\n   >>> \'Coordinates: {latitude}, {longitude}\'.format(latitude=\'37.24N\', longitude=\'-115.81W\')\n   \'Coordinates: 37.24N, -115.81W\'\n   >>> coord = {\'latitude\': \'37.24N\', \'longitude\': \'-115.81W\'}\n   >>> \'Coordinates: {latitude}, {longitude}\'.format(**coord)\n   \'Coordinates: 37.24N, -115.81W\'\n\nAccessing arguments\' attributes:\n\n   >>> c = 3-5j\n   >>> (\'The complex number {0} is formed from the real part {0.real} \'\n   ...  \'and the imaginary part {0.imag}.\').format(c)\n   \'The complex number (3-5j) is formed from the real part 3.0 and the imaginary part -5.0.\'\n   >>> class Point:\n   ...     def __init__(self, x, y):\n   ...         self.x, self.y = x, y\n   ...     def __str__(self):\n   ...         return \'Point({self.x}, {self.y})\'.format(self=self)\n   ...\n   >>> str(Point(4, 2))\n   \'Point(4, 2)\'\n\nAccessing arguments\' items:\n\n   >>> coord = (3, 5)\n   >>> \'X: {0[0]};  Y: {0[1]}\'.format(coord)\n   \'X: 3;  Y: 5\'\n\nReplacing "%s" and "%r":\n\n   >>> "repr() shows quotes: {!r}; str() doesn\'t: {!s}".format(\'test1\', \'test2\')\n   "repr() shows quotes: \'test1\'; str() doesn\'t: test2"\n\nAligning the text and specifying a width:\n\n   >>> \'{:<30}\'.format(\'left aligned\')\n   \'left aligned                  \'\n   >>> \'{:>30}\'.format(\'right aligned\')\n   \'                 right aligned\'\n   >>> \'{:^30}\'.format(\'centered\')\n   \'           centered           \'\n   >>> \'{:*^30}\'.format(\'centered\')  # use \'*\' as a fill char\n   \'***********centered***********\'\n\nReplacing "%+f", "%-f", and "% f" and specifying a sign:\n\n   >>> \'{:+f}; {:+f}\'.format(3.14, -3.14)  # show it always\n   \'+3.140000; -3.140000\'\n   >>> \'{: f}; {: f}\'.format(3.14, -3.14)  # show a space for positive numbers\n   \' 3.140000; -3.140000\'\n   >>> \'{:-f}; {:-f}\'.format(3.14, -3.14)  # show only the minus -- same as \'{:f}; {:f}\'\n   \'3.140000; -3.140000\'\n\nReplacing "%x" and "%o" and converting the value to different bases:\n\n   >>> # format also supports binary numbers\n   >>> "int: {0:d};  hex: {0:x};  oct: {0:o};  bin: {0:b}".format(42)\n   \'int: 42;  hex: 2a;  oct: 52;  bin: 101010\'\n   >>> # with 0x, 0o, or 0b as prefix:\n   >>> "int: {0:d};  hex: {0:#x};  oct: {0:#o};  bin: {0:#b}".format(42)\n   \'int: 42;  hex: 0x2a;  oct: 0o52;  bin: 0b101010\'\n\nUsing the comma as a thousands separator:\n\n   >>> \'{:,}\'.format(1234567890)\n   \'1,234,567,890\'\n\nExpressing a percentage:\n\n   >>> points = 19\n   >>> total = 22\n   >>> \'Correct answers: {:.2%}\'.format(points/total)\n   \'Correct answers: 86.36%\'\n\nUsing type-specific formatting:\n\n   >>> import datetime\n   >>> d = datetime.datetime(2010, 7, 4, 12, 15, 58)\n   >>> \'{:%Y-%m-%d %H:%M:%S}\'.format(d)\n   \'2010-07-04 12:15:58\'\n\nNesting arguments and more complex examples:\n\n   >>> for align, text in zip(\'<^>\', [\'left\', \'center\', \'right\']):\n   ...     \'{0:{fill}{align}16}\'.format(text, fill=align, align=align)\n   ...\n   \'left<<<<<<<<<<<<\'\n   \'^^^^^center^^^^^\'\n   \'>>>>>>>>>>>right\'\n   >>>\n   >>> octets = [192, 168, 0, 1]\n   >>> \'{:02X}{:02X}{:02X}{:02X}\'.format(*octets)\n   \'C0A80001\'\n   >>> int(_, 16)\n   3232235521\n   >>>\n   >>> width = 5\n   >>> for num in range(5,12): #doctest: +NORMALIZE_WHITESPACE\n   ...     for base in \'dXob\':\n   ...         print(\'{0:{width}{base}}\'.format(num, base=base, width=width), end=\' \')\n   ...     print()\n   ...\n       5     5     5   101\n       6     6     6   110\n       7     7     7   111\n       8     8    10  1000\n       9     9    11  1001\n      10     A    12  1010\n      11     B    13  1011\n',
- 'function': u'\nFunction definitions\n********************\n\nA function definition defines a user-defined function object (see\nsection *The standard type hierarchy*):\n\n   funcdef        ::= [decorators] "def" funcname "(" [parameter_list] ")" ["->" expression] ":" suite\n   decorators     ::= decorator+\n   decorator      ::= "@" dotted_name ["(" [parameter_list [","]] ")"] NEWLINE\n   dotted_name    ::= identifier ("." identifier)*\n   parameter_list ::= (defparameter ",")*\n                      | "*" [parameter] ("," defparameter)* ["," "**" parameter]\n                      | "**" parameter\n                      | defparameter [","] )\n   parameter      ::= identifier [":" expression]\n   defparameter   ::= parameter ["=" expression]\n   funcname       ::= identifier\n\nA function definition is an executable statement.  Its execution binds\nthe function name in the current local namespace to a function object\n(a wrapper around the executable code for the function).  This\nfunction object contains a reference to the current global namespace\nas the global namespace to be used when the function is called.\n\nThe function definition does not execute the function body; this gets\nexecuted only when the function is called. [3]\n\nA function definition may be wrapped by one or more *decorator*\nexpressions. Decorator expressions are evaluated when the function is\ndefined, in the scope that contains the function definition.  The\nresult must be a callable, which is invoked with the function object\nas the only argument. The returned value is bound to the function name\ninstead of the function object.  Multiple decorators are applied in\nnested fashion. For example, the following code\n\n   @f1(arg)\n   @f2\n   def func(): pass\n\nis equivalent to\n\n   def func(): pass\n   func = f1(arg)(f2(func))\n\nWhen one or more *parameters* have the form *parameter* "="\n*expression*, the function is said to have "default parameter values."\nFor a parameter with a default value, the corresponding *argument* may\nbe omitted from a call, in which case the parameter\'s default value is\nsubstituted.  If a parameter has a default value, all following\nparameters up until the ""*"" must also have a default value --- this\nis a syntactic restriction that is not expressed by the grammar.\n\n**Default parameter values are evaluated from left to right when the\nfunction definition is executed.** This means that the expression is\nevaluated once, when the function is defined, and that the same "pre-\ncomputed" value is used for each call.  This is especially important\nto understand when a default parameter is a mutable object, such as a\nlist or a dictionary: if the function modifies the object (e.g. by\nappending an item to a list), the default value is in effect modified.\nThis is generally not what was intended.  A way around this is to use\n"None" as the default, and explicitly test for it in the body of the\nfunction, e.g.:\n\n   def whats_on_the_telly(penguin=None):\n       if penguin is None:\n           penguin = []\n       penguin.append("property of the zoo")\n       return penguin\n\nFunction call semantics are described in more detail in section\n*Calls*. A function call always assigns values to all parameters\nmentioned in the parameter list, either from position arguments, from\nkeyword arguments, or from default values.  If the form\n""*identifier"" is present, it is initialized to a tuple receiving any\nexcess positional parameters, defaulting to the empty tuple.  If the\nform ""**identifier"" is present, it is initialized to a new\ndictionary receiving any excess keyword arguments, defaulting to a new\nempty dictionary. Parameters after ""*"" or ""*identifier"" are\nkeyword-only parameters and may only be passed used keyword arguments.\n\nParameters may have annotations of the form "": expression"" following\nthe parameter name.  Any parameter may have an annotation even those\nof the form "*identifier" or "**identifier".  Functions may have\n"return" annotation of the form ""-> expression"" after the parameter\nlist.  These annotations can be any valid Python expression and are\nevaluated when the function definition is executed.  Annotations may\nbe evaluated in a different order than they appear in the source code.\nThe presence of annotations does not change the semantics of a\nfunction.  The annotation values are available as values of a\ndictionary keyed by the parameters\' names in the "__annotations__"\nattribute of the function object.\n\nIt is also possible to create anonymous functions (functions not bound\nto a name), for immediate use in expressions.  This uses lambda\nexpressions, described in section *Lambdas*.  Note that the lambda\nexpression is merely a shorthand for a simplified function definition;\na function defined in a ""def"" statement can be passed around or\nassigned to another name just like a function defined by a lambda\nexpression.  The ""def"" form is actually more powerful since it\nallows the execution of multiple statements and annotations.\n\n**Programmer\'s note:** Functions are first-class objects.  A ""def""\nstatement executed inside a function definition defines a local\nfunction that can be returned or passed around.  Free variables used\nin the nested function can access the local variables of the function\ncontaining the def.  See section *Naming and binding* for details.\n\nSee also: **PEP 3107** - Function Annotations\n\n     The original specification for function annotations.\n',
- 'global': u'\nThe "global" statement\n**********************\n\n   global_stmt ::= "global" identifier ("," identifier)*\n\nThe "global" statement is a declaration which holds for the entire\ncurrent code block.  It means that the listed identifiers are to be\ninterpreted as globals.  It would be impossible to assign to a global\nvariable without "global", although free variables may refer to\nglobals without being declared global.\n\nNames listed in a "global" statement must not be used in the same code\nblock textually preceding that "global" statement.\n\nNames listed in a "global" statement must not be defined as formal\nparameters or in a "for" loop control target, "class" definition,\nfunction definition, or "import" statement.\n\n**CPython implementation detail:** The current implementation does not\nenforce the two restrictions, but programs should not abuse this\nfreedom, as future implementations may enforce them or silently change\nthe meaning of the program.\n\n**Programmer\'s note:** the "global" is a directive to the parser.  It\napplies only to code parsed at the same time as the "global"\nstatement. In particular, a "global" statement contained in a string\nor code object supplied to the built-in "exec()" function does not\naffect the code block *containing* the function call, and code\ncontained in such a string is unaffected by "global" statements in the\ncode containing the function call.  The same applies to the "eval()"\nand "compile()" functions.\n',
- 'id-classes': u'\nReserved classes of identifiers\n*******************************\n\nCertain classes of identifiers (besides keywords) have special\nmeanings.  These classes are identified by the patterns of leading and\ntrailing underscore characters:\n\n"_*"\n   Not imported by "from module import *".  The special identifier "_"\n   is used in the interactive interpreter to store the result of the\n   last evaluation; it is stored in the "builtins" module.  When not\n   in interactive mode, "_" has no special meaning and is not defined.\n   See section *The import statement*.\n\n   Note: The name "_" is often used in conjunction with\n     internationalization; refer to the documentation for the\n     "gettext" module for more information on this convention.\n\n"__*__"\n   System-defined names. These names are defined by the interpreter\n   and its implementation (including the standard library).  Current\n   system names are discussed in the *Special method names* section\n   and elsewhere.  More will likely be defined in future versions of\n   Python.  *Any* use of "__*__" names, in any context, that does not\n   follow explicitly documented use, is subject to breakage without\n   warning.\n\n"__*"\n   Class-private names.  Names in this category, when used within the\n   context of a class definition, are re-written to use a mangled form\n   to help avoid name clashes between "private" attributes of base and\n   derived classes. See section *Identifiers (Names)*.\n',
- 'identifiers': u'\nIdentifiers and keywords\n************************\n\nIdentifiers (also referred to as *names*) are described by the\nfollowing lexical definitions.\n\nThe syntax of identifiers in Python is based on the Unicode standard\nannex UAX-31, with elaboration and changes as defined below; see also\n**PEP 3131** for further details.\n\nWithin the ASCII range (U+0001..U+007F), the valid characters for\nidentifiers are the same as in Python 2.x: the uppercase and lowercase\nletters "A" through "Z", the underscore "_" and, except for the first\ncharacter, the digits "0" through "9".\n\nPython 3.0 introduces additional characters from outside the ASCII\nrange (see **PEP 3131**).  For these characters, the classification\nuses the version of the Unicode Character Database as included in the\n"unicodedata" module.\n\nIdentifiers are unlimited in length.  Case is significant.\n\n   identifier   ::= xid_start xid_continue*\n   id_start     ::= <all characters in general categories Lu, Ll, Lt, Lm, Lo, Nl, the underscore, and characters with the Other_ID_Start property>\n   id_continue  ::= <all characters in id_start, plus characters in the categories Mn, Mc, Nd, Pc and others with the Other_ID_Continue property>\n   xid_start    ::= <all characters in id_start whose NFKC normalization is in "id_start xid_continue*">\n   xid_continue ::= <all characters in id_continue whose NFKC normalization is in "id_continue*">\n\nThe Unicode category codes mentioned above stand for:\n\n* *Lu* - uppercase letters\n\n* *Ll* - lowercase letters\n\n* *Lt* - titlecase letters\n\n* *Lm* - modifier letters\n\n* *Lo* - other letters\n\n* *Nl* - letter numbers\n\n* *Mn* - nonspacing marks\n\n* *Mc* - spacing combining marks\n\n* *Nd* - decimal numbers\n\n* *Pc* - connector punctuations\n\n* *Other_ID_Start* - explicit list of characters in PropList.txt to\n  support backwards compatibility\n\n* *Other_ID_Continue* - likewise\n\nAll identifiers are converted into the normal form NFKC while parsing;\ncomparison of identifiers is based on NFKC.\n\nA non-normative HTML file listing all valid identifier characters for\nUnicode 4.1 can be found at http://www.dcl.hpi.uni-\npotsdam.de/home/loewis/table-3131.html.\n\n\nKeywords\n========\n\nThe following identifiers are used as reserved words, or *keywords* of\nthe language, and cannot be used as ordinary identifiers.  They must\nbe spelled exactly as written here:\n\n   False      class      finally    is         return\n   None       continue   for        lambda     try\n   True       def        from       nonlocal   while\n   and        del        global     not        with\n   as         elif       if         or         yield\n   assert     else       import     pass\n   break      except     in         raise\n\n\nReserved classes of identifiers\n===============================\n\nCertain classes of identifiers (besides keywords) have special\nmeanings.  These classes are identified by the patterns of leading and\ntrailing underscore characters:\n\n"_*"\n   Not imported by "from module import *".  The special identifier "_"\n   is used in the interactive interpreter to store the result of the\n   last evaluation; it is stored in the "builtins" module.  When not\n   in interactive mode, "_" has no special meaning and is not defined.\n   See section *The import statement*.\n\n   Note: The name "_" is often used in conjunction with\n     internationalization; refer to the documentation for the\n     "gettext" module for more information on this convention.\n\n"__*__"\n   System-defined names. These names are defined by the interpreter\n   and its implementation (including the standard library).  Current\n   system names are discussed in the *Special method names* section\n   and elsewhere.  More will likely be defined in future versions of\n   Python.  *Any* use of "__*__" names, in any context, that does not\n   follow explicitly documented use, is subject to breakage without\n   warning.\n\n"__*"\n   Class-private names.  Names in this category, when used within the\n   context of a class definition, are re-written to use a mangled form\n   to help avoid name clashes between "private" attributes of base and\n   derived classes. See section *Identifiers (Names)*.\n',
- 'if': u'\nThe "if" statement\n******************\n\nThe "if" statement is used for conditional execution:\n\n   if_stmt ::= "if" expression ":" suite\n               ( "elif" expression ":" suite )*\n               ["else" ":" suite]\n\nIt selects exactly one of the suites by evaluating the expressions one\nby one until one is found to be true (see section *Boolean operations*\nfor the definition of true and false); then that suite is executed\n(and no other part of the "if" statement is executed or evaluated).\nIf all expressions are false, the suite of the "else" clause, if\npresent, is executed.\n',
- 'imaginary': u'\nImaginary literals\n******************\n\nImaginary literals are described by the following lexical definitions:\n\n   imagnumber ::= (floatnumber | intpart) ("j" | "J")\n\nAn imaginary literal yields a complex number with a real part of 0.0.\nComplex numbers are represented as a pair of floating point numbers\nand have the same restrictions on their range.  To create a complex\nnumber with a nonzero real part, add a floating point number to it,\ne.g., "(3+4j)".  Some examples of imaginary literals:\n\n   3.14j   10.j    10j     .001j   1e100j  3.14e-10j\n',
- 'import': u'\nThe "import" statement\n**********************\n\n   import_stmt     ::= "import" module ["as" name] ( "," module ["as" name] )*\n                   | "from" relative_module "import" identifier ["as" name]\n                   ( "," identifier ["as" name] )*\n                   | "from" relative_module "import" "(" identifier ["as" name]\n                   ( "," identifier ["as" name] )* [","] ")"\n                   | "from" module "import" "*"\n   module          ::= (identifier ".")* identifier\n   relative_module ::= "."* module | "."+\n   name            ::= identifier\n\nThe basic import statement (no "from" clause) is executed in two\nsteps:\n\n1. find a module, loading and initializing it if necessary\n\n2. define a name or names in the local namespace for the scope\n   where the "import" statement occurs.\n\nWhen the statement contains multiple clauses (separated by commas) the\ntwo steps are carried out separately for each clause, just as though\nthe clauses had been separated out into individiual import statements.\n\nThe details of the first step, finding and loading modules are\ndescribed in greater detail in the section on the *import system*,\nwhich also describes the various types of packages and modules that\ncan be imported, as well as all the hooks that can be used to\ncustomize the import system. Note that failures in this step may\nindicate either that the module could not be located, *or* that an\nerror occurred while initializing the module, which includes execution\nof the module\'s code.\n\nIf the requested module is retrieved successfully, it will be made\navailable in the local namespace in one of three ways:\n\n* If the module name is followed by "as", then the name following\n  "as" is bound directly to the imported module.\n\n* If no other name is specified, and the module being imported is a\n  top level module, the module\'s name is bound in the local namespace\n  as a reference to the imported module\n\n* If the module being imported is *not* a top level module, then the\n  name of the top level package that contains the module is bound in\n  the local namespace as a reference to the top level package. The\n  imported module must be accessed using its full qualified name\n  rather than directly\n\nThe "from" form uses a slightly more complex process:\n\n1. find the module specified in the "from" clause, loading and\n   initializing it if necessary;\n\n2. for each of the identifiers specified in the "import" clauses:\n\n   1. check if the imported module has an attribute by that name\n\n   2. if not, attempt to import a submodule with that name and then\n      check the imported module again for that attribute\n\n   3. if the attribute is not found, "ImportError" is raised.\n\n   4. otherwise, a reference to that value is stored in the local\n      namespace, using the name in the "as" clause if it is present,\n      otherwise using the attribute name\n\nExamples:\n\n   import foo                 # foo imported and bound locally\n   import foo.bar.baz         # foo.bar.baz imported, foo bound locally\n   import foo.bar.baz as fbb  # foo.bar.baz imported and bound as fbb\n   from foo.bar import baz    # foo.bar.baz imported and bound as baz\n   from foo import attr       # foo imported and foo.attr bound as attr\n\nIf the list of identifiers is replaced by a star ("\'*\'"), all public\nnames defined in the module are bound in the local namespace for the\nscope where the "import" statement occurs.\n\nThe *public names* defined by a module are determined by checking the\nmodule\'s namespace for a variable named "__all__"; if defined, it must\nbe a sequence of strings which are names defined or imported by that\nmodule.  The names given in "__all__" are all considered public and\nare required to exist.  If "__all__" is not defined, the set of public\nnames includes all names found in the module\'s namespace which do not\nbegin with an underscore character ("\'_\'").  "__all__" should contain\nthe entire public API. It is intended to avoid accidentally exporting\nitems that are not part of the API (such as library modules which were\nimported and used within the module).\n\nThe wild card form of import --- "from module import *" --- is only\nallowed at the module level.  Attempting to use it in class or\nfunction definitions will raise a "SyntaxError".\n\nWhen specifying what module to import you do not have to specify the\nabsolute name of the module. When a module or package is contained\nwithin another package it is possible to make a relative import within\nthe same top package without having to mention the package name. By\nusing leading dots in the specified module or package after "from" you\ncan specify how high to traverse up the current package hierarchy\nwithout specifying exact names. One leading dot means the current\npackage where the module making the import exists. Two dots means up\none package level. Three dots is up two levels, etc. So if you execute\n"from . import mod" from a module in the "pkg" package then you will\nend up importing "pkg.mod". If you execute "from ..subpkg2 import mod"\nfrom within "pkg.subpkg1" you will import "pkg.subpkg2.mod". The\nspecification for relative imports is contained within **PEP 328**.\n\n"importlib.import_module()" is provided to support applications that\ndetermine dynamically the modules to be loaded.\n\n\nFuture statements\n=================\n\nA *future statement* is a directive to the compiler that a particular\nmodule should be compiled using syntax or semantics that will be\navailable in a specified future release of Python where the feature\nbecomes standard.\n\nThe future statement is intended to ease migration to future versions\nof Python that introduce incompatible changes to the language.  It\nallows use of the new features on a per-module basis before the\nrelease in which the feature becomes standard.\n\n   future_statement ::= "from" "__future__" "import" feature ["as" name]\n                        ("," feature ["as" name])*\n                        | "from" "__future__" "import" "(" feature ["as" name]\n                        ("," feature ["as" name])* [","] ")"\n   feature          ::= identifier\n   name             ::= identifier\n\nA future statement must appear near the top of the module.  The only\nlines that can appear before a future statement are:\n\n* the module docstring (if any),\n\n* comments,\n\n* blank lines, and\n\n* other future statements.\n\nThe features recognized by Python 3.0 are "absolute_import",\n"division", "generators", "unicode_literals", "print_function",\n"nested_scopes" and "with_statement".  They are all redundant because\nthey are always enabled, and only kept for backwards compatibility.\n\nA future statement is recognized and treated specially at compile\ntime: Changes to the semantics of core constructs are often\nimplemented by generating different code.  It may even be the case\nthat a new feature introduces new incompatible syntax (such as a new\nreserved word), in which case the compiler may need to parse the\nmodule differently.  Such decisions cannot be pushed off until\nruntime.\n\nFor any given release, the compiler knows which feature names have\nbeen defined, and raises a compile-time error if a future statement\ncontains a feature not known to it.\n\nThe direct runtime semantics are the same as for any import statement:\nthere is a standard module "__future__", described later, and it will\nbe imported in the usual way at the time the future statement is\nexecuted.\n\nThe interesting runtime semantics depend on the specific feature\nenabled by the future statement.\n\nNote that there is nothing special about the statement:\n\n   import __future__ [as name]\n\nThat is not a future statement; it\'s an ordinary import statement with\nno special semantics or syntax restrictions.\n\nCode compiled by calls to the built-in functions "exec()" and\n"compile()" that occur in a module "M" containing a future statement\nwill, by default, use the new syntax or semantics associated with the\nfuture statement.  This can be controlled by optional arguments to\n"compile()" --- see the documentation of that function for details.\n\nA future statement typed at an interactive interpreter prompt will\ntake effect for the rest of the interpreter session.  If an\ninterpreter is started with the *-i* option, is passed a script name\nto execute, and the script includes a future statement, it will be in\neffect in the interactive session started after the script is\nexecuted.\n\nSee also: **PEP 236** - Back to the __future__\n\n     The original proposal for the __future__ mechanism.\n',
- 'in': u'\nMembership test operations\n**************************\n\nThe operators "in" and "not in" test for membership.  "x in s"\nevaluates to true if *x* is a member of *s*, and false otherwise.  "x\nnot in s" returns the negation of "x in s".  All built-in sequences\nand set types support this as well as dictionary, for which "in" tests\nwhether the dictionary has a given key. For container types such as\nlist, tuple, set, frozenset, dict, or collections.deque, the\nexpression "x in y" is equivalent to "any(x is e or x == e for e in\ny)".\n\nFor the string and bytes types, "x in y" is true if and only if *x* is\na substring of *y*.  An equivalent test is "y.find(x) != -1".  Empty\nstrings are always considered to be a substring of any other string,\nso """ in "abc"" will return "True".\n\nFor user-defined classes which define the "__contains__()" method, "x\nin y" is true if and only if "y.__contains__(x)" is true.\n\nFor user-defined classes which do not define "__contains__()" but do\ndefine "__iter__()", "x in y" is true if some value "z" with "x == z"\nis produced while iterating over "y".  If an exception is raised\nduring the iteration, it is as if "in" raised that exception.\n\nLastly, the old-style iteration protocol is tried: if a class defines\n"__getitem__()", "x in y" is true if and only if there is a non-\nnegative integer index *i* such that "x == y[i]", and all lower\ninteger indices do not raise "IndexError" exception.  (If any other\nexception is raised, it is as if "in" raised that exception).\n\nThe operator "not in" is defined to have the inverse true value of\n"in".\n',
- 'integers': u'\nInteger literals\n****************\n\nInteger literals are described by the following lexical definitions:\n\n   integer        ::= decimalinteger | octinteger | hexinteger | bininteger\n   decimalinteger ::= nonzerodigit digit* | "0"+\n   nonzerodigit   ::= "1"..."9"\n   digit          ::= "0"..."9"\n   octinteger     ::= "0" ("o" | "O") octdigit+\n   hexinteger     ::= "0" ("x" | "X") hexdigit+\n   bininteger     ::= "0" ("b" | "B") bindigit+\n   octdigit       ::= "0"..."7"\n   hexdigit       ::= digit | "a"..."f" | "A"..."F"\n   bindigit       ::= "0" | "1"\n\nThere is no limit for the length of integer literals apart from what\ncan be stored in available memory.\n\nNote that leading zeros in a non-zero decimal number are not allowed.\nThis is for disambiguation with C-style octal literals, which Python\nused before version 3.0.\n\nSome examples of integer literals:\n\n   7     2147483647                        0o177    0b100110111\n   3     79228162514264337593543950336     0o377    0xdeadbeef\n',
- 'lambda': u'\nLambdas\n*******\n\n   lambda_expr        ::= "lambda" [parameter_list]: expression\n   lambda_expr_nocond ::= "lambda" [parameter_list]: expression_nocond\n\nLambda expressions (sometimes called lambda forms) are used to create\nanonymous functions. The expression "lambda arguments: expression"\nyields a function object.  The unnamed object behaves like a function\nobject defined with\n\n   def <lambda>(arguments):\n       return expression\n\nSee section *Function definitions* for the syntax of parameter lists.\nNote that functions created with lambda expressions cannot contain\nstatements or annotations.\n',
- 'lists': u'\nList displays\n*************\n\nA list display is a possibly empty series of expressions enclosed in\nsquare brackets:\n\n   list_display ::= "[" [expression_list | comprehension] "]"\n\nA list display yields a new list object, the contents being specified\nby either a list of expressions or a comprehension.  When a comma-\nseparated list of expressions is supplied, its elements are evaluated\nfrom left to right and placed into the list object in that order.\nWhen a comprehension is supplied, the list is constructed from the\nelements resulting from the comprehension.\n',
- 'naming': u'\nNaming and binding\n******************\n\n\nBinding of names\n================\n\n*Names* refer to objects.  Names are introduced by name binding\noperations.\n\nThe following constructs bind names: formal parameters to functions,\n"import" statements, class and function definitions (these bind the\nclass or function name in the defining block), and targets that are\nidentifiers if occurring in an assignment, "for" loop header, or after\n"as" in a "with" statement or "except" clause. The "import" statement\nof the form "from ... import *" binds all names defined in the\nimported module, except those beginning with an underscore.  This form\nmay only be used at the module level.\n\nA target occurring in a "del" statement is also considered bound for\nthis purpose (though the actual semantics are to unbind the name).\n\nEach assignment or import statement occurs within a block defined by a\nclass or function definition or at the module level (the top-level\ncode block).\n\nIf a name is bound in a block, it is a local variable of that block,\nunless declared as "nonlocal" or "global".  If a name is bound at the\nmodule level, it is a global variable.  (The variables of the module\ncode block are local and global.)  If a variable is used in a code\nblock but not defined there, it is a *free variable*.\n\nEach occurrence of a name in the program text refers to the *binding*\nof that name established by the following name resolution rules.\n\n\nResolution of names\n===================\n\nA *scope* defines the visibility of a name within a block.  If a local\nvariable is defined in a block, its scope includes that block.  If the\ndefinition occurs in a function block, the scope extends to any blocks\ncontained within the defining one, unless a contained block introduces\na different binding for the name.\n\nWhen a name is used in a code block, it is resolved using the nearest\nenclosing scope.  The set of all such scopes visible to a code block\nis called the block\'s *environment*.\n\nWhen a name is not found at all, a "NameError" exception is raised. If\nthe current scope is a function scope, and the name refers to a local\nvariable that has not yet been bound to a value at the point where the\nname is used, an "UnboundLocalError" exception is raised.\n"UnboundLocalError" is a subclass of "NameError".\n\nIf a name binding operation occurs anywhere within a code block, all\nuses of the name within the block are treated as references to the\ncurrent block.  This can lead to errors when a name is used within a\nblock before it is bound.  This rule is subtle.  Python lacks\ndeclarations and allows name binding operations to occur anywhere\nwithin a code block.  The local variables of a code block can be\ndetermined by scanning the entire text of the block for name binding\noperations.\n\nIf the "global" statement occurs within a block, all uses of the name\nspecified in the statement refer to the binding of that name in the\ntop-level namespace.  Names are resolved in the top-level namespace by\nsearching the global namespace, i.e. the namespace of the module\ncontaining the code block, and the builtins namespace, the namespace\nof the module "builtins".  The global namespace is searched first.  If\nthe name is not found there, the builtins namespace is searched.  The\n"global" statement must precede all uses of the name.\n\nThe "global" statement has the same scope as a name binding operation\nin the same block.  If the nearest enclosing scope for a free variable\ncontains a global statement, the free variable is treated as a global.\n\nThe "nonlocal" statement causes corresponding names to refer to\npreviously bound variables in the nearest enclosing function scope.\n"SyntaxError" is raised at compile time if the given name does not\nexist in any enclosing function scope.\n\nThe namespace for a module is automatically created the first time a\nmodule is imported.  The main module for a script is always called\n"__main__".\n\nClass definition blocks and arguments to "exec()" and "eval()" are\nspecial in the context of name resolution. A class definition is an\nexecutable statement that may use and define names. These references\nfollow the normal rules for name resolution with an exception that\nunbound local variables are looked up in the global namespace. The\nnamespace of the class definition becomes the attribute dictionary of\nthe class. The scope of names defined in a class block is limited to\nthe class block; it does not extend to the code blocks of methods --\nthis includes comprehensions and generator expressions since they are\nimplemented using a function scope.  This means that the following\nwill fail:\n\n   class A:\n       a = 42\n       b = list(a + i for i in range(10))\n\n\nBuiltins and restricted execution\n=================================\n\nThe builtins namespace associated with the execution of a code block\nis actually found by looking up the name "__builtins__" in its global\nnamespace; this should be a dictionary or a module (in the latter case\nthe module\'s dictionary is used).  By default, when in the "__main__"\nmodule, "__builtins__" is the built-in module "builtins"; when in any\nother module, "__builtins__" is an alias for the dictionary of the\n"builtins" module itself.  "__builtins__" can be set to a user-created\ndictionary to create a weak form of restricted execution.\n\n**CPython implementation detail:** Users should not touch\n"__builtins__"; it is strictly an implementation detail.  Users\nwanting to override values in the builtins namespace should "import"\nthe "builtins" module and modify its attributes appropriately.\n\n\nInteraction with dynamic features\n=================================\n\nName resolution of free variables occurs at runtime, not at compile\ntime. This means that the following code will print 42:\n\n   i = 10\n   def f():\n       print(i)\n   i = 42\n   f()\n\nThere are several cases where Python statements are illegal when used\nin conjunction with nested scopes that contain free variables.\n\nIf a variable is referenced in an enclosing scope, it is illegal to\ndelete the name.  An error will be reported at compile time.\n\nThe "eval()" and "exec()" functions do not have access to the full\nenvironment for resolving names.  Names may be resolved in the local\nand global namespaces of the caller.  Free variables are not resolved\nin the nearest enclosing namespace, but in the global namespace.  [1]\nThe "exec()" and "eval()" functions have optional arguments to\noverride the global and local namespace.  If only one namespace is\nspecified, it is used for both.\n',
- 'nonlocal': u'\nThe "nonlocal" statement\n************************\n\n   nonlocal_stmt ::= "nonlocal" identifier ("," identifier)*\n\nThe "nonlocal" statement causes the listed identifiers to refer to\npreviously bound variables in the nearest enclosing scope excluding\nglobals. This is important because the default behavior for binding is\nto search the local namespace first.  The statement allows\nencapsulated code to rebind variables outside of the local scope\nbesides the global (module) scope.\n\nNames listed in a "nonlocal" statement, unlike those listed in a\n"global" statement, must refer to pre-existing bindings in an\nenclosing scope (the scope in which a new binding should be created\ncannot be determined unambiguously).\n\nNames listed in a "nonlocal" statement must not collide with pre-\nexisting bindings in the local scope.\n\nSee also: **PEP 3104** - Access to Names in Outer Scopes\n\n     The specification for the "nonlocal" statement.\n',
- 'numbers': u'\nNumeric literals\n****************\n\nThere are three types of numeric literals: integers, floating point\nnumbers, and imaginary numbers.  There are no complex literals\n(complex numbers can be formed by adding a real number and an\nimaginary number).\n\nNote that numeric literals do not include a sign; a phrase like "-1"\nis actually an expression composed of the unary operator \'"-"\' and the\nliteral "1".\n',
- 'numeric-types': u'\nEmulating numeric types\n***********************\n\nThe following methods can be defined to emulate numeric objects.\nMethods corresponding to operations that are not supported by the\nparticular kind of number implemented (e.g., bitwise operations for\nnon-integral numbers) should be left undefined.\n\nobject.__add__(self, other)\nobject.__sub__(self, other)\nobject.__mul__(self, other)\nobject.__matmul__(self, other)\nobject.__truediv__(self, other)\nobject.__floordiv__(self, other)\nobject.__mod__(self, other)\nobject.__divmod__(self, other)\nobject.__pow__(self, other[, modulo])\nobject.__lshift__(self, other)\nobject.__rshift__(self, other)\nobject.__and__(self, other)\nobject.__xor__(self, other)\nobject.__or__(self, other)\n\n   These methods are called to implement the binary arithmetic\n   operations ("+", "-", "*", "@", "/", "//", "%", "divmod()",\n   "pow()", "**", "<<", ">>", "&", "^", "|").  For instance, to\n   evaluate the expression "x + y", where *x* is an instance of a\n   class that has an "__add__()" method, "x.__add__(y)" is called.\n   The "__divmod__()" method should be the equivalent to using\n   "__floordiv__()" and "__mod__()"; it should not be related to\n   "__truediv__()".  Note that "__pow__()" should be defined to accept\n   an optional third argument if the ternary version of the built-in\n   "pow()" function is to be supported.\n\n   If one of those methods does not support the operation with the\n   supplied arguments, it should return "NotImplemented".\n\nobject.__radd__(self, other)\nobject.__rsub__(self, other)\nobject.__rmul__(self, other)\nobject.__rmatmul__(self, other)\nobject.__rtruediv__(self, other)\nobject.__rfloordiv__(self, other)\nobject.__rmod__(self, other)\nobject.__rdivmod__(self, other)\nobject.__rpow__(self, other)\nobject.__rlshift__(self, other)\nobject.__rrshift__(self, other)\nobject.__rand__(self, other)\nobject.__rxor__(self, other)\nobject.__ror__(self, other)\n\n   These methods are called to implement the binary arithmetic\n   operations ("+", "-", "*", "@", "/", "//", "%", "divmod()",\n   "pow()", "**", "<<", ">>", "&", "^", "|") with reflected (swapped)\n   operands.  These functions are only called if the left operand does\n   not support the corresponding operation and the operands are of\n   different types. [2] For instance, to evaluate the expression "x -\n   y", where *y* is an instance of a class that has an "__rsub__()"\n   method, "y.__rsub__(x)" is called if "x.__sub__(y)" returns\n   *NotImplemented*.\n\n   Note that ternary "pow()" will not try calling "__rpow__()" (the\n   coercion rules would become too complicated).\n\n   Note: If the right operand\'s type is a subclass of the left\n     operand\'s type and that subclass provides the reflected method\n     for the operation, this method will be called before the left\n     operand\'s non-reflected method.  This behavior allows subclasses\n     to override their ancestors\' operations.\n\nobject.__iadd__(self, other)\nobject.__isub__(self, other)\nobject.__imul__(self, other)\nobject.__imatmul__(self, other)\nobject.__itruediv__(self, other)\nobject.__ifloordiv__(self, other)\nobject.__imod__(self, other)\nobject.__ipow__(self, other[, modulo])\nobject.__ilshift__(self, other)\nobject.__irshift__(self, other)\nobject.__iand__(self, other)\nobject.__ixor__(self, other)\nobject.__ior__(self, other)\n\n   These methods are called to implement the augmented arithmetic\n   assignments ("+=", "-=", "*=", "@=", "/=", "//=", "%=", "**=",\n   "<<=", ">>=", "&=", "^=", "|=").  These methods should attempt to\n   do the operation in-place (modifying *self*) and return the result\n   (which could be, but does not have to be, *self*).  If a specific\n   method is not defined, the augmented assignment falls back to the\n   normal methods.  For instance, if *x* is an instance of a class\n   with an "__iadd__()" method, "x += y" is equivalent to "x =\n   x.__iadd__(y)" . Otherwise, "x.__add__(y)" and "y.__radd__(x)" are\n   considered, as with the evaluation of "x + y". In certain\n   situations, augmented assignment can result in unexpected errors\n   (see *Why does a_tuple[i] += [\'item\'] raise an exception when the\n   addition works?*), but this behavior is in fact part of the data\n   model.\n\nobject.__neg__(self)\nobject.__pos__(self)\nobject.__abs__(self)\nobject.__invert__(self)\n\n   Called to implement the unary arithmetic operations ("-", "+",\n   "abs()" and "~").\n\nobject.__complex__(self)\nobject.__int__(self)\nobject.__float__(self)\nobject.__round__(self[, n])\n\n   Called to implement the built-in functions "complex()", "int()",\n   "float()" and "round()".  Should return a value of the appropriate\n   type.\n\nobject.__index__(self)\n\n   Called to implement "operator.index()", and whenever Python needs\n   to losslessly convert the numeric object to an integer object (such\n   as in slicing, or in the built-in "bin()", "hex()" and "oct()"\n   functions). Presence of this method indicates that the numeric\n   object is an integer type.  Must return an integer.\n\n   Note: In order to have a coherent integer type class, when\n     "__index__()" is defined "__int__()" should also be defined, and\n     both should return the same value.\n',
- 'objects': u'\nObjects, values and types\n*************************\n\n*Objects* are Python\'s abstraction for data.  All data in a Python\nprogram is represented by objects or by relations between objects. (In\na sense, and in conformance to Von Neumann\'s model of a "stored\nprogram computer," code is also represented by objects.)\n\nEvery object has an identity, a type and a value.  An object\'s\n*identity* never changes once it has been created; you may think of it\nas the object\'s address in memory.  The \'"is"\' operator compares the\nidentity of two objects; the "id()" function returns an integer\nrepresenting its identity.\n\n**CPython implementation detail:** For CPython, "id(x)" is the memory\naddress where "x" is stored.\n\nAn object\'s type determines the operations that the object supports\n(e.g., "does it have a length?") and also defines the possible values\nfor objects of that type.  The "type()" function returns an object\'s\ntype (which is an object itself).  Like its identity, an object\'s\n*type* is also unchangeable. [1]\n\nThe *value* of some objects can change.  Objects whose value can\nchange are said to be *mutable*; objects whose value is unchangeable\nonce they are created are called *immutable*. (The value of an\nimmutable container object that contains a reference to a mutable\nobject can change when the latter\'s value is changed; however the\ncontainer is still considered immutable, because the collection of\nobjects it contains cannot be changed.  So, immutability is not\nstrictly the same as having an unchangeable value, it is more subtle.)\nAn object\'s mutability is determined by its type; for instance,\nnumbers, strings and tuples are immutable, while dictionaries and\nlists are mutable.\n\nObjects are never explicitly destroyed; however, when they become\nunreachable they may be garbage-collected.  An implementation is\nallowed to postpone garbage collection or omit it altogether --- it is\na matter of implementation quality how garbage collection is\nimplemented, as long as no objects are collected that are still\nreachable.\n\n**CPython implementation detail:** CPython currently uses a reference-\ncounting scheme with (optional) delayed detection of cyclically linked\ngarbage, which collects most objects as soon as they become\nunreachable, but is not guaranteed to collect garbage containing\ncircular references.  See the documentation of the "gc" module for\ninformation on controlling the collection of cyclic garbage. Other\nimplementations act differently and CPython may change. Do not depend\non immediate finalization of objects when they become unreachable (so\nyou should always close files explicitly).\n\nNote that the use of the implementation\'s tracing or debugging\nfacilities may keep objects alive that would normally be collectable.\nAlso note that catching an exception with a \'"try"..."except"\'\nstatement may keep objects alive.\n\nSome objects contain references to "external" resources such as open\nfiles or windows.  It is understood that these resources are freed\nwhen the object is garbage-collected, but since garbage collection is\nnot guaranteed to happen, such objects also provide an explicit way to\nrelease the external resource, usually a "close()" method. Programs\nare strongly recommended to explicitly close such objects.  The\n\'"try"..."finally"\' statement and the \'"with"\' statement provide\nconvenient ways to do this.\n\nSome objects contain references to other objects; these are called\n*containers*. Examples of containers are tuples, lists and\ndictionaries.  The references are part of a container\'s value.  In\nmost cases, when we talk about the value of a container, we imply the\nvalues, not the identities of the contained objects; however, when we\ntalk about the mutability of a container, only the identities of the\nimmediately contained objects are implied.  So, if an immutable\ncontainer (like a tuple) contains a reference to a mutable object, its\nvalue changes if that mutable object is changed.\n\nTypes affect almost all aspects of object behavior.  Even the\nimportance of object identity is affected in some sense: for immutable\ntypes, operations that compute new values may actually return a\nreference to any existing object with the same type and value, while\nfor mutable objects this is not allowed.  E.g., after "a = 1; b = 1",\n"a" and "b" may or may not refer to the same object with the value\none, depending on the implementation, but after "c = []; d = []", "c"\nand "d" are guaranteed to refer to two different, unique, newly\ncreated empty lists. (Note that "c = d = []" assigns the same object\nto both "c" and "d".)\n',
- 'operator-summary': u'\nOperator precedence\n*******************\n\nThe following table summarizes the operator precedence in Python, from\nlowest precedence (least binding) to highest precedence (most\nbinding).  Operators in the same box have the same precedence.  Unless\nthe syntax is explicitly given, operators are binary.  Operators in\nthe same box group left to right (except for exponentiation, which\ngroups from right to left).\n\nNote that comparisons, membership tests, and identity tests, all have\nthe same precedence and have a left-to-right chaining feature as\ndescribed in the *Comparisons* section.\n\n+-------------------------------------------------+---------------------------------------+\n| Operator                                        | Description                           |\n+=================================================+=======================================+\n| "lambda"                                        | Lambda expression                     |\n+-------------------------------------------------+---------------------------------------+\n| "if" -- "else"                                  | Conditional expression                |\n+-------------------------------------------------+---------------------------------------+\n| "or"                                            | Boolean OR                            |\n+-------------------------------------------------+---------------------------------------+\n| "and"                                           | Boolean AND                           |\n+-------------------------------------------------+---------------------------------------+\n| "not" "x"                                       | Boolean NOT                           |\n+-------------------------------------------------+---------------------------------------+\n| "in", "not in", "is", "is not", "<", "<=", ">", | Comparisons, including membership     |\n| ">=", "!=", "=="                                | tests and identity tests              |\n+-------------------------------------------------+---------------------------------------+\n| "|"                                             | Bitwise OR                            |\n+-------------------------------------------------+---------------------------------------+\n| "^"                                             | Bitwise XOR                           |\n+-------------------------------------------------+---------------------------------------+\n| "&"                                             | Bitwise AND                           |\n+-------------------------------------------------+---------------------------------------+\n| "<<", ">>"                                      | Shifts                                |\n+-------------------------------------------------+---------------------------------------+\n| "+", "-"                                        | Addition and subtraction              |\n+-------------------------------------------------+---------------------------------------+\n| "*", "@", "/", "//", "%"                        | Multiplication, matrix multiplication |\n|                                                 | division, remainder [5]               |\n+-------------------------------------------------+---------------------------------------+\n| "+x", "-x", "~x"                                | Positive, negative, bitwise NOT       |\n+-------------------------------------------------+---------------------------------------+\n| "**"                                            | Exponentiation [6]                    |\n+-------------------------------------------------+---------------------------------------+\n| "await" "x"                                     | Await expression                      |\n+-------------------------------------------------+---------------------------------------+\n| "x[index]", "x[index:index]",                   | Subscription, slicing, call,          |\n| "x(arguments...)", "x.attribute"                | attribute reference                   |\n+-------------------------------------------------+---------------------------------------+\n| "(expressions...)", "[expressions...]", "{key:  | Binding or tuple display, list        |\n| value...}", "{expressions...}"                  | display, dictionary display, set      |\n|                                                 | display                               |\n+-------------------------------------------------+---------------------------------------+\n\n-[ Footnotes ]-\n\n[1] While "abs(x%y) < abs(y)" is true mathematically, for floats\n    it may not be true numerically due to roundoff.  For example, and\n    assuming a platform on which a Python float is an IEEE 754 double-\n    precision number, in order that "-1e-100 % 1e100" have the same\n    sign as "1e100", the computed result is "-1e-100 + 1e100", which\n    is numerically exactly equal to "1e100".  The function\n    "math.fmod()" returns a result whose sign matches the sign of the\n    first argument instead, and so returns "-1e-100" in this case.\n    Which approach is more appropriate depends on the application.\n\n[2] If x is very close to an exact integer multiple of y, it\'s\n    possible for "x//y" to be one larger than "(x-x%y)//y" due to\n    rounding.  In such cases, Python returns the latter result, in\n    order to preserve that "divmod(x,y)[0] * y + x % y" be very close\n    to "x".\n\n[3] The Unicode standard distinguishes between *code points* (e.g.\n    U+0041) and *abstract characters* (e.g. "LATIN CAPITAL LETTER A").\n    While most abstract characters in Unicode are only represented\n    using one code point, there is a number of abstract characters\n    that can in addition be represented using a sequence of more than\n    one code point.  For example, the abstract character "LATIN\n    CAPITAL LETTER C WITH CEDILLA" can be represented as a single\n    *precomposed character* at code position U+00C7, or as a sequence\n    of a *base character* at code position U+0043 (LATIN CAPITAL\n    LETTER C), followed by a *combining character* at code position\n    U+0327 (COMBINING CEDILLA).\n\n    The comparison operators on strings compare at the level of\n    Unicode code points. This may be counter-intuitive to humans.  For\n    example, ""\\u00C7" == "\\u0043\\u0327"" is "False", even though both\n    strings represent the same abstract character "LATIN CAPITAL\n    LETTER C WITH CEDILLA".\n\n    To compare strings at the level of abstract characters (that is,\n    in a way intuitive to humans), use "unicodedata.normalize()".\n\n[4] Due to automatic garbage-collection, free lists, and the\n    dynamic nature of descriptors, you may notice seemingly unusual\n    behaviour in certain uses of the "is" operator, like those\n    involving comparisons between instance methods, or constants.\n    Check their documentation for more info.\n\n[5] The "%" operator is also used for string formatting; the same\n    precedence applies.\n\n[6] The power operator "**" binds less tightly than an arithmetic\n    or bitwise unary operator on its right, that is, "2**-1" is "0.5".\n',
- 'pass': u'\nThe "pass" statement\n********************\n\n   pass_stmt ::= "pass"\n\n"pass" is a null operation --- when it is executed, nothing happens.\nIt is useful as a placeholder when a statement is required\nsyntactically, but no code needs to be executed, for example:\n\n   def f(arg): pass    # a function that does nothing (yet)\n\n   class C: pass       # a class with no methods (yet)\n',
- 'power': u'\nThe power operator\n******************\n\nThe power operator binds more tightly than unary operators on its\nleft; it binds less tightly than unary operators on its right.  The\nsyntax is:\n\n   power ::= await ["**" u_expr]\n\nThus, in an unparenthesized sequence of power and unary operators, the\noperators are evaluated from right to left (this does not constrain\nthe evaluation order for the operands): "-1**2" results in "-1".\n\nThe power operator has the same semantics as the built-in "pow()"\nfunction, when called with two arguments: it yields its left argument\nraised to the power of its right argument.  The numeric arguments are\nfirst converted to a common type, and the result is of that type.\n\nFor int operands, the result has the same type as the operands unless\nthe second argument is negative; in that case, all arguments are\nconverted to float and a float result is delivered. For example,\n"10**2" returns "100", but "10**-2" returns "0.01".\n\nRaising "0.0" to a negative power results in a "ZeroDivisionError".\nRaising a negative number to a fractional power results in a "complex"\nnumber. (In earlier versions it raised a "ValueError".)\n',
- 'raise': u'\nThe "raise" statement\n*********************\n\n   raise_stmt ::= "raise" [expression ["from" expression]]\n\nIf no expressions are present, "raise" re-raises the last exception\nthat was active in the current scope.  If no exception is active in\nthe current scope, a "RuntimeError" exception is raised indicating\nthat this is an error.\n\nOtherwise, "raise" evaluates the first expression as the exception\nobject.  It must be either a subclass or an instance of\n"BaseException". If it is a class, the exception instance will be\nobtained when needed by instantiating the class with no arguments.\n\nThe *type* of the exception is the exception instance\'s class, the\n*value* is the instance itself.\n\nA traceback object is normally created automatically when an exception\nis raised and attached to it as the "__traceback__" attribute, which\nis writable. You can create an exception and set your own traceback in\none step using the "with_traceback()" exception method (which returns\nthe same exception instance, with its traceback set to its argument),\nlike so:\n\n   raise Exception("foo occurred").with_traceback(tracebackobj)\n\nThe "from" clause is used for exception chaining: if given, the second\n*expression* must be another exception class or instance, which will\nthen be attached to the raised exception as the "__cause__" attribute\n(which is writable).  If the raised exception is not handled, both\nexceptions will be printed:\n\n   >>> try:\n   ...     print(1 / 0)\n   ... except Exception as exc:\n   ...     raise RuntimeError("Something bad happened") from exc\n   ...\n   Traceback (most recent call last):\n     File "<stdin>", line 2, in <module>\n   ZeroDivisionError: int division or modulo by zero\n\n   The above exception was the direct cause of the following exception:\n\n   Traceback (most recent call last):\n     File "<stdin>", line 4, in <module>\n   RuntimeError: Something bad happened\n\nA similar mechanism works implicitly if an exception is raised inside\nan exception handler or a "finally" clause: the previous exception is\nthen attached as the new exception\'s "__context__" attribute:\n\n   >>> try:\n   ...     print(1 / 0)\n   ... except:\n   ...     raise RuntimeError("Something bad happened")\n   ...\n   Traceback (most recent call last):\n     File "<stdin>", line 2, in <module>\n   ZeroDivisionError: int division or modulo by zero\n\n   During handling of the above exception, another exception occurred:\n\n   Traceback (most recent call last):\n     File "<stdin>", line 4, in <module>\n   RuntimeError: Something bad happened\n\nAdditional information on exceptions can be found in section\n*Exceptions*, and information about handling exceptions is in section\n*The try statement*.\n',
- 'return': u'\nThe "return" statement\n**********************\n\n   return_stmt ::= "return" [expression_list]\n\n"return" may only occur syntactically nested in a function definition,\nnot within a nested class definition.\n\nIf an expression list is present, it is evaluated, else "None" is\nsubstituted.\n\n"return" leaves the current function call with the expression list (or\n"None") as return value.\n\nWhen "return" passes control out of a "try" statement with a "finally"\nclause, that "finally" clause is executed before really leaving the\nfunction.\n\nIn a generator function, the "return" statement indicates that the\ngenerator is done and will cause "StopIteration" to be raised. The\nreturned value (if any) is used as an argument to construct\n"StopIteration" and becomes the "StopIteration.value" attribute.\n',
- 'sequence-types': u'\nEmulating container types\n*************************\n\nThe following methods can be defined to implement container objects.\nContainers usually are sequences (such as lists or tuples) or mappings\n(like dictionaries), but can represent other containers as well.  The\nfirst set of methods is used either to emulate a sequence or to\nemulate a mapping; the difference is that for a sequence, the\nallowable keys should be the integers *k* for which "0 <= k < N" where\n*N* is the length of the sequence, or slice objects, which define a\nrange of items.  It is also recommended that mappings provide the\nmethods "keys()", "values()", "items()", "get()", "clear()",\n"setdefault()", "pop()", "popitem()", "copy()", and "update()"\nbehaving similar to those for Python\'s standard dictionary objects.\nThe "collections" module provides a "MutableMapping" abstract base\nclass to help create those methods from a base set of "__getitem__()",\n"__setitem__()", "__delitem__()", and "keys()". Mutable sequences\nshould provide methods "append()", "count()", "index()", "extend()",\n"insert()", "pop()", "remove()", "reverse()" and "sort()", like Python\nstandard list objects.  Finally, sequence types should implement\naddition (meaning concatenation) and multiplication (meaning\nrepetition) by defining the methods "__add__()", "__radd__()",\n"__iadd__()", "__mul__()", "__rmul__()" and "__imul__()" described\nbelow; they should not define other numerical operators.  It is\nrecommended that both mappings and sequences implement the\n"__contains__()" method to allow efficient use of the "in" operator;\nfor mappings, "in" should search the mapping\'s keys; for sequences, it\nshould search through the values.  It is further recommended that both\nmappings and sequences implement the "__iter__()" method to allow\nefficient iteration through the container; for mappings, "__iter__()"\nshould be the same as "keys()"; for sequences, it should iterate\nthrough the values.\n\nobject.__len__(self)\n\n   Called to implement the built-in function "len()".  Should return\n   the length of the object, an integer ">=" 0.  Also, an object that\n   doesn\'t define a "__bool__()" method and whose "__len__()" method\n   returns zero is considered to be false in a Boolean context.\n\nobject.__length_hint__(self)\n\n   Called to implement "operator.length_hint()". Should return an\n   estimated length for the object (which may be greater or less than\n   the actual length). The length must be an integer ">=" 0. This\n   method is purely an optimization and is never required for\n   correctness.\n\n   New in version 3.4.\n\nNote: Slicing is done exclusively with the following three methods.\n  A call like\n\n     a[1:2] = b\n\n  is translated to\n\n     a[slice(1, 2, None)] = b\n\n  and so forth.  Missing slice items are always filled in with "None".\n\nobject.__getitem__(self, key)\n\n   Called to implement evaluation of "self[key]". For sequence types,\n   the accepted keys should be integers and slice objects.  Note that\n   the special interpretation of negative indexes (if the class wishes\n   to emulate a sequence type) is up to the "__getitem__()" method. If\n   *key* is of an inappropriate type, "TypeError" may be raised; if of\n   a value outside the set of indexes for the sequence (after any\n   special interpretation of negative values), "IndexError" should be\n   raised. For mapping types, if *key* is missing (not in the\n   container), "KeyError" should be raised.\n\n   Note: "for" loops expect that an "IndexError" will be raised for\n     illegal indexes to allow proper detection of the end of the\n     sequence.\n\nobject.__missing__(self, key)\n\n   Called by "dict"."__getitem__()" to implement "self[key]" for dict\n   subclasses when key is not in the dictionary.\n\nobject.__setitem__(self, key, value)\n\n   Called to implement assignment to "self[key]".  Same note as for\n   "__getitem__()".  This should only be implemented for mappings if\n   the objects support changes to the values for keys, or if new keys\n   can be added, or for sequences if elements can be replaced.  The\n   same exceptions should be raised for improper *key* values as for\n   the "__getitem__()" method.\n\nobject.__delitem__(self, key)\n\n   Called to implement deletion of "self[key]".  Same note as for\n   "__getitem__()".  This should only be implemented for mappings if\n   the objects support removal of keys, or for sequences if elements\n   can be removed from the sequence.  The same exceptions should be\n   raised for improper *key* values as for the "__getitem__()" method.\n\nobject.__iter__(self)\n\n   This method is called when an iterator is required for a container.\n   This method should return a new iterator object that can iterate\n   over all the objects in the container.  For mappings, it should\n   iterate over the keys of the container.\n\n   Iterator objects also need to implement this method; they are\n   required to return themselves.  For more information on iterator\n   objects, see *Iterator Types*.\n\nobject.__reversed__(self)\n\n   Called (if present) by the "reversed()" built-in to implement\n   reverse iteration.  It should return a new iterator object that\n   iterates over all the objects in the container in reverse order.\n\n   If the "__reversed__()" method is not provided, the "reversed()"\n   built-in will fall back to using the sequence protocol ("__len__()"\n   and "__getitem__()").  Objects that support the sequence protocol\n   should only provide "__reversed__()" if they can provide an\n   implementation that is more efficient than the one provided by\n   "reversed()".\n\nThe membership test operators ("in" and "not in") are normally\nimplemented as an iteration through a sequence.  However, container\nobjects can supply the following special method with a more efficient\nimplementation, which also does not require the object be a sequence.\n\nobject.__contains__(self, item)\n\n   Called to implement membership test operators.  Should return true\n   if *item* is in *self*, false otherwise.  For mapping objects, this\n   should consider the keys of the mapping rather than the values or\n   the key-item pairs.\n\n   For objects that don\'t define "__contains__()", the membership test\n   first tries iteration via "__iter__()", then the old sequence\n   iteration protocol via "__getitem__()", see *this section in the\n   language reference*.\n',
- 'shifting': u'\nShifting operations\n*******************\n\nThe shifting operations have lower priority than the arithmetic\noperations:\n\n   shift_expr ::= a_expr | shift_expr ( "<<" | ">>" ) a_expr\n\nThese operators accept integers as arguments.  They shift the first\nargument to the left or right by the number of bits given by the\nsecond argument.\n\nA right shift by *n* bits is defined as floor division by "pow(2,n)".\nA left shift by *n* bits is defined as multiplication with "pow(2,n)".\n\nNote: In the current implementation, the right-hand operand is\n  required to be at most "sys.maxsize".  If the right-hand operand is\n  larger than "sys.maxsize" an "OverflowError" exception is raised.\n',
- 'slicings': u'\nSlicings\n********\n\nA slicing selects a range of items in a sequence object (e.g., a\nstring, tuple or list).  Slicings may be used as expressions or as\ntargets in assignment or "del" statements.  The syntax for a slicing:\n\n   slicing      ::= primary "[" slice_list "]"\n   slice_list   ::= slice_item ("," slice_item)* [","]\n   slice_item   ::= expression | proper_slice\n   proper_slice ::= [lower_bound] ":" [upper_bound] [ ":" [stride] ]\n   lower_bound  ::= expression\n   upper_bound  ::= expression\n   stride       ::= expression\n\nThere is ambiguity in the formal syntax here: anything that looks like\nan expression list also looks like a slice list, so any subscription\ncan be interpreted as a slicing.  Rather than further complicating the\nsyntax, this is disambiguated by defining that in this case the\ninterpretation as a subscription takes priority over the\ninterpretation as a slicing (this is the case if the slice list\ncontains no proper slice).\n\nThe semantics for a slicing are as follows.  The primary is indexed\n(using the same "__getitem__()" method as normal subscription) with a\nkey that is constructed from the slice list, as follows.  If the slice\nlist contains at least one comma, the key is a tuple containing the\nconversion of the slice items; otherwise, the conversion of the lone\nslice item is the key.  The conversion of a slice item that is an\nexpression is that expression.  The conversion of a proper slice is a\nslice object (see section *The standard type hierarchy*) whose\n"start", "stop" and "step" attributes are the values of the\nexpressions given as lower bound, upper bound and stride,\nrespectively, substituting "None" for missing expressions.\n',
- 'specialattrs': u'\nSpecial Attributes\n******************\n\nThe implementation adds a few special read-only attributes to several\nobject types, where they are relevant.  Some of these are not reported\nby the "dir()" built-in function.\n\nobject.__dict__\n\n   A dictionary or other mapping object used to store an object\'s\n   (writable) attributes.\n\ninstance.__class__\n\n   The class to which a class instance belongs.\n\nclass.__bases__\n\n   The tuple of base classes of a class object.\n\nclass.__name__\n\n   The name of the class or type.\n\nclass.__qualname__\n\n   The *qualified name* of the class or type.\n\n   New in version 3.3.\n\nclass.__mro__\n\n   This attribute is a tuple of classes that are considered when\n   looking for base classes during method resolution.\n\nclass.mro()\n\n   This method can be overridden by a metaclass to customize the\n   method resolution order for its instances.  It is called at class\n   instantiation, and its result is stored in "__mro__".\n\nclass.__subclasses__()\n\n   Each class keeps a list of weak references to its immediate\n   subclasses.  This method returns a list of all those references\n   still alive. Example:\n\n      >>> int.__subclasses__()\n      [<class \'bool\'>]\n\n-[ Footnotes ]-\n\n[1] Additional information on these special methods may be found\n    in the Python Reference Manual (*Basic customization*).\n\n[2] As a consequence, the list "[1, 2]" is considered equal to\n    "[1.0, 2.0]", and similarly for tuples.\n\n[3] They must have since the parser can\'t tell the type of the\n    operands.\n\n[4] Cased characters are those with general category property\n    being one of "Lu" (Letter, uppercase), "Ll" (Letter, lowercase),\n    or "Lt" (Letter, titlecase).\n\n[5] To format only a tuple you should therefore provide a\n    singleton tuple whose only element is the tuple to be formatted.\n',
- 'specialnames': u'\nSpecial method names\n********************\n\nA class can implement certain operations that are invoked by special\nsyntax (such as arithmetic operations or subscripting and slicing) by\ndefining methods with special names. This is Python\'s approach to\n*operator overloading*, allowing classes to define their own behavior\nwith respect to language operators.  For instance, if a class defines\na method named "__getitem__()", and "x" is an instance of this class,\nthen "x[i]" is roughly equivalent to "type(x).__getitem__(x, i)".\nExcept where mentioned, attempts to execute an operation raise an\nexception when no appropriate method is defined (typically\n"AttributeError" or "TypeError").\n\nWhen implementing a class that emulates any built-in type, it is\nimportant that the emulation only be implemented to the degree that it\nmakes sense for the object being modelled.  For example, some\nsequences may work well with retrieval of individual elements, but\nextracting a slice may not make sense.  (One example of this is the\n"NodeList" interface in the W3C\'s Document Object Model.)\n\n\nBasic customization\n===================\n\nobject.__new__(cls[, ...])\n\n   Called to create a new instance of class *cls*.  "__new__()" is a\n   static method (special-cased so you need not declare it as such)\n   that takes the class of which an instance was requested as its\n   first argument.  The remaining arguments are those passed to the\n   object constructor expression (the call to the class).  The return\n   value of "__new__()" should be the new object instance (usually an\n   instance of *cls*).\n\n   Typical implementations create a new instance of the class by\n   invoking the superclass\'s "__new__()" method using\n   "super(currentclass, cls).__new__(cls[, ...])" with appropriate\n   arguments and then modifying the newly-created instance as\n   necessary before returning it.\n\n   If "__new__()" returns an instance of *cls*, then the new\n   instance\'s "__init__()" method will be invoked like\n   "__init__(self[, ...])", where *self* is the new instance and the\n   remaining arguments are the same as were passed to "__new__()".\n\n   If "__new__()" does not return an instance of *cls*, then the new\n   instance\'s "__init__()" method will not be invoked.\n\n   "__new__()" is intended mainly to allow subclasses of immutable\n   types (like int, str, or tuple) to customize instance creation.  It\n   is also commonly overridden in custom metaclasses in order to\n   customize class creation.\n\nobject.__init__(self[, ...])\n\n   Called after the instance has been created (by "__new__()"), but\n   before it is returned to the caller.  The arguments are those\n   passed to the class constructor expression.  If a base class has an\n   "__init__()" method, the derived class\'s "__init__()" method, if\n   any, must explicitly call it to ensure proper initialization of the\n   base class part of the instance; for example:\n   "BaseClass.__init__(self, [args...])".\n\n   Because "__new__()" and "__init__()" work together in constructing\n   objects ("__new__()" to create it, and "__init__()" to customise\n   it), no non-"None" value may be returned by "__init__()"; doing so\n   will cause a "TypeError" to be raised at runtime.\n\nobject.__del__(self)\n\n   Called when the instance is about to be destroyed.  This is also\n   called a destructor.  If a base class has a "__del__()" method, the\n   derived class\'s "__del__()" method, if any, must explicitly call it\n   to ensure proper deletion of the base class part of the instance.\n   Note that it is possible (though not recommended!) for the\n   "__del__()" method to postpone destruction of the instance by\n   creating a new reference to it.  It may then be called at a later\n   time when this new reference is deleted.  It is not guaranteed that\n   "__del__()" methods are called for objects that still exist when\n   the interpreter exits.\n\n   Note: "del x" doesn\'t directly call "x.__del__()" --- the former\n     decrements the reference count for "x" by one, and the latter is\n     only called when "x"\'s reference count reaches zero.  Some common\n     situations that may prevent the reference count of an object from\n     going to zero include: circular references between objects (e.g.,\n     a doubly-linked list or a tree data structure with parent and\n     child pointers); a reference to the object on the stack frame of\n     a function that caught an exception (the traceback stored in\n     "sys.exc_info()[2]" keeps the stack frame alive); or a reference\n     to the object on the stack frame that raised an unhandled\n     exception in interactive mode (the traceback stored in\n     "sys.last_traceback" keeps the stack frame alive).  The first\n     situation can only be remedied by explicitly breaking the cycles;\n     the second can be resolved by freeing the reference to the\n     traceback object when it is no longer useful, and the third can\n     be resolved by storing "None" in "sys.last_traceback". Circular\n     references which are garbage are detected and cleaned up when the\n     cyclic garbage collector is enabled (it\'s on by default). Refer\n     to the documentation for the "gc" module for more information\n     about this topic.\n\n   Warning: Due to the precarious circumstances under which\n     "__del__()" methods are invoked, exceptions that occur during\n     their execution are ignored, and a warning is printed to\n     "sys.stderr" instead. Also, when "__del__()" is invoked in\n     response to a module being deleted (e.g., when execution of the\n     program is done), other globals referenced by the "__del__()"\n     method may already have been deleted or in the process of being\n     torn down (e.g. the import machinery shutting down).  For this\n     reason, "__del__()" methods should do the absolute minimum needed\n     to maintain external invariants.  Starting with version 1.5,\n     Python guarantees that globals whose name begins with a single\n     underscore are deleted from their module before other globals are\n     deleted; if no other references to such globals exist, this may\n     help in assuring that imported modules are still available at the\n     time when the "__del__()" method is called.\n\nobject.__repr__(self)\n\n   Called by the "repr()" built-in function to compute the "official"\n   string representation of an object.  If at all possible, this\n   should look like a valid Python expression that could be used to\n   recreate an object with the same value (given an appropriate\n   environment).  If this is not possible, a string of the form\n   "<...some useful description...>" should be returned. The return\n   value must be a string object. If a class defines "__repr__()" but\n   not "__str__()", then "__repr__()" is also used when an "informal"\n   string representation of instances of that class is required.\n\n   This is typically used for debugging, so it is important that the\n   representation is information-rich and unambiguous.\n\nobject.__str__(self)\n\n   Called by "str(object)" and the built-in functions "format()" and\n   "print()" to compute the "informal" or nicely printable string\n   representation of an object.  The return value must be a *string*\n   object.\n\n   This method differs from "object.__repr__()" in that there is no\n   expectation that "__str__()" return a valid Python expression: a\n   more convenient or concise representation can be used.\n\n   The default implementation defined by the built-in type "object"\n   calls "object.__repr__()".\n\nobject.__bytes__(self)\n\n   Called by "bytes()" to compute a byte-string representation of an\n   object. This should return a "bytes" object.\n\nobject.__format__(self, format_spec)\n\n   Called by the "format()" built-in function (and by extension, the\n   "str.format()" method of class "str") to produce a "formatted"\n   string representation of an object. The "format_spec" argument is a\n   string that contains a description of the formatting options\n   desired. The interpretation of the "format_spec" argument is up to\n   the type implementing "__format__()", however most classes will\n   either delegate formatting to one of the built-in types, or use a\n   similar formatting option syntax.\n\n   See *Format Specification Mini-Language* for a description of the\n   standard formatting syntax.\n\n   The return value must be a string object.\n\n   Changed in version 3.4: The __format__ method of "object" itself\n   raises a "TypeError" if passed any non-empty string.\n\nobject.__lt__(self, other)\nobject.__le__(self, other)\nobject.__eq__(self, other)\nobject.__ne__(self, other)\nobject.__gt__(self, other)\nobject.__ge__(self, other)\n\n   These are the so-called "rich comparison" methods. The\n   correspondence between operator symbols and method names is as\n   follows: "x<y" calls "x.__lt__(y)", "x<=y" calls "x.__le__(y)",\n   "x==y" calls "x.__eq__(y)", "x!=y" calls "x.__ne__(y)", "x>y" calls\n   "x.__gt__(y)", and "x>=y" calls "x.__ge__(y)".\n\n   A rich comparison method may return the singleton "NotImplemented"\n   if it does not implement the operation for a given pair of\n   arguments. By convention, "False" and "True" are returned for a\n   successful comparison. However, these methods can return any value,\n   so if the comparison operator is used in a Boolean context (e.g.,\n   in the condition of an "if" statement), Python will call "bool()"\n   on the value to determine if the result is true or false.\n\n   By default, "__ne__()" delegates to "__eq__()" and inverts the\n   result unless it is "NotImplemented".  There are no other implied\n   relationships among the comparison operators, for example, the\n   truth of "(x<y or x==y)" does not imply "x<=y". To automatically\n   generate ordering operations from a single root operation, see\n   "functools.total_ordering()".\n\n   See the paragraph on "__hash__()" for some important notes on\n   creating *hashable* objects which support custom comparison\n   operations and are usable as dictionary keys.\n\n   There are no swapped-argument versions of these methods (to be used\n   when the left argument does not support the operation but the right\n   argument does); rather, "__lt__()" and "__gt__()" are each other\'s\n   reflection, "__le__()" and "__ge__()" are each other\'s reflection,\n   and "__eq__()" and "__ne__()" are their own reflection. If the\n   operands are of different types, and right operand\'s type is a\n   direct or indirect subclass of the left operand\'s type, the\n   reflected method of the right operand has priority, otherwise the\n   left operand\'s method has priority.  Virtual subclassing is not\n   considered.\n\nobject.__hash__(self)\n\n   Called by built-in function "hash()" and for operations on members\n   of hashed collections including "set", "frozenset", and "dict".\n   "__hash__()" should return an integer.  The only required property\n   is that objects which compare equal have the same hash value; it is\n   advised to somehow mix together (e.g. using exclusive or) the hash\n   values for the components of the object that also play a part in\n   comparison of objects.\n\n   Note: "hash()" truncates the value returned from an object\'s\n     custom "__hash__()" method to the size of a "Py_ssize_t".  This\n     is typically 8 bytes on 64-bit builds and 4 bytes on 32-bit\n     builds. If an object\'s   "__hash__()" must interoperate on builds\n     of different bit sizes, be sure to check the width on all\n     supported builds.  An easy way to do this is with "python -c\n     "import sys; print(sys.hash_info.width)"".\n\n   If a class does not define an "__eq__()" method it should not\n   define a "__hash__()" operation either; if it defines "__eq__()"\n   but not "__hash__()", its instances will not be usable as items in\n   hashable collections.  If a class defines mutable objects and\n   implements an "__eq__()" method, it should not implement\n   "__hash__()", since the implementation of hashable collections\n   requires that a key\'s hash value is immutable (if the object\'s hash\n   value changes, it will be in the wrong hash bucket).\n\n   User-defined classes have "__eq__()" and "__hash__()" methods by\n   default; with them, all objects compare unequal (except with\n   themselves) and "x.__hash__()" returns an appropriate value such\n   that "x == y" implies both that "x is y" and "hash(x) == hash(y)".\n\n   A class that overrides "__eq__()" and does not define "__hash__()"\n   will have its "__hash__()" implicitly set to "None".  When the\n   "__hash__()" method of a class is "None", instances of the class\n   will raise an appropriate "TypeError" when a program attempts to\n   retrieve their hash value, and will also be correctly identified as\n   unhashable when checking "isinstance(obj, collections.Hashable)".\n\n   If a class that overrides "__eq__()" needs to retain the\n   implementation of "__hash__()" from a parent class, the interpreter\n   must be told this explicitly by setting "__hash__ =\n   <ParentClass>.__hash__".\n\n   If a class that does not override "__eq__()" wishes to suppress\n   hash support, it should include "__hash__ = None" in the class\n   definition. A class which defines its own "__hash__()" that\n   explicitly raises a "TypeError" would be incorrectly identified as\n   hashable by an "isinstance(obj, collections.Hashable)" call.\n\n   Note: By default, the "__hash__()" values of str, bytes and\n     datetime objects are "salted" with an unpredictable random value.\n     Although they remain constant within an individual Python\n     process, they are not predictable between repeated invocations of\n     Python.This is intended to provide protection against a denial-\n     of-service caused by carefully-chosen inputs that exploit the\n     worst case performance of a dict insertion, O(n^2) complexity.\n     See http://www.ocert.org/advisories/ocert-2011-003.html for\n     details.Changing hash values affects the iteration order of\n     dicts, sets and other mappings.  Python has never made guarantees\n     about this ordering (and it typically varies between 32-bit and\n     64-bit builds).See also "PYTHONHASHSEED".\n\n   Changed in version 3.3: Hash randomization is enabled by default.\n\nobject.__bool__(self)\n\n   Called to implement truth value testing and the built-in operation\n   "bool()"; should return "False" or "True".  When this method is not\n   defined, "__len__()" is called, if it is defined, and the object is\n   considered true if its result is nonzero.  If a class defines\n   neither "__len__()" nor "__bool__()", all its instances are\n   considered true.\n\n\nCustomizing attribute access\n============================\n\nThe following methods can be defined to customize the meaning of\nattribute access (use of, assignment to, or deletion of "x.name") for\nclass instances.\n\nobject.__getattr__(self, name)\n\n   Called when an attribute lookup has not found the attribute in the\n   usual places (i.e. it is not an instance attribute nor is it found\n   in the class tree for "self").  "name" is the attribute name. This\n   method should return the (computed) attribute value or raise an\n   "AttributeError" exception.\n\n   Note that if the attribute is found through the normal mechanism,\n   "__getattr__()" is not called.  (This is an intentional asymmetry\n   between "__getattr__()" and "__setattr__()".) This is done both for\n   efficiency reasons and because otherwise "__getattr__()" would have\n   no way to access other attributes of the instance.  Note that at\n   least for instance variables, you can fake total control by not\n   inserting any values in the instance attribute dictionary (but\n   instead inserting them in another object).  See the\n   "__getattribute__()" method below for a way to actually get total\n   control over attribute access.\n\nobject.__getattribute__(self, name)\n\n   Called unconditionally to implement attribute accesses for\n   instances of the class. If the class also defines "__getattr__()",\n   the latter will not be called unless "__getattribute__()" either\n   calls it explicitly or raises an "AttributeError". This method\n   should return the (computed) attribute value or raise an\n   "AttributeError" exception. In order to avoid infinite recursion in\n   this method, its implementation should always call the base class\n   method with the same name to access any attributes it needs, for\n   example, "object.__getattribute__(self, name)".\n\n   Note: This method may still be bypassed when looking up special\n     methods as the result of implicit invocation via language syntax\n     or built-in functions. See *Special method lookup*.\n\nobject.__setattr__(self, name, value)\n\n   Called when an attribute assignment is attempted.  This is called\n   instead of the normal mechanism (i.e. store the value in the\n   instance dictionary). *name* is the attribute name, *value* is the\n   value to be assigned to it.\n\n   If "__setattr__()" wants to assign to an instance attribute, it\n   should call the base class method with the same name, for example,\n   "object.__setattr__(self, name, value)".\n\nobject.__delattr__(self, name)\n\n   Like "__setattr__()" but for attribute deletion instead of\n   assignment.  This should only be implemented if "del obj.name" is\n   meaningful for the object.\n\nobject.__dir__(self)\n\n   Called when "dir()" is called on the object. A sequence must be\n   returned. "dir()" converts the returned sequence to a list and\n   sorts it.\n\n\nImplementing Descriptors\n------------------------\n\nThe following methods only apply when an instance of the class\ncontaining the method (a so-called *descriptor* class) appears in an\n*owner* class (the descriptor must be in either the owner\'s class\ndictionary or in the class dictionary for one of its parents).  In the\nexamples below, "the attribute" refers to the attribute whose name is\nthe key of the property in the owner class\' "__dict__".\n\nobject.__get__(self, instance, owner)\n\n   Called to get the attribute of the owner class (class attribute\n   access) or of an instance of that class (instance attribute\n   access). *owner* is always the owner class, while *instance* is the\n   instance that the attribute was accessed through, or "None" when\n   the attribute is accessed through the *owner*.  This method should\n   return the (computed) attribute value or raise an "AttributeError"\n   exception.\n\nobject.__set__(self, instance, value)\n\n   Called to set the attribute on an instance *instance* of the owner\n   class to a new value, *value*.\n\nobject.__delete__(self, instance)\n\n   Called to delete the attribute on an instance *instance* of the\n   owner class.\n\nThe attribute "__objclass__" is interpreted by the "inspect" module as\nspecifying the class where this object was defined (setting this\nappropriately can assist in runtime introspection of dynamic class\nattributes). For callables, it may indicate that an instance of the\ngiven type (or a subclass) is expected or required as the first\npositional argument (for example, CPython sets this attribute for\nunbound methods that are implemented in C).\n\n\nInvoking Descriptors\n--------------------\n\nIn general, a descriptor is an object attribute with "binding\nbehavior", one whose attribute access has been overridden by methods\nin the descriptor protocol:  "__get__()", "__set__()", and\n"__delete__()". If any of those methods are defined for an object, it\nis said to be a descriptor.\n\nThe default behavior for attribute access is to get, set, or delete\nthe attribute from an object\'s dictionary. For instance, "a.x" has a\nlookup chain starting with "a.__dict__[\'x\']", then\n"type(a).__dict__[\'x\']", and continuing through the base classes of\n"type(a)" excluding metaclasses.\n\nHowever, if the looked-up value is an object defining one of the\ndescriptor methods, then Python may override the default behavior and\ninvoke the descriptor method instead.  Where this occurs in the\nprecedence chain depends on which descriptor methods were defined and\nhow they were called.\n\nThe starting point for descriptor invocation is a binding, "a.x". How\nthe arguments are assembled depends on "a":\n\nDirect Call\n   The simplest and least common call is when user code directly\n   invokes a descriptor method:    "x.__get__(a)".\n\nInstance Binding\n   If binding to an object instance, "a.x" is transformed into the\n   call: "type(a).__dict__[\'x\'].__get__(a, type(a))".\n\nClass Binding\n   If binding to a class, "A.x" is transformed into the call:\n   "A.__dict__[\'x\'].__get__(None, A)".\n\nSuper Binding\n   If "a" is an instance of "super", then the binding "super(B,\n   obj).m()" searches "obj.__class__.__mro__" for the base class "A"\n   immediately preceding "B" and then invokes the descriptor with the\n   call: "A.__dict__[\'m\'].__get__(obj, obj.__class__)".\n\nFor instance bindings, the precedence of descriptor invocation depends\non the which descriptor methods are defined.  A descriptor can define\nany combination of "__get__()", "__set__()" and "__delete__()".  If it\ndoes not define "__get__()", then accessing the attribute will return\nthe descriptor object itself unless there is a value in the object\'s\ninstance dictionary.  If the descriptor defines "__set__()" and/or\n"__delete__()", it is a data descriptor; if it defines neither, it is\na non-data descriptor.  Normally, data descriptors define both\n"__get__()" and "__set__()", while non-data descriptors have just the\n"__get__()" method.  Data descriptors with "__set__()" and "__get__()"\ndefined always override a redefinition in an instance dictionary.  In\ncontrast, non-data descriptors can be overridden by instances.\n\nPython methods (including "staticmethod()" and "classmethod()") are\nimplemented as non-data descriptors.  Accordingly, instances can\nredefine and override methods.  This allows individual instances to\nacquire behaviors that differ from other instances of the same class.\n\nThe "property()" function is implemented as a data descriptor.\nAccordingly, instances cannot override the behavior of a property.\n\n\n__slots__\n---------\n\nBy default, instances of classes have a dictionary for attribute\nstorage.  This wastes space for objects having very few instance\nvariables.  The space consumption can become acute when creating large\nnumbers of instances.\n\nThe default can be overridden by defining *__slots__* in a class\ndefinition. The *__slots__* declaration takes a sequence of instance\nvariables and reserves just enough space in each instance to hold a\nvalue for each variable.  Space is saved because *__dict__* is not\ncreated for each instance.\n\nobject.__slots__\n\n   This class variable can be assigned a string, iterable, or sequence\n   of strings with variable names used by instances.  *__slots__*\n   reserves space for the declared variables and prevents the\n   automatic creation of *__dict__* and *__weakref__* for each\n   instance.\n\n\nNotes on using *__slots__*\n~~~~~~~~~~~~~~~~~~~~~~~~~~\n\n* When inheriting from a class without *__slots__*, the *__dict__*\n  attribute of that class will always be accessible, so a *__slots__*\n  definition in the subclass is meaningless.\n\n* Without a *__dict__* variable, instances cannot be assigned new\n  variables not listed in the *__slots__* definition.  Attempts to\n  assign to an unlisted variable name raises "AttributeError". If\n  dynamic assignment of new variables is desired, then add\n  "\'__dict__\'" to the sequence of strings in the *__slots__*\n  declaration.\n\n* Without a *__weakref__* variable for each instance, classes\n  defining *__slots__* do not support weak references to its\n  instances. If weak reference support is needed, then add\n  "\'__weakref__\'" to the sequence of strings in the *__slots__*\n  declaration.\n\n* *__slots__* are implemented at the class level by creating\n  descriptors (*Implementing Descriptors*) for each variable name.  As\n  a result, class attributes cannot be used to set default values for\n  instance variables defined by *__slots__*; otherwise, the class\n  attribute would overwrite the descriptor assignment.\n\n* The action of a *__slots__* declaration is limited to the class\n  where it is defined.  As a result, subclasses will have a *__dict__*\n  unless they also define *__slots__* (which must only contain names\n  of any *additional* slots).\n\n* If a class defines a slot also defined in a base class, the\n  instance variable defined by the base class slot is inaccessible\n  (except by retrieving its descriptor directly from the base class).\n  This renders the meaning of the program undefined.  In the future, a\n  check may be added to prevent this.\n\n* Nonempty *__slots__* does not work for classes derived from\n  "variable-length" built-in types such as "int", "bytes" and "tuple".\n\n* Any non-string iterable may be assigned to *__slots__*. Mappings\n  may also be used; however, in the future, special meaning may be\n  assigned to the values corresponding to each key.\n\n* *__class__* assignment works only if both classes have the same\n  *__slots__*.\n\n\nCustomizing class creation\n==========================\n\nBy default, classes are constructed using "type()". The class body is\nexecuted in a new namespace and the class name is bound locally to the\nresult of "type(name, bases, namespace)".\n\nThe class creation process can be customised by passing the\n"metaclass" keyword argument in the class definition line, or by\ninheriting from an existing class that included such an argument. In\nthe following example, both "MyClass" and "MySubclass" are instances\nof "Meta":\n\n   class Meta(type):\n       pass\n\n   class MyClass(metaclass=Meta):\n       pass\n\n   class MySubclass(MyClass):\n       pass\n\nAny other keyword arguments that are specified in the class definition\nare passed through to all metaclass operations described below.\n\nWhen a class definition is executed, the following steps occur:\n\n* the appropriate metaclass is determined\n\n* the class namespace is prepared\n\n* the class body is executed\n\n* the class object is created\n\n\nDetermining the appropriate metaclass\n-------------------------------------\n\nThe appropriate metaclass for a class definition is determined as\nfollows:\n\n* if no bases and no explicit metaclass are given, then "type()" is\n  used\n\n* if an explicit metaclass is given and it is *not* an instance of\n  "type()", then it is used directly as the metaclass\n\n* if an instance of "type()" is given as the explicit metaclass, or\n  bases are defined, then the most derived metaclass is used\n\nThe most derived metaclass is selected from the explicitly specified\nmetaclass (if any) and the metaclasses (i.e. "type(cls)") of all\nspecified base classes. The most derived metaclass is one which is a\nsubtype of *all* of these candidate metaclasses. If none of the\ncandidate metaclasses meets that criterion, then the class definition\nwill fail with "TypeError".\n\n\nPreparing the class namespace\n-----------------------------\n\nOnce the appropriate metaclass has been identified, then the class\nnamespace is prepared. If the metaclass has a "__prepare__" attribute,\nit is called as "namespace = metaclass.__prepare__(name, bases,\n**kwds)" (where the additional keyword arguments, if any, come from\nthe class definition).\n\nIf the metaclass has no "__prepare__" attribute, then the class\nnamespace is initialised as an empty "dict()" instance.\n\nSee also: **PEP 3115** - Metaclasses in Python 3000\n\n     Introduced the "__prepare__" namespace hook\n\n\nExecuting the class body\n------------------------\n\nThe class body is executed (approximately) as "exec(body, globals(),\nnamespace)". The key difference from a normal call to "exec()" is that\nlexical scoping allows the class body (including any methods) to\nreference names from the current and outer scopes when the class\ndefinition occurs inside a function.\n\nHowever, even when the class definition occurs inside the function,\nmethods defined inside the class still cannot see names defined at the\nclass scope. Class variables must be accessed through the first\nparameter of instance or class methods, and cannot be accessed at all\nfrom static methods.\n\n\nCreating the class object\n-------------------------\n\nOnce the class namespace has been populated by executing the class\nbody, the class object is created by calling "metaclass(name, bases,\nnamespace, **kwds)" (the additional keywords passed here are the same\nas those passed to "__prepare__").\n\nThis class object is the one that will be referenced by the zero-\nargument form of "super()". "__class__" is an implicit closure\nreference created by the compiler if any methods in a class body refer\nto either "__class__" or "super". This allows the zero argument form\nof "super()" to correctly identify the class being defined based on\nlexical scoping, while the class or instance that was used to make the\ncurrent call is identified based on the first argument passed to the\nmethod.\n\nAfter the class object is created, it is passed to the class\ndecorators included in the class definition (if any) and the resulting\nobject is bound in the local namespace as the defined class.\n\nSee also: **PEP 3135** - New super\n\n     Describes the implicit "__class__" closure reference\n\n\nMetaclass example\n-----------------\n\nThe potential uses for metaclasses are boundless. Some ideas that have\nbeen explored include logging, interface checking, automatic\ndelegation, automatic property creation, proxies, frameworks, and\nautomatic resource locking/synchronization.\n\nHere is an example of a metaclass that uses an\n"collections.OrderedDict" to remember the order that class variables\nare defined:\n\n   class OrderedClass(type):\n\n        @classmethod\n        def __prepare__(metacls, name, bases, **kwds):\n           return collections.OrderedDict()\n\n        def __new__(cls, name, bases, namespace, **kwds):\n           result = type.__new__(cls, name, bases, dict(namespace))\n           result.members = tuple(namespace)\n           return result\n\n   class A(metaclass=OrderedClass):\n       def one(self): pass\n       def two(self): pass\n       def three(self): pass\n       def four(self): pass\n\n   >>> A.members\n   (\'__module__\', \'one\', \'two\', \'three\', \'four\')\n\nWhen the class definition for *A* gets executed, the process begins\nwith calling the metaclass\'s "__prepare__()" method which returns an\nempty "collections.OrderedDict".  That mapping records the methods and\nattributes of *A* as they are defined within the body of the class\nstatement. Once those definitions are executed, the ordered dictionary\nis fully populated and the metaclass\'s "__new__()" method gets\ninvoked.  That method builds the new type and it saves the ordered\ndictionary keys in an attribute called "members".\n\n\nCustomizing instance and subclass checks\n========================================\n\nThe following methods are used to override the default behavior of the\n"isinstance()" and "issubclass()" built-in functions.\n\nIn particular, the metaclass "abc.ABCMeta" implements these methods in\norder to allow the addition of Abstract Base Classes (ABCs) as\n"virtual base classes" to any class or type (including built-in\ntypes), including other ABCs.\n\nclass.__instancecheck__(self, instance)\n\n   Return true if *instance* should be considered a (direct or\n   indirect) instance of *class*. If defined, called to implement\n   "isinstance(instance, class)".\n\nclass.__subclasscheck__(self, subclass)\n\n   Return true if *subclass* should be considered a (direct or\n   indirect) subclass of *class*.  If defined, called to implement\n   "issubclass(subclass, class)".\n\nNote that these methods are looked up on the type (metaclass) of a\nclass.  They cannot be defined as class methods in the actual class.\nThis is consistent with the lookup of special methods that are called\non instances, only in this case the instance is itself a class.\n\nSee also: **PEP 3119** - Introducing Abstract Base Classes\n\n     Includes the specification for customizing "isinstance()" and\n     "issubclass()" behavior through "__instancecheck__()" and\n     "__subclasscheck__()", with motivation for this functionality in\n     the context of adding Abstract Base Classes (see the "abc"\n     module) to the language.\n\n\nEmulating callable objects\n==========================\n\nobject.__call__(self[, args...])\n\n   Called when the instance is "called" as a function; if this method\n   is defined, "x(arg1, arg2, ...)" is a shorthand for\n   "x.__call__(arg1, arg2, ...)".\n\n\nEmulating container types\n=========================\n\nThe following methods can be defined to implement container objects.\nContainers usually are sequences (such as lists or tuples) or mappings\n(like dictionaries), but can represent other containers as well.  The\nfirst set of methods is used either to emulate a sequence or to\nemulate a mapping; the difference is that for a sequence, the\nallowable keys should be the integers *k* for which "0 <= k < N" where\n*N* is the length of the sequence, or slice objects, which define a\nrange of items.  It is also recommended that mappings provide the\nmethods "keys()", "values()", "items()", "get()", "clear()",\n"setdefault()", "pop()", "popitem()", "copy()", and "update()"\nbehaving similar to those for Python\'s standard dictionary objects.\nThe "collections" module provides a "MutableMapping" abstract base\nclass to help create those methods from a base set of "__getitem__()",\n"__setitem__()", "__delitem__()", and "keys()". Mutable sequences\nshould provide methods "append()", "count()", "index()", "extend()",\n"insert()", "pop()", "remove()", "reverse()" and "sort()", like Python\nstandard list objects.  Finally, sequence types should implement\naddition (meaning concatenation) and multiplication (meaning\nrepetition) by defining the methods "__add__()", "__radd__()",\n"__iadd__()", "__mul__()", "__rmul__()" and "__imul__()" described\nbelow; they should not define other numerical operators.  It is\nrecommended that both mappings and sequences implement the\n"__contains__()" method to allow efficient use of the "in" operator;\nfor mappings, "in" should search the mapping\'s keys; for sequences, it\nshould search through the values.  It is further recommended that both\nmappings and sequences implement the "__iter__()" method to allow\nefficient iteration through the container; for mappings, "__iter__()"\nshould be the same as "keys()"; for sequences, it should iterate\nthrough the values.\n\nobject.__len__(self)\n\n   Called to implement the built-in function "len()".  Should return\n   the length of the object, an integer ">=" 0.  Also, an object that\n   doesn\'t define a "__bool__()" method and whose "__len__()" method\n   returns zero is considered to be false in a Boolean context.\n\nobject.__length_hint__(self)\n\n   Called to implement "operator.length_hint()". Should return an\n   estimated length for the object (which may be greater or less than\n   the actual length). The length must be an integer ">=" 0. This\n   method is purely an optimization and is never required for\n   correctness.\n\n   New in version 3.4.\n\nNote: Slicing is done exclusively with the following three methods.\n  A call like\n\n     a[1:2] = b\n\n  is translated to\n\n     a[slice(1, 2, None)] = b\n\n  and so forth.  Missing slice items are always filled in with "None".\n\nobject.__getitem__(self, key)\n\n   Called to implement evaluation of "self[key]". For sequence types,\n   the accepted keys should be integers and slice objects.  Note that\n   the special interpretation of negative indexes (if the class wishes\n   to emulate a sequence type) is up to the "__getitem__()" method. If\n   *key* is of an inappropriate type, "TypeError" may be raised; if of\n   a value outside the set of indexes for the sequence (after any\n   special interpretation of negative values), "IndexError" should be\n   raised. For mapping types, if *key* is missing (not in the\n   container), "KeyError" should be raised.\n\n   Note: "for" loops expect that an "IndexError" will be raised for\n     illegal indexes to allow proper detection of the end of the\n     sequence.\n\nobject.__missing__(self, key)\n\n   Called by "dict"."__getitem__()" to implement "self[key]" for dict\n   subclasses when key is not in the dictionary.\n\nobject.__setitem__(self, key, value)\n\n   Called to implement assignment to "self[key]".  Same note as for\n   "__getitem__()".  This should only be implemented for mappings if\n   the objects support changes to the values for keys, or if new keys\n   can be added, or for sequences if elements can be replaced.  The\n   same exceptions should be raised for improper *key* values as for\n   the "__getitem__()" method.\n\nobject.__delitem__(self, key)\n\n   Called to implement deletion of "self[key]".  Same note as for\n   "__getitem__()".  This should only be implemented for mappings if\n   the objects support removal of keys, or for sequences if elements\n   can be removed from the sequence.  The same exceptions should be\n   raised for improper *key* values as for the "__getitem__()" method.\n\nobject.__iter__(self)\n\n   This method is called when an iterator is required for a container.\n   This method should return a new iterator object that can iterate\n   over all the objects in the container.  For mappings, it should\n   iterate over the keys of the container.\n\n   Iterator objects also need to implement this method; they are\n   required to return themselves.  For more information on iterator\n   objects, see *Iterator Types*.\n\nobject.__reversed__(self)\n\n   Called (if present) by the "reversed()" built-in to implement\n   reverse iteration.  It should return a new iterator object that\n   iterates over all the objects in the container in reverse order.\n\n   If the "__reversed__()" method is not provided, the "reversed()"\n   built-in will fall back to using the sequence protocol ("__len__()"\n   and "__getitem__()").  Objects that support the sequence protocol\n   should only provide "__reversed__()" if they can provide an\n   implementation that is more efficient than the one provided by\n   "reversed()".\n\nThe membership test operators ("in" and "not in") are normally\nimplemented as an iteration through a sequence.  However, container\nobjects can supply the following special method with a more efficient\nimplementation, which also does not require the object be a sequence.\n\nobject.__contains__(self, item)\n\n   Called to implement membership test operators.  Should return true\n   if *item* is in *self*, false otherwise.  For mapping objects, this\n   should consider the keys of the mapping rather than the values or\n   the key-item pairs.\n\n   For objects that don\'t define "__contains__()", the membership test\n   first tries iteration via "__iter__()", then the old sequence\n   iteration protocol via "__getitem__()", see *this section in the\n   language reference*.\n\n\nEmulating numeric types\n=======================\n\nThe following methods can be defined to emulate numeric objects.\nMethods corresponding to operations that are not supported by the\nparticular kind of number implemented (e.g., bitwise operations for\nnon-integral numbers) should be left undefined.\n\nobject.__add__(self, other)\nobject.__sub__(self, other)\nobject.__mul__(self, other)\nobject.__matmul__(self, other)\nobject.__truediv__(self, other)\nobject.__floordiv__(self, other)\nobject.__mod__(self, other)\nobject.__divmod__(self, other)\nobject.__pow__(self, other[, modulo])\nobject.__lshift__(self, other)\nobject.__rshift__(self, other)\nobject.__and__(self, other)\nobject.__xor__(self, other)\nobject.__or__(self, other)\n\n   These methods are called to implement the binary arithmetic\n   operations ("+", "-", "*", "@", "/", "//", "%", "divmod()",\n   "pow()", "**", "<<", ">>", "&", "^", "|").  For instance, to\n   evaluate the expression "x + y", where *x* is an instance of a\n   class that has an "__add__()" method, "x.__add__(y)" is called.\n   The "__divmod__()" method should be the equivalent to using\n   "__floordiv__()" and "__mod__()"; it should not be related to\n   "__truediv__()".  Note that "__pow__()" should be defined to accept\n   an optional third argument if the ternary version of the built-in\n   "pow()" function is to be supported.\n\n   If one of those methods does not support the operation with the\n   supplied arguments, it should return "NotImplemented".\n\nobject.__radd__(self, other)\nobject.__rsub__(self, other)\nobject.__rmul__(self, other)\nobject.__rmatmul__(self, other)\nobject.__rtruediv__(self, other)\nobject.__rfloordiv__(self, other)\nobject.__rmod__(self, other)\nobject.__rdivmod__(self, other)\nobject.__rpow__(self, other)\nobject.__rlshift__(self, other)\nobject.__rrshift__(self, other)\nobject.__rand__(self, other)\nobject.__rxor__(self, other)\nobject.__ror__(self, other)\n\n   These methods are called to implement the binary arithmetic\n   operations ("+", "-", "*", "@", "/", "//", "%", "divmod()",\n   "pow()", "**", "<<", ">>", "&", "^", "|") with reflected (swapped)\n   operands.  These functions are only called if the left operand does\n   not support the corresponding operation and the operands are of\n   different types. [2] For instance, to evaluate the expression "x -\n   y", where *y* is an instance of a class that has an "__rsub__()"\n   method, "y.__rsub__(x)" is called if "x.__sub__(y)" returns\n   *NotImplemented*.\n\n   Note that ternary "pow()" will not try calling "__rpow__()" (the\n   coercion rules would become too complicated).\n\n   Note: If the right operand\'s type is a subclass of the left\n     operand\'s type and that subclass provides the reflected method\n     for the operation, this method will be called before the left\n     operand\'s non-reflected method.  This behavior allows subclasses\n     to override their ancestors\' operations.\n\nobject.__iadd__(self, other)\nobject.__isub__(self, other)\nobject.__imul__(self, other)\nobject.__imatmul__(self, other)\nobject.__itruediv__(self, other)\nobject.__ifloordiv__(self, other)\nobject.__imod__(self, other)\nobject.__ipow__(self, other[, modulo])\nobject.__ilshift__(self, other)\nobject.__irshift__(self, other)\nobject.__iand__(self, other)\nobject.__ixor__(self, other)\nobject.__ior__(self, other)\n\n   These methods are called to implement the augmented arithmetic\n   assignments ("+=", "-=", "*=", "@=", "/=", "//=", "%=", "**=",\n   "<<=", ">>=", "&=", "^=", "|=").  These methods should attempt to\n   do the operation in-place (modifying *self*) and return the result\n   (which could be, but does not have to be, *self*).  If a specific\n   method is not defined, the augmented assignment falls back to the\n   normal methods.  For instance, if *x* is an instance of a class\n   with an "__iadd__()" method, "x += y" is equivalent to "x =\n   x.__iadd__(y)" . Otherwise, "x.__add__(y)" and "y.__radd__(x)" are\n   considered, as with the evaluation of "x + y". In certain\n   situations, augmented assignment can result in unexpected errors\n   (see *Why does a_tuple[i] += [\'item\'] raise an exception when the\n   addition works?*), but this behavior is in fact part of the data\n   model.\n\nobject.__neg__(self)\nobject.__pos__(self)\nobject.__abs__(self)\nobject.__invert__(self)\n\n   Called to implement the unary arithmetic operations ("-", "+",\n   "abs()" and "~").\n\nobject.__complex__(self)\nobject.__int__(self)\nobject.__float__(self)\nobject.__round__(self[, n])\n\n   Called to implement the built-in functions "complex()", "int()",\n   "float()" and "round()".  Should return a value of the appropriate\n   type.\n\nobject.__index__(self)\n\n   Called to implement "operator.index()", and whenever Python needs\n   to losslessly convert the numeric object to an integer object (such\n   as in slicing, or in the built-in "bin()", "hex()" and "oct()"\n   functions). Presence of this method indicates that the numeric\n   object is an integer type.  Must return an integer.\n\n   Note: In order to have a coherent integer type class, when\n     "__index__()" is defined "__int__()" should also be defined, and\n     both should return the same value.\n\n\nWith Statement Context Managers\n===============================\n\nA *context manager* is an object that defines the runtime context to\nbe established when executing a "with" statement. The context manager\nhandles the entry into, and the exit from, the desired runtime context\nfor the execution of the block of code.  Context managers are normally\ninvoked using the "with" statement (described in section *The with\nstatement*), but can also be used by directly invoking their methods.\n\nTypical uses of context managers include saving and restoring various\nkinds of global state, locking and unlocking resources, closing opened\nfiles, etc.\n\nFor more information on context managers, see *Context Manager Types*.\n\nobject.__enter__(self)\n\n   Enter the runtime context related to this object. The "with"\n   statement will bind this method\'s return value to the target(s)\n   specified in the "as" clause of the statement, if any.\n\nobject.__exit__(self, exc_type, exc_value, traceback)\n\n   Exit the runtime context related to this object. The parameters\n   describe the exception that caused the context to be exited. If the\n   context was exited without an exception, all three arguments will\n   be "None".\n\n   If an exception is supplied, and the method wishes to suppress the\n   exception (i.e., prevent it from being propagated), it should\n   return a true value. Otherwise, the exception will be processed\n   normally upon exit from this method.\n\n   Note that "__exit__()" methods should not reraise the passed-in\n   exception; this is the caller\'s responsibility.\n\nSee also: **PEP 0343** - The "with" statement\n\n     The specification, background, and examples for the Python "with"\n     statement.\n\n\nSpecial method lookup\n=====================\n\nFor custom classes, implicit invocations of special methods are only\nguaranteed to work correctly if defined on an object\'s type, not in\nthe object\'s instance dictionary.  That behaviour is the reason why\nthe following code raises an exception:\n\n   >>> class C:\n   ...     pass\n   ...\n   >>> c = C()\n   >>> c.__len__ = lambda: 5\n   >>> len(c)\n   Traceback (most recent call last):\n     File "<stdin>", line 1, in <module>\n   TypeError: object of type \'C\' has no len()\n\nThe rationale behind this behaviour lies with a number of special\nmethods such as "__hash__()" and "__repr__()" that are implemented by\nall objects, including type objects. If the implicit lookup of these\nmethods used the conventional lookup process, they would fail when\ninvoked on the type object itself:\n\n   >>> 1 .__hash__() == hash(1)\n   True\n   >>> int.__hash__() == hash(int)\n   Traceback (most recent call last):\n     File "<stdin>", line 1, in <module>\n   TypeError: descriptor \'__hash__\' of \'int\' object needs an argument\n\nIncorrectly attempting to invoke an unbound method of a class in this\nway is sometimes referred to as \'metaclass confusion\', and is avoided\nby bypassing the instance when looking up special methods:\n\n   >>> type(1).__hash__(1) == hash(1)\n   True\n   >>> type(int).__hash__(int) == hash(int)\n   True\n\nIn addition to bypassing any instance attributes in the interest of\ncorrectness, implicit special method lookup generally also bypasses\nthe "__getattribute__()" method even of the object\'s metaclass:\n\n   >>> class Meta(type):\n   ...     def __getattribute__(*args):\n   ...         print("Metaclass getattribute invoked")\n   ...         return type.__getattribute__(*args)\n   ...\n   >>> class C(object, metaclass=Meta):\n   ...     def __len__(self):\n   ...         return 10\n   ...     def __getattribute__(*args):\n   ...         print("Class getattribute invoked")\n   ...         return object.__getattribute__(*args)\n   ...\n   >>> c = C()\n   >>> c.__len__()                 # Explicit lookup via instance\n   Class getattribute invoked\n   10\n   >>> type(c).__len__(c)          # Explicit lookup via type\n   Metaclass getattribute invoked\n   10\n   >>> len(c)                      # Implicit lookup\n   10\n\nBypassing the "__getattribute__()" machinery in this fashion provides\nsignificant scope for speed optimisations within the interpreter, at\nthe cost of some flexibility in the handling of special methods (the\nspecial method *must* be set on the class object itself in order to be\nconsistently invoked by the interpreter).\n',
- 'string-methods': u'\nString Methods\n**************\n\nStrings implement all of the *common* sequence operations, along with\nthe additional methods described below.\n\nStrings also support two styles of string formatting, one providing a\nlarge degree of flexibility and customization (see "str.format()",\n*Format String Syntax* and *String Formatting*) and the other based on\nC "printf" style formatting that handles a narrower range of types and\nis slightly harder to use correctly, but is often faster for the cases\nit can handle (*printf-style String Formatting*).\n\nThe *Text Processing Services* section of the standard library covers\na number of other modules that provide various text related utilities\n(including regular expression support in the "re" module).\n\nstr.capitalize()\n\n   Return a copy of the string with its first character capitalized\n   and the rest lowercased.\n\nstr.casefold()\n\n   Return a casefolded copy of the string. Casefolded strings may be\n   used for caseless matching.\n\n   Casefolding is similar to lowercasing but more aggressive because\n   it is intended to remove all case distinctions in a string. For\n   example, the German lowercase letter "\'\xdf\'" is equivalent to ""ss"".\n   Since it is already lowercase, "lower()" would do nothing to "\'\xdf\'";\n   "casefold()" converts it to ""ss"".\n\n   The casefolding algorithm is described in section 3.13 of the\n   Unicode Standard.\n\n   New in version 3.3.\n\nstr.center(width[, fillchar])\n\n   Return centered in a string of length *width*. Padding is done\n   using the specified *fillchar* (default is an ASCII space). The\n   original string is returned if *width* is less than or equal to\n   "len(s)".\n\nstr.count(sub[, start[, end]])\n\n   Return the number of non-overlapping occurrences of substring *sub*\n   in the range [*start*, *end*].  Optional arguments *start* and\n   *end* are interpreted as in slice notation.\n\nstr.encode(encoding="utf-8", errors="strict")\n\n   Return an encoded version of the string as a bytes object. Default\n   encoding is "\'utf-8\'". *errors* may be given to set a different\n   error handling scheme. The default for *errors* is "\'strict\'",\n   meaning that encoding errors raise a "UnicodeError". Other possible\n   values are "\'ignore\'", "\'replace\'", "\'xmlcharrefreplace\'",\n   "\'backslashreplace\'" and any other name registered via\n   "codecs.register_error()", see section *Error Handlers*. For a list\n   of possible encodings, see section *Standard Encodings*.\n\n   Changed in version 3.1: Support for keyword arguments added.\n\nstr.endswith(suffix[, start[, end]])\n\n   Return "True" if the string ends with the specified *suffix*,\n   otherwise return "False".  *suffix* can also be a tuple of suffixes\n   to look for.  With optional *start*, test beginning at that\n   position.  With optional *end*, stop comparing at that position.\n\nstr.expandtabs(tabsize=8)\n\n   Return a copy of the string where all tab characters are replaced\n   by one or more spaces, depending on the current column and the\n   given tab size.  Tab positions occur every *tabsize* characters\n   (default is 8, giving tab positions at columns 0, 8, 16 and so on).\n   To expand the string, the current column is set to zero and the\n   string is examined character by character.  If the character is a\n   tab ("\\t"), one or more space characters are inserted in the result\n   until the current column is equal to the next tab position. (The\n   tab character itself is not copied.)  If the character is a newline\n   ("\\n") or return ("\\r"), it is copied and the current column is\n   reset to zero.  Any other character is copied unchanged and the\n   current column is incremented by one regardless of how the\n   character is represented when printed.\n\n   >>> \'01\\t012\\t0123\\t01234\'.expandtabs()\n   \'01      012     0123    01234\'\n   >>> \'01\\t012\\t0123\\t01234\'.expandtabs(4)\n   \'01  012 0123    01234\'\n\nstr.find(sub[, start[, end]])\n\n   Return the lowest index in the string where substring *sub* is\n   found, such that *sub* is contained in the slice "s[start:end]".\n   Optional arguments *start* and *end* are interpreted as in slice\n   notation.  Return "-1" if *sub* is not found.\n\n   Note: The "find()" method should be used only if you need to know\n     the position of *sub*.  To check if *sub* is a substring or not,\n     use the "in" operator:\n\n        >>> \'Py\' in \'Python\'\n        True\n\nstr.format(*args, **kwargs)\n\n   Perform a string formatting operation.  The string on which this\n   method is called can contain literal text or replacement fields\n   delimited by braces "{}".  Each replacement field contains either\n   the numeric index of a positional argument, or the name of a\n   keyword argument.  Returns a copy of the string where each\n   replacement field is replaced with the string value of the\n   corresponding argument.\n\n   >>> "The sum of 1 + 2 is {0}".format(1+2)\n   \'The sum of 1 + 2 is 3\'\n\n   See *Format String Syntax* for a description of the various\n   formatting options that can be specified in format strings.\n\nstr.format_map(mapping)\n\n   Similar to "str.format(**mapping)", except that "mapping" is used\n   directly and not copied to a "dict".  This is useful if for example\n   "mapping" is a dict subclass:\n\n   >>> class Default(dict):\n   ...     def __missing__(self, key):\n   ...         return key\n   ...\n   >>> \'{name} was born in {country}\'.format_map(Default(name=\'Guido\'))\n   \'Guido was born in country\'\n\n   New in version 3.2.\n\nstr.index(sub[, start[, end]])\n\n   Like "find()", but raise "ValueError" when the substring is not\n   found.\n\nstr.isalnum()\n\n   Return true if all characters in the string are alphanumeric and\n   there is at least one character, false otherwise.  A character "c"\n   is alphanumeric if one of the following returns "True":\n   "c.isalpha()", "c.isdecimal()", "c.isdigit()", or "c.isnumeric()".\n\nstr.isalpha()\n\n   Return true if all characters in the string are alphabetic and\n   there is at least one character, false otherwise.  Alphabetic\n   characters are those characters defined in the Unicode character\n   database as "Letter", i.e., those with general category property\n   being one of "Lm", "Lt", "Lu", "Ll", or "Lo".  Note that this is\n   different from the "Alphabetic" property defined in the Unicode\n   Standard.\n\nstr.isdecimal()\n\n   Return true if all characters in the string are decimal characters\n   and there is at least one character, false otherwise. Decimal\n   characters are those from general category "Nd". This category\n   includes digit characters, and all characters that can be used to\n   form decimal-radix numbers, e.g. U+0660, ARABIC-INDIC DIGIT ZERO.\n\nstr.isdigit()\n\n   Return true if all characters in the string are digits and there is\n   at least one character, false otherwise.  Digits include decimal\n   characters and digits that need special handling, such as the\n   compatibility superscript digits.  Formally, a digit is a character\n   that has the property value Numeric_Type=Digit or\n   Numeric_Type=Decimal.\n\nstr.isidentifier()\n\n   Return true if the string is a valid identifier according to the\n   language definition, section *Identifiers and keywords*.\n\n   Use "keyword.iskeyword()" to test for reserved identifiers such as\n   "def" and "class".\n\nstr.islower()\n\n   Return true if all cased characters [4] in the string are lowercase\n   and there is at least one cased character, false otherwise.\n\nstr.isnumeric()\n\n   Return true if all characters in the string are numeric characters,\n   and there is at least one character, false otherwise. Numeric\n   characters include digit characters, and all characters that have\n   the Unicode numeric value property, e.g. U+2155, VULGAR FRACTION\n   ONE FIFTH.  Formally, numeric characters are those with the\n   property value Numeric_Type=Digit, Numeric_Type=Decimal or\n   Numeric_Type=Numeric.\n\nstr.isprintable()\n\n   Return true if all characters in the string are printable or the\n   string is empty, false otherwise.  Nonprintable characters are\n   those characters defined in the Unicode character database as\n   "Other" or "Separator", excepting the ASCII space (0x20) which is\n   considered printable.  (Note that printable characters in this\n   context are those which should not be escaped when "repr()" is\n   invoked on a string.  It has no bearing on the handling of strings\n   written to "sys.stdout" or "sys.stderr".)\n\nstr.isspace()\n\n   Return true if there are only whitespace characters in the string\n   and there is at least one character, false otherwise.  Whitespace\n   characters  are those characters defined in the Unicode character\n   database as "Other" or "Separator" and those with bidirectional\n   property being one of "WS", "B", or "S".\n\nstr.istitle()\n\n   Return true if the string is a titlecased string and there is at\n   least one character, for example uppercase characters may only\n   follow uncased characters and lowercase characters only cased ones.\n   Return false otherwise.\n\nstr.isupper()\n\n   Return true if all cased characters [4] in the string are uppercase\n   and there is at least one cased character, false otherwise.\n\nstr.join(iterable)\n\n   Return a string which is the concatenation of the strings in the\n   *iterable* *iterable*.  A "TypeError" will be raised if there are\n   any non-string values in *iterable*, including "bytes" objects.\n   The separator between elements is the string providing this method.\n\nstr.ljust(width[, fillchar])\n\n   Return the string left justified in a string of length *width*.\n   Padding is done using the specified *fillchar* (default is an ASCII\n   space). The original string is returned if *width* is less than or\n   equal to "len(s)".\n\nstr.lower()\n\n   Return a copy of the string with all the cased characters [4]\n   converted to lowercase.\n\n   The lowercasing algorithm used is described in section 3.13 of the\n   Unicode Standard.\n\nstr.lstrip([chars])\n\n   Return a copy of the string with leading characters removed.  The\n   *chars* argument is a string specifying the set of characters to be\n   removed.  If omitted or "None", the *chars* argument defaults to\n   removing whitespace.  The *chars* argument is not a prefix; rather,\n   all combinations of its values are stripped:\n\n      >>> \'   spacious   \'.lstrip()\n      \'spacious   \'\n      >>> \'www.example.com\'.lstrip(\'cmowz.\')\n      \'example.com\'\n\nstatic str.maketrans(x[, y[, z]])\n\n   This static method returns a translation table usable for\n   "str.translate()".\n\n   If there is only one argument, it must be a dictionary mapping\n   Unicode ordinals (integers) or characters (strings of length 1) to\n   Unicode ordinals, strings (of arbitrary lengths) or None.\n   Character keys will then be converted to ordinals.\n\n   If there are two arguments, they must be strings of equal length,\n   and in the resulting dictionary, each character in x will be mapped\n   to the character at the same position in y.  If there is a third\n   argument, it must be a string, whose characters will be mapped to\n   None in the result.\n\nstr.partition(sep)\n\n   Split the string at the first occurrence of *sep*, and return a\n   3-tuple containing the part before the separator, the separator\n   itself, and the part after the separator.  If the separator is not\n   found, return a 3-tuple containing the string itself, followed by\n   two empty strings.\n\nstr.replace(old, new[, count])\n\n   Return a copy of the string with all occurrences of substring *old*\n   replaced by *new*.  If the optional argument *count* is given, only\n   the first *count* occurrences are replaced.\n\nstr.rfind(sub[, start[, end]])\n\n   Return the highest index in the string where substring *sub* is\n   found, such that *sub* is contained within "s[start:end]".\n   Optional arguments *start* and *end* are interpreted as in slice\n   notation.  Return "-1" on failure.\n\nstr.rindex(sub[, start[, end]])\n\n   Like "rfind()" but raises "ValueError" when the substring *sub* is\n   not found.\n\nstr.rjust(width[, fillchar])\n\n   Return the string right justified in a string of length *width*.\n   Padding is done using the specified *fillchar* (default is an ASCII\n   space). The original string is returned if *width* is less than or\n   equal to "len(s)".\n\nstr.rpartition(sep)\n\n   Split the string at the last occurrence of *sep*, and return a\n   3-tuple containing the part before the separator, the separator\n   itself, and the part after the separator.  If the separator is not\n   found, return a 3-tuple containing two empty strings, followed by\n   the string itself.\n\nstr.rsplit(sep=None, maxsplit=-1)\n\n   Return a list of the words in the string, using *sep* as the\n   delimiter string. If *maxsplit* is given, at most *maxsplit* splits\n   are done, the *rightmost* ones.  If *sep* is not specified or\n   "None", any whitespace string is a separator.  Except for splitting\n   from the right, "rsplit()" behaves like "split()" which is\n   described in detail below.\n\nstr.rstrip([chars])\n\n   Return a copy of the string with trailing characters removed.  The\n   *chars* argument is a string specifying the set of characters to be\n   removed.  If omitted or "None", the *chars* argument defaults to\n   removing whitespace.  The *chars* argument is not a suffix; rather,\n   all combinations of its values are stripped:\n\n      >>> \'   spacious   \'.rstrip()\n      \'   spacious\'\n      >>> \'mississippi\'.rstrip(\'ipz\')\n      \'mississ\'\n\nstr.split(sep=None, maxsplit=-1)\n\n   Return a list of the words in the string, using *sep* as the\n   delimiter string.  If *maxsplit* is given, at most *maxsplit*\n   splits are done (thus, the list will have at most "maxsplit+1"\n   elements).  If *maxsplit* is not specified or "-1", then there is\n   no limit on the number of splits (all possible splits are made).\n\n   If *sep* is given, consecutive delimiters are not grouped together\n   and are deemed to delimit empty strings (for example,\n   "\'1,,2\'.split(\',\')" returns "[\'1\', \'\', \'2\']").  The *sep* argument\n   may consist of multiple characters (for example,\n   "\'1<>2<>3\'.split(\'<>\')" returns "[\'1\', \'2\', \'3\']"). Splitting an\n   empty string with a specified separator returns "[\'\']".\n\n   For example:\n\n      >>> \'1,2,3\'.split(\',\')\n      [\'1\', \'2\', \'3\']\n      >>> \'1,2,3\'.split(\',\', maxsplit=1)\n      [\'1\', \'2,3\']\n      >>> \'1,2,,3,\'.split(\',\')\n      [\'1\', \'2\', \'\', \'3\', \'\']\n\n   If *sep* is not specified or is "None", a different splitting\n   algorithm is applied: runs of consecutive whitespace are regarded\n   as a single separator, and the result will contain no empty strings\n   at the start or end if the string has leading or trailing\n   whitespace.  Consequently, splitting an empty string or a string\n   consisting of just whitespace with a "None" separator returns "[]".\n\n   For example:\n\n      >>> \'1 2 3\'.split()\n      [\'1\', \'2\', \'3\']\n      >>> \'1 2 3\'.split(maxsplit=1)\n      [\'1\', \'2 3\']\n      >>> \'   1   2   3   \'.split()\n      [\'1\', \'2\', \'3\']\n\nstr.splitlines([keepends])\n\n   Return a list of the lines in the string, breaking at line\n   boundaries.  Line breaks are not included in the resulting list\n   unless *keepends* is given and true.\n\n   This method splits on the following line boundaries.  In\n   particular, the boundaries are a superset of *universal newlines*.\n\n   +-------------------------+-------------------------------+\n   | Representation          | Description                   |\n   +=========================+===============================+\n   | "\\n"                    | Line Feed                     |\n   +-------------------------+-------------------------------+\n   | "\\r"                    | Carriage Return               |\n   +-------------------------+-------------------------------+\n   | "\\r\\n"                  | Carriage Return + Line Feed   |\n   +-------------------------+-------------------------------+\n   | "\\v" or "\\x0b"          | Line Tabulation               |\n   +-------------------------+-------------------------------+\n   | "\\f" or "\\x0c"          | Form Feed                     |\n   +-------------------------+-------------------------------+\n   | "\\x1c"                  | File Separator                |\n   +-------------------------+-------------------------------+\n   | "\\x1d"                  | Group Separator               |\n   +-------------------------+-------------------------------+\n   | "\\x1e"                  | Record Separator              |\n   +-------------------------+-------------------------------+\n   | "\\x85"                  | Next Line (C1 Control Code)   |\n   +-------------------------+-------------------------------+\n   | "\\u2028"                | Line Separator                |\n   +-------------------------+-------------------------------+\n   | "\\u2029"                | Paragraph Separator           |\n   +-------------------------+-------------------------------+\n\n   Changed in version 3.2: "\\v" and "\\f" added to list of line\n   boundaries.\n\n   For example:\n\n      >>> \'ab c\\n\\nde fg\\rkl\\r\\n\'.splitlines()\n      [\'ab c\', \'\', \'de fg\', \'kl\']\n      >>> \'ab c\\n\\nde fg\\rkl\\r\\n\'.splitlines(keepends=True)\n      [\'ab c\\n\', \'\\n\', \'de fg\\r\', \'kl\\r\\n\']\n\n   Unlike "split()" when a delimiter string *sep* is given, this\n   method returns an empty list for the empty string, and a terminal\n   line break does not result in an extra line:\n\n      >>> "".splitlines()\n      []\n      >>> "One line\\n".splitlines()\n      [\'One line\']\n\n   For comparison, "split(\'\\n\')" gives:\n\n      >>> \'\'.split(\'\\n\')\n      [\'\']\n      >>> \'Two lines\\n\'.split(\'\\n\')\n      [\'Two lines\', \'\']\n\nstr.startswith(prefix[, start[, end]])\n\n   Return "True" if string starts with the *prefix*, otherwise return\n   "False". *prefix* can also be a tuple of prefixes to look for.\n   With optional *start*, test string beginning at that position.\n   With optional *end*, stop comparing string at that position.\n\nstr.strip([chars])\n\n   Return a copy of the string with the leading and trailing\n   characters removed. The *chars* argument is a string specifying the\n   set of characters to be removed. If omitted or "None", the *chars*\n   argument defaults to removing whitespace. The *chars* argument is\n   not a prefix or suffix; rather, all combinations of its values are\n   stripped:\n\n      >>> \'   spacious   \'.strip()\n      \'spacious\'\n      >>> \'www.example.com\'.strip(\'cmowz.\')\n      \'example\'\n\n   The outermost leading and trailing *chars* argument values are\n   stripped from the string. Characters are removed from the leading\n   end until reaching a string character that is not contained in the\n   set of characters in *chars*. A similar action takes place on the\n   trailing end. For example:\n\n      >>> comment_string = \'#....... Section 3.2.1 Issue #32 .......\'\n      >>> comment_string.strip(\'.#! \')\n      \'Section 3.2.1 Issue #32\'\n\nstr.swapcase()\n\n   Return a copy of the string with uppercase characters converted to\n   lowercase and vice versa. Note that it is not necessarily true that\n   "s.swapcase().swapcase() == s".\n\nstr.title()\n\n   Return a titlecased version of the string where words start with an\n   uppercase character and the remaining characters are lowercase.\n\n   For example:\n\n      >>> \'Hello world\'.title()\n      \'Hello World\'\n\n   The algorithm uses a simple language-independent definition of a\n   word as groups of consecutive letters.  The definition works in\n   many contexts but it means that apostrophes in contractions and\n   possessives form word boundaries, which may not be the desired\n   result:\n\n      >>> "they\'re bill\'s friends from the UK".title()\n      "They\'Re Bill\'S Friends From The Uk"\n\n   A workaround for apostrophes can be constructed using regular\n   expressions:\n\n      >>> import re\n      >>> def titlecase(s):\n      ...     return re.sub(r"[A-Za-z]+(\'[A-Za-z]+)?",\n      ...                   lambda mo: mo.group(0)[0].upper() +\n      ...                              mo.group(0)[1:].lower(),\n      ...                   s)\n      ...\n      >>> titlecase("they\'re bill\'s friends.")\n      "They\'re Bill\'s Friends."\n\nstr.translate(table)\n\n   Return a copy of the string in which each character has been mapped\n   through the given translation table.  The table must be an object\n   that implements indexing via "__getitem__()", typically a *mapping*\n   or *sequence*.  When indexed by a Unicode ordinal (an integer), the\n   table object can do any of the following: return a Unicode ordinal\n   or a string, to map the character to one or more other characters;\n   return "None", to delete the character from the return string; or\n   raise a "LookupError" exception, to map the character to itself.\n\n   You can use "str.maketrans()" to create a translation map from\n   character-to-character mappings in different formats.\n\n   See also the "codecs" module for a more flexible approach to custom\n   character mappings.\n\nstr.upper()\n\n   Return a copy of the string with all the cased characters [4]\n   converted to uppercase.  Note that "str.upper().isupper()" might be\n   "False" if "s" contains uncased characters or if the Unicode\n   category of the resulting character(s) is not "Lu" (Letter,\n   uppercase), but e.g. "Lt" (Letter, titlecase).\n\n   The uppercasing algorithm used is described in section 3.13 of the\n   Unicode Standard.\n\nstr.zfill(width)\n\n   Return a copy of the string left filled with ASCII "\'0\'" digits to\n   make a string of length *width*. A leading sign prefix\n   ("\'+\'"/"\'-\'") is handled by inserting the padding *after* the sign\n   character rather than before. The original string is returned if\n   *width* is less than or equal to "len(s)".\n\n   For example:\n\n      >>> "42".zfill(5)\n      \'00042\'\n      >>> "-42".zfill(5)\n      \'-0042\'\n',
- 'strings': u'\nString and Bytes literals\n*************************\n\nString literals are described by the following lexical definitions:\n\n   stringliteral   ::= [stringprefix](shortstring | longstring)\n   stringprefix    ::= "r" | "u" | "R" | "U"\n   shortstring     ::= "\'" shortstringitem* "\'" | \'"\' shortstringitem* \'"\'\n   longstring      ::= "\'\'\'" longstringitem* "\'\'\'" | \'"""\' longstringitem* \'"""\'\n   shortstringitem ::= shortstringchar | stringescapeseq\n   longstringitem  ::= longstringchar | stringescapeseq\n   shortstringchar ::= <any source character except "\\" or newline or the quote>\n   longstringchar  ::= <any source character except "\\">\n   stringescapeseq ::= "\\" <any source character>\n\n   bytesliteral   ::= bytesprefix(shortbytes | longbytes)\n   bytesprefix    ::= "b" | "B" | "br" | "Br" | "bR" | "BR" | "rb" | "rB" | "Rb" | "RB"\n   shortbytes     ::= "\'" shortbytesitem* "\'" | \'"\' shortbytesitem* \'"\'\n   longbytes      ::= "\'\'\'" longbytesitem* "\'\'\'" | \'"""\' longbytesitem* \'"""\'\n   shortbytesitem ::= shortbyteschar | bytesescapeseq\n   longbytesitem  ::= longbyteschar | bytesescapeseq\n   shortbyteschar ::= <any ASCII character except "\\" or newline or the quote>\n   longbyteschar  ::= <any ASCII character except "\\">\n   bytesescapeseq ::= "\\" <any ASCII character>\n\nOne syntactic restriction not indicated by these productions is that\nwhitespace is not allowed between the "stringprefix" or "bytesprefix"\nand the rest of the literal. The source character set is defined by\nthe encoding declaration; it is UTF-8 if no encoding declaration is\ngiven in the source file; see section *Encoding declarations*.\n\nIn plain English: Both types of literals can be enclosed in matching\nsingle quotes ("\'") or double quotes (""").  They can also be enclosed\nin matching groups of three single or double quotes (these are\ngenerally referred to as *triple-quoted strings*).  The backslash\n("\\") character is used to escape characters that otherwise have a\nspecial meaning, such as newline, backslash itself, or the quote\ncharacter.\n\nBytes literals are always prefixed with "\'b\'" or "\'B\'"; they produce\nan instance of the "bytes" type instead of the "str" type.  They may\nonly contain ASCII characters; bytes with a numeric value of 128 or\ngreater must be expressed with escapes.\n\nAs of Python 3.3 it is possible again to prefix string literals with a\n"u" prefix to simplify maintenance of dual 2.x and 3.x codebases.\n\nBoth string and bytes literals may optionally be prefixed with a\nletter "\'r\'" or "\'R\'"; such strings are called *raw strings* and treat\nbackslashes as literal characters.  As a result, in string literals,\n"\'\\U\'" and "\'\\u\'" escapes in raw strings are not treated specially.\nGiven that Python 2.x\'s raw unicode literals behave differently than\nPython 3.x\'s the "\'ur\'" syntax is not supported.\n\nNew in version 3.3: The "\'rb\'" prefix of raw bytes literals has been\nadded as a synonym of "\'br\'".\n\nNew in version 3.3: Support for the unicode legacy literal\n("u\'value\'") was reintroduced to simplify the maintenance of dual\nPython 2.x and 3.x codebases. See **PEP 414** for more information.\n\nIn triple-quoted literals, unescaped newlines and quotes are allowed\n(and are retained), except that three unescaped quotes in a row\nterminate the literal.  (A "quote" is the character used to open the\nliteral, i.e. either "\'" or """.)\n\nUnless an "\'r\'" or "\'R\'" prefix is present, escape sequences in string\nand bytes literals are interpreted according to rules similar to those\nused by Standard C.  The recognized escape sequences are:\n\n+-------------------+-----------------------------------+---------+\n| Escape Sequence   | Meaning                           | Notes   |\n+===================+===================================+=========+\n| "\\newline"        | Backslash and newline ignored     |         |\n+-------------------+-----------------------------------+---------+\n| "\\\\"              | Backslash ("\\")                   |         |\n+-------------------+-----------------------------------+---------+\n| "\\\'"              | Single quote ("\'")                |         |\n+-------------------+-----------------------------------+---------+\n| "\\""              | Double quote (""")                |         |\n+-------------------+-----------------------------------+---------+\n| "\\a"              | ASCII Bell (BEL)                  |         |\n+-------------------+-----------------------------------+---------+\n| "\\b"              | ASCII Backspace (BS)              |         |\n+-------------------+-----------------------------------+---------+\n| "\\f"              | ASCII Formfeed (FF)               |         |\n+-------------------+-----------------------------------+---------+\n| "\\n"              | ASCII Linefeed (LF)               |         |\n+-------------------+-----------------------------------+---------+\n| "\\r"              | ASCII Carriage Return (CR)        |         |\n+-------------------+-----------------------------------+---------+\n| "\\t"              | ASCII Horizontal Tab (TAB)        |         |\n+-------------------+-----------------------------------+---------+\n| "\\v"              | ASCII Vertical Tab (VT)           |         |\n+-------------------+-----------------------------------+---------+\n| "\\ooo"            | Character with octal value *ooo*  | (1,3)   |\n+-------------------+-----------------------------------+---------+\n| "\\xhh"            | Character with hex value *hh*     | (2,3)   |\n+-------------------+-----------------------------------+---------+\n\nEscape sequences only recognized in string literals are:\n\n+-------------------+-----------------------------------+---------+\n| Escape Sequence   | Meaning                           | Notes   |\n+===================+===================================+=========+\n| "\\N{name}"        | Character named *name* in the     | (4)     |\n|                   | Unicode database                  |         |\n+-------------------+-----------------------------------+---------+\n| "\\uxxxx"          | Character with 16-bit hex value   | (5)     |\n|                   | *xxxx*                            |         |\n+-------------------+-----------------------------------+---------+\n| "\\Uxxxxxxxx"      | Character with 32-bit hex value   | (6)     |\n|                   | *xxxxxxxx*                        |         |\n+-------------------+-----------------------------------+---------+\n\nNotes:\n\n1. As in Standard C, up to three octal digits are accepted.\n\n2. Unlike in Standard C, exactly two hex digits are required.\n\n3. In a bytes literal, hexadecimal and octal escapes denote the\n   byte with the given value. In a string literal, these escapes\n   denote a Unicode character with the given value.\n\n4. Changed in version 3.3: Support for name aliases [1] has been\n   added.\n\n5. Individual code units which form parts of a surrogate pair can\n   be encoded using this escape sequence.  Exactly four hex digits are\n   required.\n\n6. Any Unicode character can be encoded this way.  Exactly eight\n   hex digits are required.\n\nUnlike Standard C, all unrecognized escape sequences are left in the\nstring unchanged, i.e., *the backslash is left in the result*.  (This\nbehavior is useful when debugging: if an escape sequence is mistyped,\nthe resulting output is more easily recognized as broken.)  It is also\nimportant to note that the escape sequences only recognized in string\nliterals fall into the category of unrecognized escapes for bytes\nliterals.\n\nEven in a raw literal, quotes can be escaped with a backslash, but the\nbackslash remains in the result; for example, "r"\\""" is a valid\nstring literal consisting of two characters: a backslash and a double\nquote; "r"\\"" is not a valid string literal (even a raw string cannot\nend in an odd number of backslashes).  Specifically, *a raw literal\ncannot end in a single backslash* (since the backslash would escape\nthe following quote character).  Note also that a single backslash\nfollowed by a newline is interpreted as those two characters as part\nof the literal, *not* as a line continuation.\n',
- 'subscriptions': u'\nSubscriptions\n*************\n\nA subscription selects an item of a sequence (string, tuple or list)\nor mapping (dictionary) object:\n\n   subscription ::= primary "[" expression_list "]"\n\nThe primary must evaluate to an object that supports subscription\n(lists or dictionaries for example).  User-defined objects can support\nsubscription by defining a "__getitem__()" method.\n\nFor built-in objects, there are two types of objects that support\nsubscription:\n\nIf the primary is a mapping, the expression list must evaluate to an\nobject whose value is one of the keys of the mapping, and the\nsubscription selects the value in the mapping that corresponds to that\nkey.  (The expression list is a tuple except if it has exactly one\nitem.)\n\nIf the primary is a sequence, the expression (list) must evaluate to\nan integer or a slice (as discussed in the following section).\n\nThe formal syntax makes no special provision for negative indices in\nsequences; however, built-in sequences all provide a "__getitem__()"\nmethod that interprets negative indices by adding the length of the\nsequence to the index (so that "x[-1]" selects the last item of "x").\nThe resulting value must be a nonnegative integer less than the number\nof items in the sequence, and the subscription selects the item whose\nindex is that value (counting from zero). Since the support for\nnegative indices and slicing occurs in the object\'s "__getitem__()"\nmethod, subclasses overriding this method will need to explicitly add\nthat support.\n\nA string\'s items are characters.  A character is not a separate data\ntype but a string of exactly one character.\n',
- 'truth': u'\nTruth Value Testing\n*******************\n\nAny object can be tested for truth value, for use in an "if" or\n"while" condition or as operand of the Boolean operations below. The\nfollowing values are considered false:\n\n* "None"\n\n* "False"\n\n* zero of any numeric type, for example, "0", "0.0", "0j".\n\n* any empty sequence, for example, "\'\'", "()", "[]".\n\n* any empty mapping, for example, "{}".\n\n* instances of user-defined classes, if the class defines a\n  "__bool__()" or "__len__()" method, when that method returns the\n  integer zero or "bool" value "False". [1]\n\nAll other values are considered true --- so objects of many types are\nalways true.\n\nOperations and built-in functions that have a Boolean result always\nreturn "0" or "False" for false and "1" or "True" for true, unless\notherwise stated. (Important exception: the Boolean operations "or"\nand "and" always return one of their operands.)\n',
- 'try': u'\nThe "try" statement\n*******************\n\nThe "try" statement specifies exception handlers and/or cleanup code\nfor a group of statements:\n\n   try_stmt  ::= try1_stmt | try2_stmt\n   try1_stmt ::= "try" ":" suite\n                 ("except" [expression ["as" identifier]] ":" suite)+\n                 ["else" ":" suite]\n                 ["finally" ":" suite]\n   try2_stmt ::= "try" ":" suite\n                 "finally" ":" suite\n\nThe "except" clause(s) specify one or more exception handlers. When no\nexception occurs in the "try" clause, no exception handler is\nexecuted. When an exception occurs in the "try" suite, a search for an\nexception handler is started.  This search inspects the except clauses\nin turn until one is found that matches the exception.  An expression-\nless except clause, if present, must be last; it matches any\nexception.  For an except clause with an expression, that expression\nis evaluated, and the clause matches the exception if the resulting\nobject is "compatible" with the exception.  An object is compatible\nwith an exception if it is the class or a base class of the exception\nobject or a tuple containing an item compatible with the exception.\n\nIf no except clause matches the exception, the search for an exception\nhandler continues in the surrounding code and on the invocation stack.\n[1]\n\nIf the evaluation of an expression in the header of an except clause\nraises an exception, the original search for a handler is canceled and\na search starts for the new exception in the surrounding code and on\nthe call stack (it is treated as if the entire "try" statement raised\nthe exception).\n\nWhen a matching except clause is found, the exception is assigned to\nthe target specified after the "as" keyword in that except clause, if\npresent, and the except clause\'s suite is executed.  All except\nclauses must have an executable block.  When the end of this block is\nreached, execution continues normally after the entire try statement.\n(This means that if two nested handlers exist for the same exception,\nand the exception occurs in the try clause of the inner handler, the\nouter handler will not handle the exception.)\n\nWhen an exception has been assigned using "as target", it is cleared\nat the end of the except clause.  This is as if\n\n   except E as N:\n       foo\n\nwas translated to\n\n   except E as N:\n       try:\n           foo\n       finally:\n           del N\n\nThis means the exception must be assigned to a different name to be\nable to refer to it after the except clause.  Exceptions are cleared\nbecause with the traceback attached to them, they form a reference\ncycle with the stack frame, keeping all locals in that frame alive\nuntil the next garbage collection occurs.\n\nBefore an except clause\'s suite is executed, details about the\nexception are stored in the "sys" module and can be accessed via\n"sys.exc_info()". "sys.exc_info()" returns a 3-tuple consisting of the\nexception class, the exception instance and a traceback object (see\nsection *The standard type hierarchy*) identifying the point in the\nprogram where the exception occurred.  "sys.exc_info()" values are\nrestored to their previous values (before the call) when returning\nfrom a function that handled an exception.\n\nThe optional "else" clause is executed if and when control flows off\nthe end of the "try" clause. [2] Exceptions in the "else" clause are\nnot handled by the preceding "except" clauses.\n\nIf "finally" is present, it specifies a \'cleanup\' handler.  The "try"\nclause is executed, including any "except" and "else" clauses.  If an\nexception occurs in any of the clauses and is not handled, the\nexception is temporarily saved. The "finally" clause is executed.  If\nthere is a saved exception it is re-raised at the end of the "finally"\nclause.  If the "finally" clause raises another exception, the saved\nexception is set as the context of the new exception. If the "finally"\nclause executes a "return" or "break" statement, the saved exception\nis discarded:\n\n   >>> def f():\n   ...     try:\n   ...         1/0\n   ...     finally:\n   ...         return 42\n   ...\n   >>> f()\n   42\n\nThe exception information is not available to the program during\nexecution of the "finally" clause.\n\nWhen a "return", "break" or "continue" statement is executed in the\n"try" suite of a "try"..."finally" statement, the "finally" clause is\nalso executed \'on the way out.\' A "continue" statement is illegal in\nthe "finally" clause. (The reason is a problem with the current\nimplementation --- this restriction may be lifted in the future).\n\nThe return value of a function is determined by the last "return"\nstatement executed.  Since the "finally" clause always executes, a\n"return" statement executed in the "finally" clause will always be the\nlast one executed:\n\n   >>> def foo():\n   ...     try:\n   ...         return \'try\'\n   ...     finally:\n   ...         return \'finally\'\n   ...\n   >>> foo()\n   \'finally\'\n\nAdditional information on exceptions can be found in section\n*Exceptions*, and information on using the "raise" statement to\ngenerate exceptions may be found in section *The raise statement*.\n',
- 'types': u'\nThe standard type hierarchy\n***************************\n\nBelow is a list of the types that are built into Python.  Extension\nmodules (written in C, Java, or other languages, depending on the\nimplementation) can define additional types.  Future versions of\nPython may add types to the type hierarchy (e.g., rational numbers,\nefficiently stored arrays of integers, etc.), although such additions\nwill often be provided via the standard library instead.\n\nSome of the type descriptions below contain a paragraph listing\n\'special attributes.\'  These are attributes that provide access to the\nimplementation and are not intended for general use.  Their definition\nmay change in the future.\n\nNone\n   This type has a single value.  There is a single object with this\n   value. This object is accessed through the built-in name "None". It\n   is used to signify the absence of a value in many situations, e.g.,\n   it is returned from functions that don\'t explicitly return\n   anything. Its truth value is false.\n\nNotImplemented\n   This type has a single value.  There is a single object with this\n   value. This object is accessed through the built-in name\n   "NotImplemented". Numeric methods and rich comparison methods\n   should return this value if they do not implement the operation for\n   the operands provided.  (The interpreter will then try the\n   reflected operation, or some other fallback, depending on the\n   operator.)  Its truth value is true.\n\n   See *Implementing the arithmetic operations* for more details.\n\nEllipsis\n   This type has a single value.  There is a single object with this\n   value. This object is accessed through the literal "..." or the\n   built-in name "Ellipsis".  Its truth value is true.\n\n"numbers.Number"\n   These are created by numeric literals and returned as results by\n   arithmetic operators and arithmetic built-in functions.  Numeric\n   objects are immutable; once created their value never changes.\n   Python numbers are of course strongly related to mathematical\n   numbers, but subject to the limitations of numerical representation\n   in computers.\n\n   Python distinguishes between integers, floating point numbers, and\n   complex numbers:\n\n   "numbers.Integral"\n      These represent elements from the mathematical set of integers\n      (positive and negative).\n\n      There are two types of integers:\n\n      Integers ("int")\n\n         These represent numbers in an unlimited range, subject to\n         available (virtual) memory only.  For the purpose of shift\n         and mask operations, a binary representation is assumed, and\n         negative numbers are represented in a variant of 2\'s\n         complement which gives the illusion of an infinite string of\n         sign bits extending to the left.\n\n      Booleans ("bool")\n         These represent the truth values False and True.  The two\n         objects representing the values "False" and "True" are the\n         only Boolean objects. The Boolean type is a subtype of the\n         integer type, and Boolean values behave like the values 0 and\n         1, respectively, in almost all contexts, the exception being\n         that when converted to a string, the strings ""False"" or\n         ""True"" are returned, respectively.\n\n      The rules for integer representation are intended to give the\n      most meaningful interpretation of shift and mask operations\n      involving negative integers.\n\n   "numbers.Real" ("float")\n      These represent machine-level double precision floating point\n      numbers. You are at the mercy of the underlying machine\n      architecture (and C or Java implementation) for the accepted\n      range and handling of overflow. Python does not support single-\n      precision floating point numbers; the savings in processor and\n      memory usage that are usually the reason for using these are\n      dwarfed by the overhead of using objects in Python, so there is\n      no reason to complicate the language with two kinds of floating\n      point numbers.\n\n   "numbers.Complex" ("complex")\n      These represent complex numbers as a pair of machine-level\n      double precision floating point numbers.  The same caveats apply\n      as for floating point numbers. The real and imaginary parts of a\n      complex number "z" can be retrieved through the read-only\n      attributes "z.real" and "z.imag".\n\nSequences\n   These represent finite ordered sets indexed by non-negative\n   numbers. The built-in function "len()" returns the number of items\n   of a sequence. When the length of a sequence is *n*, the index set\n   contains the numbers 0, 1, ..., *n*-1.  Item *i* of sequence *a* is\n   selected by "a[i]".\n\n   Sequences also support slicing: "a[i:j]" selects all items with\n   index *k* such that *i* "<=" *k* "<" *j*.  When used as an\n   expression, a slice is a sequence of the same type.  This implies\n   that the index set is renumbered so that it starts at 0.\n\n   Some sequences also support "extended slicing" with a third "step"\n   parameter: "a[i:j:k]" selects all items of *a* with index *x* where\n   "x = i + n*k", *n* ">=" "0" and *i* "<=" *x* "<" *j*.\n\n   Sequences are distinguished according to their mutability:\n\n   Immutable sequences\n      An object of an immutable sequence type cannot change once it is\n      created.  (If the object contains references to other objects,\n      these other objects may be mutable and may be changed; however,\n      the collection of objects directly referenced by an immutable\n      object cannot change.)\n\n      The following types are immutable sequences:\n\n      Strings\n         A string is a sequence of values that represent Unicode code\n         points. All the code points in the range "U+0000 - U+10FFFF"\n         can be represented in a string.  Python doesn\'t have a "char"\n         type; instead, every code point in the string is represented\n         as a string object with length "1".  The built-in function\n         "ord()" converts a code point from its string form to an\n         integer in the range "0 - 10FFFF"; "chr()" converts an\n         integer in the range "0 - 10FFFF" to the corresponding length\n         "1" string object. "str.encode()" can be used to convert a\n         "str" to "bytes" using the given text encoding, and\n         "bytes.decode()" can be used to achieve the opposite.\n\n      Tuples\n         The items of a tuple are arbitrary Python objects. Tuples of\n         two or more items are formed by comma-separated lists of\n         expressions.  A tuple of one item (a \'singleton\') can be\n         formed by affixing a comma to an expression (an expression by\n         itself does not create a tuple, since parentheses must be\n         usable for grouping of expressions).  An empty tuple can be\n         formed by an empty pair of parentheses.\n\n      Bytes\n         A bytes object is an immutable array.  The items are 8-bit\n         bytes, represented by integers in the range 0 <= x < 256.\n         Bytes literals (like "b\'abc\'") and the built-in function\n         "bytes()" can be used to construct bytes objects.  Also,\n         bytes objects can be decoded to strings via the "decode()"\n         method.\n\n   Mutable sequences\n      Mutable sequences can be changed after they are created.  The\n      subscription and slicing notations can be used as the target of\n      assignment and "del" (delete) statements.\n\n      There are currently two intrinsic mutable sequence types:\n\n      Lists\n         The items of a list are arbitrary Python objects.  Lists are\n         formed by placing a comma-separated list of expressions in\n         square brackets. (Note that there are no special cases needed\n         to form lists of length 0 or 1.)\n\n      Byte Arrays\n         A bytearray object is a mutable array. They are created by\n         the built-in "bytearray()" constructor.  Aside from being\n         mutable (and hence unhashable), byte arrays otherwise provide\n         the same interface and functionality as immutable bytes\n         objects.\n\n      The extension module "array" provides an additional example of a\n      mutable sequence type, as does the "collections" module.\n\nSet types\n   These represent unordered, finite sets of unique, immutable\n   objects. As such, they cannot be indexed by any subscript. However,\n   they can be iterated over, and the built-in function "len()"\n   returns the number of items in a set. Common uses for sets are fast\n   membership testing, removing duplicates from a sequence, and\n   computing mathematical operations such as intersection, union,\n   difference, and symmetric difference.\n\n   For set elements, the same immutability rules apply as for\n   dictionary keys. Note that numeric types obey the normal rules for\n   numeric comparison: if two numbers compare equal (e.g., "1" and\n   "1.0"), only one of them can be contained in a set.\n\n   There are currently two intrinsic set types:\n\n   Sets\n      These represent a mutable set. They are created by the built-in\n      "set()" constructor and can be modified afterwards by several\n      methods, such as "add()".\n\n   Frozen sets\n      These represent an immutable set.  They are created by the\n      built-in "frozenset()" constructor.  As a frozenset is immutable\n      and *hashable*, it can be used again as an element of another\n      set, or as a dictionary key.\n\nMappings\n   These represent finite sets of objects indexed by arbitrary index\n   sets. The subscript notation "a[k]" selects the item indexed by "k"\n   from the mapping "a"; this can be used in expressions and as the\n   target of assignments or "del" statements. The built-in function\n   "len()" returns the number of items in a mapping.\n\n   There is currently a single intrinsic mapping type:\n\n   Dictionaries\n      These represent finite sets of objects indexed by nearly\n      arbitrary values.  The only types of values not acceptable as\n      keys are values containing lists or dictionaries or other\n      mutable types that are compared by value rather than by object\n      identity, the reason being that the efficient implementation of\n      dictionaries requires a key\'s hash value to remain constant.\n      Numeric types used for keys obey the normal rules for numeric\n      comparison: if two numbers compare equal (e.g., "1" and "1.0")\n      then they can be used interchangeably to index the same\n      dictionary entry.\n\n      Dictionaries are mutable; they can be created by the "{...}"\n      notation (see section *Dictionary displays*).\n\n      The extension modules "dbm.ndbm" and "dbm.gnu" provide\n      additional examples of mapping types, as does the "collections"\n      module.\n\nCallable types\n   These are the types to which the function call operation (see\n   section *Calls*) can be applied:\n\n   User-defined functions\n      A user-defined function object is created by a function\n      definition (see section *Function definitions*).  It should be\n      called with an argument list containing the same number of items\n      as the function\'s formal parameter list.\n\n      Special attributes:\n\n      +---------------------------+---------------------------------+-------------+\n      | Attribute                 | Meaning                         |             |\n      +===========================+=================================+=============+\n      | "__doc__"                 | The function\'s documentation    | Writable    |\n      |                           | string, or "None" if            |             |\n      |                           | unavailable; not inherited by   |             |\n      |                           | subclasses                      |             |\n      +---------------------------+---------------------------------+-------------+\n      | "__name__"                | The function\'s name             | Writable    |\n      +---------------------------+---------------------------------+-------------+\n      | "__qualname__"            | The function\'s *qualified name* | Writable    |\n      |                           | New in version 3.3.             |             |\n      +---------------------------+---------------------------------+-------------+\n      | "__module__"              | The name of the module the      | Writable    |\n      |                           | function was defined in, or     |             |\n      |                           | "None" if unavailable.          |             |\n      +---------------------------+---------------------------------+-------------+\n      | "__defaults__"            | A tuple containing default      | Writable    |\n      |                           | argument values for those       |             |\n      |                           | arguments that have defaults,   |             |\n      |                           | or "None" if no arguments have  |             |\n      |                           | a default value                 |             |\n      +---------------------------+---------------------------------+-------------+\n      | "__code__"                | The code object representing    | Writable    |\n      |                           | the compiled function body.     |             |\n      +---------------------------+---------------------------------+-------------+\n      | "__globals__"             | A reference to the dictionary   | Read-only   |\n      |                           | that holds the function\'s       |             |\n      |                           | global variables --- the global |             |\n      |                           | namespace of the module in      |             |\n      |                           | which the function was defined. |             |\n      +---------------------------+---------------------------------+-------------+\n      | "__dict__"                | The namespace supporting        | Writable    |\n      |                           | arbitrary function attributes.  |             |\n      +---------------------------+---------------------------------+-------------+\n      | "__closure__"             | "None" or a tuple of cells that | Read-only   |\n      |                           | contain bindings for the        |             |\n      |                           | function\'s free variables.      |             |\n      +---------------------------+---------------------------------+-------------+\n      | "__annotations__"         | A dict containing annotations   | Writable    |\n      |                           | of parameters.  The keys of the |             |\n      |                           | dict are the parameter names,   |             |\n      |                           | and "\'return\'" for the return   |             |\n      |                           | annotation, if provided.        |             |\n      +---------------------------+---------------------------------+-------------+\n      | "__kwdefaults__"          | A dict containing defaults for  | Writable    |\n      |                           | keyword-only parameters.        |             |\n      +---------------------------+---------------------------------+-------------+\n\n      Most of the attributes labelled "Writable" check the type of the\n      assigned value.\n\n      Function objects also support getting and setting arbitrary\n      attributes, which can be used, for example, to attach metadata\n      to functions.  Regular attribute dot-notation is used to get and\n      set such attributes. *Note that the current implementation only\n      supports function attributes on user-defined functions. Function\n      attributes on built-in functions may be supported in the\n      future.*\n\n      Additional information about a function\'s definition can be\n      retrieved from its code object; see the description of internal\n      types below.\n\n   Instance methods\n      An instance method object combines a class, a class instance and\n      any callable object (normally a user-defined function).\n\n      Special read-only attributes: "__self__" is the class instance\n      object, "__func__" is the function object; "__doc__" is the\n      method\'s documentation (same as "__func__.__doc__"); "__name__"\n      is the method name (same as "__func__.__name__"); "__module__"\n      is the name of the module the method was defined in, or "None"\n      if unavailable.\n\n      Methods also support accessing (but not setting) the arbitrary\n      function attributes on the underlying function object.\n\n      User-defined method objects may be created when getting an\n      attribute of a class (perhaps via an instance of that class), if\n      that attribute is a user-defined function object or a class\n      method object.\n\n      When an instance method object is created by retrieving a user-\n      defined function object from a class via one of its instances,\n      its "__self__" attribute is the instance, and the method object\n      is said to be bound.  The new method\'s "__func__" attribute is\n      the original function object.\n\n      When a user-defined method object is created by retrieving\n      another method object from a class or instance, the behaviour is\n      the same as for a function object, except that the "__func__"\n      attribute of the new instance is not the original method object\n      but its "__func__" attribute.\n\n      When an instance method object is created by retrieving a class\n      method object from a class or instance, its "__self__" attribute\n      is the class itself, and its "__func__" attribute is the\n      function object underlying the class method.\n\n      When an instance method object is called, the underlying\n      function ("__func__") is called, inserting the class instance\n      ("__self__") in front of the argument list.  For instance, when\n      "C" is a class which contains a definition for a function "f()",\n      and "x" is an instance of "C", calling "x.f(1)" is equivalent to\n      calling "C.f(x, 1)".\n\n      When an instance method object is derived from a class method\n      object, the "class instance" stored in "__self__" will actually\n      be the class itself, so that calling either "x.f(1)" or "C.f(1)"\n      is equivalent to calling "f(C,1)" where "f" is the underlying\n      function.\n\n      Note that the transformation from function object to instance\n      method object happens each time the attribute is retrieved from\n      the instance.  In some cases, a fruitful optimization is to\n      assign the attribute to a local variable and call that local\n      variable. Also notice that this transformation only happens for\n      user-defined functions; other callable objects (and all non-\n      callable objects) are retrieved without transformation.  It is\n      also important to note that user-defined functions which are\n      attributes of a class instance are not converted to bound\n      methods; this *only* happens when the function is an attribute\n      of the class.\n\n   Generator functions\n      A function or method which uses the "yield" statement (see\n      section *The yield statement*) is called a *generator function*.\n      Such a function, when called, always returns an iterator object\n      which can be used to execute the body of the function:  calling\n      the iterator\'s "iterator.__next__()" method will cause the\n      function to execute until it provides a value using the "yield"\n      statement.  When the function executes a "return" statement or\n      falls off the end, a "StopIteration" exception is raised and the\n      iterator will have reached the end of the set of values to be\n      returned.\n\n   Coroutine functions\n      A function or method which is defined using "async def" is\n      called a *coroutine function*.  Such a function, when called,\n      returns a *coroutine* object.  It may contain "await"\n      expressions, as well as "async with" and "async for" statements.\n      See also the *Coroutine Objects* section.\n\n   Built-in functions\n      A built-in function object is a wrapper around a C function.\n      Examples of built-in functions are "len()" and "math.sin()"\n      ("math" is a standard built-in module). The number and type of\n      the arguments are determined by the C function. Special read-\n      only attributes: "__doc__" is the function\'s documentation\n      string, or "None" if unavailable; "__name__" is the function\'s\n      name; "__self__" is set to "None" (but see the next item);\n      "__module__" is the name of the module the function was defined\n      in or "None" if unavailable.\n\n   Built-in methods\n      This is really a different disguise of a built-in function, this\n      time containing an object passed to the C function as an\n      implicit extra argument.  An example of a built-in method is\n      "alist.append()", assuming *alist* is a list object. In this\n      case, the special read-only attribute "__self__" is set to the\n      object denoted by *alist*.\n\n   Classes\n      Classes are callable.  These objects normally act as factories\n      for new instances of themselves, but variations are possible for\n      class types that override "__new__()".  The arguments of the\n      call are passed to "__new__()" and, in the typical case, to\n      "__init__()" to initialize the new instance.\n\n   Class Instances\n      Instances of arbitrary classes can be made callable by defining\n      a "__call__()" method in their class.\n\nModules\n   Modules are a basic organizational unit of Python code, and are\n   created by the *import system* as invoked either by the "import"\n   statement (see "import"), or by calling functions such as\n   "importlib.import_module()" and built-in "__import__()".  A module\n   object has a namespace implemented by a dictionary object (this is\n   the dictionary referenced by the "__globals__" attribute of\n   functions defined in the module).  Attribute references are\n   translated to lookups in this dictionary, e.g., "m.x" is equivalent\n   to "m.__dict__["x"]". A module object does not contain the code\n   object used to initialize the module (since it isn\'t needed once\n   the initialization is done).\n\n   Attribute assignment updates the module\'s namespace dictionary,\n   e.g., "m.x = 1" is equivalent to "m.__dict__["x"] = 1".\n\n   Special read-only attribute: "__dict__" is the module\'s namespace\n   as a dictionary object.\n\n   **CPython implementation detail:** Because of the way CPython\n   clears module dictionaries, the module dictionary will be cleared\n   when the module falls out of scope even if the dictionary still has\n   live references.  To avoid this, copy the dictionary or keep the\n   module around while using its dictionary directly.\n\n   Predefined (writable) attributes: "__name__" is the module\'s name;\n   "__doc__" is the module\'s documentation string, or "None" if\n   unavailable; "__file__" is the pathname of the file from which the\n   module was loaded, if it was loaded from a file. The "__file__"\n   attribute may be missing for certain types of modules, such as C\n   modules that are statically linked into the interpreter; for\n   extension modules loaded dynamically from a shared library, it is\n   the pathname of the shared library file.\n\nCustom classes\n   Custom class types are typically created by class definitions (see\n   section *Class definitions*).  A class has a namespace implemented\n   by a dictionary object. Class attribute references are translated\n   to lookups in this dictionary, e.g., "C.x" is translated to\n   "C.__dict__["x"]" (although there are a number of hooks which allow\n   for other means of locating attributes). When the attribute name is\n   not found there, the attribute search continues in the base\n   classes. This search of the base classes uses the C3 method\n   resolution order which behaves correctly even in the presence of\n   \'diamond\' inheritance structures where there are multiple\n   inheritance paths leading back to a common ancestor. Additional\n   details on the C3 MRO used by Python can be found in the\n   documentation accompanying the 2.3 release at\n   https://www.python.org/download/releases/2.3/mro/.\n\n   When a class attribute reference (for class "C", say) would yield a\n   class method object, it is transformed into an instance method\n   object whose "__self__" attributes is "C".  When it would yield a\n   static method object, it is transformed into the object wrapped by\n   the static method object. See section *Implementing Descriptors*\n   for another way in which attributes retrieved from a class may\n   differ from those actually contained in its "__dict__".\n\n   Class attribute assignments update the class\'s dictionary, never\n   the dictionary of a base class.\n\n   A class object can be called (see above) to yield a class instance\n   (see below).\n\n   Special attributes: "__name__" is the class name; "__module__" is\n   the module name in which the class was defined; "__dict__" is the\n   dictionary containing the class\'s namespace; "__bases__" is a tuple\n   (possibly empty or a singleton) containing the base classes, in the\n   order of their occurrence in the base class list; "__doc__" is the\n   class\'s documentation string, or None if undefined.\n\nClass instances\n   A class instance is created by calling a class object (see above).\n   A class instance has a namespace implemented as a dictionary which\n   is the first place in which attribute references are searched.\n   When an attribute is not found there, and the instance\'s class has\n   an attribute by that name, the search continues with the class\n   attributes.  If a class attribute is found that is a user-defined\n   function object, it is transformed into an instance method object\n   whose "__self__" attribute is the instance.  Static method and\n   class method objects are also transformed; see above under\n   "Classes".  See section *Implementing Descriptors* for another way\n   in which attributes of a class retrieved via its instances may\n   differ from the objects actually stored in the class\'s "__dict__".\n   If no class attribute is found, and the object\'s class has a\n   "__getattr__()" method, that is called to satisfy the lookup.\n\n   Attribute assignments and deletions update the instance\'s\n   dictionary, never a class\'s dictionary.  If the class has a\n   "__setattr__()" or "__delattr__()" method, this is called instead\n   of updating the instance dictionary directly.\n\n   Class instances can pretend to be numbers, sequences, or mappings\n   if they have methods with certain special names.  See section\n   *Special method names*.\n\n   Special attributes: "__dict__" is the attribute dictionary;\n   "__class__" is the instance\'s class.\n\nI/O objects (also known as file objects)\n   A *file object* represents an open file.  Various shortcuts are\n   available to create file objects: the "open()" built-in function,\n   and also "os.popen()", "os.fdopen()", and the "makefile()" method\n   of socket objects (and perhaps by other functions or methods\n   provided by extension modules).\n\n   The objects "sys.stdin", "sys.stdout" and "sys.stderr" are\n   initialized to file objects corresponding to the interpreter\'s\n   standard input, output and error streams; they are all open in text\n   mode and therefore follow the interface defined by the\n   "io.TextIOBase" abstract class.\n\nInternal types\n   A few types used internally by the interpreter are exposed to the\n   user. Their definitions may change with future versions of the\n   interpreter, but they are mentioned here for completeness.\n\n   Code objects\n      Code objects represent *byte-compiled* executable Python code,\n      or *bytecode*. The difference between a code object and a\n      function object is that the function object contains an explicit\n      reference to the function\'s globals (the module in which it was\n      defined), while a code object contains no context; also the\n      default argument values are stored in the function object, not\n      in the code object (because they represent values calculated at\n      run-time).  Unlike function objects, code objects are immutable\n      and contain no references (directly or indirectly) to mutable\n      objects.\n\n      Special read-only attributes: "co_name" gives the function name;\n      "co_argcount" is the number of positional arguments (including\n      arguments with default values); "co_nlocals" is the number of\n      local variables used by the function (including arguments);\n      "co_varnames" is a tuple containing the names of the local\n      variables (starting with the argument names); "co_cellvars" is a\n      tuple containing the names of local variables that are\n      referenced by nested functions; "co_freevars" is a tuple\n      containing the names of free variables; "co_code" is a string\n      representing the sequence of bytecode instructions; "co_consts"\n      is a tuple containing the literals used by the bytecode;\n      "co_names" is a tuple containing the names used by the bytecode;\n      "co_filename" is the filename from which the code was compiled;\n      "co_firstlineno" is the first line number of the function;\n      "co_lnotab" is a string encoding the mapping from bytecode\n      offsets to line numbers (for details see the source code of the\n      interpreter); "co_stacksize" is the required stack size\n      (including local variables); "co_flags" is an integer encoding a\n      number of flags for the interpreter.\n\n      The following flag bits are defined for "co_flags": bit "0x04"\n      is set if the function uses the "*arguments" syntax to accept an\n      arbitrary number of positional arguments; bit "0x08" is set if\n      the function uses the "**keywords" syntax to accept arbitrary\n      keyword arguments; bit "0x20" is set if the function is a\n      generator.\n\n      Future feature declarations ("from __future__ import division")\n      also use bits in "co_flags" to indicate whether a code object\n      was compiled with a particular feature enabled: bit "0x2000" is\n      set if the function was compiled with future division enabled;\n      bits "0x10" and "0x1000" were used in earlier versions of\n      Python.\n\n      Other bits in "co_flags" are reserved for internal use.\n\n      If a code object represents a function, the first item in\n      "co_consts" is the documentation string of the function, or\n      "None" if undefined.\n\n   Frame objects\n      Frame objects represent execution frames.  They may occur in\n      traceback objects (see below).\n\n      Special read-only attributes: "f_back" is to the previous stack\n      frame (towards the caller), or "None" if this is the bottom\n      stack frame; "f_code" is the code object being executed in this\n      frame; "f_locals" is the dictionary used to look up local\n      variables; "f_globals" is used for global variables;\n      "f_builtins" is used for built-in (intrinsic) names; "f_lasti"\n      gives the precise instruction (this is an index into the\n      bytecode string of the code object).\n\n      Special writable attributes: "f_trace", if not "None", is a\n      function called at the start of each source code line (this is\n      used by the debugger); "f_lineno" is the current line number of\n      the frame --- writing to this from within a trace function jumps\n      to the given line (only for the bottom-most frame).  A debugger\n      can implement a Jump command (aka Set Next Statement) by writing\n      to f_lineno.\n\n      Frame objects support one method:\n\n      frame.clear()\n\n         This method clears all references to local variables held by\n         the frame.  Also, if the frame belonged to a generator, the\n         generator is finalized.  This helps break reference cycles\n         involving frame objects (for example when catching an\n         exception and storing its traceback for later use).\n\n         "RuntimeError" is raised if the frame is currently executing.\n\n         New in version 3.4.\n\n   Traceback objects\n      Traceback objects represent a stack trace of an exception.  A\n      traceback object is created when an exception occurs.  When the\n      search for an exception handler unwinds the execution stack, at\n      each unwound level a traceback object is inserted in front of\n      the current traceback.  When an exception handler is entered,\n      the stack trace is made available to the program. (See section\n      *The try statement*.) It is accessible as the third item of the\n      tuple returned by "sys.exc_info()". When the program contains no\n      suitable handler, the stack trace is written (nicely formatted)\n      to the standard error stream; if the interpreter is interactive,\n      it is also made available to the user as "sys.last_traceback".\n\n      Special read-only attributes: "tb_next" is the next level in the\n      stack trace (towards the frame where the exception occurred), or\n      "None" if there is no next level; "tb_frame" points to the\n      execution frame of the current level; "tb_lineno" gives the line\n      number where the exception occurred; "tb_lasti" indicates the\n      precise instruction.  The line number and last instruction in\n      the traceback may differ from the line number of its frame\n      object if the exception occurred in a "try" statement with no\n      matching except clause or with a finally clause.\n\n   Slice objects\n      Slice objects are used to represent slices for "__getitem__()"\n      methods.  They are also created by the built-in "slice()"\n      function.\n\n      Special read-only attributes: "start" is the lower bound; "stop"\n      is the upper bound; "step" is the step value; each is "None" if\n      omitted.  These attributes can have any type.\n\n      Slice objects support one method:\n\n      slice.indices(self, length)\n\n         This method takes a single integer argument *length* and\n         computes information about the slice that the slice object\n         would describe if applied to a sequence of *length* items.\n         It returns a tuple of three integers; respectively these are\n         the *start* and *stop* indices and the *step* or stride\n         length of the slice. Missing or out-of-bounds indices are\n         handled in a manner consistent with regular slices.\n\n   Static method objects\n      Static method objects provide a way of defeating the\n      transformation of function objects to method objects described\n      above. A static method object is a wrapper around any other\n      object, usually a user-defined method object. When a static\n      method object is retrieved from a class or a class instance, the\n      object actually returned is the wrapped object, which is not\n      subject to any further transformation. Static method objects are\n      not themselves callable, although the objects they wrap usually\n      are. Static method objects are created by the built-in\n      "staticmethod()" constructor.\n\n   Class method objects\n      A class method object, like a static method object, is a wrapper\n      around another object that alters the way in which that object\n      is retrieved from classes and class instances. The behaviour of\n      class method objects upon such retrieval is described above,\n      under "User-defined methods". Class method objects are created\n      by the built-in "classmethod()" constructor.\n',
- 'typesfunctions': u'\nFunctions\n*********\n\nFunction objects are created by function definitions.  The only\noperation on a function object is to call it: "func(argument-list)".\n\nThere are really two flavors of function objects: built-in functions\nand user-defined functions.  Both support the same operation (to call\nthe function), but the implementation is different, hence the\ndifferent object types.\n\nSee *Function definitions* for more information.\n',
- 'typesmapping': u'\nMapping Types --- "dict"\n************************\n\nA *mapping* object maps *hashable* values to arbitrary objects.\nMappings are mutable objects.  There is currently only one standard\nmapping type, the *dictionary*.  (For other containers see the built-\nin "list", "set", and "tuple" classes, and the "collections" module.)\n\nA dictionary\'s keys are *almost* arbitrary values.  Values that are\nnot *hashable*, that is, values containing lists, dictionaries or\nother mutable types (that are compared by value rather than by object\nidentity) may not be used as keys.  Numeric types used for keys obey\nthe normal rules for numeric comparison: if two numbers compare equal\n(such as "1" and "1.0") then they can be used interchangeably to index\nthe same dictionary entry.  (Note however, that since computers store\nfloating-point numbers as approximations it is usually unwise to use\nthem as dictionary keys.)\n\nDictionaries can be created by placing a comma-separated list of "key:\nvalue" pairs within braces, for example: "{\'jack\': 4098, \'sjoerd\':\n4127}" or "{4098: \'jack\', 4127: \'sjoerd\'}", or by the "dict"\nconstructor.\n\nclass class dict(**kwarg)\nclass class dict(mapping, **kwarg)\nclass class dict(iterable, **kwarg)\n\n   Return a new dictionary initialized from an optional positional\n   argument and a possibly empty set of keyword arguments.\n\n   If no positional argument is given, an empty dictionary is created.\n   If a positional argument is given and it is a mapping object, a\n   dictionary is created with the same key-value pairs as the mapping\n   object.  Otherwise, the positional argument must be an *iterable*\n   object.  Each item in the iterable must itself be an iterable with\n   exactly two objects.  The first object of each item becomes a key\n   in the new dictionary, and the second object the corresponding\n   value.  If a key occurs more than once, the last value for that key\n   becomes the corresponding value in the new dictionary.\n\n   If keyword arguments are given, the keyword arguments and their\n   values are added to the dictionary created from the positional\n   argument.  If a key being added is already present, the value from\n   the keyword argument replaces the value from the positional\n   argument.\n\n   To illustrate, the following examples all return a dictionary equal\n   to "{"one": 1, "two": 2, "three": 3}":\n\n      >>> a = dict(one=1, two=2, three=3)\n      >>> b = {\'one\': 1, \'two\': 2, \'three\': 3}\n      >>> c = dict(zip([\'one\', \'two\', \'three\'], [1, 2, 3]))\n      >>> d = dict([(\'two\', 2), (\'one\', 1), (\'three\', 3)])\n      >>> e = dict({\'three\': 3, \'one\': 1, \'two\': 2})\n      >>> a == b == c == d == e\n      True\n\n   Providing keyword arguments as in the first example only works for\n   keys that are valid Python identifiers.  Otherwise, any valid keys\n   can be used.\n\n   These are the operations that dictionaries support (and therefore,\n   custom mapping types should support too):\n\n   len(d)\n\n      Return the number of items in the dictionary *d*.\n\n   d[key]\n\n      Return the item of *d* with key *key*.  Raises a "KeyError" if\n      *key* is not in the map.\n\n      If a subclass of dict defines a method "__missing__()" and *key*\n      is not present, the "d[key]" operation calls that method with\n      the key *key* as argument.  The "d[key]" operation then returns\n      or raises whatever is returned or raised by the\n      "__missing__(key)" call. No other operations or methods invoke\n      "__missing__()". If "__missing__()" is not defined, "KeyError"\n      is raised. "__missing__()" must be a method; it cannot be an\n      instance variable:\n\n         >>> class Counter(dict):\n         ...     def __missing__(self, key):\n         ...         return 0\n         >>> c = Counter()\n         >>> c[\'red\']\n         0\n         >>> c[\'red\'] += 1\n         >>> c[\'red\']\n         1\n\n      The example above shows part of the implementation of\n      "collections.Counter".  A different "__missing__" method is used\n      by "collections.defaultdict".\n\n   d[key] = value\n\n      Set "d[key]" to *value*.\n\n   del d[key]\n\n      Remove "d[key]" from *d*.  Raises a "KeyError" if *key* is not\n      in the map.\n\n   key in d\n\n      Return "True" if *d* has a key *key*, else "False".\n\n   key not in d\n\n      Equivalent to "not key in d".\n\n   iter(d)\n\n      Return an iterator over the keys of the dictionary.  This is a\n      shortcut for "iter(d.keys())".\n\n   clear()\n\n      Remove all items from the dictionary.\n\n   copy()\n\n      Return a shallow copy of the dictionary.\n\n   classmethod fromkeys(seq[, value])\n\n      Create a new dictionary with keys from *seq* and values set to\n      *value*.\n\n      "fromkeys()" is a class method that returns a new dictionary.\n      *value* defaults to "None".\n\n   get(key[, default])\n\n      Return the value for *key* if *key* is in the dictionary, else\n      *default*. If *default* is not given, it defaults to "None", so\n      that this method never raises a "KeyError".\n\n   items()\n\n      Return a new view of the dictionary\'s items ("(key, value)"\n      pairs). See the *documentation of view objects*.\n\n   keys()\n\n      Return a new view of the dictionary\'s keys.  See the\n      *documentation of view objects*.\n\n   pop(key[, default])\n\n      If *key* is in the dictionary, remove it and return its value,\n      else return *default*.  If *default* is not given and *key* is\n      not in the dictionary, a "KeyError" is raised.\n\n   popitem()\n\n      Remove and return an arbitrary "(key, value)" pair from the\n      dictionary.\n\n      "popitem()" is useful to destructively iterate over a\n      dictionary, as often used in set algorithms.  If the dictionary\n      is empty, calling "popitem()" raises a "KeyError".\n\n   setdefault(key[, default])\n\n      If *key* is in the dictionary, return its value.  If not, insert\n      *key* with a value of *default* and return *default*.  *default*\n      defaults to "None".\n\n   update([other])\n\n      Update the dictionary with the key/value pairs from *other*,\n      overwriting existing keys.  Return "None".\n\n      "update()" accepts either another dictionary object or an\n      iterable of key/value pairs (as tuples or other iterables of\n      length two).  If keyword arguments are specified, the dictionary\n      is then updated with those key/value pairs: "d.update(red=1,\n      blue=2)".\n\n   values()\n\n      Return a new view of the dictionary\'s values.  See the\n      *documentation of view objects*.\n\n   Dictionaries compare equal if and only if they have the same "(key,\n   value)" pairs. Order comparisons (\'<\', \'<=\', \'>=\', \'>\') raise\n   "TypeError".\n\nSee also: "types.MappingProxyType" can be used to create a read-only\n  view of a "dict".\n\n\nDictionary view objects\n=======================\n\nThe objects returned by "dict.keys()", "dict.values()" and\n"dict.items()" are *view objects*.  They provide a dynamic view on the\ndictionary\'s entries, which means that when the dictionary changes,\nthe view reflects these changes.\n\nDictionary views can be iterated over to yield their respective data,\nand support membership tests:\n\nlen(dictview)\n\n   Return the number of entries in the dictionary.\n\niter(dictview)\n\n   Return an iterator over the keys, values or items (represented as\n   tuples of "(key, value)") in the dictionary.\n\n   Keys and values are iterated over in an arbitrary order which is\n   non-random, varies across Python implementations, and depends on\n   the dictionary\'s history of insertions and deletions. If keys,\n   values and items views are iterated over with no intervening\n   modifications to the dictionary, the order of items will directly\n   correspond.  This allows the creation of "(value, key)" pairs using\n   "zip()": "pairs = zip(d.values(), d.keys())".  Another way to\n   create the same list is "pairs = [(v, k) for (k, v) in d.items()]".\n\n   Iterating views while adding or deleting entries in the dictionary\n   may raise a "RuntimeError" or fail to iterate over all entries.\n\nx in dictview\n\n   Return "True" if *x* is in the underlying dictionary\'s keys, values\n   or items (in the latter case, *x* should be a "(key, value)"\n   tuple).\n\nKeys views are set-like since their entries are unique and hashable.\nIf all values are hashable, so that "(key, value)" pairs are unique\nand hashable, then the items view is also set-like.  (Values views are\nnot treated as set-like since the entries are generally not unique.)\nFor set-like views, all of the operations defined for the abstract\nbase class "collections.abc.Set" are available (for example, "==",\n"<", or "^").\n\nAn example of dictionary view usage:\n\n   >>> dishes = {\'eggs\': 2, \'sausage\': 1, \'bacon\': 1, \'spam\': 500}\n   >>> keys = dishes.keys()\n   >>> values = dishes.values()\n\n   >>> # iteration\n   >>> n = 0\n   >>> for val in values:\n   ...     n += val\n   >>> print(n)\n   504\n\n   >>> # keys and values are iterated over in the same order\n   >>> list(keys)\n   [\'eggs\', \'bacon\', \'sausage\', \'spam\']\n   >>> list(values)\n   [2, 1, 1, 500]\n\n   >>> # view objects are dynamic and reflect dict changes\n   >>> del dishes[\'eggs\']\n   >>> del dishes[\'sausage\']\n   >>> list(keys)\n   [\'spam\', \'bacon\']\n\n   >>> # set operations\n   >>> keys & {\'eggs\', \'bacon\', \'salad\'}\n   {\'bacon\'}\n   >>> keys ^ {\'sausage\', \'juice\'}\n   {\'juice\', \'sausage\', \'bacon\', \'spam\'}\n',
- 'typesmethods': u'\nMethods\n*******\n\nMethods are functions that are called using the attribute notation.\nThere are two flavors: built-in methods (such as "append()" on lists)\nand class instance methods.  Built-in methods are described with the\ntypes that support them.\n\nIf you access a method (a function defined in a class namespace)\nthrough an instance, you get a special object: a *bound method* (also\ncalled *instance method*) object. When called, it will add the "self"\nargument to the argument list.  Bound methods have two special read-\nonly attributes: "m.__self__" is the object on which the method\noperates, and "m.__func__" is the function implementing the method.\nCalling "m(arg-1, arg-2, ..., arg-n)" is completely equivalent to\ncalling "m.__func__(m.__self__, arg-1, arg-2, ..., arg-n)".\n\nLike function objects, bound method objects support getting arbitrary\nattributes.  However, since method attributes are actually stored on\nthe underlying function object ("meth.__func__"), setting method\nattributes on bound methods is disallowed.  Attempting to set an\nattribute on a method results in an "AttributeError" being raised.  In\norder to set a method attribute, you need to explicitly set it on the\nunderlying function object:\n\n   >>> class C:\n   ...     def method(self):\n   ...         pass\n   ...\n   >>> c = C()\n   >>> c.method.whoami = \'my name is method\'  # can\'t set on the method\n   Traceback (most recent call last):\n     File "<stdin>", line 1, in <module>\n   AttributeError: \'method\' object has no attribute \'whoami\'\n   >>> c.method.__func__.whoami = \'my name is method\'\n   >>> c.method.whoami\n   \'my name is method\'\n\nSee *The standard type hierarchy* for more information.\n',
- 'typesmodules': u'\nModules\n*******\n\nThe only special operation on a module is attribute access: "m.name",\nwhere *m* is a module and *name* accesses a name defined in *m*\'s\nsymbol table. Module attributes can be assigned to.  (Note that the\n"import" statement is not, strictly speaking, an operation on a module\nobject; "import foo" does not require a module object named *foo* to\nexist, rather it requires an (external) *definition* for a module\nnamed *foo* somewhere.)\n\nA special attribute of every module is "__dict__". This is the\ndictionary containing the module\'s symbol table. Modifying this\ndictionary will actually change the module\'s symbol table, but direct\nassignment to the "__dict__" attribute is not possible (you can write\n"m.__dict__[\'a\'] = 1", which defines "m.a" to be "1", but you can\'t\nwrite "m.__dict__ = {}").  Modifying "__dict__" directly is not\nrecommended.\n\nModules built into the interpreter are written like this: "<module\n\'sys\' (built-in)>".  If loaded from a file, they are written as\n"<module \'os\' from \'/usr/local/lib/pythonX.Y/os.pyc\'>".\n',
- 'typesseq': u'\nSequence Types --- "list", "tuple", "range"\n*******************************************\n\nThere are three basic sequence types: lists, tuples, and range\nobjects. Additional sequence types tailored for processing of *binary\ndata* and *text strings* are described in dedicated sections.\n\n\nCommon Sequence Operations\n==========================\n\nThe operations in the following table are supported by most sequence\ntypes, both mutable and immutable. The "collections.abc.Sequence" ABC\nis provided to make it easier to correctly implement these operations\non custom sequence types.\n\nThis table lists the sequence operations sorted in ascending priority.\nIn the table, *s* and *t* are sequences of the same type, *n*, *i*,\n*j* and *k* are integers and *x* is an arbitrary object that meets any\ntype and value restrictions imposed by *s*.\n\nThe "in" and "not in" operations have the same priorities as the\ncomparison operations. The "+" (concatenation) and "*" (repetition)\noperations have the same priority as the corresponding numeric\noperations.\n\n+----------------------------+----------------------------------+------------+\n| Operation                  | Result                           | Notes      |\n+============================+==================================+============+\n| "x in s"                   | "True" if an item of *s* is      | (1)        |\n|                            | equal to *x*, else "False"       |            |\n+----------------------------+----------------------------------+------------+\n| "x not in s"               | "False" if an item of *s* is     | (1)        |\n|                            | equal to *x*, else "True"        |            |\n+----------------------------+----------------------------------+------------+\n| "s + t"                    | the concatenation of *s* and *t* | (6)(7)     |\n+----------------------------+----------------------------------+------------+\n| "s * n" or "n * s"         | equivalent to adding *s* to      | (2)(7)     |\n|                            | itself *n* times                 |            |\n+----------------------------+----------------------------------+------------+\n| "s[i]"                     | *i*th item of *s*, origin 0      | (3)        |\n+----------------------------+----------------------------------+------------+\n| "s[i:j]"                   | slice of *s* from *i* to *j*     | (3)(4)     |\n+----------------------------+----------------------------------+------------+\n| "s[i:j:k]"                 | slice of *s* from *i* to *j*     | (3)(5)     |\n|                            | with step *k*                    |            |\n+----------------------------+----------------------------------+------------+\n| "len(s)"                   | length of *s*                    |            |\n+----------------------------+----------------------------------+------------+\n| "min(s)"                   | smallest item of *s*             |            |\n+----------------------------+----------------------------------+------------+\n| "max(s)"                   | largest item of *s*              |            |\n+----------------------------+----------------------------------+------------+\n| "s.index(x[, i[, j]])"     | index of the first occurrence of | (8)        |\n|                            | *x* in *s* (at or after index    |            |\n|                            | *i* and before index *j*)        |            |\n+----------------------------+----------------------------------+------------+\n| "s.count(x)"               | total number of occurrences of   |            |\n|                            | *x* in *s*                       |            |\n+----------------------------+----------------------------------+------------+\n\nSequences of the same type also support comparisons.  In particular,\ntuples and lists are compared lexicographically by comparing\ncorresponding elements. This means that to compare equal, every\nelement must compare equal and the two sequences must be of the same\ntype and have the same length.  (For full details see *Comparisons* in\nthe language reference.)\n\nNotes:\n\n1. While the "in" and "not in" operations are used only for simple\n   containment testing in the general case, some specialised sequences\n   (such as "str", "bytes" and "bytearray") also use them for\n   subsequence testing:\n\n      >>> "gg" in "eggs"\n      True\n\n2. Values of *n* less than "0" are treated as "0" (which yields an\n   empty sequence of the same type as *s*).  Note that items in the\n   sequence *s* are not copied; they are referenced multiple times.\n   This often haunts new Python programmers; consider:\n\n      >>> lists = [[]] * 3\n      >>> lists\n      [[], [], []]\n      >>> lists[0].append(3)\n      >>> lists\n      [[3], [3], [3]]\n\n   What has happened is that "[[]]" is a one-element list containing\n   an empty list, so all three elements of "[[]] * 3" are references\n   to this single empty list.  Modifying any of the elements of\n   "lists" modifies this single list. You can create a list of\n   different lists this way:\n\n      >>> lists = [[] for i in range(3)]\n      >>> lists[0].append(3)\n      >>> lists[1].append(5)\n      >>> lists[2].append(7)\n      >>> lists\n      [[3], [5], [7]]\n\n   Further explanation is available in the FAQ entry *How do I create\n   a multidimensional list?*.\n\n3. If *i* or *j* is negative, the index is relative to the end of\n   the string: "len(s) + i" or "len(s) + j" is substituted.  But note\n   that "-0" is still "0".\n\n4. The slice of *s* from *i* to *j* is defined as the sequence of\n   items with index *k* such that "i <= k < j".  If *i* or *j* is\n   greater than "len(s)", use "len(s)".  If *i* is omitted or "None",\n   use "0".  If *j* is omitted or "None", use "len(s)".  If *i* is\n   greater than or equal to *j*, the slice is empty.\n\n5. The slice of *s* from *i* to *j* with step *k* is defined as the\n   sequence of items with index  "x = i + n*k" such that "0 <= n <\n   (j-i)/k".  In other words, the indices are "i", "i+k", "i+2*k",\n   "i+3*k" and so on, stopping when *j* is reached (but never\n   including *j*).  If *i* or *j* is greater than "len(s)", use\n   "len(s)".  If *i* or *j* are omitted or "None", they become "end"\n   values (which end depends on the sign of *k*).  Note, *k* cannot be\n   zero. If *k* is "None", it is treated like "1".\n\n6. Concatenating immutable sequences always results in a new\n   object. This means that building up a sequence by repeated\n   concatenation will have a quadratic runtime cost in the total\n   sequence length. To get a linear runtime cost, you must switch to\n   one of the alternatives below:\n\n   * if concatenating "str" objects, you can build a list and use\n     "str.join()" at the end or else write to an "io.StringIO"\n     instance and retrieve its value when complete\n\n   * if concatenating "bytes" objects, you can similarly use\n     "bytes.join()" or "io.BytesIO", or you can do in-place\n     concatenation with a "bytearray" object.  "bytearray" objects are\n     mutable and have an efficient overallocation mechanism\n\n   * if concatenating "tuple" objects, extend a "list" instead\n\n   * for other types, investigate the relevant class documentation\n\n7. Some sequence types (such as "range") only support item\n   sequences that follow specific patterns, and hence don\'t support\n   sequence concatenation or repetition.\n\n8. "index" raises "ValueError" when *x* is not found in *s*. When\n   supported, the additional arguments to the index method allow\n   efficient searching of subsections of the sequence. Passing the\n   extra arguments is roughly equivalent to using "s[i:j].index(x)",\n   only without copying any data and with the returned index being\n   relative to the start of the sequence rather than the start of the\n   slice.\n\n\nImmutable Sequence Types\n========================\n\nThe only operation that immutable sequence types generally implement\nthat is not also implemented by mutable sequence types is support for\nthe "hash()" built-in.\n\nThis support allows immutable sequences, such as "tuple" instances, to\nbe used as "dict" keys and stored in "set" and "frozenset" instances.\n\nAttempting to hash an immutable sequence that contains unhashable\nvalues will result in "TypeError".\n\n\nMutable Sequence Types\n======================\n\nThe operations in the following table are defined on mutable sequence\ntypes. The "collections.abc.MutableSequence" ABC is provided to make\nit easier to correctly implement these operations on custom sequence\ntypes.\n\nIn the table *s* is an instance of a mutable sequence type, *t* is any\niterable object and *x* is an arbitrary object that meets any type and\nvalue restrictions imposed by *s* (for example, "bytearray" only\naccepts integers that meet the value restriction "0 <= x <= 255").\n\n+--------------------------------+----------------------------------+-----------------------+\n| Operation                      | Result                           | Notes                 |\n+================================+==================================+=======================+\n| "s[i] = x"                     | item *i* of *s* is replaced by   |                       |\n|                                | *x*                              |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s[i:j] = t"                   | slice of *s* from *i* to *j* is  |                       |\n|                                | replaced by the contents of the  |                       |\n|                                | iterable *t*                     |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "del s[i:j]"                   | same as "s[i:j] = []"            |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s[i:j:k] = t"                 | the elements of "s[i:j:k]" are   | (1)                   |\n|                                | replaced by those of *t*         |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "del s[i:j:k]"                 | removes the elements of          |                       |\n|                                | "s[i:j:k]" from the list         |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s.append(x)"                  | appends *x* to the end of the    |                       |\n|                                | sequence (same as                |                       |\n|                                | "s[len(s):len(s)] = [x]")        |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s.clear()"                    | removes all items from "s" (same | (5)                   |\n|                                | as "del s[:]")                   |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s.copy()"                     | creates a shallow copy of "s"    | (5)                   |\n|                                | (same as "s[:]")                 |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s.extend(t)" or "s += t"      | extends *s* with the contents of |                       |\n|                                | *t* (for the most part the same  |                       |\n|                                | as "s[len(s):len(s)] = t")       |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s *= n"                       | updates *s* with its contents    | (6)                   |\n|                                | repeated *n* times               |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s.insert(i, x)"               | inserts *x* into *s* at the      |                       |\n|                                | index given by *i* (same as      |                       |\n|                                | "s[i:i] = [x]")                  |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s.pop([i])"                   | retrieves the item at *i* and    | (2)                   |\n|                                | also removes it from *s*         |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s.remove(x)"                  | remove the first item from *s*   | (3)                   |\n|                                | where "s[i] == x"                |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s.reverse()"                  | reverses the items of *s* in     | (4)                   |\n|                                | place                            |                       |\n+--------------------------------+----------------------------------+-----------------------+\n\nNotes:\n\n1. *t* must have the same length as the slice it is replacing.\n\n2. The optional argument *i* defaults to "-1", so that by default\n   the last item is removed and returned.\n\n3. "remove" raises "ValueError" when *x* is not found in *s*.\n\n4. The "reverse()" method modifies the sequence in place for\n   economy of space when reversing a large sequence.  To remind users\n   that it operates by side effect, it does not return the reversed\n   sequence.\n\n5. "clear()" and "copy()" are included for consistency with the\n   interfaces of mutable containers that don\'t support slicing\n   operations (such as "dict" and "set")\n\n   New in version 3.3: "clear()" and "copy()" methods.\n\n6. The value *n* is an integer, or an object implementing\n   "__index__()".  Zero and negative values of *n* clear the sequence.\n   Items in the sequence are not copied; they are referenced multiple\n   times, as explained for "s * n" under *Common Sequence Operations*.\n\n\nLists\n=====\n\nLists are mutable sequences, typically used to store collections of\nhomogeneous items (where the precise degree of similarity will vary by\napplication).\n\nclass class list([iterable])\n\n   Lists may be constructed in several ways:\n\n   * Using a pair of square brackets to denote the empty list: "[]"\n\n   * Using square brackets, separating items with commas: "[a]",\n     "[a, b, c]"\n\n   * Using a list comprehension: "[x for x in iterable]"\n\n   * Using the type constructor: "list()" or "list(iterable)"\n\n   The constructor builds a list whose items are the same and in the\n   same order as *iterable*\'s items.  *iterable* may be either a\n   sequence, a container that supports iteration, or an iterator\n   object.  If *iterable* is already a list, a copy is made and\n   returned, similar to "iterable[:]". For example, "list(\'abc\')"\n   returns "[\'a\', \'b\', \'c\']" and "list( (1, 2, 3) )" returns "[1, 2,\n   3]". If no argument is given, the constructor creates a new empty\n   list, "[]".\n\n   Many other operations also produce lists, including the "sorted()"\n   built-in.\n\n   Lists implement all of the *common* and *mutable* sequence\n   operations. Lists also provide the following additional method:\n\n   sort(*, key=None, reverse=None)\n\n      This method sorts the list in place, using only "<" comparisons\n      between items. Exceptions are not suppressed - if any comparison\n      operations fail, the entire sort operation will fail (and the\n      list will likely be left in a partially modified state).\n\n      "sort()" accepts two arguments that can only be passed by\n      keyword (*keyword-only arguments*):\n\n      *key* specifies a function of one argument that is used to\n      extract a comparison key from each list element (for example,\n      "key=str.lower"). The key corresponding to each item in the list\n      is calculated once and then used for the entire sorting process.\n      The default value of "None" means that list items are sorted\n      directly without calculating a separate key value.\n\n      The "functools.cmp_to_key()" utility is available to convert a\n      2.x style *cmp* function to a *key* function.\n\n      *reverse* is a boolean value.  If set to "True", then the list\n      elements are sorted as if each comparison were reversed.\n\n      This method modifies the sequence in place for economy of space\n      when sorting a large sequence.  To remind users that it operates\n      by side effect, it does not return the sorted sequence (use\n      "sorted()" to explicitly request a new sorted list instance).\n\n      The "sort()" method is guaranteed to be stable.  A sort is\n      stable if it guarantees not to change the relative order of\n      elements that compare equal --- this is helpful for sorting in\n      multiple passes (for example, sort by department, then by salary\n      grade).\n\n      **CPython implementation detail:** While a list is being sorted,\n      the effect of attempting to mutate, or even inspect, the list is\n      undefined.  The C implementation of Python makes the list appear\n      empty for the duration, and raises "ValueError" if it can detect\n      that the list has been mutated during a sort.\n\n\nTuples\n======\n\nTuples are immutable sequences, typically used to store collections of\nheterogeneous data (such as the 2-tuples produced by the "enumerate()"\nbuilt-in). Tuples are also used for cases where an immutable sequence\nof homogeneous data is needed (such as allowing storage in a "set" or\n"dict" instance).\n\nclass class tuple([iterable])\n\n   Tuples may be constructed in a number of ways:\n\n   * Using a pair of parentheses to denote the empty tuple: "()"\n\n   * Using a trailing comma for a singleton tuple: "a," or "(a,)"\n\n   * Separating items with commas: "a, b, c" or "(a, b, c)"\n\n   * Using the "tuple()" built-in: "tuple()" or "tuple(iterable)"\n\n   The constructor builds a tuple whose items are the same and in the\n   same order as *iterable*\'s items.  *iterable* may be either a\n   sequence, a container that supports iteration, or an iterator\n   object.  If *iterable* is already a tuple, it is returned\n   unchanged. For example, "tuple(\'abc\')" returns "(\'a\', \'b\', \'c\')"\n   and "tuple( [1, 2, 3] )" returns "(1, 2, 3)". If no argument is\n   given, the constructor creates a new empty tuple, "()".\n\n   Note that it is actually the comma which makes a tuple, not the\n   parentheses. The parentheses are optional, except in the empty\n   tuple case, or when they are needed to avoid syntactic ambiguity.\n   For example, "f(a, b, c)" is a function call with three arguments,\n   while "f((a, b, c))" is a function call with a 3-tuple as the sole\n   argument.\n\n   Tuples implement all of the *common* sequence operations.\n\nFor heterogeneous collections of data where access by name is clearer\nthan access by index, "collections.namedtuple()" may be a more\nappropriate choice than a simple tuple object.\n\n\nRanges\n======\n\nThe "range" type represents an immutable sequence of numbers and is\ncommonly used for looping a specific number of times in "for" loops.\n\nclass class range(stop)\nclass class range(start, stop[, step])\n\n   The arguments to the range constructor must be integers (either\n   built-in "int" or any object that implements the "__index__"\n   special method).  If the *step* argument is omitted, it defaults to\n   "1". If the *start* argument is omitted, it defaults to "0". If\n   *step* is zero, "ValueError" is raised.\n\n   For a positive *step*, the contents of a range "r" are determined\n   by the formula "r[i] = start + step*i" where "i >= 0" and "r[i] <\n   stop".\n\n   For a negative *step*, the contents of the range are still\n   determined by the formula "r[i] = start + step*i", but the\n   constraints are "i >= 0" and "r[i] > stop".\n\n   A range object will be empty if "r[0]" does not meet the value\n   constraint. Ranges do support negative indices, but these are\n   interpreted as indexing from the end of the sequence determined by\n   the positive indices.\n\n   Ranges containing absolute values larger than "sys.maxsize" are\n   permitted but some features (such as "len()") may raise\n   "OverflowError".\n\n   Range examples:\n\n      >>> list(range(10))\n      [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]\n      >>> list(range(1, 11))\n      [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]\n      >>> list(range(0, 30, 5))\n      [0, 5, 10, 15, 20, 25]\n      >>> list(range(0, 10, 3))\n      [0, 3, 6, 9]\n      >>> list(range(0, -10, -1))\n      [0, -1, -2, -3, -4, -5, -6, -7, -8, -9]\n      >>> list(range(0))\n      []\n      >>> list(range(1, 0))\n      []\n\n   Ranges implement all of the *common* sequence operations except\n   concatenation and repetition (due to the fact that range objects\n   can only represent sequences that follow a strict pattern and\n   repetition and concatenation will usually violate that pattern).\n\nThe advantage of the "range" type over a regular "list" or "tuple" is\nthat a "range" object will always take the same (small) amount of\nmemory, no matter the size of the range it represents (as it only\nstores the "start", "stop" and "step" values, calculating individual\nitems and subranges as needed).\n\nRange objects implement the "collections.abc.Sequence" ABC, and\nprovide features such as containment tests, element index lookup,\nslicing and support for negative indices (see *Sequence Types ---\nlist, tuple, range*):\n\n>>> r = range(0, 20, 2)\n>>> r\nrange(0, 20, 2)\n>>> 11 in r\nFalse\n>>> 10 in r\nTrue\n>>> r.index(10)\n5\n>>> r[5]\n10\n>>> r[:5]\nrange(0, 10, 2)\n>>> r[-1]\n18\n\nTesting range objects for equality with "==" and "!=" compares them as\nsequences.  That is, two range objects are considered equal if they\nrepresent the same sequence of values.  (Note that two range objects\nthat compare equal might have different "start", "stop" and "step"\nattributes, for example "range(0) == range(2, 1, 3)" or "range(0, 3,\n2) == range(0, 4, 2)".)\n\nChanged in version 3.2: Implement the Sequence ABC. Support slicing\nand negative indices. Test "int" objects for membership in constant\ntime instead of iterating through all items.\n\nChanged in version 3.3: Define \'==\' and \'!=\' to compare range objects\nbased on the sequence of values they define (instead of comparing\nbased on object identity).\n\nNew in version 3.3: The "start", "stop" and "step" attributes.\n',
- 'typesseq-mutable': u'\nMutable Sequence Types\n**********************\n\nThe operations in the following table are defined on mutable sequence\ntypes. The "collections.abc.MutableSequence" ABC is provided to make\nit easier to correctly implement these operations on custom sequence\ntypes.\n\nIn the table *s* is an instance of a mutable sequence type, *t* is any\niterable object and *x* is an arbitrary object that meets any type and\nvalue restrictions imposed by *s* (for example, "bytearray" only\naccepts integers that meet the value restriction "0 <= x <= 255").\n\n+--------------------------------+----------------------------------+-----------------------+\n| Operation                      | Result                           | Notes                 |\n+================================+==================================+=======================+\n| "s[i] = x"                     | item *i* of *s* is replaced by   |                       |\n|                                | *x*                              |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s[i:j] = t"                   | slice of *s* from *i* to *j* is  |                       |\n|                                | replaced by the contents of the  |                       |\n|                                | iterable *t*                     |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "del s[i:j]"                   | same as "s[i:j] = []"            |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s[i:j:k] = t"                 | the elements of "s[i:j:k]" are   | (1)                   |\n|                                | replaced by those of *t*         |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "del s[i:j:k]"                 | removes the elements of          |                       |\n|                                | "s[i:j:k]" from the list         |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s.append(x)"                  | appends *x* to the end of the    |                       |\n|                                | sequence (same as                |                       |\n|                                | "s[len(s):len(s)] = [x]")        |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s.clear()"                    | removes all items from "s" (same | (5)                   |\n|                                | as "del s[:]")                   |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s.copy()"                     | creates a shallow copy of "s"    | (5)                   |\n|                                | (same as "s[:]")                 |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s.extend(t)" or "s += t"      | extends *s* with the contents of |                       |\n|                                | *t* (for the most part the same  |                       |\n|                                | as "s[len(s):len(s)] = t")       |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s *= n"                       | updates *s* with its contents    | (6)                   |\n|                                | repeated *n* times               |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s.insert(i, x)"               | inserts *x* into *s* at the      |                       |\n|                                | index given by *i* (same as      |                       |\n|                                | "s[i:i] = [x]")                  |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s.pop([i])"                   | retrieves the item at *i* and    | (2)                   |\n|                                | also removes it from *s*         |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s.remove(x)"                  | remove the first item from *s*   | (3)                   |\n|                                | where "s[i] == x"                |                       |\n+--------------------------------+----------------------------------+-----------------------+\n| "s.reverse()"                  | reverses the items of *s* in     | (4)                   |\n|                                | place                            |                       |\n+--------------------------------+----------------------------------+-----------------------+\n\nNotes:\n\n1. *t* must have the same length as the slice it is replacing.\n\n2. The optional argument *i* defaults to "-1", so that by default\n   the last item is removed and returned.\n\n3. "remove" raises "ValueError" when *x* is not found in *s*.\n\n4. The "reverse()" method modifies the sequence in place for\n   economy of space when reversing a large sequence.  To remind users\n   that it operates by side effect, it does not return the reversed\n   sequence.\n\n5. "clear()" and "copy()" are included for consistency with the\n   interfaces of mutable containers that don\'t support slicing\n   operations (such as "dict" and "set")\n\n   New in version 3.3: "clear()" and "copy()" methods.\n\n6. The value *n* is an integer, or an object implementing\n   "__index__()".  Zero and negative values of *n* clear the sequence.\n   Items in the sequence are not copied; they are referenced multiple\n   times, as explained for "s * n" under *Common Sequence Operations*.\n',
- 'unary': u'\nUnary arithmetic and bitwise operations\n***************************************\n\nAll unary arithmetic and bitwise operations have the same priority:\n\n   u_expr ::= power | "-" u_expr | "+" u_expr | "~" u_expr\n\nThe unary "-" (minus) operator yields the negation of its numeric\nargument.\n\nThe unary "+" (plus) operator yields its numeric argument unchanged.\n\nThe unary "~" (invert) operator yields the bitwise inversion of its\ninteger argument.  The bitwise inversion of "x" is defined as\n"-(x+1)".  It only applies to integral numbers.\n\nIn all three cases, if the argument does not have the proper type, a\n"TypeError" exception is raised.\n',
- 'while': u'\nThe "while" statement\n*********************\n\nThe "while" statement is used for repeated execution as long as an\nexpression is true:\n\n   while_stmt ::= "while" expression ":" suite\n                  ["else" ":" suite]\n\nThis repeatedly tests the expression and, if it is true, executes the\nfirst suite; if the expression is false (which may be the first time\nit is tested) the suite of the "else" clause, if present, is executed\nand the loop terminates.\n\nA "break" statement executed in the first suite terminates the loop\nwithout executing the "else" clause\'s suite.  A "continue" statement\nexecuted in the first suite skips the rest of the suite and goes back\nto testing the expression.\n',
- 'with': u'\nThe "with" statement\n********************\n\nThe "with" statement is used to wrap the execution of a block with\nmethods defined by a context manager (see section *With Statement\nContext Managers*). This allows common "try"..."except"..."finally"\nusage patterns to be encapsulated for convenient reuse.\n\n   with_stmt ::= "with" with_item ("," with_item)* ":" suite\n   with_item ::= expression ["as" target]\n\nThe execution of the "with" statement with one "item" proceeds as\nfollows:\n\n1. The context expression (the expression given in the "with_item")\n   is evaluated to obtain a context manager.\n\n2. The context manager\'s "__exit__()" is loaded for later use.\n\n3. The context manager\'s "__enter__()" method is invoked.\n\n4. If a target was included in the "with" statement, the return\n   value from "__enter__()" is assigned to it.\n\n   Note: The "with" statement guarantees that if the "__enter__()"\n     method returns without an error, then "__exit__()" will always be\n     called. Thus, if an error occurs during the assignment to the\n     target list, it will be treated the same as an error occurring\n     within the suite would be. See step 6 below.\n\n5. The suite is executed.\n\n6. The context manager\'s "__exit__()" method is invoked.  If an\n   exception caused the suite to be exited, its type, value, and\n   traceback are passed as arguments to "__exit__()". Otherwise, three\n   "None" arguments are supplied.\n\n   If the suite was exited due to an exception, and the return value\n   from the "__exit__()" method was false, the exception is reraised.\n   If the return value was true, the exception is suppressed, and\n   execution continues with the statement following the "with"\n   statement.\n\n   If the suite was exited for any reason other than an exception, the\n   return value from "__exit__()" is ignored, and execution proceeds\n   at the normal location for the kind of exit that was taken.\n\nWith more than one item, the context managers are processed as if\nmultiple "with" statements were nested:\n\n   with A() as a, B() as b:\n       suite\n\nis equivalent to\n\n   with A() as a:\n       with B() as b:\n           suite\n\nChanged in version 3.1: Support for multiple context expressions.\n\nSee also: **PEP 0343** - The "with" statement\n\n     The specification, background, and examples for the Python "with"\n     statement.\n',
- 'yield': u'\nThe "yield" statement\n*********************\n\n   yield_stmt ::= yield_expression\n\nA "yield" statement is semantically equivalent to a *yield\nexpression*. The yield statement can be used to omit the parentheses\nthat would otherwise be required in the equivalent yield expression\nstatement. For example, the yield statements\n\n   yield <expr>\n   yield from <expr>\n\nare equivalent to the yield expression statements\n\n   (yield <expr>)\n   (yield from <expr>)\n\nYield expressions and statements are only used when defining a\n*generator* function, and are only used in the body of the generator\nfunction.  Using yield in a function definition is sufficient to cause\nthat definition to create a generator function instead of a normal\nfunction.\n\nFor full details of "yield" semantics, refer to the *Yield\nexpressions* section.\n'}
+# Autogenerated by Sphinx on Mon May 16 13:41:38 2016
+topics = {'assert': '\n'
+           'The "assert" statement\n'
+           '**********************\n'
+           '\n'
+           'Assert statements are a convenient way to insert debugging '
+           'assertions\n'
+           'into a program:\n'
+           '\n'
+           '   assert_stmt ::= "assert" expression ["," expression]\n'
+           '\n'
+           'The simple form, "assert expression", is equivalent to\n'
+           '\n'
+           '   if __debug__:\n'
+           '       if not expression: raise AssertionError\n'
+           '\n'
+           'The extended form, "assert expression1, expression2", is '
+           'equivalent to\n'
+           '\n'
+           '   if __debug__:\n'
+           '       if not expression1: raise AssertionError(expression2)\n'
+           '\n'
+           'These equivalences assume that "__debug__" and "AssertionError" '
+           'refer\n'
+           'to the built-in variables with those names.  In the current\n'
+           'implementation, the built-in variable "__debug__" is "True" under\n'
+           'normal circumstances, "False" when optimization is requested '
+           '(command\n'
+           'line option -O).  The current code generator emits no code for an\n'
+           'assert statement when optimization is requested at compile time.  '
+           'Note\n'
+           'that it is unnecessary to include the source code for the '
+           'expression\n'
+           'that failed in the error message; it will be displayed as part of '
+           'the\n'
+           'stack trace.\n'
+           '\n'
+           'Assignments to "__debug__" are illegal.  The value for the '
+           'built-in\n'
+           'variable is determined when the interpreter starts.\n',
+ 'assignment': '\n'
+               'Assignment statements\n'
+               '*********************\n'
+               '\n'
+               'Assignment statements are used to (re)bind names to values and '
+               'to\n'
+               'modify attributes or items of mutable objects:\n'
+               '\n'
+               '   assignment_stmt ::= (target_list "=")+ (expression_list | '
+               'yield_expression)\n'
+               '   target_list     ::= target ("," target)* [","]\n'
+               '   target          ::= identifier\n'
+               '              | "(" target_list ")"\n'
+               '              | "[" target_list "]"\n'
+               '              | attributeref\n'
+               '              | subscription\n'
+               '              | slicing\n'
+               '              | "*" target\n'
+               '\n'
+               '(See section Primaries for the syntax definitions for '
+               '*attributeref*,\n'
+               '*subscription*, and *slicing*.)\n'
+               '\n'
+               'An assignment statement evaluates the expression list '
+               '(remember that\n'
+               'this can be a single expression or a comma-separated list, the '
+               'latter\n'
+               'yielding a tuple) and assigns the single resulting object to '
+               'each of\n'
+               'the target lists, from left to right.\n'
+               '\n'
+               'Assignment is defined recursively depending on the form of the '
+               'target\n'
+               '(list). When a target is part of a mutable object (an '
+               'attribute\n'
+               'reference, subscription or slicing), the mutable object must\n'
+               'ultimately perform the assignment and decide about its '
+               'validity, and\n'
+               'may raise an exception if the assignment is unacceptable.  The '
+               'rules\n'
+               'observed by various types and the exceptions raised are given '
+               'with the\n'
+               'definition of the object types (see section The standard type\n'
+               'hierarchy).\n'
+               '\n'
+               'Assignment of an object to a target list, optionally enclosed '
+               'in\n'
+               'parentheses or square brackets, is recursively defined as '
+               'follows.\n'
+               '\n'
+               '* If the target list is a single target: The object is '
+               'assigned to\n'
+               '  that target.\n'
+               '\n'
+               '* If the target list is a comma-separated list of targets: '
+               'The\n'
+               '  object must be an iterable with the same number of items as '
+               'there\n'
+               '  are targets in the target list, and the items are assigned, '
+               'from\n'
+               '  left to right, to the corresponding targets.\n'
+               '\n'
+               '  * If the target list contains one target prefixed with an\n'
+               '    asterisk, called a "starred" target: The object must be a '
+               'sequence\n'
+               '    with at least as many items as there are targets in the '
+               'target\n'
+               '    list, minus one.  The first items of the sequence are '
+               'assigned,\n'
+               '    from left to right, to the targets before the starred '
+               'target.  The\n'
+               '    final items of the sequence are assigned to the targets '
+               'after the\n'
+               '    starred target.  A list of the remaining items in the '
+               'sequence is\n'
+               '    then assigned to the starred target (the list can be '
+               'empty).\n'
+               '\n'
+               '  * Else: The object must be a sequence with the same number '
+               'of\n'
+               '    items as there are targets in the target list, and the '
+               'items are\n'
+               '    assigned, from left to right, to the corresponding '
+               'targets.\n'
+               '\n'
+               'Assignment of an object to a single target is recursively '
+               'defined as\n'
+               'follows.\n'
+               '\n'
+               '* If the target is an identifier (name):\n'
+               '\n'
+               '  * If the name does not occur in a "global" or "nonlocal" '
+               'statement\n'
+               '    in the current code block: the name is bound to the object '
+               'in the\n'
+               '    current local namespace.\n'
+               '\n'
+               '  * Otherwise: the name is bound to the object in the global\n'
+               '    namespace or the outer namespace determined by '
+               '"nonlocal",\n'
+               '    respectively.\n'
+               '\n'
+               '  The name is rebound if it was already bound.  This may cause '
+               'the\n'
+               '  reference count for the object previously bound to the name '
+               'to reach\n'
+               '  zero, causing the object to be deallocated and its '
+               'destructor (if it\n'
+               '  has one) to be called.\n'
+               '\n'
+               '* If the target is a target list enclosed in parentheses or '
+               'in\n'
+               '  square brackets: The object must be an iterable with the '
+               'same number\n'
+               '  of items as there are targets in the target list, and its '
+               'items are\n'
+               '  assigned, from left to right, to the corresponding targets.\n'
+               '\n'
+               '* If the target is an attribute reference: The primary '
+               'expression in\n'
+               '  the reference is evaluated.  It should yield an object with\n'
+               '  assignable attributes; if this is not the case, "TypeError" '
+               'is\n'
+               '  raised.  That object is then asked to assign the assigned '
+               'object to\n'
+               '  the given attribute; if it cannot perform the assignment, it '
+               'raises\n'
+               '  an exception (usually but not necessarily '
+               '"AttributeError").\n'
+               '\n'
+               '  Note: If the object is a class instance and the attribute '
+               'reference\n'
+               '  occurs on both sides of the assignment operator, the RHS '
+               'expression,\n'
+               '  "a.x" can access either an instance attribute or (if no '
+               'instance\n'
+               '  attribute exists) a class attribute.  The LHS target "a.x" '
+               'is always\n'
+               '  set as an instance attribute, creating it if necessary.  '
+               'Thus, the\n'
+               '  two occurrences of "a.x" do not necessarily refer to the '
+               'same\n'
+               '  attribute: if the RHS expression refers to a class '
+               'attribute, the\n'
+               '  LHS creates a new instance attribute as the target of the\n'
+               '  assignment:\n'
+               '\n'
+               '     class Cls:\n'
+               '         x = 3             # class variable\n'
+               '     inst = Cls()\n'
+               '     inst.x = inst.x + 1   # writes inst.x as 4 leaving Cls.x '
+               'as 3\n'
+               '\n'
+               '  This description does not necessarily apply to descriptor\n'
+               '  attributes, such as properties created with "property()".\n'
+               '\n'
+               '* If the target is a subscription: The primary expression in '
+               'the\n'
+               '  reference is evaluated.  It should yield either a mutable '
+               'sequence\n'
+               '  object (such as a list) or a mapping object (such as a '
+               'dictionary).\n'
+               '  Next, the subscript expression is evaluated.\n'
+               '\n'
+               '  If the primary is a mutable sequence object (such as a '
+               'list), the\n'
+               '  subscript must yield an integer.  If it is negative, the '
+               "sequence's\n"
+               '  length is added to it.  The resulting value must be a '
+               'nonnegative\n'
+               "  integer less than the sequence's length, and the sequence is "
+               'asked\n'
+               '  to assign the assigned object to its item with that index.  '
+               'If the\n'
+               '  index is out of range, "IndexError" is raised (assignment to '
+               'a\n'
+               '  subscripted sequence cannot add new items to a list).\n'
+               '\n'
+               '  If the primary is a mapping object (such as a dictionary), '
+               'the\n'
+               "  subscript must have a type compatible with the mapping's key "
+               'type,\n'
+               '  and the mapping is then asked to create a key/datum pair '
+               'which maps\n'
+               '  the subscript to the assigned object.  This can either '
+               'replace an\n'
+               '  existing key/value pair with the same key value, or insert a '
+               'new\n'
+               '  key/value pair (if no key with the same value existed).\n'
+               '\n'
+               '  For user-defined objects, the "__setitem__()" method is '
+               'called with\n'
+               '  appropriate arguments.\n'
+               '\n'
+               '* If the target is a slicing: The primary expression in the\n'
+               '  reference is evaluated.  It should yield a mutable sequence '
+               'object\n'
+               '  (such as a list).  The assigned object should be a sequence '
+               'object\n'
+               '  of the same type.  Next, the lower and upper bound '
+               'expressions are\n'
+               '  evaluated, insofar they are present; defaults are zero and '
+               'the\n'
+               "  sequence's length.  The bounds should evaluate to integers. "
+               'If\n'
+               "  either bound is negative, the sequence's length is added to "
+               'it.  The\n'
+               '  resulting bounds are clipped to lie between zero and the '
+               "sequence's\n"
+               '  length, inclusive.  Finally, the sequence object is asked to '
+               'replace\n'
+               '  the slice with the items of the assigned sequence.  The '
+               'length of\n'
+               '  the slice may be different from the length of the assigned '
+               'sequence,\n'
+               '  thus changing the length of the target sequence, if the '
+               'target\n'
+               '  sequence allows it.\n'
+               '\n'
+               '**CPython implementation detail:** In the current '
+               'implementation, the\n'
+               'syntax for targets is taken to be the same as for expressions, '
+               'and\n'
+               'invalid syntax is rejected during the code generation phase, '
+               'causing\n'
+               'less detailed error messages.\n'
+               '\n'
+               'Although the definition of assignment implies that overlaps '
+               'between\n'
+               "the left-hand side and the right-hand side are 'simultaneous' "
+               '(for\n'
+               'example "a, b = b, a" swaps two variables), overlaps *within* '
+               'the\n'
+               'collection of assigned-to variables occur left-to-right, '
+               'sometimes\n'
+               'resulting in confusion.  For instance, the following program '
+               'prints\n'
+               '"[0, 2]":\n'
+               '\n'
+               '   x = [0, 1]\n'
+               '   i = 0\n'
+               '   i, x[i] = 1, 2         # i is updated, then x[i] is '
+               'updated\n'
+               '   print(x)\n'
+               '\n'
+               'See also:\n'
+               '\n'
+               '  **PEP 3132** - Extended Iterable Unpacking\n'
+               '     The specification for the "*target" feature.\n'
+               '\n'
+               '\n'
+               'Augmented assignment statements\n'
+               '===============================\n'
+               '\n'
+               'Augmented assignment is the combination, in a single '
+               'statement, of a\n'
+               'binary operation and an assignment statement:\n'
+               '\n'
+               '   augmented_assignment_stmt ::= augtarget augop '
+               '(expression_list | yield_expression)\n'
+               '   augtarget                 ::= identifier | attributeref | '
+               'subscription | slicing\n'
+               '   augop                     ::= "+=" | "-=" | "*=" | "@=" | '
+               '"/=" | "//=" | "%=" | "**="\n'
+               '             | ">>=" | "<<=" | "&=" | "^=" | "|="\n'
+               '\n'
+               '(See section Primaries for the syntax definitions of the last '
+               'three\n'
+               'symbols.)\n'
+               '\n'
+               'An augmented assignment evaluates the target (which, unlike '
+               'normal\n'
+               'assignment statements, cannot be an unpacking) and the '
+               'expression\n'
+               'list, performs the binary operation specific to the type of '
+               'assignment\n'
+               'on the two operands, and assigns the result to the original '
+               'target.\n'
+               'The target is only evaluated once.\n'
+               '\n'
+               'An augmented assignment expression like "x += 1" can be '
+               'rewritten as\n'
+               '"x = x + 1" to achieve a similar, but not exactly equal '
+               'effect. In the\n'
+               'augmented version, "x" is only evaluated once. Also, when '
+               'possible,\n'
+               'the actual operation is performed *in-place*, meaning that '
+               'rather than\n'
+               'creating a new object and assigning that to the target, the '
+               'old object\n'
+               'is modified instead.\n'
+               '\n'
+               'Unlike normal assignments, augmented assignments evaluate the '
+               'left-\n'
+               'hand side *before* evaluating the right-hand side.  For '
+               'example, "a[i]\n'
+               '+= f(x)" first looks-up "a[i]", then it evaluates "f(x)" and '
+               'performs\n'
+               'the addition, and lastly, it writes the result back to '
+               '"a[i]".\n'
+               '\n'
+               'With the exception of assigning to tuples and multiple targets '
+               'in a\n'
+               'single statement, the assignment done by augmented assignment\n'
+               'statements is handled the same way as normal assignments. '
+               'Similarly,\n'
+               'with the exception of the possible *in-place* behavior, the '
+               'binary\n'
+               'operation performed by augmented assignment is the same as the '
+               'normal\n'
+               'binary operations.\n'
+               '\n'
+               'For targets which are attribute references, the same caveat '
+               'about\n'
+               'class and instance attributes applies as for regular '
+               'assignments.\n',
+ 'atom-identifiers': '\n'
+                     'Identifiers (Names)\n'
+                     '*******************\n'
+                     '\n'
+                     'An identifier occurring as an atom is a name.  See '
+                     'section Identifiers\n'
+                     'and keywords for lexical definition and section Naming '
+                     'and binding for\n'
+                     'documentation of naming and binding.\n'
+                     '\n'
+                     'When the name is bound to an object, evaluation of the '
+                     'atom yields\n'
+                     'that object. When a name is not bound, an attempt to '
+                     'evaluate it\n'
+                     'raises a "NameError" exception.\n'
+                     '\n'
+                     '**Private name mangling:** When an identifier that '
+                     'textually occurs in\n'
+                     'a class definition begins with two or more underscore '
+                     'characters and\n'
+                     'does not end in two or more underscores, it is '
+                     'considered a *private\n'
+                     'name* of that class. Private names are transformed to a '
+                     'longer form\n'
+                     'before code is generated for them.  The transformation '
+                     'inserts the\n'
+                     'class name, with leading underscores removed and a '
+                     'single underscore\n'
+                     'inserted, in front of the name.  For example, the '
+                     'identifier "__spam"\n'
+                     'occurring in a class named "Ham" will be transformed to '
+                     '"_Ham__spam".\n'
+                     'This transformation is independent of the syntactical '
+                     'context in which\n'
+                     'the identifier is used.  If the transformed name is '
+                     'extremely long\n'
+                     '(longer than 255 characters), implementation defined '
+                     'truncation may\n'
+                     'happen. If the class name consists only of underscores, '
+                     'no\n'
+                     'transformation is done.\n',
+ 'atom-literals': '\n'
+                  'Literals\n'
+                  '********\n'
+                  '\n'
+                  'Python supports string and bytes literals and various '
+                  'numeric\n'
+                  'literals:\n'
+                  '\n'
+                  '   literal ::= stringliteral | bytesliteral\n'
+                  '               | integer | floatnumber | imagnumber\n'
+                  '\n'
+                  'Evaluation of a literal yields an object of the given type '
+                  '(string,\n'
+                  'bytes, integer, floating point number, complex number) with '
+                  'the given\n'
+                  'value.  The value may be approximated in the case of '
+                  'floating point\n'
+                  'and imaginary (complex) literals.  See section Literals for '
+                  'details.\n'
+                  '\n'
+                  'All literals correspond to immutable data types, and hence '
+                  'the\n'
+                  "object's identity is less important than its value.  "
+                  'Multiple\n'
+                  'evaluations of literals with the same value (either the '
+                  'same\n'
+                  'occurrence in the program text or a different occurrence) '
+                  'may obtain\n'
+                  'the same object or a different object with the same '
+                  'value.\n',
+ 'attribute-access': '\n'
+                     'Customizing attribute access\n'
+                     '****************************\n'
+                     '\n'
+                     'The following methods can be defined to customize the '
+                     'meaning of\n'
+                     'attribute access (use of, assignment to, or deletion of '
+                     '"x.name") for\n'
+                     'class instances.\n'
+                     '\n'
+                     'object.__getattr__(self, name)\n'
+                     '\n'
+                     '   Called when an attribute lookup has not found the '
+                     'attribute in the\n'
+                     '   usual places (i.e. it is not an instance attribute '
+                     'nor is it found\n'
+                     '   in the class tree for "self").  "name" is the '
+                     'attribute name. This\n'
+                     '   method should return the (computed) attribute value '
+                     'or raise an\n'
+                     '   "AttributeError" exception.\n'
+                     '\n'
+                     '   Note that if the attribute is found through the '
+                     'normal mechanism,\n'
+                     '   "__getattr__()" is not called.  (This is an '
+                     'intentional asymmetry\n'
+                     '   between "__getattr__()" and "__setattr__()".) This is '
+                     'done both for\n'
+                     '   efficiency reasons and because otherwise '
+                     '"__getattr__()" would have\n'
+                     '   no way to access other attributes of the instance.  '
+                     'Note that at\n'
+                     '   least for instance variables, you can fake total '
+                     'control by not\n'
+                     '   inserting any values in the instance attribute '
+                     'dictionary (but\n'
+                     '   instead inserting them in another object).  See the\n'
+                     '   "__getattribute__()" method below for a way to '
+                     'actually get total\n'
+                     '   control over attribute access.\n'
+                     '\n'
+                     'object.__getattribute__(self, name)\n'
+                     '\n'
+                     '   Called unconditionally to implement attribute '
+                     'accesses for\n'
+                     '   instances of the class. If the class also defines '
+                     '"__getattr__()",\n'
+                     '   the latter will not be called unless '
+                     '"__getattribute__()" either\n'
+                     '   calls it explicitly or raises an "AttributeError". '
+                     'This method\n'
+                     '   should return the (computed) attribute value or raise '
+                     'an\n'
+                     '   "AttributeError" exception. In order to avoid '
+                     'infinite recursion in\n'
+                     '   this method, its implementation should always call '
+                     'the base class\n'
+                     '   method with the same name to access any attributes it '
+                     'needs, for\n'
+                     '   example, "object.__getattribute__(self, name)".\n'
+                     '\n'
+                     '   Note: This method may still be bypassed when looking '
+                     'up special\n'
+                     '     methods as the result of implicit invocation via '
+                     'language syntax\n'
+                     '     or built-in functions. See Special method lookup.\n'
+                     '\n'
+                     'object.__setattr__(self, name, value)\n'
+                     '\n'
+                     '   Called when an attribute assignment is attempted.  '
+                     'This is called\n'
+                     '   instead of the normal mechanism (i.e. store the value '
+                     'in the\n'
+                     '   instance dictionary). *name* is the attribute name, '
+                     '*value* is the\n'
+                     '   value to be assigned to it.\n'
+                     '\n'
+                     '   If "__setattr__()" wants to assign to an instance '
+                     'attribute, it\n'
+                     '   should call the base class method with the same name, '
+                     'for example,\n'
+                     '   "object.__setattr__(self, name, value)".\n'
+                     '\n'
+                     'object.__delattr__(self, name)\n'
+                     '\n'
+                     '   Like "__setattr__()" but for attribute deletion '
+                     'instead of\n'
+                     '   assignment.  This should only be implemented if "del '
+                     'obj.name" is\n'
+                     '   meaningful for the object.\n'
+                     '\n'
+                     'object.__dir__(self)\n'
+                     '\n'
+                     '   Called when "dir()" is called on the object. A '
+                     'sequence must be\n'
+                     '   returned. "dir()" converts the returned sequence to a '
+                     'list and\n'
+                     '   sorts it.\n'
+                     '\n'
+                     '\n'
+                     'Implementing Descriptors\n'
+                     '========================\n'
+                     '\n'
+                     'The following methods only apply when an instance of the '
+                     'class\n'
+                     'containing the method (a so-called *descriptor* class) '
+                     'appears in an\n'
+                     '*owner* class (the descriptor must be in either the '
+                     "owner's class\n"
+                     'dictionary or in the class dictionary for one of its '
+                     'parents).  In the\n'
+                     'examples below, "the attribute" refers to the attribute '
+                     'whose name is\n'
+                     "the key of the property in the owner class' "
+                     '"__dict__".\n'
+                     '\n'
+                     'object.__get__(self, instance, owner)\n'
+                     '\n'
+                     '   Called to get the attribute of the owner class (class '
+                     'attribute\n'
+                     '   access) or of an instance of that class (instance '
+                     'attribute\n'
+                     '   access). *owner* is always the owner class, while '
+                     '*instance* is the\n'
+                     '   instance that the attribute was accessed through, or '
+                     '"None" when\n'
+                     '   the attribute is accessed through the *owner*.  This '
+                     'method should\n'
+                     '   return the (computed) attribute value or raise an '
+                     '"AttributeError"\n'
+                     '   exception.\n'
+                     '\n'
+                     'object.__set__(self, instance, value)\n'
+                     '\n'
+                     '   Called to set the attribute on an instance *instance* '
+                     'of the owner\n'
+                     '   class to a new value, *value*.\n'
+                     '\n'
+                     'object.__delete__(self, instance)\n'
+                     '\n'
+                     '   Called to delete the attribute on an instance '
+                     '*instance* of the\n'
+                     '   owner class.\n'
+                     '\n'
+                     'The attribute "__objclass__" is interpreted by the '
+                     '"inspect" module as\n'
+                     'specifying the class where this object was defined '
+                     '(setting this\n'
+                     'appropriately can assist in runtime introspection of '
+                     'dynamic class\n'
+                     'attributes). For callables, it may indicate that an '
+                     'instance of the\n'
+                     'given type (or a subclass) is expected or required as '
+                     'the first\n'
+                     'positional argument (for example, CPython sets this '
+                     'attribute for\n'
+                     'unbound methods that are implemented in C).\n'
+                     '\n'
+                     '\n'
+                     'Invoking Descriptors\n'
+                     '====================\n'
+                     '\n'
+                     'In general, a descriptor is an object attribute with '
+                     '"binding\n'
+                     'behavior", one whose attribute access has been '
+                     'overridden by methods\n'
+                     'in the descriptor protocol:  "__get__()", "__set__()", '
+                     'and\n'
+                     '"__delete__()". If any of those methods are defined for '
+                     'an object, it\n'
+                     'is said to be a descriptor.\n'
+                     '\n'
+                     'The default behavior for attribute access is to get, '
+                     'set, or delete\n'
+                     "the attribute from an object's dictionary. For instance, "
+                     '"a.x" has a\n'
+                     'lookup chain starting with "a.__dict__[\'x\']", then\n'
+                     '"type(a).__dict__[\'x\']", and continuing through the '
+                     'base classes of\n'
+                     '"type(a)" excluding metaclasses.\n'
+                     '\n'
+                     'However, if the looked-up value is an object defining '
+                     'one of the\n'
+                     'descriptor methods, then Python may override the default '
+                     'behavior and\n'
+                     'invoke the descriptor method instead.  Where this occurs '
+                     'in the\n'
+                     'precedence chain depends on which descriptor methods '
+                     'were defined and\n'
+                     'how they were called.\n'
+                     '\n'
+                     'The starting point for descriptor invocation is a '
+                     'binding, "a.x". How\n'
+                     'the arguments are assembled depends on "a":\n'
+                     '\n'
+                     'Direct Call\n'
+                     '   The simplest and least common call is when user code '
+                     'directly\n'
+                     '   invokes a descriptor method:    "x.__get__(a)".\n'
+                     '\n'
+                     'Instance Binding\n'
+                     '   If binding to an object instance, "a.x" is '
+                     'transformed into the\n'
+                     '   call: "type(a).__dict__[\'x\'].__get__(a, type(a))".\n'
+                     '\n'
+                     'Class Binding\n'
+                     '   If binding to a class, "A.x" is transformed into the '
+                     'call:\n'
+                     '   "A.__dict__[\'x\'].__get__(None, A)".\n'
+                     '\n'
+                     'Super Binding\n'
+                     '   If "a" is an instance of "super", then the binding '
+                     '"super(B,\n'
+                     '   obj).m()" searches "obj.__class__.__mro__" for the '
+                     'base class "A"\n'
+                     '   immediately preceding "B" and then invokes the '
+                     'descriptor with the\n'
+                     '   call: "A.__dict__[\'m\'].__get__(obj, '
+                     'obj.__class__)".\n'
+                     '\n'
+                     'For instance bindings, the precedence of descriptor '
+                     'invocation depends\n'
+                     'on the which descriptor methods are defined.  A '
+                     'descriptor can define\n'
+                     'any combination of "__get__()", "__set__()" and '
+                     '"__delete__()".  If it\n'
+                     'does not define "__get__()", then accessing the '
+                     'attribute will return\n'
+                     'the descriptor object itself unless there is a value in '
+                     "the object's\n"
+                     'instance dictionary.  If the descriptor defines '
+                     '"__set__()" and/or\n'
+                     '"__delete__()", it is a data descriptor; if it defines '
+                     'neither, it is\n'
+                     'a non-data descriptor.  Normally, data descriptors '
+                     'define both\n'
+                     '"__get__()" and "__set__()", while non-data descriptors '
+                     'have just the\n'
+                     '"__get__()" method.  Data descriptors with "__set__()" '
+                     'and "__get__()"\n'
+                     'defined always override a redefinition in an instance '
+                     'dictionary.  In\n'
+                     'contrast, non-data descriptors can be overridden by '
+                     'instances.\n'
+                     '\n'
+                     'Python methods (including "staticmethod()" and '
+                     '"classmethod()") are\n'
+                     'implemented as non-data descriptors.  Accordingly, '
+                     'instances can\n'
+                     'redefine and override methods.  This allows individual '
+                     'instances to\n'
+                     'acquire behaviors that differ from other instances of '
+                     'the same class.\n'
+                     '\n'
+                     'The "property()" function is implemented as a data '
+                     'descriptor.\n'
+                     'Accordingly, instances cannot override the behavior of a '
+                     'property.\n'
+                     '\n'
+                     '\n'
+                     '__slots__\n'
+                     '=========\n'
+                     '\n'
+                     'By default, instances of classes have a dictionary for '
+                     'attribute\n'
+                     'storage.  This wastes space for objects having very few '
+                     'instance\n'
+                     'variables.  The space consumption can become acute when '
+                     'creating large\n'
+                     'numbers of instances.\n'
+                     '\n'
+                     'The default can be overridden by defining *__slots__* in '
+                     'a class\n'
+                     'definition. The *__slots__* declaration takes a sequence '
+                     'of instance\n'
+                     'variables and reserves just enough space in each '
+                     'instance to hold a\n'
+                     'value for each variable.  Space is saved because '
+                     '*__dict__* is not\n'
+                     'created for each instance.\n'
+                     '\n'
+                     'object.__slots__\n'
+                     '\n'
+                     '   This class variable can be assigned a string, '
+                     'iterable, or sequence\n'
+                     '   of strings with variable names used by instances.  '
+                     '*__slots__*\n'
+                     '   reserves space for the declared variables and '
+                     'prevents the\n'
+                     '   automatic creation of *__dict__* and *__weakref__* '
+                     'for each\n'
+                     '   instance.\n'
+                     '\n'
+                     '\n'
+                     'Notes on using *__slots__*\n'
+                     '--------------------------\n'
+                     '\n'
+                     '* When inheriting from a class without *__slots__*, the '
+                     '*__dict__*\n'
+                     '  attribute of that class will always be accessible, so '
+                     'a *__slots__*\n'
+                     '  definition in the subclass is meaningless.\n'
+                     '\n'
+                     '* Without a *__dict__* variable, instances cannot be '
+                     'assigned new\n'
+                     '  variables not listed in the *__slots__* definition.  '
+                     'Attempts to\n'
+                     '  assign to an unlisted variable name raises '
+                     '"AttributeError". If\n'
+                     '  dynamic assignment of new variables is desired, then '
+                     'add\n'
+                     '  "\'__dict__\'" to the sequence of strings in the '
+                     '*__slots__*\n'
+                     '  declaration.\n'
+                     '\n'
+                     '* Without a *__weakref__* variable for each instance, '
+                     'classes\n'
+                     '  defining *__slots__* do not support weak references to '
+                     'its\n'
+                     '  instances. If weak reference support is needed, then '
+                     'add\n'
+                     '  "\'__weakref__\'" to the sequence of strings in the '
+                     '*__slots__*\n'
+                     '  declaration.\n'
+                     '\n'
+                     '* *__slots__* are implemented at the class level by '
+                     'creating\n'
+                     '  descriptors (Implementing Descriptors) for each '
+                     'variable name.  As a\n'
+                     '  result, class attributes cannot be used to set default '
+                     'values for\n'
+                     '  instance variables defined by *__slots__*; otherwise, '
+                     'the class\n'
+                     '  attribute would overwrite the descriptor assignment.\n'
+                     '\n'
+                     '* The action of a *__slots__* declaration is limited to '
+                     'the class\n'
+                     '  where it is defined.  As a result, subclasses will '
+                     'have a *__dict__*\n'
+                     '  unless they also define *__slots__* (which must only '
+                     'contain names\n'
+                     '  of any *additional* slots).\n'
+                     '\n'
+                     '* If a class defines a slot also defined in a base '
+                     'class, the\n'
+                     '  instance variable defined by the base class slot is '
+                     'inaccessible\n'
+                     '  (except by retrieving its descriptor directly from the '
+                     'base class).\n'
+                     '  This renders the meaning of the program undefined.  In '
+                     'the future, a\n'
+                     '  check may be added to prevent this.\n'
+                     '\n'
+                     '* Nonempty *__slots__* does not work for classes derived '
+                     'from\n'
+                     '  "variable-length" built-in types such as "int", '
+                     '"bytes" and "tuple".\n'
+                     '\n'
+                     '* Any non-string iterable may be assigned to '
+                     '*__slots__*. Mappings\n'
+                     '  may also be used; however, in the future, special '
+                     'meaning may be\n'
+                     '  assigned to the values corresponding to each key.\n'
+                     '\n'
+                     '* *__class__* assignment works only if both classes have '
+                     'the same\n'
+                     '  *__slots__*.\n',
+ 'attribute-references': '\n'
+                         'Attribute references\n'
+                         '********************\n'
+                         '\n'
+                         'An attribute reference is a primary followed by a '
+                         'period and a name:\n'
+                         '\n'
+                         '   attributeref ::= primary "." identifier\n'
+                         '\n'
+                         'The primary must evaluate to an object of a type '
+                         'that supports\n'
+                         'attribute references, which most objects do.  This '
+                         'object is then\n'
+                         'asked to produce the attribute whose name is the '
+                         'identifier.  This\n'
+                         'production can be customized by overriding the '
+                         '"__getattr__()" method.\n'
+                         'If this attribute is not available, the exception '
+                         '"AttributeError" is\n'
+                         'raised.  Otherwise, the type and value of the object '
+                         'produced is\n'
+                         'determined by the object.  Multiple evaluations of '
+                         'the same attribute\n'
+                         'reference may yield different objects.\n',
+ 'augassign': '\n'
+              'Augmented assignment statements\n'
+              '*******************************\n'
+              '\n'
+              'Augmented assignment is the combination, in a single statement, '
+              'of a\n'
+              'binary operation and an assignment statement:\n'
+              '\n'
+              '   augmented_assignment_stmt ::= augtarget augop '
+              '(expression_list | yield_expression)\n'
+              '   augtarget                 ::= identifier | attributeref | '
+              'subscription | slicing\n'
+              '   augop                     ::= "+=" | "-=" | "*=" | "@=" | '
+              '"/=" | "//=" | "%=" | "**="\n'
+              '             | ">>=" | "<<=" | "&=" | "^=" | "|="\n'
+              '\n'
+              '(See section Primaries for the syntax definitions of the last '
+              'three\n'
+              'symbols.)\n'
+              '\n'
+              'An augmented assignment evaluates the target (which, unlike '
+              'normal\n'
+              'assignment statements, cannot be an unpacking) and the '
+              'expression\n'
+              'list, performs the binary operation specific to the type of '
+              'assignment\n'
+              'on the two operands, and assigns the result to the original '
+              'target.\n'
+              'The target is only evaluated once.\n'
+              '\n'
+              'An augmented assignment expression like "x += 1" can be '
+              'rewritten as\n'
+              '"x = x + 1" to achieve a similar, but not exactly equal effect. '
+              'In the\n'
+              'augmented version, "x" is only evaluated once. Also, when '
+              'possible,\n'
+              'the actual operation is performed *in-place*, meaning that '
+              'rather than\n'
+              'creating a new object and assigning that to the target, the old '
+              'object\n'
+              'is modified instead.\n'
+              '\n'
+              'Unlike normal assignments, augmented assignments evaluate the '
+              'left-\n'
+              'hand side *before* evaluating the right-hand side.  For '
+              'example, "a[i]\n'
+              '+= f(x)" first looks-up "a[i]", then it evaluates "f(x)" and '
+              'performs\n'
+              'the addition, and lastly, it writes the result back to "a[i]".\n'
+              '\n'
+              'With the exception of assigning to tuples and multiple targets '
+              'in a\n'
+              'single statement, the assignment done by augmented assignment\n'
+              'statements is handled the same way as normal assignments. '
+              'Similarly,\n'
+              'with the exception of the possible *in-place* behavior, the '
+              'binary\n'
+              'operation performed by augmented assignment is the same as the '
+              'normal\n'
+              'binary operations.\n'
+              '\n'
+              'For targets which are attribute references, the same caveat '
+              'about\n'
+              'class and instance attributes applies as for regular '
+              'assignments.\n',
+ 'binary': '\n'
+           'Binary arithmetic operations\n'
+           '****************************\n'
+           '\n'
+           'The binary arithmetic operations have the conventional priority\n'
+           'levels.  Note that some of these operations also apply to certain '
+           'non-\n'
+           'numeric types.  Apart from the power operator, there are only two\n'
+           'levels, one for multiplicative operators and one for additive\n'
+           'operators:\n'
+           '\n'
+           '   m_expr ::= u_expr | m_expr "*" u_expr | m_expr "@" m_expr |\n'
+           '              m_expr "//" u_expr| m_expr "/" u_expr |\n'
+           '              m_expr "%" u_expr\n'
+           '   a_expr ::= m_expr | a_expr "+" m_expr | a_expr "-" m_expr\n'
+           '\n'
+           'The "*" (multiplication) operator yields the product of its '
+           'arguments.\n'
+           'The arguments must either both be numbers, or one argument must be '
+           'an\n'
+           'integer and the other must be a sequence. In the former case, the\n'
+           'numbers are converted to a common type and then multiplied '
+           'together.\n'
+           'In the latter case, sequence repetition is performed; a negative\n'
+           'repetition factor yields an empty sequence.\n'
+           '\n'
+           'The "@" (at) operator is intended to be used for matrix\n'
+           'multiplication.  No builtin Python types implement this operator.\n'
+           '\n'
+           'New in version 3.5.\n'
+           '\n'
+           'The "/" (division) and "//" (floor division) operators yield the\n'
+           'quotient of their arguments.  The numeric arguments are first\n'
+           'converted to a common type. Division of integers yields a float, '
+           'while\n'
+           'floor division of integers results in an integer; the result is '
+           'that\n'
+           "of mathematical division with the 'floor' function applied to the\n"
+           'result.  Division by zero raises the "ZeroDivisionError" '
+           'exception.\n'
+           '\n'
+           'The "%" (modulo) operator yields the remainder from the division '
+           'of\n'
+           'the first argument by the second.  The numeric arguments are '
+           'first\n'
+           'converted to a common type.  A zero right argument raises the\n'
+           '"ZeroDivisionError" exception.  The arguments may be floating '
+           'point\n'
+           'numbers, e.g., "3.14%0.7" equals "0.34" (since "3.14" equals '
+           '"4*0.7 +\n'
+           '0.34".)  The modulo operator always yields a result with the same '
+           'sign\n'
+           'as its second operand (or zero); the absolute value of the result '
+           'is\n'
+           'strictly smaller than the absolute value of the second operand '
+           '[1].\n'
+           '\n'
+           'The floor division and modulo operators are connected by the '
+           'following\n'
+           'identity: "x == (x//y)*y + (x%y)".  Floor division and modulo are '
+           'also\n'
+           'connected with the built-in function "divmod()": "divmod(x, y) ==\n'
+           '(x//y, x%y)". [2].\n'
+           '\n'
+           'In addition to performing the modulo operation on numbers, the '
+           '"%"\n'
+           'operator is also overloaded by string objects to perform '
+           'old-style\n'
+           'string formatting (also known as interpolation).  The syntax for\n'
+           'string formatting is described in the Python Library Reference,\n'
+           'section printf-style String Formatting.\n'
+           '\n'
+           'The floor division operator, the modulo operator, and the '
+           '"divmod()"\n'
+           'function are not defined for complex numbers.  Instead, convert to '
+           'a\n'
+           'floating point number using the "abs()" function if appropriate.\n'
+           '\n'
+           'The "+" (addition) operator yields the sum of its arguments.  The\n'
+           'arguments must either both be numbers or both be sequences of the '
+           'same\n'
+           'type.  In the former case, the numbers are converted to a common '
+           'type\n'
+           'and then added together. In the latter case, the sequences are\n'
+           'concatenated.\n'
+           '\n'
+           'The "-" (subtraction) operator yields the difference of its '
+           'arguments.\n'
+           'The numeric arguments are first converted to a common type.\n',
+ 'bitwise': '\n'
+            'Binary bitwise operations\n'
+            '*************************\n'
+            '\n'
+            'Each of the three bitwise operations has a different priority '
+            'level:\n'
+            '\n'
+            '   and_expr ::= shift_expr | and_expr "&" shift_expr\n'
+            '   xor_expr ::= and_expr | xor_expr "^" and_expr\n'
+            '   or_expr  ::= xor_expr | or_expr "|" xor_expr\n'
+            '\n'
+            'The "&" operator yields the bitwise AND of its arguments, which '
+            'must\n'
+            'be integers.\n'
+            '\n'
+            'The "^" operator yields the bitwise XOR (exclusive OR) of its\n'
+            'arguments, which must be integers.\n'
+            '\n'
+            'The "|" operator yields the bitwise (inclusive) OR of its '
+            'arguments,\n'
+            'which must be integers.\n',
+ 'bltin-code-objects': '\n'
+                       'Code Objects\n'
+                       '************\n'
+                       '\n'
+                       'Code objects are used by the implementation to '
+                       'represent "pseudo-\n'
+                       'compiled" executable Python code such as a function '
+                       'body. They differ\n'
+                       "from function objects because they don't contain a "
+                       'reference to their\n'
+                       'global execution environment.  Code objects are '
+                       'returned by the built-\n'
+                       'in "compile()" function and can be extracted from '
+                       'function objects\n'
+                       'through their "__code__" attribute. See also the '
+                       '"code" module.\n'
+                       '\n'
+                       'A code object can be executed or evaluated by passing '
+                       'it (instead of a\n'
+                       'source string) to the "exec()" or "eval()"  built-in '
+                       'functions.\n'
+                       '\n'
+                       'See The standard type hierarchy for more '
+                       'information.\n',
+ 'bltin-ellipsis-object': '\n'
+                          'The Ellipsis Object\n'
+                          '*******************\n'
+                          '\n'
+                          'This object is commonly used by slicing (see '
+                          'Slicings).  It supports\n'
+                          'no special operations.  There is exactly one '
+                          'ellipsis object, named\n'
+                          '"Ellipsis" (a built-in name).  "type(Ellipsis)()" '
+                          'produces the\n'
+                          '"Ellipsis" singleton.\n'
+                          '\n'
+                          'It is written as "Ellipsis" or "...".\n',
+ 'bltin-null-object': '\n'
+                      'The Null Object\n'
+                      '***************\n'
+                      '\n'
+                      "This object is returned by functions that don't "
+                      'explicitly return a\n'
+                      'value.  It supports no special operations.  There is '
+                      'exactly one null\n'
+                      'object, named "None" (a built-in name).  "type(None)()" '
+                      'produces the\n'
+                      'same singleton.\n'
+                      '\n'
+                      'It is written as "None".\n',
+ 'bltin-type-objects': '\n'
+                       'Type Objects\n'
+                       '************\n'
+                       '\n'
+                       'Type objects represent the various object types.  An '
+                       "object's type is\n"
+                       'accessed by the built-in function "type()".  There are '
+                       'no special\n'
+                       'operations on types.  The standard module "types" '
+                       'defines names for\n'
+                       'all standard built-in types.\n'
+                       '\n'
+                       'Types are written like this: "<class \'int\'>".\n',
+ 'booleans': '\n'
+             'Boolean operations\n'
+             '******************\n'
+             '\n'
+             '   or_test  ::= and_test | or_test "or" and_test\n'
+             '   and_test ::= not_test | and_test "and" not_test\n'
+             '   not_test ::= comparison | "not" not_test\n'
+             '\n'
+             'In the context of Boolean operations, and also when expressions '
+             'are\n'
+             'used by control flow statements, the following values are '
+             'interpreted\n'
+             'as false: "False", "None", numeric zero of all types, and empty\n'
+             'strings and containers (including strings, tuples, lists,\n'
+             'dictionaries, sets and frozensets).  All other values are '
+             'interpreted\n'
+             'as true.  User-defined objects can customize their truth value '
+             'by\n'
+             'providing a "__bool__()" method.\n'
+             '\n'
+             'The operator "not" yields "True" if its argument is false, '
+             '"False"\n'
+             'otherwise.\n'
+             '\n'
+             'The expression "x and y" first evaluates *x*; if *x* is false, '
+             'its\n'
+             'value is returned; otherwise, *y* is evaluated and the resulting '
+             'value\n'
+             'is returned.\n'
+             '\n'
+             'The expression "x or y" first evaluates *x*; if *x* is true, its '
+             'value\n'
+             'is returned; otherwise, *y* is evaluated and the resulting value '
+             'is\n'
+             'returned.\n'
+             '\n'
+             '(Note that neither "and" nor "or" restrict the value and type '
+             'they\n'
+             'return to "False" and "True", but rather return the last '
+             'evaluated\n'
+             'argument.  This is sometimes useful, e.g., if "s" is a string '
+             'that\n'
+             'should be replaced by a default value if it is empty, the '
+             'expression\n'
+             '"s or \'foo\'" yields the desired value.  Because "not" has to '
+             'create a\n'
+             'new value, it returns a boolean value regardless of the type of '
+             'its\n'
+             'argument (for example, "not \'foo\'" produces "False" rather '
+             'than "\'\'".)\n',
+ 'break': '\n'
+          'The "break" statement\n'
+          '*********************\n'
+          '\n'
+          '   break_stmt ::= "break"\n'
+          '\n'
+          '"break" may only occur syntactically nested in a "for" or "while"\n'
+          'loop, but not nested in a function or class definition within that\n'
+          'loop.\n'
+          '\n'
+          'It terminates the nearest enclosing loop, skipping the optional '
+          '"else"\n'
+          'clause if the loop has one.\n'
+          '\n'
+          'If a "for" loop is terminated by "break", the loop control target\n'
+          'keeps its current value.\n'
+          '\n'
+          'When "break" passes control out of a "try" statement with a '
+          '"finally"\n'
+          'clause, that "finally" clause is executed before really leaving '
+          'the\n'
+          'loop.\n',
+ 'callable-types': '\n'
+                   'Emulating callable objects\n'
+                   '**************************\n'
+                   '\n'
+                   'object.__call__(self[, args...])\n'
+                   '\n'
+                   '   Called when the instance is "called" as a function; if '
+                   'this method\n'
+                   '   is defined, "x(arg1, arg2, ...)" is a shorthand for\n'
+                   '   "x.__call__(arg1, arg2, ...)".\n',
+ 'calls': '\n'
+          'Calls\n'
+          '*****\n'
+          '\n'
+          'A call calls a callable object (e.g., a *function*) with a '
+          'possibly\n'
+          'empty series of *arguments*:\n'
+          '\n'
+          '   call                 ::= primary "(" [argument_list [","] | '
+          'comprehension] ")"\n'
+          '   argument_list        ::= positional_arguments ["," '
+          'keyword_arguments]\n'
+          '                       ["," "*" expression] ["," '
+          'keyword_arguments]\n'
+          '                       ["," "**" expression]\n'
+          '                     | keyword_arguments ["," "*" expression]\n'
+          '                       ["," keyword_arguments] ["," "**" '
+          'expression]\n'
+          '                     | "*" expression ["," keyword_arguments] ["," '
+          '"**" expression]\n'
+          '                     | "**" expression\n'
+          '   positional_arguments ::= expression ("," expression)*\n'
+          '   keyword_arguments    ::= keyword_item ("," keyword_item)*\n'
+          '   keyword_item         ::= identifier "=" expression\n'
+          '\n'
+          'An optional trailing comma may be present after the positional and\n'
+          'keyword arguments but does not affect the semantics.\n'
+          '\n'
+          'The primary must evaluate to a callable object (user-defined\n'
+          'functions, built-in functions, methods of built-in objects, class\n'
+          'objects, methods of class instances, and all objects having a\n'
+          '"__call__()" method are callable).  All argument expressions are\n'
+          'evaluated before the call is attempted.  Please refer to section\n'
+          'Function definitions for the syntax of formal *parameter* lists.\n'
+          '\n'
+          'If keyword arguments are present, they are first converted to\n'
+          'positional arguments, as follows.  First, a list of unfilled slots '
+          'is\n'
+          'created for the formal parameters.  If there are N positional\n'
+          'arguments, they are placed in the first N slots.  Next, for each\n'
+          'keyword argument, the identifier is used to determine the\n'
+          'corresponding slot (if the identifier is the same as the first '
+          'formal\n'
+          'parameter name, the first slot is used, and so on).  If the slot '
+          'is\n'
+          'already filled, a "TypeError" exception is raised. Otherwise, the\n'
+          'value of the argument is placed in the slot, filling it (even if '
+          'the\n'
+          'expression is "None", it fills the slot).  When all arguments have\n'
+          'been processed, the slots that are still unfilled are filled with '
+          'the\n'
+          'corresponding default value from the function definition.  '
+          '(Default\n'
+          'values are calculated, once, when the function is defined; thus, a\n'
+          'mutable object such as a list or dictionary used as default value '
+          'will\n'
+          "be shared by all calls that don't specify an argument value for "
+          'the\n'
+          'corresponding slot; this should usually be avoided.)  If there are '
+          'any\n'
+          'unfilled slots for which no default value is specified, a '
+          '"TypeError"\n'
+          'exception is raised.  Otherwise, the list of filled slots is used '
+          'as\n'
+          'the argument list for the call.\n'
+          '\n'
+          '**CPython implementation detail:** An implementation may provide\n'
+          'built-in functions whose positional parameters do not have names, '
+          'even\n'
+          "if they are 'named' for the purpose of documentation, and which\n"
+          'therefore cannot be supplied by keyword.  In CPython, this is the '
+          'case\n'
+          'for functions implemented in C that use "PyArg_ParseTuple()" to '
+          'parse\n'
+          'their arguments.\n'
+          '\n'
+          'If there are more positional arguments than there are formal '
+          'parameter\n'
+          'slots, a "TypeError" exception is raised, unless a formal '
+          'parameter\n'
+          'using the syntax "*identifier" is present; in this case, that '
+          'formal\n'
+          'parameter receives a tuple containing the excess positional '
+          'arguments\n'
+          '(or an empty tuple if there were no excess positional arguments).\n'
+          '\n'
+          'If any keyword argument does not correspond to a formal parameter\n'
+          'name, a "TypeError" exception is raised, unless a formal parameter\n'
+          'using the syntax "**identifier" is present; in this case, that '
+          'formal\n'
+          'parameter receives a dictionary containing the excess keyword\n'
+          'arguments (using the keywords as keys and the argument values as\n'
+          'corresponding values), or a (new) empty dictionary if there were '
+          'no\n'
+          'excess keyword arguments.\n'
+          '\n'
+          'If the syntax "*expression" appears in the function call, '
+          '"expression"\n'
+          'must evaluate to an iterable.  Elements from this iterable are '
+          'treated\n'
+          'as if they were additional positional arguments; if there are\n'
+          'positional arguments *x1*, ..., *xN*, and "expression" evaluates to '
+          'a\n'
+          'sequence *y1*, ..., *yM*, this is equivalent to a call with M+N\n'
+          'positional arguments *x1*, ..., *xN*, *y1*, ..., *yM*.\n'
+          '\n'
+          'A consequence of this is that although the "*expression" syntax '
+          'may\n'
+          'appear *after* some keyword arguments, it is processed *before* '
+          'the\n'
+          'keyword arguments (and the "**expression" argument, if any -- see\n'
+          'below).  So:\n'
+          '\n'
+          '   >>> def f(a, b):\n'
+          '   ...     print(a, b)\n'
+          '   ...\n'
+          '   >>> f(b=1, *(2,))\n'
+          '   2 1\n'
+          '   >>> f(a=1, *(2,))\n'
+          '   Traceback (most recent call last):\n'
+          '     File "<stdin>", line 1, in ?\n'
+          "   TypeError: f() got multiple values for keyword argument 'a'\n"
+          '   >>> f(1, *(2,))\n'
+          '   1 2\n'
+          '\n'
+          'It is unusual for both keyword arguments and the "*expression" '
+          'syntax\n'
+          'to be used in the same call, so in practice this confusion does '
+          'not\n'
+          'arise.\n'
+          '\n'
+          'If the syntax "**expression" appears in the function call,\n'
+          '"expression" must evaluate to a mapping, the contents of which are\n'
+          'treated as additional keyword arguments.  In the case of a keyword\n'
+          'appearing in both "expression" and as an explicit keyword argument, '
+          'a\n'
+          '"TypeError" exception is raised.\n'
+          '\n'
+          'Formal parameters using the syntax "*identifier" or "**identifier"\n'
+          'cannot be used as positional argument slots or as keyword argument\n'
+          'names.\n'
+          '\n'
+          'A call always returns some value, possibly "None", unless it raises '
+          'an\n'
+          'exception.  How this value is computed depends on the type of the\n'
+          'callable object.\n'
+          '\n'
+          'If it is---\n'
+          '\n'
+          'a user-defined function:\n'
+          '   The code block for the function is executed, passing it the\n'
+          '   argument list.  The first thing the code block will do is bind '
+          'the\n'
+          '   formal parameters to the arguments; this is described in '
+          'section\n'
+          '   Function definitions.  When the code block executes a "return"\n'
+          '   statement, this specifies the return value of the function '
+          'call.\n'
+          '\n'
+          'a built-in function or method:\n'
+          '   The result is up to the interpreter; see Built-in Functions for '
+          'the\n'
+          '   descriptions of built-in functions and methods.\n'
+          '\n'
+          'a class object:\n'
+          '   A new instance of that class is returned.\n'
+          '\n'
+          'a class instance method:\n'
+          '   The corresponding user-defined function is called, with an '
+          'argument\n'
+          '   list that is one longer than the argument list of the call: the\n'
+          '   instance becomes the first argument.\n'
+          '\n'
+          'a class instance:\n'
+          '   The class must define a "__call__()" method; the effect is then '
+          'the\n'
+          '   same as if that method was called.\n',
+ 'class': '\n'
+          'Class definitions\n'
+          '*****************\n'
+          '\n'
+          'A class definition defines a class object (see section The '
+          'standard\n'
+          'type hierarchy):\n'
+          '\n'
+          '   classdef    ::= [decorators] "class" classname [inheritance] ":" '
+          'suite\n'
+          '   inheritance ::= "(" [parameter_list] ")"\n'
+          '   classname   ::= identifier\n'
+          '\n'
+          'A class definition is an executable statement.  The inheritance '
+          'list\n'
+          'usually gives a list of base classes (see Customizing class '
+          'creation\n'
+          'for more advanced uses), so each item in the list should evaluate '
+          'to a\n'
+          'class object which allows subclassing.  Classes without an '
+          'inheritance\n'
+          'list inherit, by default, from the base class "object"; hence,\n'
+          '\n'
+          '   class Foo:\n'
+          '       pass\n'
+          '\n'
+          'is equivalent to\n'
+          '\n'
+          '   class Foo(object):\n'
+          '       pass\n'
+          '\n'
+          "The class's suite is then executed in a new execution frame (see\n"
+          'Naming and binding), using a newly created local namespace and the\n'
+          'original global namespace. (Usually, the suite contains mostly\n'
+          "function definitions.)  When the class's suite finishes execution, "
+          'its\n'
+          'execution frame is discarded but its local namespace is saved. [4] '
+          'A\n'
+          'class object is then created using the inheritance list for the '
+          'base\n'
+          'classes and the saved local namespace for the attribute '
+          'dictionary.\n'
+          'The class name is bound to this class object in the original local\n'
+          'namespace.\n'
+          '\n'
+          'Class creation can be customized heavily using metaclasses.\n'
+          '\n'
+          'Classes can also be decorated: just like when decorating '
+          'functions,\n'
+          '\n'
+          '   @f1(arg)\n'
+          '   @f2\n'
+          '   class Foo: pass\n'
+          '\n'
+          'is equivalent to\n'
+          '\n'
+          '   class Foo: pass\n'
+          '   Foo = f1(arg)(f2(Foo))\n'
+          '\n'
+          'The evaluation rules for the decorator expressions are the same as '
+          'for\n'
+          'function decorators.  The result must be a class object, which is '
+          'then\n'
+          'bound to the class name.\n'
+          '\n'
+          "**Programmer's note:** Variables defined in the class definition "
+          'are\n'
+          'class attributes; they are shared by instances.  Instance '
+          'attributes\n'
+          'can be set in a method with "self.name = value".  Both class and\n'
+          'instance attributes are accessible through the notation '
+          '""self.name"",\n'
+          'and an instance attribute hides a class attribute with the same '
+          'name\n'
+          'when accessed in this way.  Class attributes can be used as '
+          'defaults\n'
+          'for instance attributes, but using mutable values there can lead '
+          'to\n'
+          'unexpected results.  Descriptors can be used to create instance\n'
+          'variables with different implementation details.\n'
+          '\n'
+          'See also: **PEP 3115** - Metaclasses in Python 3 **PEP 3129** -\n'
+          '  Class Decorators\n',
+ 'comparisons': '\n'
+                'Comparisons\n'
+                '***********\n'
+                '\n'
+                'Unlike C, all comparison operations in Python have the same '
+                'priority,\n'
+                'which is lower than that of any arithmetic, shifting or '
+                'bitwise\n'
+                'operation.  Also unlike C, expressions like "a < b < c" have '
+                'the\n'
+                'interpretation that is conventional in mathematics:\n'
+                '\n'
+                '   comparison    ::= or_expr ( comp_operator or_expr )*\n'
+                '   comp_operator ::= "<" | ">" | "==" | ">=" | "<=" | "!="\n'
+                '                     | "is" ["not"] | ["not"] "in"\n'
+                '\n'
+                'Comparisons yield boolean values: "True" or "False".\n'
+                '\n'
+                'Comparisons can be chained arbitrarily, e.g., "x < y <= z" '
+                'is\n'
+                'equivalent to "x < y and y <= z", except that "y" is '
+                'evaluated only\n'
+                'once (but in both cases "z" is not evaluated at all when "x < '
+                'y" is\n'
+                'found to be false).\n'
+                '\n'
+                'Formally, if *a*, *b*, *c*, ..., *y*, *z* are expressions and '
+                '*op1*,\n'
+                '*op2*, ..., *opN* are comparison operators, then "a op1 b op2 '
+                'c ... y\n'
+                'opN z" is equivalent to "a op1 b and b op2 c and ... y opN '
+                'z", except\n'
+                'that each expression is evaluated at most once.\n'
+                '\n'
+                'Note that "a op1 b op2 c" doesn\'t imply any kind of '
+                'comparison between\n'
+                '*a* and *c*, so that, e.g., "x < y > z" is perfectly legal '
+                '(though\n'
+                'perhaps not pretty).\n'
+                '\n'
+                '\n'
+                'Value comparisons\n'
+                '=================\n'
+                '\n'
+                'The operators "<", ">", "==", ">=", "<=", and "!=" compare '
+                'the values\n'
+                'of two objects.  The objects do not need to have the same '
+                'type.\n'
+                '\n'
+                'Chapter Objects, values and types states that objects have a '
+                'value (in\n'
+                'addition to type and identity).  The value of an object is a '
+                'rather\n'
+                'abstract notion in Python: For example, there is no canonical '
+                'access\n'
+                "method for an object's value.  Also, there is no requirement "
+                'that the\n'
+                'value of an object should be constructed in a particular way, '
+                'e.g.\n'
+                'comprised of all its data attributes. Comparison operators '
+                'implement a\n'
+                'particular notion of what the value of an object is.  One can '
+                'think of\n'
+                'them as defining the value of an object indirectly, by means '
+                'of their\n'
+                'comparison implementation.\n'
+                '\n'
+                'Because all types are (direct or indirect) subtypes of '
+                '"object", they\n'
+                'inherit the default comparison behavior from "object".  Types '
+                'can\n'
+                'customize their comparison behavior by implementing *rich '
+                'comparison\n'
+                'methods* like "__lt__()", described in Basic customization.\n'
+                '\n'
+                'The default behavior for equality comparison ("==" and "!=") '
+                'is based\n'
+                'on the identity of the objects.  Hence, equality comparison '
+                'of\n'
+                'instances with the same identity results in equality, and '
+                'equality\n'
+                'comparison of instances with different identities results in\n'
+                'inequality.  A motivation for this default behavior is the '
+                'desire that\n'
+                'all objects should be reflexive (i.e. "x is y" implies "x == '
+                'y").\n'
+                '\n'
+                'A default order comparison ("<", ">", "<=", and ">=") is not '
+                'provided;\n'
+                'an attempt raises "TypeError".  A motivation for this default '
+                'behavior\n'
+                'is the lack of a similar invariant as for equality.\n'
+                '\n'
+                'The behavior of the default equality comparison, that '
+                'instances with\n'
+                'different identities are always unequal, may be in contrast '
+                'to what\n'
+                'types will need that have a sensible definition of object '
+                'value and\n'
+                'value-based equality.  Such types will need to customize '
+                'their\n'
+                'comparison behavior, and in fact, a number of built-in types '
+                'have done\n'
+                'that.\n'
+                '\n'
+                'The following list describes the comparison behavior of the '
+                'most\n'
+                'important built-in types.\n'
+                '\n'
+                '* Numbers of built-in numeric types (Numeric Types --- int, '
+                'float,\n'
+                '  complex) and of the standard library types '
+                '"fractions.Fraction" and\n'
+                '  "decimal.Decimal" can be compared within and across their '
+                'types,\n'
+                '  with the restriction that complex numbers do not support '
+                'order\n'
+                '  comparison.  Within the limits of the types involved, they '
+                'compare\n'
+                '  mathematically (algorithmically) correct without loss of '
+                'precision.\n'
+                '\n'
+                '  The not-a-number values "float(\'NaN\')" and '
+                '"Decimal(\'NaN\')" are\n'
+                '  special.  They are identical to themselves ("x is x" is '
+                'true) but\n'
+                '  are not equal to themselves ("x == x" is false).  '
+                'Additionally,\n'
+                '  comparing any number to a not-a-number value will return '
+                '"False".\n'
+                '  For example, both "3 < float(\'NaN\')" and "float(\'NaN\') '
+                '< 3" will\n'
+                '  return "False".\n'
+                '\n'
+                '* Binary sequences (instances of "bytes" or "bytearray") can '
+                'be\n'
+                '  compared within and across their types.  They compare\n'
+                '  lexicographically using the numeric values of their '
+                'elements.\n'
+                '\n'
+                '* Strings (instances of "str") compare lexicographically '
+                'using the\n'
+                '  numerical Unicode code points (the result of the built-in '
+                'function\n'
+                '  "ord()") of their characters. [3]\n'
+                '\n'
+                '  Strings and binary sequences cannot be directly compared.\n'
+                '\n'
+                '* Sequences (instances of "tuple", "list", or "range") can '
+                'be\n'
+                '  compared only within each of their types, with the '
+                'restriction that\n'
+                '  ranges do not support order comparison.  Equality '
+                'comparison across\n'
+                '  these types results in unequality, and ordering comparison '
+                'across\n'
+                '  these types raises "TypeError".\n'
+                '\n'
+                '  Sequences compare lexicographically using comparison of\n'
+                '  corresponding elements, whereby reflexivity of the elements '
+                'is\n'
+                '  enforced.\n'
+                '\n'
+                '  In enforcing reflexivity of elements, the comparison of '
+                'collections\n'
+                '  assumes that for a collection element "x", "x == x" is '
+                'always true.\n'
+                '  Based on that assumption, element identity is compared '
+                'first, and\n'
+                '  element comparison is performed only for distinct '
+                'elements.  This\n'
+                '  approach yields the same result as a strict element '
+                'comparison\n'
+                '  would, if the compared elements are reflexive.  For '
+                'non-reflexive\n'
+                '  elements, the result is different than for strict element\n'
+                '  comparison, and may be surprising:  The non-reflexive '
+                'not-a-number\n'
+                '  values for example result in the following comparison '
+                'behavior when\n'
+                '  used in a list:\n'
+                '\n'
+                "     >>> nan = float('NaN')\n"
+                '     >>> nan is nan\n'
+                '     True\n'
+                '     >>> nan == nan\n'
+                '     False                 <-- the defined non-reflexive '
+                'behavior of NaN\n'
+                '     >>> [nan] == [nan]\n'
+                '     True                  <-- list enforces reflexivity and '
+                'tests identity first\n'
+                '\n'
+                '  Lexicographical comparison between built-in collections '
+                'works as\n'
+                '  follows:\n'
+                '\n'
+                '  * For two collections to compare equal, they must be of the '
+                'same\n'
+                '    type, have the same length, and each pair of '
+                'corresponding\n'
+                '    elements must compare equal (for example, "[1,2] == '
+                '(1,2)" is\n'
+                '    false because the type is not the same).\n'
+                '\n'
+                '  * Collections that support order comparison are ordered the '
+                'same\n'
+                '    as their first unequal elements (for example, "[1,2,x] <= '
+                '[1,2,y]"\n'
+                '    has the same value as "x <= y").  If a corresponding '
+                'element does\n'
+                '    not exist, the shorter collection is ordered first (for '
+                'example,\n'
+                '    "[1,2] < [1,2,3]" is true).\n'
+                '\n'
+                '* Mappings (instances of "dict") compare equal if and only if '
+                'they\n'
+                '  have equal *(key, value)* pairs. Equality comparison of the '
+                'keys and\n'
+                '  elements enforces reflexivity.\n'
+                '\n'
+                '  Order comparisons ("<", ">", "<=", and ">=") raise '
+                '"TypeError".\n'
+                '\n'
+                '* Sets (instances of "set" or "frozenset") can be compared '
+                'within\n'
+                '  and across their types.\n'
+                '\n'
+                '  They define order comparison operators to mean subset and '
+                'superset\n'
+                '  tests.  Those relations do not define total orderings (for '
+                'example,\n'
+                '  the two sets "{1,2}" and "{2,3}" are not equal, nor subsets '
+                'of one\n'
+                '  another, nor supersets of one another).  Accordingly, sets '
+                'are not\n'
+                '  appropriate arguments for functions which depend on total '
+                'ordering\n'
+                '  (for example, "min()", "max()", and "sorted()" produce '
+                'undefined\n'
+                '  results given a list of sets as inputs).\n'
+                '\n'
+                '  Comparison of sets enforces reflexivity of its elements.\n'
+                '\n'
+                '* Most other built-in types have no comparison methods '
+                'implemented,\n'
+                '  so they inherit the default comparison behavior.\n'
+                '\n'
+                'User-defined classes that customize their comparison behavior '
+                'should\n'
+                'follow some consistency rules, if possible:\n'
+                '\n'
+                '* Equality comparison should be reflexive. In other words, '
+                'identical\n'
+                '  objects should compare equal:\n'
+                '\n'
+                '     "x is y" implies "x == y"\n'
+                '\n'
+                '* Comparison should be symmetric. In other words, the '
+                'following\n'
+                '  expressions should have the same result:\n'
+                '\n'
+                '     "x == y" and "y == x"\n'
+                '\n'
+                '     "x != y" and "y != x"\n'
+                '\n'
+                '     "x < y" and "y > x"\n'
+                '\n'
+                '     "x <= y" and "y >= x"\n'
+                '\n'
+                '* Comparison should be transitive. The following '
+                '(non-exhaustive)\n'
+                '  examples illustrate that:\n'
+                '\n'
+                '     "x > y and y > z" implies "x > z"\n'
+                '\n'
+                '     "x < y and y <= z" implies "x < z"\n'
+                '\n'
+                '* Inverse comparison should result in the boolean negation. '
+                'In other\n'
+                '  words, the following expressions should have the same '
+                'result:\n'
+                '\n'
+                '     "x == y" and "not x != y"\n'
+                '\n'
+                '     "x < y" and "not x >= y" (for total ordering)\n'
+                '\n'
+                '     "x > y" and "not x <= y" (for total ordering)\n'
+                '\n'
+                '  The last two expressions apply to totally ordered '
+                'collections (e.g.\n'
+                '  to sequences, but not to sets or mappings). See also the\n'
+                '  "total_ordering()" decorator.\n'
+                '\n'
+                'Python does not enforce these consistency rules. In fact, '
+                'the\n'
+                'not-a-number values are an example for not following these '
+                'rules.\n'
+                '\n'
+                '\n'
+                'Membership test operations\n'
+                '==========================\n'
+                '\n'
+                'The operators "in" and "not in" test for membership.  "x in '
+                's"\n'
+                'evaluates to true if *x* is a member of *s*, and false '
+                'otherwise.  "x\n'
+                'not in s" returns the negation of "x in s".  All built-in '
+                'sequences\n'
+                'and set types support this as well as dictionary, for which '
+                '"in" tests\n'
+                'whether the dictionary has a given key. For container types '
+                'such as\n'
+                'list, tuple, set, frozenset, dict, or collections.deque, the\n'
+                'expression "x in y" is equivalent to "any(x is e or x == e '
+                'for e in\n'
+                'y)".\n'
+                '\n'
+                'For the string and bytes types, "x in y" is true if and only '
+                'if *x* is\n'
+                'a substring of *y*.  An equivalent test is "y.find(x) != '
+                '-1".  Empty\n'
+                'strings are always considered to be a substring of any other '
+                'string,\n'
+                'so """ in "abc"" will return "True".\n'
+                '\n'
+                'For user-defined classes which define the "__contains__()" '
+                'method, "x\n'
+                'in y" is true if and only if "y.__contains__(x)" is true.\n'
+                '\n'
+                'For user-defined classes which do not define "__contains__()" '
+                'but do\n'
+                'define "__iter__()", "x in y" is true if some value "z" with '
+                '"x == z"\n'
+                'is produced while iterating over "y".  If an exception is '
+                'raised\n'
+                'during the iteration, it is as if "in" raised that '
+                'exception.\n'
+                '\n'
+                'Lastly, the old-style iteration protocol is tried: if a class '
+                'defines\n'
+                '"__getitem__()", "x in y" is true if and only if there is a '
+                'non-\n'
+                'negative integer index *i* such that "x == y[i]", and all '
+                'lower\n'
+                'integer indices do not raise "IndexError" exception.  (If any '
+                'other\n'
+                'exception is raised, it is as if "in" raised that '
+                'exception).\n'
+                '\n'
+                'The operator "not in" is defined to have the inverse true '
+                'value of\n'
+                '"in".\n'
+                '\n'
+                '\n'
+                'Identity comparisons\n'
+                '====================\n'
+                '\n'
+                'The operators "is" and "is not" test for object identity: "x '
+                'is y" is\n'
+                'true if and only if *x* and *y* are the same object.  "x is '
+                'not y"\n'
+                'yields the inverse truth value. [4]\n',
+ 'compound': '\n'
+             'Compound statements\n'
+             '*******************\n'
+             '\n'
+             'Compound statements contain (groups of) other statements; they '
+             'affect\n'
+             'or control the execution of those other statements in some way.  '
+             'In\n'
+             'general, compound statements span multiple lines, although in '
+             'simple\n'
+             'incarnations a whole compound statement may be contained in one '
+             'line.\n'
+             '\n'
+             'The "if", "while" and "for" statements implement traditional '
+             'control\n'
+             'flow constructs.  "try" specifies exception handlers and/or '
+             'cleanup\n'
+             'code for a group of statements, while the "with" statement '
+             'allows the\n'
+             'execution of initialization and finalization code around a block '
+             'of\n'
+             'code.  Function and class definitions are also syntactically '
+             'compound\n'
+             'statements.\n'
+             '\n'
+             "A compound statement consists of one or more 'clauses.'  A "
+             'clause\n'
+             "consists of a header and a 'suite.'  The clause headers of a\n"
+             'particular compound statement are all at the same indentation '
+             'level.\n'
+             'Each clause header begins with a uniquely identifying keyword '
+             'and ends\n'
+             'with a colon.  A suite is a group of statements controlled by a\n'
+             'clause.  A suite can be one or more semicolon-separated simple\n'
+             'statements on the same line as the header, following the '
+             "header's\n"
+             'colon, or it can be one or more indented statements on '
+             'subsequent\n'
+             'lines.  Only the latter form of a suite can contain nested '
+             'compound\n'
+             "statements; the following is illegal, mostly because it wouldn't "
+             'be\n'
+             'clear to which "if" clause a following "else" clause would '
+             'belong:\n'
+             '\n'
+             '   if test1: if test2: print(x)\n'
+             '\n'
+             'Also note that the semicolon binds tighter than the colon in '
+             'this\n'
+             'context, so that in the following example, either all or none of '
+             'the\n'
+             '"print()" calls are executed:\n'
+             '\n'
+             '   if x < y < z: print(x); print(y); print(z)\n'
+             '\n'
+             'Summarizing:\n'
+             '\n'
+             '   compound_stmt ::= if_stmt\n'
+             '                     | while_stmt\n'
+             '                     | for_stmt\n'
+             '                     | try_stmt\n'
+             '                     | with_stmt\n'
+             '                     | funcdef\n'
+             '                     | classdef\n'
+             '                     | async_with_stmt\n'
+             '                     | async_for_stmt\n'
+             '                     | async_funcdef\n'
+             '   suite         ::= stmt_list NEWLINE | NEWLINE INDENT '
+             'statement+ DEDENT\n'
+             '   statement     ::= stmt_list NEWLINE | compound_stmt\n'
+             '   stmt_list     ::= simple_stmt (";" simple_stmt)* [";"]\n'
+             '\n'
+             'Note that statements always end in a "NEWLINE" possibly followed '
+             'by a\n'
+             '"DEDENT".  Also note that optional continuation clauses always '
+             'begin\n'
+             'with a keyword that cannot start a statement, thus there are no\n'
+             'ambiguities (the \'dangling "else"\' problem is solved in Python '
+             'by\n'
+             'requiring nested "if" statements to be indented).\n'
+             '\n'
+             'The formatting of the grammar rules in the following sections '
+             'places\n'
+             'each clause on a separate line for clarity.\n'
+             '\n'
+             '\n'
+             'The "if" statement\n'
+             '==================\n'
+             '\n'
+             'The "if" statement is used for conditional execution:\n'
+             '\n'
+             '   if_stmt ::= "if" expression ":" suite\n'
+             '               ( "elif" expression ":" suite )*\n'
+             '               ["else" ":" suite]\n'
+             '\n'
+             'It selects exactly one of the suites by evaluating the '
+             'expressions one\n'
+             'by one until one is found to be true (see section Boolean '
+             'operations\n'
+             'for the definition of true and false); then that suite is '
+             'executed\n'
+             '(and no other part of the "if" statement is executed or '
+             'evaluated).\n'
+             'If all expressions are false, the suite of the "else" clause, '
+             'if\n'
+             'present, is executed.\n'
+             '\n'
+             '\n'
+             'The "while" statement\n'
+             '=====================\n'
+             '\n'
+             'The "while" statement is used for repeated execution as long as '
+             'an\n'
+             'expression is true:\n'
+             '\n'
+             '   while_stmt ::= "while" expression ":" suite\n'
+             '                  ["else" ":" suite]\n'
+             '\n'
+             'This repeatedly tests the expression and, if it is true, '
+             'executes the\n'
+             'first suite; if the expression is false (which may be the first '
+             'time\n'
+             'it is tested) the suite of the "else" clause, if present, is '
+             'executed\n'
+             'and the loop terminates.\n'
+             '\n'
+             'A "break" statement executed in the first suite terminates the '
+             'loop\n'
+             'without executing the "else" clause\'s suite.  A "continue" '
+             'statement\n'
+             'executed in the first suite skips the rest of the suite and goes '
+             'back\n'
+             'to testing the expression.\n'
+             '\n'
+             '\n'
+             'The "for" statement\n'
+             '===================\n'
+             '\n'
+             'The "for" statement is used to iterate over the elements of a '
+             'sequence\n'
+             '(such as a string, tuple or list) or other iterable object:\n'
+             '\n'
+             '   for_stmt ::= "for" target_list "in" expression_list ":" '
+             'suite\n'
+             '                ["else" ":" suite]\n'
+             '\n'
+             'The expression list is evaluated once; it should yield an '
+             'iterable\n'
+             'object.  An iterator is created for the result of the\n'
+             '"expression_list".  The suite is then executed once for each '
+             'item\n'
+             'provided by the iterator, in the order returned by the '
+             'iterator.  Each\n'
+             'item in turn is assigned to the target list using the standard '
+             'rules\n'
+             'for assignments (see Assignment statements), and then the suite '
+             'is\n'
+             'executed.  When the items are exhausted (which is immediately '
+             'when the\n'
+             'sequence is empty or an iterator raises a "StopIteration" '
+             'exception),\n'
+             'the suite in the "else" clause, if present, is executed, and the '
+             'loop\n'
+             'terminates.\n'
+             '\n'
+             'A "break" statement executed in the first suite terminates the '
+             'loop\n'
+             'without executing the "else" clause\'s suite.  A "continue" '
+             'statement\n'
+             'executed in the first suite skips the rest of the suite and '
+             'continues\n'
+             'with the next item, or with the "else" clause if there is no '
+             'next\n'
+             'item.\n'
+             '\n'
+             'The for-loop makes assignments to the variables(s) in the target '
+             'list.\n'
+             'This overwrites all previous assignments to those variables '
+             'including\n'
+             'those made in the suite of the for-loop:\n'
+             '\n'
+             '   for i in range(10):\n'
+             '       print(i)\n'
+             '       i = 5             # this will not affect the for-loop\n'
+             '                         # because i will be overwritten with '
+             'the next\n'
+             '                         # index in the range\n'
+             '\n'
+             'Names in the target list are not deleted when the loop is '
+             'finished,\n'
+             'but if the sequence is empty, they will not have been assigned '
+             'to at\n'
+             'all by the loop.  Hint: the built-in function "range()" returns '
+             'an\n'
+             "iterator of integers suitable to emulate the effect of Pascal's "
+             '"for i\n'
+             ':= a to b do"; e.g., "list(range(3))" returns the list "[0, 1, '
+             '2]".\n'
+             '\n'
+             'Note: There is a subtlety when the sequence is being modified by '
+             'the\n'
+             '  loop (this can only occur for mutable sequences, i.e. lists).  '
+             'An\n'
+             '  internal counter is used to keep track of which item is used '
+             'next,\n'
+             '  and this is incremented on each iteration.  When this counter '
+             'has\n'
+             '  reached the length of the sequence the loop terminates.  This '
+             'means\n'
+             '  that if the suite deletes the current (or a previous) item '
+             'from the\n'
+             '  sequence, the next item will be skipped (since it gets the '
+             'index of\n'
+             '  the current item which has already been treated).  Likewise, '
+             'if the\n'
+             '  suite inserts an item in the sequence before the current item, '
+             'the\n'
+             '  current item will be treated again the next time through the '
+             'loop.\n'
+             '  This can lead to nasty bugs that can be avoided by making a\n'
+             '  temporary copy using a slice of the whole sequence, e.g.,\n'
+             '\n'
+             '     for x in a[:]:\n'
+             '         if x < 0: a.remove(x)\n'
+             '\n'
+             '\n'
+             'The "try" statement\n'
+             '===================\n'
+             '\n'
+             'The "try" statement specifies exception handlers and/or cleanup '
+             'code\n'
+             'for a group of statements:\n'
+             '\n'
+             '   try_stmt  ::= try1_stmt | try2_stmt\n'
+             '   try1_stmt ::= "try" ":" suite\n'
+             '                 ("except" [expression ["as" identifier]] ":" '
+             'suite)+\n'
+             '                 ["else" ":" suite]\n'
+             '                 ["finally" ":" suite]\n'
+             '   try2_stmt ::= "try" ":" suite\n'
+             '                 "finally" ":" suite\n'
+             '\n'
+             'The "except" clause(s) specify one or more exception handlers. '
+             'When no\n'
+             'exception occurs in the "try" clause, no exception handler is\n'
+             'executed. When an exception occurs in the "try" suite, a search '
+             'for an\n'
+             'exception handler is started.  This search inspects the except '
+             'clauses\n'
+             'in turn until one is found that matches the exception.  An '
+             'expression-\n'
+             'less except clause, if present, must be last; it matches any\n'
+             'exception.  For an except clause with an expression, that '
+             'expression\n'
+             'is evaluated, and the clause matches the exception if the '
+             'resulting\n'
+             'object is "compatible" with the exception.  An object is '
+             'compatible\n'
+             'with an exception if it is the class or a base class of the '
+             'exception\n'
+             'object or a tuple containing an item compatible with the '
+             'exception.\n'
+             '\n'
+             'If no except clause matches the exception, the search for an '
+             'exception\n'
+             'handler continues in the surrounding code and on the invocation '
+             'stack.\n'
+             '[1]\n'
+             '\n'
+             'If the evaluation of an expression in the header of an except '
+             'clause\n'
+             'raises an exception, the original search for a handler is '
+             'canceled and\n'
+             'a search starts for the new exception in the surrounding code '
+             'and on\n'
+             'the call stack (it is treated as if the entire "try" statement '
+             'raised\n'
+             'the exception).\n'
+             '\n'
+             'When a matching except clause is found, the exception is '
+             'assigned to\n'
+             'the target specified after the "as" keyword in that except '
+             'clause, if\n'
+             "present, and the except clause's suite is executed.  All except\n"
+             'clauses must have an executable block.  When the end of this '
+             'block is\n'
+             'reached, execution continues normally after the entire try '
+             'statement.\n'
+             '(This means that if two nested handlers exist for the same '
+             'exception,\n'
+             'and the exception occurs in the try clause of the inner handler, '
+             'the\n'
+             'outer handler will not handle the exception.)\n'
+             '\n'
+             'When an exception has been assigned using "as target", it is '
+             'cleared\n'
+             'at the end of the except clause.  This is as if\n'
+             '\n'
+             '   except E as N:\n'
+             '       foo\n'
+             '\n'
+             'was translated to\n'
+             '\n'
+             '   except E as N:\n'
+             '       try:\n'
+             '           foo\n'
+             '       finally:\n'
+             '           del N\n'
+             '\n'
+             'This means the exception must be assigned to a different name to '
+             'be\n'
+             'able to refer to it after the except clause.  Exceptions are '
+             'cleared\n'
+             'because with the traceback attached to them, they form a '
+             'reference\n'
+             'cycle with the stack frame, keeping all locals in that frame '
+             'alive\n'
+             'until the next garbage collection occurs.\n'
+             '\n'
+             "Before an except clause's suite is executed, details about the\n"
+             'exception are stored in the "sys" module and can be accessed '
+             'via\n'
+             '"sys.exc_info()". "sys.exc_info()" returns a 3-tuple consisting '
+             'of the\n'
+             'exception class, the exception instance and a traceback object '
+             '(see\n'
+             'section The standard type hierarchy) identifying the point in '
+             'the\n'
+             'program where the exception occurred.  "sys.exc_info()" values '
+             'are\n'
+             'restored to their previous values (before the call) when '
+             'returning\n'
+             'from a function that handled an exception.\n'
+             '\n'
+             'The optional "else" clause is executed if and when control flows '
+             'off\n'
+             'the end of the "try" clause. [2] Exceptions in the "else" clause '
+             'are\n'
+             'not handled by the preceding "except" clauses.\n'
+             '\n'
+             'If "finally" is present, it specifies a \'cleanup\' handler.  '
+             'The "try"\n'
+             'clause is executed, including any "except" and "else" clauses.  '
+             'If an\n'
+             'exception occurs in any of the clauses and is not handled, the\n'
+             'exception is temporarily saved. The "finally" clause is '
+             'executed.  If\n'
+             'there is a saved exception it is re-raised at the end of the '
+             '"finally"\n'
+             'clause.  If the "finally" clause raises another exception, the '
+             'saved\n'
+             'exception is set as the context of the new exception. If the '
+             '"finally"\n'
+             'clause executes a "return" or "break" statement, the saved '
+             'exception\n'
+             'is discarded:\n'
+             '\n'
+             '   >>> def f():\n'
+             '   ...     try:\n'
+             '   ...         1/0\n'
+             '   ...     finally:\n'
+             '   ...         return 42\n'
+             '   ...\n'
+             '   >>> f()\n'
+             '   42\n'
+             '\n'
+             'The exception information is not available to the program '
+             'during\n'
+             'execution of the "finally" clause.\n'
+             '\n'
+             'When a "return", "break" or "continue" statement is executed in '
+             'the\n'
+             '"try" suite of a "try"..."finally" statement, the "finally" '
+             'clause is\n'
+             'also executed \'on the way out.\' A "continue" statement is '
+             'illegal in\n'
+             'the "finally" clause. (The reason is a problem with the current\n'
+             'implementation --- this restriction may be lifted in the '
+             'future).\n'
+             '\n'
+             'The return value of a function is determined by the last '
+             '"return"\n'
+             'statement executed.  Since the "finally" clause always executes, '
+             'a\n'
+             '"return" statement executed in the "finally" clause will always '
+             'be the\n'
+             'last one executed:\n'
+             '\n'
+             '   >>> def foo():\n'
+             '   ...     try:\n'
+             "   ...         return 'try'\n"
+             '   ...     finally:\n'
+             "   ...         return 'finally'\n"
+             '   ...\n'
+             '   >>> foo()\n'
+             "   'finally'\n"
+             '\n'
+             'Additional information on exceptions can be found in section\n'
+             'Exceptions, and information on using the "raise" statement to '
+             'generate\n'
+             'exceptions may be found in section The raise statement.\n'
+             '\n'
+             '\n'
+             'The "with" statement\n'
+             '====================\n'
+             '\n'
+             'The "with" statement is used to wrap the execution of a block '
+             'with\n'
+             'methods defined by a context manager (see section With '
+             'Statement\n'
+             'Context Managers). This allows common '
+             '"try"..."except"..."finally"\n'
+             'usage patterns to be encapsulated for convenient reuse.\n'
+             '\n'
+             '   with_stmt ::= "with" with_item ("," with_item)* ":" suite\n'
+             '   with_item ::= expression ["as" target]\n'
+             '\n'
+             'The execution of the "with" statement with one "item" proceeds '
+             'as\n'
+             'follows:\n'
+             '\n'
+             '1. The context expression (the expression given in the '
+             '"with_item")\n'
+             '   is evaluated to obtain a context manager.\n'
+             '\n'
+             '2. The context manager\'s "__exit__()" is loaded for later use.\n'
+             '\n'
+             '3. The context manager\'s "__enter__()" method is invoked.\n'
+             '\n'
+             '4. If a target was included in the "with" statement, the return\n'
+             '   value from "__enter__()" is assigned to it.\n'
+             '\n'
+             '   Note: The "with" statement guarantees that if the '
+             '"__enter__()"\n'
+             '     method returns without an error, then "__exit__()" will '
+             'always be\n'
+             '     called. Thus, if an error occurs during the assignment to '
+             'the\n'
+             '     target list, it will be treated the same as an error '
+             'occurring\n'
+             '     within the suite would be. See step 6 below.\n'
+             '\n'
+             '5. The suite is executed.\n'
+             '\n'
+             '6. The context manager\'s "__exit__()" method is invoked.  If '
+             'an\n'
+             '   exception caused the suite to be exited, its type, value, '
+             'and\n'
+             '   traceback are passed as arguments to "__exit__()". Otherwise, '
+             'three\n'
+             '   "None" arguments are supplied.\n'
+             '\n'
+             '   If the suite was exited due to an exception, and the return '
+             'value\n'
+             '   from the "__exit__()" method was false, the exception is '
+             'reraised.\n'
+             '   If the return value was true, the exception is suppressed, '
+             'and\n'
+             '   execution continues with the statement following the "with"\n'
+             '   statement.\n'
+             '\n'
+             '   If the suite was exited for any reason other than an '
+             'exception, the\n'
+             '   return value from "__exit__()" is ignored, and execution '
+             'proceeds\n'
+             '   at the normal location for the kind of exit that was taken.\n'
+             '\n'
+             'With more than one item, the context managers are processed as '
+             'if\n'
+             'multiple "with" statements were nested:\n'
+             '\n'
+             '   with A() as a, B() as b:\n'
+             '       suite\n'
+             '\n'
+             'is equivalent to\n'
+             '\n'
+             '   with A() as a:\n'
+             '       with B() as b:\n'
+             '           suite\n'
+             '\n'
+             'Changed in version 3.1: Support for multiple context '
+             'expressions.\n'
+             '\n'
+             'See also:\n'
+             '\n'
+             '  **PEP 343** - The "with" statement\n'
+             '     The specification, background, and examples for the Python '
+             '"with"\n'
+             '     statement.\n'
+             '\n'
+             '\n'
+             'Function definitions\n'
+             '====================\n'
+             '\n'
+             'A function definition defines a user-defined function object '
+             '(see\n'
+             'section The standard type hierarchy):\n'
+             '\n'
+             '   funcdef                 ::= [decorators] "def" funcname "(" '
+             '[parameter_list] ")" ["->" expression] ":" suite\n'
+             '   decorators              ::= decorator+\n'
+             '   decorator               ::= "@" dotted_name ["(" '
+             '[parameter_list [","]] ")"] NEWLINE\n'
+             '   dotted_name             ::= identifier ("." identifier)*\n'
+             '   parameter_list          ::= defparameter ("," defparameter)* '
+             '["," [parameter_list_starargs]]\n'
+             '                      | parameter_list_starargs\n'
+             '   parameter_list_starargs ::= "*" [parameter] ("," '
+             'defparameter)* ["," ["**" parameter [","]]]\n'
+             '                               | "**" parameter [","]\n'
+             '   parameter               ::= identifier [":" expression]\n'
+             '   defparameter            ::= parameter ["=" expression]\n'
+             '   funcname                ::= identifier\n'
+             '\n'
+             'A function definition is an executable statement.  Its execution '
+             'binds\n'
+             'the function name in the current local namespace to a function '
+             'object\n'
+             '(a wrapper around the executable code for the function).  This\n'
+             'function object contains a reference to the current global '
+             'namespace\n'
+             'as the global namespace to be used when the function is called.\n'
+             '\n'
+             'The function definition does not execute the function body; this '
+             'gets\n'
+             'executed only when the function is called. [3]\n'
+             '\n'
+             'A function definition may be wrapped by one or more *decorator*\n'
+             'expressions. Decorator expressions are evaluated when the '
+             'function is\n'
+             'defined, in the scope that contains the function definition.  '
+             'The\n'
+             'result must be a callable, which is invoked with the function '
+             'object\n'
+             'as the only argument. The returned value is bound to the '
+             'function name\n'
+             'instead of the function object.  Multiple decorators are applied '
+             'in\n'
+             'nested fashion. For example, the following code\n'
+             '\n'
+             '   @f1(arg)\n'
+             '   @f2\n'
+             '   def func(): pass\n'
+             '\n'
+             'is equivalent to\n'
+             '\n'
+             '   def func(): pass\n'
+             '   func = f1(arg)(f2(func))\n'
+             '\n'
+             'When one or more *parameters* have the form *parameter* "="\n'
+             '*expression*, the function is said to have "default parameter '
+             'values."\n'
+             'For a parameter with a default value, the corresponding '
+             '*argument* may\n'
+             "be omitted from a call, in which case the parameter's default "
+             'value is\n'
+             'substituted.  If a parameter has a default value, all following\n'
+             'parameters up until the ""*"" must also have a default value --- '
+             'this\n'
+             'is a syntactic restriction that is not expressed by the '
+             'grammar.\n'
+             '\n'
+             '**Default parameter values are evaluated from left to right when '
+             'the\n'
+             'function definition is executed.** This means that the '
+             'expression is\n'
+             'evaluated once, when the function is defined, and that the same '
+             '"pre-\n'
+             'computed" value is used for each call.  This is especially '
+             'important\n'
+             'to understand when a default parameter is a mutable object, such '
+             'as a\n'
+             'list or a dictionary: if the function modifies the object (e.g. '
+             'by\n'
+             'appending an item to a list), the default value is in effect '
+             'modified.\n'
+             'This is generally not what was intended.  A way around this is '
+             'to use\n'
+             '"None" as the default, and explicitly test for it in the body of '
+             'the\n'
+             'function, e.g.:\n'
+             '\n'
+             '   def whats_on_the_telly(penguin=None):\n'
+             '       if penguin is None:\n'
+             '           penguin = []\n'
+             '       penguin.append("property of the zoo")\n'
+             '       return penguin\n'
+             '\n'
+             'Function call semantics are described in more detail in section '
+             'Calls.\n'
+             'A function call always assigns values to all parameters '
+             'mentioned in\n'
+             'the parameter list, either from position arguments, from '
+             'keyword\n'
+             'arguments, or from default values.  If the form ""*identifier"" '
+             'is\n'
+             'present, it is initialized to a tuple receiving any excess '
+             'positional\n'
+             'parameters, defaulting to the empty tuple.  If the form\n'
+             '""**identifier"" is present, it is initialized to a new '
+             'dictionary\n'
+             'receiving any excess keyword arguments, defaulting to a new '
+             'empty\n'
+             'dictionary. Parameters after ""*"" or ""*identifier"" are '
+             'keyword-only\n'
+             'parameters and may only be passed used keyword arguments.\n'
+             '\n'
+             'Parameters may have annotations of the form "": expression"" '
+             'following\n'
+             'the parameter name.  Any parameter may have an annotation even '
+             'those\n'
+             'of the form "*identifier" or "**identifier".  Functions may '
+             'have\n'
+             '"return" annotation of the form ""-> expression"" after the '
+             'parameter\n'
+             'list.  These annotations can be any valid Python expression and '
+             'are\n'
+             'evaluated when the function definition is executed.  Annotations '
+             'may\n'
+             'be evaluated in a different order than they appear in the source '
+             'code.\n'
+             'The presence of annotations does not change the semantics of a\n'
+             'function.  The annotation values are available as values of a\n'
+             "dictionary keyed by the parameters' names in the "
+             '"__annotations__"\n'
+             'attribute of the function object.\n'
+             '\n'
+             'It is also possible to create anonymous functions (functions not '
+             'bound\n'
+             'to a name), for immediate use in expressions.  This uses lambda\n'
+             'expressions, described in section Lambdas.  Note that the '
+             'lambda\n'
+             'expression is merely a shorthand for a simplified function '
+             'definition;\n'
+             'a function defined in a ""def"" statement can be passed around '
+             'or\n'
+             'assigned to another name just like a function defined by a '
+             'lambda\n'
+             'expression.  The ""def"" form is actually more powerful since '
+             'it\n'
+             'allows the execution of multiple statements and annotations.\n'
+             '\n'
+             "**Programmer's note:** Functions are first-class objects.  A "
+             '""def""\n'
+             'statement executed inside a function definition defines a local\n'
+             'function that can be returned or passed around.  Free variables '
+             'used\n'
+             'in the nested function can access the local variables of the '
+             'function\n'
+             'containing the def.  See section Naming and binding for '
+             'details.\n'
+             '\n'
+             'See also:\n'
+             '\n'
+             '  **PEP 3107** - Function Annotations\n'
+             '     The original specification for function annotations.\n'
+             '\n'
+             '\n'
+             'Class definitions\n'
+             '=================\n'
+             '\n'
+             'A class definition defines a class object (see section The '
+             'standard\n'
+             'type hierarchy):\n'
+             '\n'
+             '   classdef    ::= [decorators] "class" classname [inheritance] '
+             '":" suite\n'
+             '   inheritance ::= "(" [parameter_list] ")"\n'
+             '   classname   ::= identifier\n'
+             '\n'
+             'A class definition is an executable statement.  The inheritance '
+             'list\n'
+             'usually gives a list of base classes (see Customizing class '
+             'creation\n'
+             'for more advanced uses), so each item in the list should '
+             'evaluate to a\n'
+             'class object which allows subclassing.  Classes without an '
+             'inheritance\n'
+             'list inherit, by default, from the base class "object"; hence,\n'
+             '\n'
+             '   class Foo:\n'
+             '       pass\n'
+             '\n'
+             'is equivalent to\n'
+             '\n'
+             '   class Foo(object):\n'
+             '       pass\n'
+             '\n'
+             "The class's suite is then executed in a new execution frame "
+             '(see\n'
+             'Naming and binding), using a newly created local namespace and '
+             'the\n'
+             'original global namespace. (Usually, the suite contains mostly\n'
+             "function definitions.)  When the class's suite finishes "
+             'execution, its\n'
+             'execution frame is discarded but its local namespace is saved. '
+             '[4] A\n'
+             'class object is then created using the inheritance list for the '
+             'base\n'
+             'classes and the saved local namespace for the attribute '
+             'dictionary.\n'
+             'The class name is bound to this class object in the original '
+             'local\n'
+             'namespace.\n'
+             '\n'
+             'Class creation can be customized heavily using metaclasses.\n'
+             '\n'
+             'Classes can also be decorated: just like when decorating '
+             'functions,\n'
+             '\n'
+             '   @f1(arg)\n'
+             '   @f2\n'
+             '   class Foo: pass\n'
+             '\n'
+             'is equivalent to\n'
+             '\n'
+             '   class Foo: pass\n'
+             '   Foo = f1(arg)(f2(Foo))\n'
+             '\n'
+             'The evaluation rules for the decorator expressions are the same '
+             'as for\n'
+             'function decorators.  The result must be a class object, which '
+             'is then\n'
+             'bound to the class name.\n'
+             '\n'
+             "**Programmer's note:** Variables defined in the class definition "
+             'are\n'
+             'class attributes; they are shared by instances.  Instance '
+             'attributes\n'
+             'can be set in a method with "self.name = value".  Both class '
+             'and\n'
+             'instance attributes are accessible through the notation '
+             '""self.name"",\n'
+             'and an instance attribute hides a class attribute with the same '
+             'name\n'
+             'when accessed in this way.  Class attributes can be used as '
+             'defaults\n'
+             'for instance attributes, but using mutable values there can lead '
+             'to\n'
+             'unexpected results.  Descriptors can be used to create instance\n'
+             'variables with different implementation details.\n'
+             '\n'
+             'See also: **PEP 3115** - Metaclasses in Python 3 **PEP 3129** -\n'
+             '  Class Decorators\n'
+             '\n'
+             '\n'
+             'Coroutines\n'
+             '==========\n'
+             '\n'
+             'New in version 3.5.\n'
+             '\n'
+             '\n'
+             'Coroutine function definition\n'
+             '-----------------------------\n'
+             '\n'
+             '   async_funcdef ::= [decorators] "async" "def" funcname "(" '
+             '[parameter_list] ")" ["->" expression] ":" suite\n'
+             '\n'
+             'Execution of Python coroutines can be suspended and resumed at '
+             'many\n'
+             'points (see *coroutine*).  In the body of a coroutine, any '
+             '"await" and\n'
+             '"async" identifiers become reserved keywords; "await" '
+             'expressions,\n'
+             '"async for" and "async with" can only be used in coroutine '
+             'bodies.\n'
+             '\n'
+             'Functions defined with "async def" syntax are always coroutine\n'
+             'functions, even if they do not contain "await" or "async" '
+             'keywords.\n'
+             '\n'
+             'It is a "SyntaxError" to use "yield" expressions in "async def"\n'
+             'coroutines.\n'
+             '\n'
+             'An example of a coroutine function:\n'
+             '\n'
+             '   async def func(param1, param2):\n'
+             '       do_stuff()\n'
+             '       await some_coroutine()\n'
+             '\n'
+             '\n'
+             'The "async for" statement\n'
+             '-------------------------\n'
+             '\n'
+             '   async_for_stmt ::= "async" for_stmt\n'
+             '\n'
+             'An *asynchronous iterable* is able to call asynchronous code in '
+             'its\n'
+             '*iter* implementation, and *asynchronous iterator* can call\n'
+             'asynchronous code in its *next* method.\n'
+             '\n'
+             'The "async for" statement allows convenient iteration over\n'
+             'asynchronous iterators.\n'
+             '\n'
+             'The following code:\n'
+             '\n'
+             '   async for TARGET in ITER:\n'
+             '       BLOCK\n'
+             '   else:\n'
+             '       BLOCK2\n'
+             '\n'
+             'Is semantically equivalent to:\n'
+             '\n'
+             '   iter = (ITER)\n'
+             '   iter = await type(iter).__aiter__(iter)\n'
+             '   running = True\n'
+             '   while running:\n'
+             '       try:\n'
+             '           TARGET = await type(iter).__anext__(iter)\n'
+             '       except StopAsyncIteration:\n'
+             '           running = False\n'
+             '       else:\n'
+             '           BLOCK\n'
+             '   else:\n'
+             '       BLOCK2\n'
+             '\n'
+             'See also "__aiter__()" and "__anext__()" for details.\n'
+             '\n'
+             'It is a "SyntaxError" to use "async for" statement outside of '
+             'an\n'
+             '"async def" function.\n'
+             '\n'
+             '\n'
+             'The "async with" statement\n'
+             '--------------------------\n'
+             '\n'
+             '   async_with_stmt ::= "async" with_stmt\n'
+             '\n'
+             'An *asynchronous context manager* is a *context manager* that is '
+             'able\n'
+             'to suspend execution in its *enter* and *exit* methods.\n'
+             '\n'
+             'The following code:\n'
+             '\n'
+             '   async with EXPR as VAR:\n'
+             '       BLOCK\n'
+             '\n'
+             'Is semantically equivalent to:\n'
+             '\n'
+             '   mgr = (EXPR)\n'
+             '   aexit = type(mgr).__aexit__\n'
+             '   aenter = type(mgr).__aenter__(mgr)\n'
+             '   exc = True\n'
+             '\n'
+             '   VAR = await aenter\n'
+             '   try:\n'
+             '       BLOCK\n'
+             '   except:\n'
+             '       if not await aexit(mgr, *sys.exc_info()):\n'
+             '           raise\n'
+             '   else:\n'
+             '       await aexit(mgr, None, None, None)\n'
+             '\n'
+             'See also "__aenter__()" and "__aexit__()" for details.\n'
+             '\n'
+             'It is a "SyntaxError" to use "async with" statement outside of '
+             'an\n'
+             '"async def" function.\n'
+             '\n'
+             'See also: **PEP 492** - Coroutines with async and await syntax\n'
+             '\n'
+             '-[ Footnotes ]-\n'
+             '\n'
+             '[1] The exception is propagated to the invocation stack unless\n'
+             '    there is a "finally" clause which happens to raise another\n'
+             '    exception. That new exception causes the old one to be '
+             'lost.\n'
+             '\n'
+             '[2] Currently, control "flows off the end" except in the case '
+             'of\n'
+             '    an exception or the execution of a "return", "continue", or\n'
+             '    "break" statement.\n'
+             '\n'
+             '[3] A string literal appearing as the first statement in the\n'
+             '    function body is transformed into the function\'s "__doc__"\n'
+             "    attribute and therefore the function's *docstring*.\n"
+             '\n'
+             '[4] A string literal appearing as the first statement in the '
+             'class\n'
+             '    body is transformed into the namespace\'s "__doc__" item '
+             'and\n'
+             "    therefore the class's *docstring*.\n",
+ 'context-managers': '\n'
+                     'With Statement Context Managers\n'
+                     '*******************************\n'
+                     '\n'
+                     'A *context manager* is an object that defines the '
+                     'runtime context to\n'
+                     'be established when executing a "with" statement. The '
+                     'context manager\n'
+                     'handles the entry into, and the exit from, the desired '
+                     'runtime context\n'
+                     'for the execution of the block of code.  Context '
+                     'managers are normally\n'
+                     'invoked using the "with" statement (described in section '
+                     'The with\n'
+                     'statement), but can also be used by directly invoking '
+                     'their methods.\n'
+                     '\n'
+                     'Typical uses of context managers include saving and '
+                     'restoring various\n'
+                     'kinds of global state, locking and unlocking resources, '
+                     'closing opened\n'
+                     'files, etc.\n'
+                     '\n'
+                     'For more information on context managers, see Context '
+                     'Manager Types.\n'
+                     '\n'
+                     'object.__enter__(self)\n'
+                     '\n'
+                     '   Enter the runtime context related to this object. The '
+                     '"with"\n'
+                     "   statement will bind this method's return value to the "
+                     'target(s)\n'
+                     '   specified in the "as" clause of the statement, if '
+                     'any.\n'
+                     '\n'
+                     'object.__exit__(self, exc_type, exc_value, traceback)\n'
+                     '\n'
+                     '   Exit the runtime context related to this object. The '
+                     'parameters\n'
+                     '   describe the exception that caused the context to be '
+                     'exited. If the\n'
+                     '   context was exited without an exception, all three '
+                     'arguments will\n'
+                     '   be "None".\n'
+                     '\n'
+                     '   If an exception is supplied, and the method wishes to '
+                     'suppress the\n'
+                     '   exception (i.e., prevent it from being propagated), '
+                     'it should\n'
+                     '   return a true value. Otherwise, the exception will be '
+                     'processed\n'
+                     '   normally upon exit from this method.\n'
+                     '\n'
+                     '   Note that "__exit__()" methods should not reraise the '
+                     'passed-in\n'
+                     "   exception; this is the caller's responsibility.\n"
+                     '\n'
+                     'See also:\n'
+                     '\n'
+                     '  **PEP 343** - The "with" statement\n'
+                     '     The specification, background, and examples for the '
+                     'Python "with"\n'
+                     '     statement.\n',
+ 'continue': '\n'
+             'The "continue" statement\n'
+             '************************\n'
+             '\n'
+             '   continue_stmt ::= "continue"\n'
+             '\n'
+             '"continue" may only occur syntactically nested in a "for" or '
+             '"while"\n'
+             'loop, but not nested in a function or class definition or '
+             '"finally"\n'
+             'clause within that loop.  It continues with the next cycle of '
+             'the\n'
+             'nearest enclosing loop.\n'
+             '\n'
+             'When "continue" passes control out of a "try" statement with a\n'
+             '"finally" clause, that "finally" clause is executed before '
+             'really\n'
+             'starting the next loop cycle.\n',
+ 'conversions': '\n'
+                'Arithmetic conversions\n'
+                '**********************\n'
+                '\n'
+                'When a description of an arithmetic operator below uses the '
+                'phrase\n'
+                '"the numeric arguments are converted to a common type," this '
+                'means\n'
+                'that the operator implementation for built-in types works as '
+                'follows:\n'
+                '\n'
+                '* If either argument is a complex number, the other is '
+                'converted to\n'
+                '  complex;\n'
+                '\n'
+                '* otherwise, if either argument is a floating point number, '
+                'the\n'
+                '  other is converted to floating point;\n'
+                '\n'
+                '* otherwise, both must be integers and no conversion is '
+                'necessary.\n'
+                '\n'
+                'Some additional rules apply for certain operators (e.g., a '
+                'string as a\n'
+                "left argument to the '%' operator).  Extensions must define "
+                'their own\n'
+                'conversion behavior.\n',
+ 'customization': '\n'
+                  'Basic customization\n'
+                  '*******************\n'
+                  '\n'
+                  'object.__new__(cls[, ...])\n'
+                  '\n'
+                  '   Called to create a new instance of class *cls*.  '
+                  '"__new__()" is a\n'
+                  '   static method (special-cased so you need not declare it '
+                  'as such)\n'
+                  '   that takes the class of which an instance was requested '
+                  'as its\n'
+                  '   first argument.  The remaining arguments are those '
+                  'passed to the\n'
+                  '   object constructor expression (the call to the class).  '
+                  'The return\n'
+                  '   value of "__new__()" should be the new object instance '
+                  '(usually an\n'
+                  '   instance of *cls*).\n'
+                  '\n'
+                  '   Typical implementations create a new instance of the '
+                  'class by\n'
+                  '   invoking the superclass\'s "__new__()" method using\n'
+                  '   "super(currentclass, cls).__new__(cls[, ...])" with '
+                  'appropriate\n'
+                  '   arguments and then modifying the newly-created instance '
+                  'as\n'
+                  '   necessary before returning it.\n'
+                  '\n'
+                  '   If "__new__()" returns an instance of *cls*, then the '
+                  'new\n'
+                  '   instance\'s "__init__()" method will be invoked like\n'
+                  '   "__init__(self[, ...])", where *self* is the new '
+                  'instance and the\n'
+                  '   remaining arguments are the same as were passed to '
+                  '"__new__()".\n'
+                  '\n'
+                  '   If "__new__()" does not return an instance of *cls*, '
+                  'then the new\n'
+                  '   instance\'s "__init__()" method will not be invoked.\n'
+                  '\n'
+                  '   "__new__()" is intended mainly to allow subclasses of '
+                  'immutable\n'
+                  '   types (like int, str, or tuple) to customize instance '
+                  'creation.  It\n'
+                  '   is also commonly overridden in custom metaclasses in '
+                  'order to\n'
+                  '   customize class creation.\n'
+                  '\n'
+                  'object.__init__(self[, ...])\n'
+                  '\n'
+                  '   Called after the instance has been created (by '
+                  '"__new__()"), but\n'
+                  '   before it is returned to the caller.  The arguments are '
+                  'those\n'
+                  '   passed to the class constructor expression.  If a base '
+                  'class has an\n'
+                  '   "__init__()" method, the derived class\'s "__init__()" '
+                  'method, if\n'
+                  '   any, must explicitly call it to ensure proper '
+                  'initialization of the\n'
+                  '   base class part of the instance; for example:\n'
+                  '   "BaseClass.__init__(self, [args...])".\n'
+                  '\n'
+                  '   Because "__new__()" and "__init__()" work together in '
+                  'constructing\n'
+                  '   objects ("__new__()" to create it, and "__init__()" to '
+                  'customise\n'
+                  '   it), no non-"None" value may be returned by '
+                  '"__init__()"; doing so\n'
+                  '   will cause a "TypeError" to be raised at runtime.\n'
+                  '\n'
+                  'object.__del__(self)\n'
+                  '\n'
+                  '   Called when the instance is about to be destroyed.  This '
+                  'is also\n'
+                  '   called a destructor.  If a base class has a "__del__()" '
+                  'method, the\n'
+                  '   derived class\'s "__del__()" method, if any, must '
+                  'explicitly call it\n'
+                  '   to ensure proper deletion of the base class part of the '
+                  'instance.\n'
+                  '   Note that it is possible (though not recommended!) for '
+                  'the\n'
+                  '   "__del__()" method to postpone destruction of the '
+                  'instance by\n'
+                  '   creating a new reference to it.  It may then be called '
+                  'at a later\n'
+                  '   time when this new reference is deleted.  It is not '
+                  'guaranteed that\n'
+                  '   "__del__()" methods are called for objects that still '
+                  'exist when\n'
+                  '   the interpreter exits.\n'
+                  '\n'
+                  '   Note: "del x" doesn\'t directly call "x.__del__()" --- '
+                  'the former\n'
+                  '     decrements the reference count for "x" by one, and the '
+                  'latter is\n'
+                  '     only called when "x"\'s reference count reaches zero.  '
+                  'Some common\n'
+                  '     situations that may prevent the reference count of an '
+                  'object from\n'
+                  '     going to zero include: circular references between '
+                  'objects (e.g.,\n'
+                  '     a doubly-linked list or a tree data structure with '
+                  'parent and\n'
+                  '     child pointers); a reference to the object on the '
+                  'stack frame of\n'
+                  '     a function that caught an exception (the traceback '
+                  'stored in\n'
+                  '     "sys.exc_info()[2]" keeps the stack frame alive); or a '
+                  'reference\n'
+                  '     to the object on the stack frame that raised an '
+                  'unhandled\n'
+                  '     exception in interactive mode (the traceback stored '
+                  'in\n'
+                  '     "sys.last_traceback" keeps the stack frame alive).  '
+                  'The first\n'
+                  '     situation can only be remedied by explicitly breaking '
+                  'the cycles;\n'
+                  '     the second can be resolved by freeing the reference to '
+                  'the\n'
+                  '     traceback object when it is no longer useful, and the '
+                  'third can\n'
+                  '     be resolved by storing "None" in "sys.last_traceback". '
+                  'Circular\n'
+                  '     references which are garbage are detected and cleaned '
+                  'up when the\n'
+                  "     cyclic garbage collector is enabled (it's on by "
+                  'default). Refer\n'
+                  '     to the documentation for the "gc" module for more '
+                  'information\n'
+                  '     about this topic.\n'
+                  '\n'
+                  '   Warning: Due to the precarious circumstances under '
+                  'which\n'
+                  '     "__del__()" methods are invoked, exceptions that occur '
+                  'during\n'
+                  '     their execution are ignored, and a warning is printed '
+                  'to\n'
+                  '     "sys.stderr" instead. Also, when "__del__()" is '
+                  'invoked in\n'
+                  '     response to a module being deleted (e.g., when '
+                  'execution of the\n'
+                  '     program is done), other globals referenced by the '
+                  '"__del__()"\n'
+                  '     method may already have been deleted or in the process '
+                  'of being\n'
+                  '     torn down (e.g. the import machinery shutting down).  '
+                  'For this\n'
+                  '     reason, "__del__()" methods should do the absolute '
+                  'minimum needed\n'
+                  '     to maintain external invariants.  Starting with '
+                  'version 1.5,\n'
+                  '     Python guarantees that globals whose name begins with '
+                  'a single\n'
+                  '     underscore are deleted from their module before other '
+                  'globals are\n'
+                  '     deleted; if no other references to such globals exist, '
+                  'this may\n'
+                  '     help in assuring that imported modules are still '
+                  'available at the\n'
+                  '     time when the "__del__()" method is called.\n'
+                  '\n'
+                  'object.__repr__(self)\n'
+                  '\n'
+                  '   Called by the "repr()" built-in function to compute the '
+                  '"official"\n'
+                  '   string representation of an object.  If at all possible, '
+                  'this\n'
+                  '   should look like a valid Python expression that could be '
+                  'used to\n'
+                  '   recreate an object with the same value (given an '
+                  'appropriate\n'
+                  '   environment).  If this is not possible, a string of the '
+                  'form\n'
+                  '   "<...some useful description...>" should be returned. '
+                  'The return\n'
+                  '   value must be a string object. If a class defines '
+                  '"__repr__()" but\n'
+                  '   not "__str__()", then "__repr__()" is also used when an '
+                  '"informal"\n'
+                  '   string representation of instances of that class is '
+                  'required.\n'
+                  '\n'
+                  '   This is typically used for debugging, so it is important '
+                  'that the\n'
+                  '   representation is information-rich and unambiguous.\n'
+                  '\n'
+                  'object.__str__(self)\n'
+                  '\n'
+                  '   Called by "str(object)" and the built-in functions '
+                  '"format()" and\n'
+                  '   "print()" to compute the "informal" or nicely printable '
+                  'string\n'
+                  '   representation of an object.  The return value must be a '
+                  'string\n'
+                  '   object.\n'
+                  '\n'
+                  '   This method differs from "object.__repr__()" in that '
+                  'there is no\n'
+                  '   expectation that "__str__()" return a valid Python '
+                  'expression: a\n'
+                  '   more convenient or concise representation can be used.\n'
+                  '\n'
+                  '   The default implementation defined by the built-in type '
+                  '"object"\n'
+                  '   calls "object.__repr__()".\n'
+                  '\n'
+                  'object.__bytes__(self)\n'
+                  '\n'
+                  '   Called by "bytes()" to compute a byte-string '
+                  'representation of an\n'
+                  '   object. This should return a "bytes" object.\n'
+                  '\n'
+                  'object.__format__(self, format_spec)\n'
+                  '\n'
+                  '   Called by the "format()" built-in function, and by '
+                  'extension,\n'
+                  '   evaluation of formatted string literals and the '
+                  '"str.format()"\n'
+                  '   method, to produce a "formatted" string representation '
+                  'of an\n'
+                  '   object. The "format_spec" argument is a string that '
+                  'contains a\n'
+                  '   description of the formatting options desired. The '
+                  'interpretation\n'
+                  '   of the "format_spec" argument is up to the type '
+                  'implementing\n'
+                  '   "__format__()", however most classes will either '
+                  'delegate\n'
+                  '   formatting to one of the built-in types, or use a '
+                  'similar\n'
+                  '   formatting option syntax.\n'
+                  '\n'
+                  '   See Format Specification Mini-Language for a description '
+                  'of the\n'
+                  '   standard formatting syntax.\n'
+                  '\n'
+                  '   The return value must be a string object.\n'
+                  '\n'
+                  '   Changed in version 3.4: The __format__ method of '
+                  '"object" itself\n'
+                  '   raises a "TypeError" if passed any non-empty string.\n'
+                  '\n'
+                  'object.__lt__(self, other)\n'
+                  'object.__le__(self, other)\n'
+                  'object.__eq__(self, other)\n'
+                  'object.__ne__(self, other)\n'
+                  'object.__gt__(self, other)\n'
+                  'object.__ge__(self, other)\n'
+                  '\n'
+                  '   These are the so-called "rich comparison" methods. The\n'
+                  '   correspondence between operator symbols and method names '
+                  'is as\n'
+                  '   follows: "x<y" calls "x.__lt__(y)", "x<=y" calls '
+                  '"x.__le__(y)",\n'
+                  '   "x==y" calls "x.__eq__(y)", "x!=y" calls "x.__ne__(y)", '
+                  '"x>y" calls\n'
+                  '   "x.__gt__(y)", and "x>=y" calls "x.__ge__(y)".\n'
+                  '\n'
+                  '   A rich comparison method may return the singleton '
+                  '"NotImplemented"\n'
+                  '   if it does not implement the operation for a given pair '
+                  'of\n'
+                  '   arguments. By convention, "False" and "True" are '
+                  'returned for a\n'
+                  '   successful comparison. However, these methods can return '
+                  'any value,\n'
+                  '   so if the comparison operator is used in a Boolean '
+                  'context (e.g.,\n'
+                  '   in the condition of an "if" statement), Python will call '
+                  '"bool()"\n'
+                  '   on the value to determine if the result is true or '
+                  'false.\n'
+                  '\n'
+                  '   By default, "__ne__()" delegates to "__eq__()" and '
+                  'inverts the\n'
+                  '   result unless it is "NotImplemented".  There are no '
+                  'other implied\n'
+                  '   relationships among the comparison operators, for '
+                  'example, the\n'
+                  '   truth of "(x<y or x==y)" does not imply "x<=y". To '
+                  'automatically\n'
+                  '   generate ordering operations from a single root '
+                  'operation, see\n'
+                  '   "functools.total_ordering()".\n'
+                  '\n'
+                  '   See the paragraph on "__hash__()" for some important '
+                  'notes on\n'
+                  '   creating *hashable* objects which support custom '
+                  'comparison\n'
+                  '   operations and are usable as dictionary keys.\n'
+                  '\n'
+                  '   There are no swapped-argument versions of these methods '
+                  '(to be used\n'
+                  '   when the left argument does not support the operation '
+                  'but the right\n'
+                  '   argument does); rather, "__lt__()" and "__gt__()" are '
+                  "each other's\n"
+                  '   reflection, "__le__()" and "__ge__()" are each other\'s '
+                  'reflection,\n'
+                  '   and "__eq__()" and "__ne__()" are their own reflection. '
+                  'If the\n'
+                  "   operands are of different types, and right operand's "
+                  'type is a\n'
+                  "   direct or indirect subclass of the left operand's type, "
+                  'the\n'
+                  '   reflected method of the right operand has priority, '
+                  'otherwise the\n'
+                  "   left operand's method has priority.  Virtual subclassing "
+                  'is not\n'
+                  '   considered.\n'
+                  '\n'
+                  'object.__hash__(self)\n'
+                  '\n'
+                  '   Called by built-in function "hash()" and for operations '
+                  'on members\n'
+                  '   of hashed collections including "set", "frozenset", and '
+                  '"dict".\n'
+                  '   "__hash__()" should return an integer.  The only '
+                  'required property\n'
+                  '   is that objects which compare equal have the same hash '
+                  'value; it is\n'
+                  '   advised to somehow mix together (e.g. using exclusive '
+                  'or) the hash\n'
+                  '   values for the components of the object that also play a '
+                  'part in\n'
+                  '   comparison of objects.\n'
+                  '\n'
+                  '   Note: "hash()" truncates the value returned from an '
+                  "object's\n"
+                  '     custom "__hash__()" method to the size of a '
+                  '"Py_ssize_t".  This\n'
+                  '     is typically 8 bytes on 64-bit builds and 4 bytes on '
+                  '32-bit\n'
+                  '     builds. If an object\'s   "__hash__()" must '
+                  'interoperate on builds\n'
+                  '     of different bit sizes, be sure to check the width on '
+                  'all\n'
+                  '     supported builds.  An easy way to do this is with '
+                  '"python -c\n'
+                  '     "import sys; print(sys.hash_info.width)"".\n'
+                  '\n'
+                  '   If a class does not define an "__eq__()" method it '
+                  'should not\n'
+                  '   define a "__hash__()" operation either; if it defines '
+                  '"__eq__()"\n'
+                  '   but not "__hash__()", its instances will not be usable '
+                  'as items in\n'
+                  '   hashable collections.  If a class defines mutable '
+                  'objects and\n'
+                  '   implements an "__eq__()" method, it should not '
+                  'implement\n'
+                  '   "__hash__()", since the implementation of hashable '
+                  'collections\n'
+                  "   requires that a key's hash value is immutable (if the "
+                  "object's hash\n"
+                  '   value changes, it will be in the wrong hash bucket).\n'
+                  '\n'
+                  '   User-defined classes have "__eq__()" and "__hash__()" '
+                  'methods by\n'
+                  '   default; with them, all objects compare unequal (except '
+                  'with\n'
+                  '   themselves) and "x.__hash__()" returns an appropriate '
+                  'value such\n'
+                  '   that "x == y" implies both that "x is y" and "hash(x) == '
+                  'hash(y)".\n'
+                  '\n'
+                  '   A class that overrides "__eq__()" and does not define '
+                  '"__hash__()"\n'
+                  '   will have its "__hash__()" implicitly set to "None".  '
+                  'When the\n'
+                  '   "__hash__()" method of a class is "None", instances of '
+                  'the class\n'
+                  '   will raise an appropriate "TypeError" when a program '
+                  'attempts to\n'
+                  '   retrieve their hash value, and will also be correctly '
+                  'identified as\n'
+                  '   unhashable when checking "isinstance(obj, '
+                  'collections.Hashable)".\n'
+                  '\n'
+                  '   If a class that overrides "__eq__()" needs to retain '
+                  'the\n'
+                  '   implementation of "__hash__()" from a parent class, the '
+                  'interpreter\n'
+                  '   must be told this explicitly by setting "__hash__ =\n'
+                  '   <ParentClass>.__hash__".\n'
+                  '\n'
+                  '   If a class that does not override "__eq__()" wishes to '
+                  'suppress\n'
+                  '   hash support, it should include "__hash__ = None" in the '
+                  'class\n'
+                  '   definition. A class which defines its own "__hash__()" '
+                  'that\n'
+                  '   explicitly raises a "TypeError" would be incorrectly '
+                  'identified as\n'
+                  '   hashable by an "isinstance(obj, collections.Hashable)" '
+                  'call.\n'
+                  '\n'
+                  '   Note: By default, the "__hash__()" values of str, bytes '
+                  'and\n'
+                  '     datetime objects are "salted" with an unpredictable '
+                  'random value.\n'
+                  '     Although they remain constant within an individual '
+                  'Python\n'
+                  '     process, they are not predictable between repeated '
+                  'invocations of\n'
+                  '     Python.This is intended to provide protection against '
+                  'a denial-\n'
+                  '     of-service caused by carefully-chosen inputs that '
+                  'exploit the\n'
+                  '     worst case performance of a dict insertion, O(n^2) '
+                  'complexity.\n'
+                  '     See '
+                  'http://www.ocert.org/advisories/ocert-2011-003.html for\n'
+                  '     details.Changing hash values affects the iteration '
+                  'order of\n'
+                  '     dicts, sets and other mappings.  Python has never made '
+                  'guarantees\n'
+                  '     about this ordering (and it typically varies between '
+                  '32-bit and\n'
+                  '     64-bit builds).See also "PYTHONHASHSEED".\n'
+                  '\n'
+                  '   Changed in version 3.3: Hash randomization is enabled by '
+                  'default.\n'
+                  '\n'
+                  'object.__bool__(self)\n'
+                  '\n'
+                  '   Called to implement truth value testing and the built-in '
+                  'operation\n'
+                  '   "bool()"; should return "False" or "True".  When this '
+                  'method is not\n'
+                  '   defined, "__len__()" is called, if it is defined, and '
+                  'the object is\n'
+                  '   considered true if its result is nonzero.  If a class '
+                  'defines\n'
+                  '   neither "__len__()" nor "__bool__()", all its instances '
+                  'are\n'
+                  '   considered true.\n',
+ 'debugger': '\n'
+             '"pdb" --- The Python Debugger\n'
+             '*****************************\n'
+             '\n'
+             '**Source code:** Lib/pdb.py\n'
+             '\n'
+             '======================================================================\n'
+             '\n'
+             'The module "pdb" defines an interactive source code debugger '
+             'for\n'
+             'Python programs.  It supports setting (conditional) breakpoints '
+             'and\n'
+             'single stepping at the source line level, inspection of stack '
+             'frames,\n'
+             'source code listing, and evaluation of arbitrary Python code in '
+             'the\n'
+             'context of any stack frame.  It also supports post-mortem '
+             'debugging\n'
+             'and can be called under program control.\n'
+             '\n'
+             'The debugger is extensible -- it is actually defined as the '
+             'class\n'
+             '"Pdb". This is currently undocumented but easily understood by '
+             'reading\n'
+             'the source.  The extension interface uses the modules "bdb" and '
+             '"cmd".\n'
+             '\n'
+             'The debugger\'s prompt is "(Pdb)". Typical usage to run a '
+             'program under\n'
+             'control of the debugger is:\n'
+             '\n'
+             '   >>> import pdb\n'
+             '   >>> import mymodule\n'
+             "   >>> pdb.run('mymodule.test()')\n"
+             '   > <string>(0)?()\n'
+             '   (Pdb) continue\n'
+             '   > <string>(1)?()\n'
+             '   (Pdb) continue\n'
+             "   NameError: 'spam'\n"
+             '   > <string>(1)?()\n'
+             '   (Pdb)\n'
+             '\n'
+             'Changed in version 3.3: Tab-completion via the "readline" module '
+             'is\n'
+             'available for commands and command arguments, e.g. the current '
+             'global\n'
+             'and local names are offered as arguments of the "p" command.\n'
+             '\n'
+             '"pdb.py" can also be invoked as a script to debug other '
+             'scripts.  For\n'
+             'example:\n'
+             '\n'
+             '   python3 -m pdb myscript.py\n'
+             '\n'
+             'When invoked as a script, pdb will automatically enter '
+             'post-mortem\n'
+             'debugging if the program being debugged exits abnormally.  After '
+             'post-\n'
+             'mortem debugging (or after normal exit of the program), pdb '
+             'will\n'
+             "restart the program.  Automatic restarting preserves pdb's state "
+             '(such\n'
+             'as breakpoints) and in most cases is more useful than quitting '
+             'the\n'
+             "debugger upon program's exit.\n"
+             '\n'
+             'New in version 3.2: "pdb.py" now accepts a "-c" option that '
+             'executes\n'
+             'commands as if given in a ".pdbrc" file, see Debugger Commands.\n'
+             '\n'
+             'The typical usage to break into the debugger from a running '
+             'program is\n'
+             'to insert\n'
+             '\n'
+             '   import pdb; pdb.set_trace()\n'
+             '\n'
+             'at the location you want to break into the debugger.  You can '
+             'then\n'
+             'step through the code following this statement, and continue '
+             'running\n'
+             'without the debugger using the "continue" command.\n'
+             '\n'
+             'The typical usage to inspect a crashed program is:\n'
+             '\n'
+             '   >>> import pdb\n'
+             '   >>> import mymodule\n'
+             '   >>> mymodule.test()\n'
+             '   Traceback (most recent call last):\n'
+             '     File "<stdin>", line 1, in ?\n'
+             '     File "./mymodule.py", line 4, in test\n'
+             '       test2()\n'
+             '     File "./mymodule.py", line 3, in test2\n'
+             '       print(spam)\n'
+             '   NameError: spam\n'
+             '   >>> pdb.pm()\n'
+             '   > ./mymodule.py(3)test2()\n'
+             '   -> print(spam)\n'
+             '   (Pdb)\n'
+             '\n'
+             'The module defines the following functions; each enters the '
+             'debugger\n'
+             'in a slightly different way:\n'
+             '\n'
+             'pdb.run(statement, globals=None, locals=None)\n'
+             '\n'
+             '   Execute the *statement* (given as a string or a code object) '
+             'under\n'
+             '   debugger control.  The debugger prompt appears before any '
+             'code is\n'
+             '   executed; you can set breakpoints and type "continue", or you '
+             'can\n'
+             '   step through the statement using "step" or "next" (all these\n'
+             '   commands are explained below).  The optional *globals* and '
+             '*locals*\n'
+             '   arguments specify the environment in which the code is '
+             'executed; by\n'
+             '   default the dictionary of the module "__main__" is used.  '
+             '(See the\n'
+             '   explanation of the built-in "exec()" or "eval()" functions.)\n'
+             '\n'
+             'pdb.runeval(expression, globals=None, locals=None)\n'
+             '\n'
+             '   Evaluate the *expression* (given as a string or a code '
+             'object)\n'
+             '   under debugger control.  When "runeval()" returns, it returns '
+             'the\n'
+             '   value of the expression.  Otherwise this function is similar '
+             'to\n'
+             '   "run()".\n'
+             '\n'
+             'pdb.runcall(function, *args, **kwds)\n'
+             '\n'
+             '   Call the *function* (a function or method object, not a '
+             'string)\n'
+             '   with the given arguments.  When "runcall()" returns, it '
+             'returns\n'
+             '   whatever the function call returned.  The debugger prompt '
+             'appears\n'
+             '   as soon as the function is entered.\n'
+             '\n'
+             'pdb.set_trace()\n'
+             '\n'
+             '   Enter the debugger at the calling stack frame.  This is '
+             'useful to\n'
+             '   hard-code a breakpoint at a given point in a program, even if '
+             'the\n'
+             '   code is not otherwise being debugged (e.g. when an assertion\n'
+             '   fails).\n'
+             '\n'
+             'pdb.post_mortem(traceback=None)\n'
+             '\n'
+             '   Enter post-mortem debugging of the given *traceback* object.  '
+             'If no\n'
+             '   *traceback* is given, it uses the one of the exception that '
+             'is\n'
+             '   currently being handled (an exception must be being handled '
+             'if the\n'
+             '   default is to be used).\n'
+             '\n'
+             'pdb.pm()\n'
+             '\n'
+             '   Enter post-mortem debugging of the traceback found in\n'
+             '   "sys.last_traceback".\n'
+             '\n'
+             'The "run*" functions and "set_trace()" are aliases for '
+             'instantiating\n'
+             'the "Pdb" class and calling the method of the same name.  If you '
+             'want\n'
+             'to access further features, you have to do this yourself:\n'
+             '\n'
+             "class pdb.Pdb(completekey='tab', stdin=None, stdout=None, "
+             'skip=None, nosigint=False)\n'
+             '\n'
+             '   "Pdb" is the debugger class.\n'
+             '\n'
+             '   The *completekey*, *stdin* and *stdout* arguments are passed '
+             'to the\n'
+             '   underlying "cmd.Cmd" class; see the description there.\n'
+             '\n'
+             '   The *skip* argument, if given, must be an iterable of '
+             'glob-style\n'
+             '   module name patterns.  The debugger will not step into frames '
+             'that\n'
+             '   originate in a module that matches one of these patterns. '
+             '[1]\n'
+             '\n'
+             '   By default, Pdb sets a handler for the SIGINT signal (which '
+             'is sent\n'
+             '   when the user presses "Ctrl-C" on the console) when you give '
+             'a\n'
+             '   "continue" command. This allows you to break into the '
+             'debugger\n'
+             '   again by pressing "Ctrl-C".  If you want Pdb not to touch '
+             'the\n'
+             '   SIGINT handler, set *nosigint* tot true.\n'
+             '\n'
+             '   Example call to enable tracing with *skip*:\n'
+             '\n'
+             "      import pdb; pdb.Pdb(skip=['django.*']).set_trace()\n"
+             '\n'
+             '   New in version 3.1: The *skip* argument.\n'
+             '\n'
+             '   New in version 3.2: The *nosigint* argument.  Previously, a '
+             'SIGINT\n'
+             '   handler was never set by Pdb.\n'
+             '\n'
+             '   run(statement, globals=None, locals=None)\n'
+             '   runeval(expression, globals=None, locals=None)\n'
+             '   runcall(function, *args, **kwds)\n'
+             '   set_trace()\n'
+             '\n'
+             '      See the documentation for the functions explained above.\n'
+             '\n'
+             '\n'
+             'Debugger Commands\n'
+             '=================\n'
+             '\n'
+             'The commands recognized by the debugger are listed below.  Most\n'
+             'commands can be abbreviated to one or two letters as indicated; '
+             'e.g.\n'
+             '"h(elp)" means that either "h" or "help" can be used to enter '
+             'the help\n'
+             'command (but not "he" or "hel", nor "H" or "Help" or "HELP").\n'
+             'Arguments to commands must be separated by whitespace (spaces '
+             'or\n'
+             'tabs).  Optional arguments are enclosed in square brackets '
+             '("[]") in\n'
+             'the command syntax; the square brackets must not be typed.\n'
+             'Alternatives in the command syntax are separated by a vertical '
+             'bar\n'
+             '("|").\n'
+             '\n'
+             'Entering a blank line repeats the last command entered.  '
+             'Exception: if\n'
+             'the last command was a "list" command, the next 11 lines are '
+             'listed.\n'
+             '\n'
+             "Commands that the debugger doesn't recognize are assumed to be "
+             'Python\n'
+             'statements and are executed in the context of the program being\n'
+             'debugged.  Python statements can also be prefixed with an '
+             'exclamation\n'
+             'point ("!").  This is a powerful way to inspect the program '
+             'being\n'
+             'debugged; it is even possible to change a variable or call a '
+             'function.\n'
+             'When an exception occurs in such a statement, the exception name '
+             'is\n'
+             "printed but the debugger's state is not changed.\n"
+             '\n'
+             'The debugger supports aliases.  Aliases can have parameters '
+             'which\n'
+             'allows one a certain level of adaptability to the context under\n'
+             'examination.\n'
+             '\n'
+             'Multiple commands may be entered on a single line, separated by '
+             '";;".\n'
+             '(A single ";" is not used as it is the separator for multiple '
+             'commands\n'
+             'in a line that is passed to the Python parser.)  No intelligence '
+             'is\n'
+             'applied to separating the commands; the input is split at the '
+             'first\n'
+             '";;" pair, even if it is in the middle of a quoted string.\n'
+             '\n'
+             'If a file ".pdbrc" exists in the user\'s home directory or in '
+             'the\n'
+             'current directory, it is read in and executed as if it had been '
+             'typed\n'
+             'at the debugger prompt.  This is particularly useful for '
+             'aliases.  If\n'
+             'both files exist, the one in the home directory is read first '
+             'and\n'
+             'aliases defined there can be overridden by the local file.\n'
+             '\n'
+             'Changed in version 3.2: ".pdbrc" can now contain commands that\n'
+             'continue debugging, such as "continue" or "next".  Previously, '
+             'these\n'
+             'commands had no effect.\n'
+             '\n'
+             'h(elp) [command]\n'
+             '\n'
+             '   Without argument, print the list of available commands.  With '
+             'a\n'
+             '   *command* as argument, print help about that command.  "help '
+             'pdb"\n'
+             '   displays the full documentation (the docstring of the "pdb"\n'
+             '   module).  Since the *command* argument must be an identifier, '
+             '"help\n'
+             '   exec" must be entered to get help on the "!" command.\n'
+             '\n'
+             'w(here)\n'
+             '\n'
+             '   Print a stack trace, with the most recent frame at the '
+             'bottom.  An\n'
+             '   arrow indicates the current frame, which determines the '
+             'context of\n'
+             '   most commands.\n'
+             '\n'
+             'd(own) [count]\n'
+             '\n'
+             '   Move the current frame *count* (default one) levels down in '
+             'the\n'
+             '   stack trace (to a newer frame).\n'
+             '\n'
+             'u(p) [count]\n'
+             '\n'
+             '   Move the current frame *count* (default one) levels up in the '
+             'stack\n'
+             '   trace (to an older frame).\n'
+             '\n'
+             'b(reak) [([filename:]lineno | function) [, condition]]\n'
+             '\n'
+             '   With a *lineno* argument, set a break there in the current '
+             'file.\n'
+             '   With a *function* argument, set a break at the first '
+             'executable\n'
+             '   statement within that function.  The line number may be '
+             'prefixed\n'
+             '   with a filename and a colon, to specify a breakpoint in '
+             'another\n'
+             "   file (probably one that hasn't been loaded yet).  The file "
+             'is\n'
+             '   searched on "sys.path".  Note that each breakpoint is '
+             'assigned a\n'
+             '   number to which all the other breakpoint commands refer.\n'
+             '\n'
+             '   If a second argument is present, it is an expression which '
+             'must\n'
+             '   evaluate to true before the breakpoint is honored.\n'
+             '\n'
+             '   Without argument, list all breaks, including for each '
+             'breakpoint,\n'
+             '   the number of times that breakpoint has been hit, the '
+             'current\n'
+             '   ignore count, and the associated condition if any.\n'
+             '\n'
+             'tbreak [([filename:]lineno | function) [, condition]]\n'
+             '\n'
+             '   Temporary breakpoint, which is removed automatically when it '
+             'is\n'
+             '   first hit. The arguments are the same as for "break".\n'
+             '\n'
+             'cl(ear) [filename:lineno | bpnumber [bpnumber ...]]\n'
+             '\n'
+             '   With a *filename:lineno* argument, clear all the breakpoints '
+             'at\n'
+             '   this line. With a space separated list of breakpoint numbers, '
+             'clear\n'
+             '   those breakpoints. Without argument, clear all breaks (but '
+             'first\n'
+             '   ask confirmation).\n'
+             '\n'
+             'disable [bpnumber [bpnumber ...]]\n'
+             '\n'
+             '   Disable the breakpoints given as a space separated list of\n'
+             '   breakpoint numbers.  Disabling a breakpoint means it cannot '
+             'cause\n'
+             '   the program to stop execution, but unlike clearing a '
+             'breakpoint, it\n'
+             '   remains in the list of breakpoints and can be (re-)enabled.\n'
+             '\n'
+             'enable [bpnumber [bpnumber ...]]\n'
+             '\n'
+             '   Enable the breakpoints specified.\n'
+             '\n'
+             'ignore bpnumber [count]\n'
+             '\n'
+             '   Set the ignore count for the given breakpoint number.  If '
+             'count is\n'
+             '   omitted, the ignore count is set to 0.  A breakpoint becomes '
+             'active\n'
+             '   when the ignore count is zero.  When non-zero, the count is\n'
+             '   decremented each time the breakpoint is reached and the '
+             'breakpoint\n'
+             '   is not disabled and any associated condition evaluates to '
+             'true.\n'
+             '\n'
+             'condition bpnumber [condition]\n'
+             '\n'
+             '   Set a new *condition* for the breakpoint, an expression which '
+             'must\n'
+             '   evaluate to true before the breakpoint is honored.  If '
+             '*condition*\n'
+             '   is absent, any existing condition is removed; i.e., the '
+             'breakpoint\n'
+             '   is made unconditional.\n'
+             '\n'
+             'commands [bpnumber]\n'
+             '\n'
+             '   Specify a list of commands for breakpoint number *bpnumber*.  '
+             'The\n'
+             '   commands themselves appear on the following lines.  Type a '
+             'line\n'
+             '   containing just "end" to terminate the commands. An example:\n'
+             '\n'
+             '      (Pdb) commands 1\n'
+             '      (com) p some_variable\n'
+             '      (com) end\n'
+             '      (Pdb)\n'
+             '\n'
+             '   To remove all commands from a breakpoint, type commands and '
+             'follow\n'
+             '   it immediately with "end"; that is, give no commands.\n'
+             '\n'
+             '   With no *bpnumber* argument, commands refers to the last '
+             'breakpoint\n'
+             '   set.\n'
+             '\n'
+             '   You can use breakpoint commands to start your program up '
+             'again.\n'
+             '   Simply use the continue command, or step, or any other '
+             'command that\n'
+             '   resumes execution.\n'
+             '\n'
+             '   Specifying any command resuming execution (currently '
+             'continue,\n'
+             '   step, next, return, jump, quit and their abbreviations) '
+             'terminates\n'
+             '   the command list (as if that command was immediately followed '
+             'by\n'
+             '   end). This is because any time you resume execution (even '
+             'with a\n'
+             '   simple next or step), you may encounter another '
+             'breakpoint--which\n'
+             '   could have its own command list, leading to ambiguities about '
+             'which\n'
+             '   list to execute.\n'
+             '\n'
+             "   If you use the 'silent' command in the command list, the "
+             'usual\n'
+             '   message about stopping at a breakpoint is not printed.  This '
+             'may be\n'
+             '   desirable for breakpoints that are to print a specific '
+             'message and\n'
+             '   then continue.  If none of the other commands print anything, '
+             'you\n'
+             '   see no sign that the breakpoint was reached.\n'
+             '\n'
+             's(tep)\n'
+             '\n'
+             '   Execute the current line, stop at the first possible '
+             'occasion\n'
+             '   (either in a function that is called or on the next line in '
+             'the\n'
+             '   current function).\n'
+             '\n'
+             'n(ext)\n'
+             '\n'
+             '   Continue execution until the next line in the current '
+             'function is\n'
+             '   reached or it returns.  (The difference between "next" and '
+             '"step"\n'
+             '   is that "step" stops inside a called function, while "next"\n'
+             '   executes called functions at (nearly) full speed, only '
+             'stopping at\n'
+             '   the next line in the current function.)\n'
+             '\n'
+             'unt(il) [lineno]\n'
+             '\n'
+             '   Without argument, continue execution until the line with a '
+             'number\n'
+             '   greater than the current one is reached.\n'
+             '\n'
+             '   With a line number, continue execution until a line with a '
+             'number\n'
+             '   greater or equal to that is reached.  In both cases, also '
+             'stop when\n'
+             '   the current frame returns.\n'
+             '\n'
+             '   Changed in version 3.2: Allow giving an explicit line '
+             'number.\n'
+             '\n'
+             'r(eturn)\n'
+             '\n'
+             '   Continue execution until the current function returns.\n'
+             '\n'
+             'c(ont(inue))\n'
+             '\n'
+             '   Continue execution, only stop when a breakpoint is '
+             'encountered.\n'
+             '\n'
+             'j(ump) lineno\n'
+             '\n'
+             '   Set the next line that will be executed.  Only available in '
+             'the\n'
+             '   bottom-most frame.  This lets you jump back and execute code '
+             'again,\n'
+             "   or jump forward to skip code that you don't want to run.\n"
+             '\n'
+             '   It should be noted that not all jumps are allowed -- for '
+             'instance\n'
+             '   it is not possible to jump into the middle of a "for" loop or '
+             'out\n'
+             '   of a "finally" clause.\n'
+             '\n'
+             'l(ist) [first[, last]]\n'
+             '\n'
+             '   List source code for the current file.  Without arguments, '
+             'list 11\n'
+             '   lines around the current line or continue the previous '
+             'listing.\n'
+             '   With "." as argument, list 11 lines around the current line.  '
+             'With\n'
+             '   one argument, list 11 lines around at that line.  With two\n'
+             '   arguments, list the given range; if the second argument is '
+             'less\n'
+             '   than the first, it is interpreted as a count.\n'
+             '\n'
+             '   The current line in the current frame is indicated by "->".  '
+             'If an\n'
+             '   exception is being debugged, the line where the exception '
+             'was\n'
+             '   originally raised or propagated is indicated by ">>", if it '
+             'differs\n'
+             '   from the current line.\n'
+             '\n'
+             '   New in version 3.2: The ">>" marker.\n'
+             '\n'
+             'll | longlist\n'
+             '\n'
+             '   List all source code for the current function or frame.\n'
+             '   Interesting lines are marked as for "list".\n'
+             '\n'
+             '   New in version 3.2.\n'
+             '\n'
+             'a(rgs)\n'
+             '\n'
+             '   Print the argument list of the current function.\n'
+             '\n'
+             'p expression\n'
+             '\n'
+             '   Evaluate the *expression* in the current context and print '
+             'its\n'
+             '   value.\n'
+             '\n'
+             '   Note: "print()" can also be used, but is not a debugger '
+             'command\n'
+             '     --- this executes the Python "print()" function.\n'
+             '\n'
+             'pp expression\n'
+             '\n'
+             '   Like the "p" command, except the value of the expression is '
+             'pretty-\n'
+             '   printed using the "pprint" module.\n'
+             '\n'
+             'whatis expression\n'
+             '\n'
+             '   Print the type of the *expression*.\n'
+             '\n'
+             'source expression\n'
+             '\n'
+             '   Try to get source code for the given object and display it.\n'
+             '\n'
+             '   New in version 3.2.\n'
+             '\n'
+             'display [expression]\n'
+             '\n'
+             '   Display the value of the expression if it changed, each time\n'
+             '   execution stops in the current frame.\n'
+             '\n'
+             '   Without expression, list all display expressions for the '
+             'current\n'
+             '   frame.\n'
+             '\n'
+             '   New in version 3.2.\n'
+             '\n'
+             'undisplay [expression]\n'
+             '\n'
+             '   Do not display the expression any more in the current frame.\n'
+             '   Without expression, clear all display expressions for the '
+             'current\n'
+             '   frame.\n'
+             '\n'
+             '   New in version 3.2.\n'
+             '\n'
+             'interact\n'
+             '\n'
+             '   Start an interative interpreter (using the "code" module) '
+             'whose\n'
+             '   global namespace contains all the (global and local) names '
+             'found in\n'
+             '   the current scope.\n'
+             '\n'
+             '   New in version 3.2.\n'
+             '\n'
+             'alias [name [command]]\n'
+             '\n'
+             '   Create an alias called *name* that executes *command*.  The '
+             'command\n'
+             '   must *not* be enclosed in quotes.  Replaceable parameters can '
+             'be\n'
+             '   indicated by "%1", "%2", and so on, while "%*" is replaced by '
+             'all\n'
+             '   the parameters. If no command is given, the current alias '
+             'for\n'
+             '   *name* is shown. If no arguments are given, all aliases are '
+             'listed.\n'
+             '\n'
+             '   Aliases may be nested and can contain anything that can be '
+             'legally\n'
+             '   typed at the pdb prompt.  Note that internal pdb commands '
+             '*can* be\n'
+             '   overridden by aliases.  Such a command is then hidden until '
+             'the\n'
+             '   alias is removed.  Aliasing is recursively applied to the '
+             'first\n'
+             '   word of the command line; all other words in the line are '
+             'left\n'
+             '   alone.\n'
+             '\n'
+             '   As an example, here are two useful aliases (especially when '
+             'placed\n'
+             '   in the ".pdbrc" file):\n'
+             '\n'
+             '      # Print instance variables (usage "pi classInst")\n'
+             '      alias pi for k in %1.__dict__.keys(): '
+             'print("%1.",k,"=",%1.__dict__[k])\n'
+             '      # Print instance variables in self\n'
+             '      alias ps pi self\n'
+             '\n'
+             'unalias name\n'
+             '\n'
+             '   Delete the specified alias.\n'
+             '\n'
+             '! statement\n'
+             '\n'
+             '   Execute the (one-line) *statement* in the context of the '
+             'current\n'
+             '   stack frame. The exclamation point can be omitted unless the '
+             'first\n'
+             '   word of the statement resembles a debugger command.  To set '
+             'a\n'
+             '   global variable, you can prefix the assignment command with '
+             'a\n'
+             '   "global" statement on the same line, e.g.:\n'
+             '\n'
+             "      (Pdb) global list_options; list_options = ['-l']\n"
+             '      (Pdb)\n'
+             '\n'
+             'run [args ...]\n'
+             'restart [args ...]\n'
+             '\n'
+             '   Restart the debugged Python program.  If an argument is '
+             'supplied,\n'
+             '   it is split with "shlex" and the result is used as the new\n'
+             '   "sys.argv". History, breakpoints, actions and debugger '
+             'options are\n'
+             '   preserved. "restart" is an alias for "run".\n'
+             '\n'
+             'q(uit)\n'
+             '\n'
+             '   Quit from the debugger.  The program being executed is '
+             'aborted.\n'
+             '\n'
+             '-[ Footnotes ]-\n'
+             '\n'
+             '[1] Whether a frame is considered to originate in a certain '
+             'module\n'
+             '    is determined by the "__name__" in the frame globals.\n',
+ 'del': '\n'
+        'The "del" statement\n'
+        '*******************\n'
+        '\n'
+        '   del_stmt ::= "del" target_list\n'
+        '\n'
+        'Deletion is recursively defined very similar to the way assignment '
+        'is\n'
+        'defined. Rather than spelling it out in full details, here are some\n'
+        'hints.\n'
+        '\n'
+        'Deletion of a target list recursively deletes each target, from left\n'
+        'to right.\n'
+        '\n'
+        'Deletion of a name removes the binding of that name from the local '
+        'or\n'
+        'global namespace, depending on whether the name occurs in a "global"\n'
+        'statement in the same code block.  If the name is unbound, a\n'
+        '"NameError" exception will be raised.\n'
+        '\n'
+        'Deletion of attribute references, subscriptions and slicings is '
+        'passed\n'
+        'to the primary object involved; deletion of a slicing is in general\n'
+        'equivalent to assignment of an empty slice of the right type (but '
+        'even\n'
+        'this is determined by the sliced object).\n'
+        '\n'
+        'Changed in version 3.2: Previously it was illegal to delete a name\n'
+        'from the local namespace if it occurs as a free variable in a nested\n'
+        'block.\n',
+ 'dict': '\n'
+         'Dictionary displays\n'
+         '*******************\n'
+         '\n'
+         'A dictionary display is a possibly empty series of key/datum pairs\n'
+         'enclosed in curly braces:\n'
+         '\n'
+         '   dict_display       ::= "{" [key_datum_list | dict_comprehension] '
+         '"}"\n'
+         '   key_datum_list     ::= key_datum ("," key_datum)* [","]\n'
+         '   key_datum          ::= expression ":" expression\n'
+         '   dict_comprehension ::= expression ":" expression comp_for\n'
+         '\n'
+         'A dictionary display yields a new dictionary object.\n'
+         '\n'
+         'If a comma-separated sequence of key/datum pairs is given, they are\n'
+         'evaluated from left to right to define the entries of the '
+         'dictionary:\n'
+         'each key object is used as a key into the dictionary to store the\n'
+         'corresponding datum.  This means that you can specify the same key\n'
+         "multiple times in the key/datum list, and the final dictionary's "
+         'value\n'
+         'for that key will be the last one given.\n'
+         '\n'
+         'A dict comprehension, in contrast to list and set comprehensions,\n'
+         'needs two expressions separated with a colon followed by the usual\n'
+         '"for" and "if" clauses. When the comprehension is run, the '
+         'resulting\n'
+         'key and value elements are inserted in the new dictionary in the '
+         'order\n'
+         'they are produced.\n'
+         '\n'
+         'Restrictions on the types of the key values are listed earlier in\n'
+         'section The standard type hierarchy.  (To summarize, the key type\n'
+         'should be *hashable*, which excludes all mutable objects.)  Clashes\n'
+         'between duplicate keys are not detected; the last datum (textually\n'
+         'rightmost in the display) stored for a given key value prevails.\n',
+ 'dynamic-features': '\n'
+                     'Interaction with dynamic features\n'
+                     '*********************************\n'
+                     '\n'
+                     'Name resolution of free variables occurs at runtime, not '
+                     'at compile\n'
+                     'time. This means that the following code will print 42:\n'
+                     '\n'
+                     '   i = 10\n'
+                     '   def f():\n'
+                     '       print(i)\n'
+                     '   i = 42\n'
+                     '   f()\n'
+                     '\n'
+                     'There are several cases where Python statements are '
+                     'illegal when used\n'
+                     'in conjunction with nested scopes that contain free '
+                     'variables.\n'
+                     '\n'
+                     'If a variable is referenced in an enclosing scope, it is '
+                     'illegal to\n'
+                     'delete the name.  An error will be reported at compile '
+                     'time.\n'
+                     '\n'
+                     'The "eval()" and "exec()" functions do not have access '
+                     'to the full\n'
+                     'environment for resolving names.  Names may be resolved '
+                     'in the local\n'
+                     'and global namespaces of the caller.  Free variables are '
+                     'not resolved\n'
+                     'in the nearest enclosing namespace, but in the global '
+                     'namespace.  [1]\n'
+                     'The "exec()" and "eval()" functions have optional '
+                     'arguments to\n'
+                     'override the global and local namespace.  If only one '
+                     'namespace is\n'
+                     'specified, it is used for both.\n',
+ 'else': '\n'
+         'The "if" statement\n'
+         '******************\n'
+         '\n'
+         'The "if" statement is used for conditional execution:\n'
+         '\n'
+         '   if_stmt ::= "if" expression ":" suite\n'
+         '               ( "elif" expression ":" suite )*\n'
+         '               ["else" ":" suite]\n'
+         '\n'
+         'It selects exactly one of the suites by evaluating the expressions '
+         'one\n'
+         'by one until one is found to be true (see section Boolean '
+         'operations\n'
+         'for the definition of true and false); then that suite is executed\n'
+         '(and no other part of the "if" statement is executed or evaluated).\n'
+         'If all expressions are false, the suite of the "else" clause, if\n'
+         'present, is executed.\n',
+ 'exceptions': '\n'
+               'Exceptions\n'
+               '**********\n'
+               '\n'
+               'Exceptions are a means of breaking out of the normal flow of '
+               'control\n'
+               'of a code block in order to handle errors or other '
+               'exceptional\n'
+               'conditions.  An exception is *raised* at the point where the '
+               'error is\n'
+               'detected; it may be *handled* by the surrounding code block or '
+               'by any\n'
+               'code block that directly or indirectly invoked the code block '
+               'where\n'
+               'the error occurred.\n'
+               '\n'
+               'The Python interpreter raises an exception when it detects a '
+               'run-time\n'
+               'error (such as division by zero).  A Python program can also\n'
+               'explicitly raise an exception with the "raise" statement. '
+               'Exception\n'
+               'handlers are specified with the "try" ... "except" statement.  '
+               'The\n'
+               '"finally" clause of such a statement can be used to specify '
+               'cleanup\n'
+               'code which does not handle the exception, but is executed '
+               'whether an\n'
+               'exception occurred or not in the preceding code.\n'
+               '\n'
+               'Python uses the "termination" model of error handling: an '
+               'exception\n'
+               'handler can find out what happened and continue execution at '
+               'an outer\n'
+               'level, but it cannot repair the cause of the error and retry '
+               'the\n'
+               'failing operation (except by re-entering the offending piece '
+               'of code\n'
+               'from the top).\n'
+               '\n'
+               'When an exception is not handled at all, the interpreter '
+               'terminates\n'
+               'execution of the program, or returns to its interactive main '
+               'loop.  In\n'
+               'either case, it prints a stack backtrace, except when the '
+               'exception is\n'
+               '"SystemExit".\n'
+               '\n'
+               'Exceptions are identified by class instances.  The "except" '
+               'clause is\n'
+               'selected depending on the class of the instance: it must '
+               'reference the\n'
+               'class of the instance or a base class thereof.  The instance '
+               'can be\n'
+               'received by the handler and can carry additional information '
+               'about the\n'
+               'exceptional condition.\n'
+               '\n'
+               'Note: Exception messages are not part of the Python API.  '
+               'Their\n'
+               '  contents may change from one version of Python to the next '
+               'without\n'
+               '  warning and should not be relied on by code which will run '
+               'under\n'
+               '  multiple versions of the interpreter.\n'
+               '\n'
+               'See also the description of the "try" statement in section The '
+               'try\n'
+               'statement and "raise" statement in section The raise '
+               'statement.\n'
+               '\n'
+               '-[ Footnotes ]-\n'
+               '\n'
+               '[1] This limitation occurs because the code that is executed '
+               'by\n'
+               '    these operations is not available at the time the module '
+               'is\n'
+               '    compiled.\n',
+ 'execmodel': '\n'
+              'Execution model\n'
+              '***************\n'
+              '\n'
+              '\n'
+              'Structure of a program\n'
+              '======================\n'
+              '\n'
+              'A Python program is constructed from code blocks. A *block* is '
+              'a piece\n'
+              'of Python program text that is executed as a unit. The '
+              'following are\n'
+              'blocks: a module, a function body, and a class definition. '
+              'Each\n'
+              'command typed interactively is a block.  A script file (a file '
+              'given\n'
+              'as standard input to the interpreter or specified as a command '
+              'line\n'
+              'argument to the interpreter) is a code block.  A script command '
+              '(a\n'
+              'command specified on the interpreter command line with the '
+              "'**-c**'\n"
+              'option) is a code block.  The string argument passed to the '
+              'built-in\n'
+              'functions "eval()" and "exec()" is a code block.\n'
+              '\n'
+              'A code block is executed in an *execution frame*.  A frame '
+              'contains\n'
+              'some administrative information (used for debugging) and '
+              'determines\n'
+              "where and how execution continues after the code block's "
+              'execution has\n'
+              'completed.\n'
+              '\n'
+              '\n'
+              'Naming and binding\n'
+              '==================\n'
+              '\n'
+              '\n'
+              'Binding of names\n'
+              '----------------\n'
+              '\n'
+              '*Names* refer to objects.  Names are introduced by name '
+              'binding\n'
+              'operations.\n'
+              '\n'
+              'The following constructs bind names: formal parameters to '
+              'functions,\n'
+              '"import" statements, class and function definitions (these bind '
+              'the\n'
+              'class or function name in the defining block), and targets that '
+              'are\n'
+              'identifiers if occurring in an assignment, "for" loop header, '
+              'or after\n'
+              '"as" in a "with" statement or "except" clause. The "import" '
+              'statement\n'
+              'of the form "from ... import *" binds all names defined in the\n'
+              'imported module, except those beginning with an underscore.  '
+              'This form\n'
+              'may only be used at the module level.\n'
+              '\n'
+              'A target occurring in a "del" statement is also considered '
+              'bound for\n'
+              'this purpose (though the actual semantics are to unbind the '
+              'name).\n'
+              '\n'
+              'Each assignment or import statement occurs within a block '
+              'defined by a\n'
+              'class or function definition or at the module level (the '
+              'top-level\n'
+              'code block).\n'
+              '\n'
+              'If a name is bound in a block, it is a local variable of that '
+              'block,\n'
+              'unless declared as "nonlocal" or "global".  If a name is bound '
+              'at the\n'
+              'module level, it is a global variable.  (The variables of the '
+              'module\n'
+              'code block are local and global.)  If a variable is used in a '
+              'code\n'
+              'block but not defined there, it is a *free variable*.\n'
+              '\n'
+              'Each occurrence of a name in the program text refers to the '
+              '*binding*\n'
+              'of that name established by the following name resolution '
+              'rules.\n'
+              '\n'
+              '\n'
+              'Resolution of names\n'
+              '-------------------\n'
+              '\n'
+              'A *scope* defines the visibility of a name within a block.  If '
+              'a local\n'
+              'variable is defined in a block, its scope includes that block.  '
+              'If the\n'
+              'definition occurs in a function block, the scope extends to any '
+              'blocks\n'
+              'contained within the defining one, unless a contained block '
+              'introduces\n'
+              'a different binding for the name.\n'
+              '\n'
+              'When a name is used in a code block, it is resolved using the '
+              'nearest\n'
+              'enclosing scope.  The set of all such scopes visible to a code '
+              'block\n'
+              "is called the block's *environment*.\n"
+              '\n'
+              'When a name is not found at all, a "NameError" exception is '
+              'raised. If\n'
+              'the current scope is a function scope, and the name refers to a '
+              'local\n'
+              'variable that has not yet been bound to a value at the point '
+              'where the\n'
+              'name is used, an "UnboundLocalError" exception is raised.\n'
+              '"UnboundLocalError" is a subclass of "NameError".\n'
+              '\n'
+              'If a name binding operation occurs anywhere within a code '
+              'block, all\n'
+              'uses of the name within the block are treated as references to '
+              'the\n'
+              'current block.  This can lead to errors when a name is used '
+              'within a\n'
+              'block before it is bound.  This rule is subtle.  Python lacks\n'
+              'declarations and allows name binding operations to occur '
+              'anywhere\n'
+              'within a code block.  The local variables of a code block can '
+              'be\n'
+              'determined by scanning the entire text of the block for name '
+              'binding\n'
+              'operations.\n'
+              '\n'
+              'If the "global" statement occurs within a block, all uses of '
+              'the name\n'
+              'specified in the statement refer to the binding of that name in '
+              'the\n'
+              'top-level namespace.  Names are resolved in the top-level '
+              'namespace by\n'
+              'searching the global namespace, i.e. the namespace of the '
+              'module\n'
+              'containing the code block, and the builtins namespace, the '
+              'namespace\n'
+              'of the module "builtins".  The global namespace is searched '
+              'first.  If\n'
+              'the name is not found there, the builtins namespace is '
+              'searched.  The\n'
+              '"global" statement must precede all uses of the name.\n'
+              '\n'
+              'The "global" statement has the same scope as a name binding '
+              'operation\n'
+              'in the same block.  If the nearest enclosing scope for a free '
+              'variable\n'
+              'contains a global statement, the free variable is treated as a '
+              'global.\n'
+              '\n'
+              'The "nonlocal" statement causes corresponding names to refer '
+              'to\n'
+              'previously bound variables in the nearest enclosing function '
+              'scope.\n'
+              '"SyntaxError" is raised at compile time if the given name does '
+              'not\n'
+              'exist in any enclosing function scope.\n'
+              '\n'
+              'The namespace for a module is automatically created the first '
+              'time a\n'
+              'module is imported.  The main module for a script is always '
+              'called\n'
+              '"__main__".\n'
+              '\n'
+              'Class definition blocks and arguments to "exec()" and "eval()" '
+              'are\n'
+              'special in the context of name resolution. A class definition '
+              'is an\n'
+              'executable statement that may use and define names. These '
+              'references\n'
+              'follow the normal rules for name resolution with an exception '
+              'that\n'
+              'unbound local variables are looked up in the global namespace. '
+              'The\n'
+              'namespace of the class definition becomes the attribute '
+              'dictionary of\n'
+              'the class. The scope of names defined in a class block is '
+              'limited to\n'
+              'the class block; it does not extend to the code blocks of '
+              'methods --\n'
+              'this includes comprehensions and generator expressions since '
+              'they are\n'
+              'implemented using a function scope.  This means that the '
+              'following\n'
+              'will fail:\n'
+              '\n'
+              '   class A:\n'
+              '       a = 42\n'
+              '       b = list(a + i for i in range(10))\n'
+              '\n'
+              '\n'
+              'Builtins and restricted execution\n'
+              '---------------------------------\n'
+              '\n'
+              'The builtins namespace associated with the execution of a code '
+              'block\n'
+              'is actually found by looking up the name "__builtins__" in its '
+              'global\n'
+              'namespace; this should be a dictionary or a module (in the '
+              'latter case\n'
+              "the module's dictionary is used).  By default, when in the "
+              '"__main__"\n'
+              'module, "__builtins__" is the built-in module "builtins"; when '
+              'in any\n'
+              'other module, "__builtins__" is an alias for the dictionary of '
+              'the\n'
+              '"builtins" module itself.  "__builtins__" can be set to a '
+              'user-created\n'
+              'dictionary to create a weak form of restricted execution.\n'
+              '\n'
+              '**CPython implementation detail:** Users should not touch\n'
+              '"__builtins__"; it is strictly an implementation detail.  '
+              'Users\n'
+              'wanting to override values in the builtins namespace should '
+              '"import"\n'
+              'the "builtins" module and modify its attributes appropriately.\n'
+              '\n'
+              '\n'
+              'Interaction with dynamic features\n'
+              '---------------------------------\n'
+              '\n'
+              'Name resolution of free variables occurs at runtime, not at '
+              'compile\n'
+              'time. This means that the following code will print 42:\n'
+              '\n'
+              '   i = 10\n'
+              '   def f():\n'
+              '       print(i)\n'
+              '   i = 42\n'
+              '   f()\n'
+              '\n'
+              'There are several cases where Python statements are illegal '
+              'when used\n'
+              'in conjunction with nested scopes that contain free variables.\n'
+              '\n'
+              'If a variable is referenced in an enclosing scope, it is '
+              'illegal to\n'
+              'delete the name.  An error will be reported at compile time.\n'
+              '\n'
+              'The "eval()" and "exec()" functions do not have access to the '
+              'full\n'
+              'environment for resolving names.  Names may be resolved in the '
+              'local\n'
+              'and global namespaces of the caller.  Free variables are not '
+              'resolved\n'
+              'in the nearest enclosing namespace, but in the global '
+              'namespace.  [1]\n'
+              'The "exec()" and "eval()" functions have optional arguments to\n'
+              'override the global and local namespace.  If only one namespace '
+              'is\n'
+              'specified, it is used for both.\n'
+              '\n'
+              '\n'
+              'Exceptions\n'
+              '==========\n'
+              '\n'
+              'Exceptions are a means of breaking out of the normal flow of '
+              'control\n'
+              'of a code block in order to handle errors or other exceptional\n'
+              'conditions.  An exception is *raised* at the point where the '
+              'error is\n'
+              'detected; it may be *handled* by the surrounding code block or '
+              'by any\n'
+              'code block that directly or indirectly invoked the code block '
+              'where\n'
+              'the error occurred.\n'
+              '\n'
+              'The Python interpreter raises an exception when it detects a '
+              'run-time\n'
+              'error (such as division by zero).  A Python program can also\n'
+              'explicitly raise an exception with the "raise" statement. '
+              'Exception\n'
+              'handlers are specified with the "try" ... "except" statement.  '
+              'The\n'
+              '"finally" clause of such a statement can be used to specify '
+              'cleanup\n'
+              'code which does not handle the exception, but is executed '
+              'whether an\n'
+              'exception occurred or not in the preceding code.\n'
+              '\n'
+              'Python uses the "termination" model of error handling: an '
+              'exception\n'
+              'handler can find out what happened and continue execution at an '
+              'outer\n'
+              'level, but it cannot repair the cause of the error and retry '
+              'the\n'
+              'failing operation (except by re-entering the offending piece of '
+              'code\n'
+              'from the top).\n'
+              '\n'
+              'When an exception is not handled at all, the interpreter '
+              'terminates\n'
+              'execution of the program, or returns to its interactive main '
+              'loop.  In\n'
+              'either case, it prints a stack backtrace, except when the '
+              'exception is\n'
+              '"SystemExit".\n'
+              '\n'
+              'Exceptions are identified by class instances.  The "except" '
+              'clause is\n'
+              'selected depending on the class of the instance: it must '
+              'reference the\n'
+              'class of the instance or a base class thereof.  The instance '
+              'can be\n'
+              'received by the handler and can carry additional information '
+              'about the\n'
+              'exceptional condition.\n'
+              '\n'
+              'Note: Exception messages are not part of the Python API.  '
+              'Their\n'
+              '  contents may change from one version of Python to the next '
+              'without\n'
+              '  warning and should not be relied on by code which will run '
+              'under\n'
+              '  multiple versions of the interpreter.\n'
+              '\n'
+              'See also the description of the "try" statement in section The '
+              'try\n'
+              'statement and "raise" statement in section The raise '
+              'statement.\n'
+              '\n'
+              '-[ Footnotes ]-\n'
+              '\n'
+              '[1] This limitation occurs because the code that is executed '
+              'by\n'
+              '    these operations is not available at the time the module '
+              'is\n'
+              '    compiled.\n',
+ 'exprlists': '\n'
+              'Expression lists\n'
+              '****************\n'
+              '\n'
+              '   expression_list ::= expression ( "," expression )* [","]\n'
+              '\n'
+              'An expression list containing at least one comma yields a '
+              'tuple.  The\n'
+              'length of the tuple is the number of expressions in the list.  '
+              'The\n'
+              'expressions are evaluated from left to right.\n'
+              '\n'
+              'The trailing comma is required only to create a single tuple '
+              '(a.k.a. a\n'
+              '*singleton*); it is optional in all other cases.  A single '
+              'expression\n'
+              "without a trailing comma doesn't create a tuple, but rather "
+              'yields the\n'
+              'value of that expression. (To create an empty tuple, use an '
+              'empty pair\n'
+              'of parentheses: "()".)\n',
+ 'floating': '\n'
+             'Floating point literals\n'
+             '***********************\n'
+             '\n'
+             'Floating point literals are described by the following lexical\n'
+             'definitions:\n'
+             '\n'
+             '   floatnumber   ::= pointfloat | exponentfloat\n'
+             '   pointfloat    ::= [intpart] fraction | intpart "."\n'
+             '   exponentfloat ::= (intpart | pointfloat) exponent\n'
+             '   intpart       ::= digit+\n'
+             '   fraction      ::= "." digit+\n'
+             '   exponent      ::= ("e" | "E") ["+" | "-"] digit+\n'
+             '\n'
+             'Note that the integer and exponent parts are always interpreted '
+             'using\n'
+             'radix 10. For example, "077e010" is legal, and denotes the same '
+             'number\n'
+             'as "77e10". The allowed range of floating point literals is\n'
+             'implementation-dependent. Some examples of floating point '
+             'literals:\n'
+             '\n'
+             '   3.14    10.    .001    1e100    3.14e-10    0e0\n'
+             '\n'
+             'Note that numeric literals do not include a sign; a phrase like '
+             '"-1"\n'
+             'is actually an expression composed of the unary operator "-" and '
+             'the\n'
+             'literal "1".\n',
+ 'for': '\n'
+        'The "for" statement\n'
+        '*******************\n'
+        '\n'
+        'The "for" statement is used to iterate over the elements of a '
+        'sequence\n'
+        '(such as a string, tuple or list) or other iterable object:\n'
+        '\n'
+        '   for_stmt ::= "for" target_list "in" expression_list ":" suite\n'
+        '                ["else" ":" suite]\n'
+        '\n'
+        'The expression list is evaluated once; it should yield an iterable\n'
+        'object.  An iterator is created for the result of the\n'
+        '"expression_list".  The suite is then executed once for each item\n'
+        'provided by the iterator, in the order returned by the iterator.  '
+        'Each\n'
+        'item in turn is assigned to the target list using the standard rules\n'
+        'for assignments (see Assignment statements), and then the suite is\n'
+        'executed.  When the items are exhausted (which is immediately when '
+        'the\n'
+        'sequence is empty or an iterator raises a "StopIteration" '
+        'exception),\n'
+        'the suite in the "else" clause, if present, is executed, and the '
+        'loop\n'
+        'terminates.\n'
+        '\n'
+        'A "break" statement executed in the first suite terminates the loop\n'
+        'without executing the "else" clause\'s suite.  A "continue" '
+        'statement\n'
+        'executed in the first suite skips the rest of the suite and '
+        'continues\n'
+        'with the next item, or with the "else" clause if there is no next\n'
+        'item.\n'
+        '\n'
+        'The for-loop makes assignments to the variables(s) in the target '
+        'list.\n'
+        'This overwrites all previous assignments to those variables '
+        'including\n'
+        'those made in the suite of the for-loop:\n'
+        '\n'
+        '   for i in range(10):\n'
+        '       print(i)\n'
+        '       i = 5             # this will not affect the for-loop\n'
+        '                         # because i will be overwritten with the '
+        'next\n'
+        '                         # index in the range\n'
+        '\n'
+        'Names in the target list are not deleted when the loop is finished,\n'
+        'but if the sequence is empty, they will not have been assigned to at\n'
+        'all by the loop.  Hint: the built-in function "range()" returns an\n'
+        'iterator of integers suitable to emulate the effect of Pascal\'s "for '
+        'i\n'
+        ':= a to b do"; e.g., "list(range(3))" returns the list "[0, 1, 2]".\n'
+        '\n'
+        'Note: There is a subtlety when the sequence is being modified by the\n'
+        '  loop (this can only occur for mutable sequences, i.e. lists).  An\n'
+        '  internal counter is used to keep track of which item is used next,\n'
+        '  and this is incremented on each iteration.  When this counter has\n'
+        '  reached the length of the sequence the loop terminates.  This '
+        'means\n'
+        '  that if the suite deletes the current (or a previous) item from '
+        'the\n'
+        '  sequence, the next item will be skipped (since it gets the index '
+        'of\n'
+        '  the current item which has already been treated).  Likewise, if '
+        'the\n'
+        '  suite inserts an item in the sequence before the current item, the\n'
+        '  current item will be treated again the next time through the loop.\n'
+        '  This can lead to nasty bugs that can be avoided by making a\n'
+        '  temporary copy using a slice of the whole sequence, e.g.,\n'
+        '\n'
+        '     for x in a[:]:\n'
+        '         if x < 0: a.remove(x)\n',
+ 'formatstrings': '\n'
+                  'Format String Syntax\n'
+                  '********************\n'
+                  '\n'
+                  'The "str.format()" method and the "Formatter" class share '
+                  'the same\n'
+                  'syntax for format strings (although in the case of '
+                  '"Formatter",\n'
+                  'subclasses can define their own format string syntax).  The '
+                  'syntax is\n'
+                  'related to that of formatted string literals, but there '
+                  'are\n'
+                  'differences.\n'
+                  '\n'
+                  'Format strings contain "replacement fields" surrounded by '
+                  'curly braces\n'
+                  '"{}". Anything that is not contained in braces is '
+                  'considered literal\n'
+                  'text, which is copied unchanged to the output.  If you need '
+                  'to include\n'
+                  'a brace character in the literal text, it can be escaped by '
+                  'doubling:\n'
+                  '"{{" and "}}".\n'
+                  '\n'
+                  'The grammar for a replacement field is as follows:\n'
+                  '\n'
+                  '      replacement_field ::= "{" [field_name] ["!" '
+                  'conversion] [":" format_spec] "}"\n'
+                  '      field_name        ::= arg_name ("." attribute_name | '
+                  '"[" element_index "]")*\n'
+                  '      arg_name          ::= [identifier | integer]\n'
+                  '      attribute_name    ::= identifier\n'
+                  '      element_index     ::= integer | index_string\n'
+                  '      index_string      ::= <any source character except '
+                  '"]"> +\n'
+                  '      conversion        ::= "r" | "s" | "a"\n'
+                  '      format_spec       ::= <described in the next '
+                  'section>\n'
+                  '\n'
+                  'In less formal terms, the replacement field can start with '
+                  'a\n'
+                  '*field_name* that specifies the object whose value is to be '
+                  'formatted\n'
+                  'and inserted into the output instead of the replacement '
+                  'field. The\n'
+                  '*field_name* is optionally followed by a  *conversion* '
+                  'field, which is\n'
+                  'preceded by an exclamation point "\'!\'", and a '
+                  '*format_spec*, which is\n'
+                  'preceded by a colon "\':\'".  These specify a non-default '
+                  'format for the\n'
+                  'replacement value.\n'
+                  '\n'
+                  'See also the Format Specification Mini-Language section.\n'
+                  '\n'
+                  'The *field_name* itself begins with an *arg_name* that is '
+                  'either a\n'
+                  "number or a keyword.  If it's a number, it refers to a "
+                  'positional\n'
+                  "argument, and if it's a keyword, it refers to a named "
+                  'keyword\n'
+                  'argument.  If the numerical arg_names in a format string '
+                  'are 0, 1, 2,\n'
+                  '... in sequence, they can all be omitted (not just some) '
+                  'and the\n'
+                  'numbers 0, 1, 2, ... will be automatically inserted in that '
+                  'order.\n'
+                  'Because *arg_name* is not quote-delimited, it is not '
+                  'possible to\n'
+                  'specify arbitrary dictionary keys (e.g., the strings '
+                  '"\'10\'" or\n'
+                  '"\':-]\'") within a format string. The *arg_name* can be '
+                  'followed by any\n'
+                  'number of index or attribute expressions. An expression of '
+                  'the form\n'
+                  '"\'.name\'" selects the named attribute using "getattr()", '
+                  'while an\n'
+                  'expression of the form "\'[index]\'" does an index lookup '
+                  'using\n'
+                  '"__getitem__()".\n'
+                  '\n'
+                  'Changed in version 3.1: The positional argument specifiers '
+                  'can be\n'
+                  'omitted, so "\'{} {}\'" is equivalent to "\'{0} {1}\'".\n'
+                  '\n'
+                  'Some simple format string examples:\n'
+                  '\n'
+                  '   "First, thou shalt count to {0}"  # References first '
+                  'positional argument\n'
+                  '   "Bring me a {}"                   # Implicitly '
+                  'references the first positional argument\n'
+                  '   "From {} to {}"                   # Same as "From {0} to '
+                  '{1}"\n'
+                  '   "My quest is {name}"              # References keyword '
+                  "argument 'name'\n"
+                  '   "Weight in tons {0.weight}"       # \'weight\' attribute '
+                  'of first positional arg\n'
+                  '   "Units destroyed: {players[0]}"   # First element of '
+                  "keyword argument 'players'.\n"
+                  '\n'
+                  'The *conversion* field causes a type coercion before '
+                  'formatting.\n'
+                  'Normally, the job of formatting a value is done by the '
+                  '"__format__()"\n'
+                  'method of the value itself.  However, in some cases it is '
+                  'desirable to\n'
+                  'force a type to be formatted as a string, overriding its '
+                  'own\n'
+                  'definition of formatting.  By converting the value to a '
+                  'string before\n'
+                  'calling "__format__()", the normal formatting logic is '
+                  'bypassed.\n'
+                  '\n'
+                  'Three conversion flags are currently supported: "\'!s\'" '
+                  'which calls\n'
+                  '"str()" on the value, "\'!r\'" which calls "repr()" and '
+                  '"\'!a\'" which\n'
+                  'calls "ascii()".\n'
+                  '\n'
+                  'Some examples:\n'
+                  '\n'
+                  '   "Harold\'s a clever {0!s}"        # Calls str() on the '
+                  'argument first\n'
+                  '   "Bring out the holy {name!r}"    # Calls repr() on the '
+                  'argument first\n'
+                  '   "More {!a}"                      # Calls ascii() on the '
+                  'argument first\n'
+                  '\n'
+                  'The *format_spec* field contains a specification of how the '
+                  'value\n'
+                  'should be presented, including such details as field width, '
+                  'alignment,\n'
+                  'padding, decimal precision and so on.  Each value type can '
+                  'define its\n'
+                  'own "formatting mini-language" or interpretation of the '
+                  '*format_spec*.\n'
+                  '\n'
+                  'Most built-in types support a common formatting '
+                  'mini-language, which\n'
+                  'is described in the next section.\n'
+                  '\n'
+                  'A *format_spec* field can also include nested replacement '
+                  'fields\n'
+                  'within it. These nested replacement fields may contain a '
+                  'field name,\n'
+                  'conversion flag and format specification, but deeper '
+                  'nesting is not\n'
+                  'allowed.  The replacement fields within the format_spec '
+                  'are\n'
+                  'substituted before the *format_spec* string is interpreted. '
+                  'This\n'
+                  'allows the formatting of a value to be dynamically '
+                  'specified.\n'
+                  '\n'
+                  'See the Format examples section for some examples.\n'
+                  '\n'
+                  '\n'
+                  'Format Specification Mini-Language\n'
+                  '==================================\n'
+                  '\n'
+                  '"Format specifications" are used within replacement fields '
+                  'contained\n'
+                  'within a format string to define how individual values are '
+                  'presented\n'
+                  '(see Format String Syntax and Formatted string literals). '
+                  'They can\n'
+                  'also be passed directly to the built-in "format()" '
+                  'function.  Each\n'
+                  'formattable type may define how the format specification is '
+                  'to be\n'
+                  'interpreted.\n'
+                  '\n'
+                  'Most built-in types implement the following options for '
+                  'format\n'
+                  'specifications, although some of the formatting options are '
+                  'only\n'
+                  'supported by the numeric types.\n'
+                  '\n'
+                  'A general convention is that an empty format string ("""") '
+                  'produces\n'
+                  'the same result as if you had called "str()" on the value. '
+                  'A non-empty\n'
+                  'format string typically modifies the result.\n'
+                  '\n'
+                  'The general form of a *standard format specifier* is:\n'
+                  '\n'
+                  '   format_spec ::= '
+                  '[[fill]align][sign][#][0][width][,][.precision][type]\n'
+                  '   fill        ::= <any character>\n'
+                  '   align       ::= "<" | ">" | "=" | "^"\n'
+                  '   sign        ::= "+" | "-" | " "\n'
+                  '   width       ::= integer\n'
+                  '   precision   ::= integer\n'
+                  '   type        ::= "b" | "c" | "d" | "e" | "E" | "f" | "F" '
+                  '| "g" | "G" | "n" | "o" | "s" | "x" | "X" | "%"\n'
+                  '\n'
+                  'If a valid *align* value is specified, it can be preceded '
+                  'by a *fill*\n'
+                  'character that can be any character and defaults to a space '
+                  'if\n'
+                  'omitted. It is not possible to use a literal curly brace '
+                  '(""{"" or\n'
+                  '""}"") as the *fill* character in a formatted string '
+                  'literal or when\n'
+                  'using the "str.format()" method.  However, it is possible '
+                  'to insert a\n'
+                  'curly brace with a nested replacement field.  This '
+                  "limitation doesn't\n"
+                  'affect the "format()" function.\n'
+                  '\n'
+                  'The meaning of the various alignment options is as '
+                  'follows:\n'
+                  '\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | Option    | '
+                  'Meaning                                                    '
+                  '|\n'
+                  '   '
+                  '+===========+============================================================+\n'
+                  '   | "\'<\'"     | Forces the field to be left-aligned '
+                  'within the available   |\n'
+                  '   |           | space (this is the default for most '
+                  'objects).              |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'>\'"     | Forces the field to be right-aligned '
+                  'within the available  |\n'
+                  '   |           | space (this is the default for '
+                  'numbers).                   |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'=\'"     | Forces the padding to be placed after '
+                  'the sign (if any)    |\n'
+                  '   |           | but before the digits.  This is used for '
+                  'printing fields   |\n'
+                  "   |           | in the form '+000000120'. This alignment "
+                  'option is only    |\n'
+                  '   |           | valid for numeric types.  It becomes the '
+                  "default when '0'  |\n"
+                  '   |           | immediately precedes the field '
+                  'width.                      |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'^\'"     | Forces the field to be centered within '
+                  'the available       |\n'
+                  '   |           | '
+                  'space.                                                     '
+                  '|\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '\n'
+                  'Note that unless a minimum field width is defined, the '
+                  'field width\n'
+                  'will always be the same size as the data to fill it, so '
+                  'that the\n'
+                  'alignment option has no meaning in this case.\n'
+                  '\n'
+                  'The *sign* option is only valid for number types, and can '
+                  'be one of\n'
+                  'the following:\n'
+                  '\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | Option    | '
+                  'Meaning                                                    '
+                  '|\n'
+                  '   '
+                  '+===========+============================================================+\n'
+                  '   | "\'+\'"     | indicates that a sign should be used for '
+                  'both positive as  |\n'
+                  '   |           | well as negative '
+                  'numbers.                                  |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'-\'"     | indicates that a sign should be used '
+                  'only for negative     |\n'
+                  '   |           | numbers (this is the default '
+                  'behavior).                    |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | space     | indicates that a leading space should be '
+                  'used on positive  |\n'
+                  '   |           | numbers, and a minus sign on negative '
+                  'numbers.             |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '\n'
+                  'The "\'#\'" option causes the "alternate form" to be used '
+                  'for the\n'
+                  'conversion.  The alternate form is defined differently for '
+                  'different\n'
+                  'types.  This option is only valid for integer, float, '
+                  'complex and\n'
+                  'Decimal types. For integers, when binary, octal, or '
+                  'hexadecimal output\n'
+                  'is used, this option adds the prefix respective "\'0b\'", '
+                  '"\'0o\'", or\n'
+                  '"\'0x\'" to the output value. For floats, complex and '
+                  'Decimal the\n'
+                  'alternate form causes the result of the conversion to '
+                  'always contain a\n'
+                  'decimal-point character, even if no digits follow it. '
+                  'Normally, a\n'
+                  'decimal-point character appears in the result of these '
+                  'conversions\n'
+                  'only if a digit follows it. In addition, for "\'g\'" and '
+                  '"\'G\'"\n'
+                  'conversions, trailing zeros are not removed from the '
+                  'result.\n'
+                  '\n'
+                  'The "\',\'" option signals the use of a comma for a '
+                  'thousands separator.\n'
+                  'For a locale aware separator, use the "\'n\'" integer '
+                  'presentation type\n'
+                  'instead.\n'
+                  '\n'
+                  'Changed in version 3.1: Added the "\',\'" option (see also '
+                  '**PEP 378**).\n'
+                  '\n'
+                  '*width* is a decimal integer defining the minimum field '
+                  'width.  If not\n'
+                  'specified, then the field width will be determined by the '
+                  'content.\n'
+                  '\n'
+                  'When no explicit alignment is given, preceding the *width* '
+                  'field by a\n'
+                  'zero ("\'0\'") character enables sign-aware zero-padding '
+                  'for numeric\n'
+                  'types.  This is equivalent to a *fill* character of "\'0\'" '
+                  'with an\n'
+                  '*alignment* type of "\'=\'".\n'
+                  '\n'
+                  'The *precision* is a decimal number indicating how many '
+                  'digits should\n'
+                  'be displayed after the decimal point for a floating point '
+                  'value\n'
+                  'formatted with "\'f\'" and "\'F\'", or before and after the '
+                  'decimal point\n'
+                  'for a floating point value formatted with "\'g\'" or '
+                  '"\'G\'".  For non-\n'
+                  'number types the field indicates the maximum field size - '
+                  'in other\n'
+                  'words, how many characters will be used from the field '
+                  'content. The\n'
+                  '*precision* is not allowed for integer values.\n'
+                  '\n'
+                  'Finally, the *type* determines how the data should be '
+                  'presented.\n'
+                  '\n'
+                  'The available string presentation types are:\n'
+                  '\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | Type      | '
+                  'Meaning                                                    '
+                  '|\n'
+                  '   '
+                  '+===========+============================================================+\n'
+                  '   | "\'s\'"     | String format. This is the default type '
+                  'for strings and    |\n'
+                  '   |           | may be '
+                  'omitted.                                            |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | None      | The same as '
+                  '"\'s\'".                                         |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '\n'
+                  'The available integer presentation types are:\n'
+                  '\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | Type      | '
+                  'Meaning                                                    '
+                  '|\n'
+                  '   '
+                  '+===========+============================================================+\n'
+                  '   | "\'b\'"     | Binary format. Outputs the number in '
+                  'base 2.               |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'c\'"     | Character. Converts the integer to the '
+                  'corresponding       |\n'
+                  '   |           | unicode character before '
+                  'printing.                         |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'d\'"     | Decimal Integer. Outputs the number in '
+                  'base 10.            |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'o\'"     | Octal format. Outputs the number in base '
+                  '8.                |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'x\'"     | Hex format. Outputs the number in base '
+                  '16, using lower-    |\n'
+                  '   |           | case letters for the digits above '
+                  '9.                       |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'X\'"     | Hex format. Outputs the number in base '
+                  '16, using upper-    |\n'
+                  '   |           | case letters for the digits above '
+                  '9.                       |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'n\'"     | Number. This is the same as "\'d\'", '
+                  'except that it uses the |\n'
+                  '   |           | current locale setting to insert the '
+                  'appropriate number    |\n'
+                  '   |           | separator '
+                  'characters.                                      |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | None      | The same as '
+                  '"\'d\'".                                         |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '\n'
+                  'In addition to the above presentation types, integers can '
+                  'be formatted\n'
+                  'with the floating point presentation types listed below '
+                  '(except "\'n\'"\n'
+                  'and None). When doing so, "float()" is used to convert the '
+                  'integer to\n'
+                  'a floating point number before formatting.\n'
+                  '\n'
+                  'The available presentation types for floating point and '
+                  'decimal values\n'
+                  'are:\n'
+                  '\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | Type      | '
+                  'Meaning                                                    '
+                  '|\n'
+                  '   '
+                  '+===========+============================================================+\n'
+                  '   | "\'e\'"     | Exponent notation. Prints the number in '
+                  'scientific         |\n'
+                  "   |           | notation using the letter 'e' to indicate "
+                  'the exponent.    |\n'
+                  '   |           | The default precision is '
+                  '"6".                              |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'E\'"     | Exponent notation. Same as "\'e\'" '
+                  'except it uses an upper   |\n'
+                  "   |           | case 'E' as the separator "
+                  'character.                       |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'f\'"     | Fixed point. Displays the number as a '
+                  'fixed-point number.  |\n'
+                  '   |           | The default precision is '
+                  '"6".                              |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'F\'"     | Fixed point. Same as "\'f\'", but '
+                  'converts "nan" to "NAN"    |\n'
+                  '   |           | and "inf" to '
+                  '"INF".                                        |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'g\'"     | General format.  For a given precision '
+                  '"p >= 1", this      |\n'
+                  '   |           | rounds the number to "p" significant '
+                  'digits and then       |\n'
+                  '   |           | formats the result in either fixed-point '
+                  'format or in      |\n'
+                  '   |           | scientific notation, depending on its '
+                  'magnitude.  The      |\n'
+                  '   |           | precise rules are as follows: suppose that '
+                  'the result      |\n'
+                  '   |           | formatted with presentation type "\'e\'" '
+                  'and precision "p-1" |\n'
+                  '   |           | would have exponent "exp".  Then if "-4 <= '
+                  'exp < p", the   |\n'
+                  '   |           | number is formatted with presentation type '
+                  '"\'f\'" and       |\n'
+                  '   |           | precision "p-1-exp".  Otherwise, the '
+                  'number is formatted   |\n'
+                  '   |           | with presentation type "\'e\'" and '
+                  'precision "p-1". In both  |\n'
+                  '   |           | cases insignificant trailing zeros are '
+                  'removed from the    |\n'
+                  '   |           | significand, and the decimal point is also '
+                  'removed if      |\n'
+                  '   |           | there are no remaining digits following '
+                  'it.  Positive and  |\n'
+                  '   |           | negative infinity, positive and negative '
+                  'zero, and nans,   |\n'
+                  '   |           | are formatted as "inf", "-inf", "0", "-0" '
+                  'and "nan"        |\n'
+                  '   |           | respectively, regardless of the '
+                  'precision.  A precision of |\n'
+                  '   |           | "0" is treated as equivalent to a '
+                  'precision of "1". The    |\n'
+                  '   |           | default precision is '
+                  '"6".                                  |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'G\'"     | General format. Same as "\'g\'" except '
+                  'switches to "\'E\'" if  |\n'
+                  '   |           | the number gets too large. The '
+                  'representations of infinity |\n'
+                  '   |           | and NaN are uppercased, '
+                  'too.                               |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'n\'"     | Number. This is the same as "\'g\'", '
+                  'except that it uses the |\n'
+                  '   |           | current locale setting to insert the '
+                  'appropriate number    |\n'
+                  '   |           | separator '
+                  'characters.                                      |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | "\'%\'"     | Percentage. Multiplies the number by 100 '
+                  'and displays in   |\n'
+                  '   |           | fixed ("\'f\'") format, followed by a '
+                  'percent sign.          |\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '   | None      | Similar to "\'g\'", except that '
+                  'fixed-point notation, when   |\n'
+                  '   |           | used, has at least one digit past the '
+                  'decimal point. The   |\n'
+                  '   |           | default precision is as high as needed to '
+                  'represent the    |\n'
+                  '   |           | particular value. The overall effect is to '
+                  'match the       |\n'
+                  '   |           | output of "str()" as altered by the other '
+                  'format           |\n'
+                  '   |           | '
+                  'modifiers.                                                 '
+                  '|\n'
+                  '   '
+                  '+-----------+------------------------------------------------------------+\n'
+                  '\n'
+                  '\n'
+                  'Format examples\n'
+                  '===============\n'
+                  '\n'
+                  'This section contains examples of the "str.format()" syntax '
+                  'and\n'
+                  'comparison with the old "%"-formatting.\n'
+                  '\n'
+                  'In most of the cases the syntax is similar to the old '
+                  '"%"-formatting,\n'
+                  'with the addition of the "{}" and with ":" used instead of '
+                  '"%". For\n'
+                  'example, "\'%03.2f\'" can be translated to "\'{:03.2f}\'".\n'
+                  '\n'
+                  'The new format syntax also supports new and different '
+                  'options, shown\n'
+                  'in the follow examples.\n'
+                  '\n'
+                  'Accessing arguments by position:\n'
+                  '\n'
+                  "   >>> '{0}, {1}, {2}'.format('a', 'b', 'c')\n"
+                  "   'a, b, c'\n"
+                  "   >>> '{}, {}, {}'.format('a', 'b', 'c')  # 3.1+ only\n"
+                  "   'a, b, c'\n"
+                  "   >>> '{2}, {1}, {0}'.format('a', 'b', 'c')\n"
+                  "   'c, b, a'\n"
+                  "   >>> '{2}, {1}, {0}'.format(*'abc')      # unpacking "
+                  'argument sequence\n'
+                  "   'c, b, a'\n"
+                  "   >>> '{0}{1}{0}'.format('abra', 'cad')   # arguments' "
+                  'indices can be repeated\n'
+                  "   'abracadabra'\n"
+                  '\n'
+                  'Accessing arguments by name:\n'
+                  '\n'
+                  "   >>> 'Coordinates: {latitude}, "
+                  "{longitude}'.format(latitude='37.24N', "
+                  "longitude='-115.81W')\n"
+                  "   'Coordinates: 37.24N, -115.81W'\n"
+                  "   >>> coord = {'latitude': '37.24N', 'longitude': "
+                  "'-115.81W'}\n"
+                  "   >>> 'Coordinates: {latitude}, "
+                  "{longitude}'.format(**coord)\n"
+                  "   'Coordinates: 37.24N, -115.81W'\n"
+                  '\n'
+                  "Accessing arguments' attributes:\n"
+                  '\n'
+                  '   >>> c = 3-5j\n'
+                  "   >>> ('The complex number {0} is formed from the real "
+                  "part {0.real} '\n"
+                  "   ...  'and the imaginary part {0.imag}.').format(c)\n"
+                  "   'The complex number (3-5j) is formed from the real part "
+                  "3.0 and the imaginary part -5.0.'\n"
+                  '   >>> class Point:\n'
+                  '   ...     def __init__(self, x, y):\n'
+                  '   ...         self.x, self.y = x, y\n'
+                  '   ...     def __str__(self):\n'
+                  "   ...         return 'Point({self.x}, "
+                  "{self.y})'.format(self=self)\n"
+                  '   ...\n'
+                  '   >>> str(Point(4, 2))\n'
+                  "   'Point(4, 2)'\n"
+                  '\n'
+                  "Accessing arguments' items:\n"
+                  '\n'
+                  '   >>> coord = (3, 5)\n'
+                  "   >>> 'X: {0[0]};  Y: {0[1]}'.format(coord)\n"
+                  "   'X: 3;  Y: 5'\n"
+                  '\n'
+                  'Replacing "%s" and "%r":\n'
+                  '\n'
+                  '   >>> "repr() shows quotes: {!r}; str() doesn\'t: '
+                  '{!s}".format(\'test1\', \'test2\')\n'
+                  '   "repr() shows quotes: \'test1\'; str() doesn\'t: test2"\n'
+                  '\n'
+                  'Aligning the text and specifying a width:\n'
+                  '\n'
+                  "   >>> '{:<30}'.format('left aligned')\n"
+                  "   'left aligned                  '\n"
+                  "   >>> '{:>30}'.format('right aligned')\n"
+                  "   '                 right aligned'\n"
+                  "   >>> '{:^30}'.format('centered')\n"
+                  "   '           centered           '\n"
+                  "   >>> '{:*^30}'.format('centered')  # use '*' as a fill "
+                  'char\n'
+                  "   '***********centered***********'\n"
+                  '\n'
+                  'Replacing "%+f", "%-f", and "% f" and specifying a sign:\n'
+                  '\n'
+                  "   >>> '{:+f}; {:+f}'.format(3.14, -3.14)  # show it "
+                  'always\n'
+                  "   '+3.140000; -3.140000'\n"
+                  "   >>> '{: f}; {: f}'.format(3.14, -3.14)  # show a space "
+                  'for positive numbers\n'
+                  "   ' 3.140000; -3.140000'\n"
+                  "   >>> '{:-f}; {:-f}'.format(3.14, -3.14)  # show only the "
+                  "minus -- same as '{:f}; {:f}'\n"
+                  "   '3.140000; -3.140000'\n"
+                  '\n'
+                  'Replacing "%x" and "%o" and converting the value to '
+                  'different bases:\n'
+                  '\n'
+                  '   >>> # format also supports binary numbers\n'
+                  '   >>> "int: {0:d};  hex: {0:x};  oct: {0:o};  bin: '
+                  '{0:b}".format(42)\n'
+                  "   'int: 42;  hex: 2a;  oct: 52;  bin: 101010'\n"
+                  '   >>> # with 0x, 0o, or 0b as prefix:\n'
+                  '   >>> "int: {0:d};  hex: {0:#x};  oct: {0:#o};  bin: '
+                  '{0:#b}".format(42)\n'
+                  "   'int: 42;  hex: 0x2a;  oct: 0o52;  bin: 0b101010'\n"
+                  '\n'
+                  'Using the comma as a thousands separator:\n'
+                  '\n'
+                  "   >>> '{:,}'.format(1234567890)\n"
+                  "   '1,234,567,890'\n"
+                  '\n'
+                  'Expressing a percentage:\n'
+                  '\n'
+                  '   >>> points = 19\n'
+                  '   >>> total = 22\n'
+                  "   >>> 'Correct answers: {:.2%}'.format(points/total)\n"
+                  "   'Correct answers: 86.36%'\n"
+                  '\n'
+                  'Using type-specific formatting:\n'
+                  '\n'
+                  '   >>> import datetime\n'
+                  '   >>> d = datetime.datetime(2010, 7, 4, 12, 15, 58)\n'
+                  "   >>> '{:%Y-%m-%d %H:%M:%S}'.format(d)\n"
+                  "   '2010-07-04 12:15:58'\n"
+                  '\n'
+                  'Nesting arguments and more complex examples:\n'
+                  '\n'
+                  "   >>> for align, text in zip('<^>', ['left', 'center', "
+                  "'right']):\n"
+                  "   ...     '{0:{fill}{align}16}'.format(text, fill=align, "
+                  'align=align)\n'
+                  '   ...\n'
+                  "   'left<<<<<<<<<<<<'\n"
+                  "   '^^^^^center^^^^^'\n"
+                  "   '>>>>>>>>>>>right'\n"
+                  '   >>>\n'
+                  '   >>> octets = [192, 168, 0, 1]\n'
+                  "   >>> '{:02X}{:02X}{:02X}{:02X}'.format(*octets)\n"
+                  "   'C0A80001'\n"
+                  '   >>> int(_, 16)\n'
+                  '   3232235521\n'
+                  '   >>>\n'
+                  '   >>> width = 5\n'
+                  '   >>> for num in range(5,12): #doctest: '
+                  '+NORMALIZE_WHITESPACE\n'
+                  "   ...     for base in 'dXob':\n"
+                  "   ...         print('{0:{width}{base}}'.format(num, "
+                  "base=base, width=width), end=' ')\n"
+                  '   ...     print()\n'
+                  '   ...\n'
+                  '       5     5     5   101\n'
+                  '       6     6     6   110\n'
+                  '       7     7     7   111\n'
+                  '       8     8    10  1000\n'
+                  '       9     9    11  1001\n'
+                  '      10     A    12  1010\n'
+                  '      11     B    13  1011\n',
+ 'function': '\n'
+             'Function definitions\n'
+             '********************\n'
+             '\n'
+             'A function definition defines a user-defined function object '
+             '(see\n'
+             'section The standard type hierarchy):\n'
+             '\n'
+             '   funcdef                 ::= [decorators] "def" funcname "(" '
+             '[parameter_list] ")" ["->" expression] ":" suite\n'
+             '   decorators              ::= decorator+\n'
+             '   decorator               ::= "@" dotted_name ["(" '
+             '[parameter_list [","]] ")"] NEWLINE\n'
+             '   dotted_name             ::= identifier ("." identifier)*\n'
+             '   parameter_list          ::= defparameter ("," defparameter)* '
+             '["," [parameter_list_starargs]]\n'
+             '                      | parameter_list_starargs\n'
+             '   parameter_list_starargs ::= "*" [parameter] ("," '
+             'defparameter)* ["," ["**" parameter [","]]]\n'
+             '                               | "**" parameter [","]\n'
+             '   parameter               ::= identifier [":" expression]\n'
+             '   defparameter            ::= parameter ["=" expression]\n'
+             '   funcname                ::= identifier\n'
+             '\n'
+             'A function definition is an executable statement.  Its execution '
+             'binds\n'
+             'the function name in the current local namespace to a function '
+             'object\n'
+             '(a wrapper around the executable code for the function).  This\n'
+             'function object contains a reference to the current global '
+             'namespace\n'
+             'as the global namespace to be used when the function is called.\n'
+             '\n'
+             'The function definition does not execute the function body; this '
+             'gets\n'
+             'executed only when the function is called. [3]\n'
+             '\n'
+             'A function definition may be wrapped by one or more *decorator*\n'
+             'expressions. Decorator expressions are evaluated when the '
+             'function is\n'
+             'defined, in the scope that contains the function definition.  '
+             'The\n'
+             'result must be a callable, which is invoked with the function '
+             'object\n'
+             'as the only argument. The returned value is bound to the '
+             'function name\n'
+             'instead of the function object.  Multiple decorators are applied '
+             'in\n'
+             'nested fashion. For example, the following code\n'
+             '\n'
+             '   @f1(arg)\n'
+             '   @f2\n'
+             '   def func(): pass\n'
+             '\n'
+             'is equivalent to\n'
+             '\n'
+             '   def func(): pass\n'
+             '   func = f1(arg)(f2(func))\n'
+             '\n'
+             'When one or more *parameters* have the form *parameter* "="\n'
+             '*expression*, the function is said to have "default parameter '
+             'values."\n'
+             'For a parameter with a default value, the corresponding '
+             '*argument* may\n'
+             "be omitted from a call, in which case the parameter's default "
+             'value is\n'
+             'substituted.  If a parameter has a default value, all following\n'
+             'parameters up until the ""*"" must also have a default value --- '
+             'this\n'
+             'is a syntactic restriction that is not expressed by the '
+             'grammar.\n'
+             '\n'
+             '**Default parameter values are evaluated from left to right when '
+             'the\n'
+             'function definition is executed.** This means that the '
+             'expression is\n'
+             'evaluated once, when the function is defined, and that the same '
+             '"pre-\n'
+             'computed" value is used for each call.  This is especially '
+             'important\n'
+             'to understand when a default parameter is a mutable object, such '
+             'as a\n'
+             'list or a dictionary: if the function modifies the object (e.g. '
+             'by\n'
+             'appending an item to a list), the default value is in effect '
+             'modified.\n'
+             'This is generally not what was intended.  A way around this is '
+             'to use\n'
+             '"None" as the default, and explicitly test for it in the body of '
+             'the\n'
+             'function, e.g.:\n'
+             '\n'
+             '   def whats_on_the_telly(penguin=None):\n'
+             '       if penguin is None:\n'
+             '           penguin = []\n'
+             '       penguin.append("property of the zoo")\n'
+             '       return penguin\n'
+             '\n'
+             'Function call semantics are described in more detail in section '
+             'Calls.\n'
+             'A function call always assigns values to all parameters '
+             'mentioned in\n'
+             'the parameter list, either from position arguments, from '
+             'keyword\n'
+             'arguments, or from default values.  If the form ""*identifier"" '
+             'is\n'
+             'present, it is initialized to a tuple receiving any excess '
+             'positional\n'
+             'parameters, defaulting to the empty tuple.  If the form\n'
+             '""**identifier"" is present, it is initialized to a new '
+             'dictionary\n'
+             'receiving any excess keyword arguments, defaulting to a new '
+             'empty\n'
+             'dictionary. Parameters after ""*"" or ""*identifier"" are '
+             'keyword-only\n'
+             'parameters and may only be passed used keyword arguments.\n'
+             '\n'
+             'Parameters may have annotations of the form "": expression"" '
+             'following\n'
+             'the parameter name.  Any parameter may have an annotation even '
+             'those\n'
+             'of the form "*identifier" or "**identifier".  Functions may '
+             'have\n'
+             '"return" annotation of the form ""-> expression"" after the '
+             'parameter\n'
+             'list.  These annotations can be any valid Python expression and '
+             'are\n'
+             'evaluated when the function definition is executed.  Annotations '
+             'may\n'
+             'be evaluated in a different order than they appear in the source '
+             'code.\n'
+             'The presence of annotations does not change the semantics of a\n'
+             'function.  The annotation values are available as values of a\n'
+             "dictionary keyed by the parameters' names in the "
+             '"__annotations__"\n'
+             'attribute of the function object.\n'
+             '\n'
+             'It is also possible to create anonymous functions (functions not '
+             'bound\n'
+             'to a name), for immediate use in expressions.  This uses lambda\n'
+             'expressions, described in section Lambdas.  Note that the '
+             'lambda\n'
+             'expression is merely a shorthand for a simplified function '
+             'definition;\n'
+             'a function defined in a ""def"" statement can be passed around '
+             'or\n'
+             'assigned to another name just like a function defined by a '
+             'lambda\n'
+             'expression.  The ""def"" form is actually more powerful since '
+             'it\n'
+             'allows the execution of multiple statements and annotations.\n'
+             '\n'
+             "**Programmer's note:** Functions are first-class objects.  A "
+             '""def""\n'
+             'statement executed inside a function definition defines a local\n'
+             'function that can be returned or passed around.  Free variables '
+             'used\n'
+             'in the nested function can access the local variables of the '
+             'function\n'
+             'containing the def.  See section Naming and binding for '
+             'details.\n'
+             '\n'
+             'See also:\n'
+             '\n'
+             '  **PEP 3107** - Function Annotations\n'
+             '     The original specification for function annotations.\n',
+ 'global': '\n'
+           'The "global" statement\n'
+           '**********************\n'
+           '\n'
+           '   global_stmt ::= "global" identifier ("," identifier)*\n'
+           '\n'
+           'The "global" statement is a declaration which holds for the '
+           'entire\n'
+           'current code block.  It means that the listed identifiers are to '
+           'be\n'
+           'interpreted as globals.  It would be impossible to assign to a '
+           'global\n'
+           'variable without "global", although free variables may refer to\n'
+           'globals without being declared global.\n'
+           '\n'
+           'Names listed in a "global" statement must not be used in the same '
+           'code\n'
+           'block textually preceding that "global" statement.\n'
+           '\n'
+           'Names listed in a "global" statement must not be defined as '
+           'formal\n'
+           'parameters or in a "for" loop control target, "class" definition,\n'
+           'function definition, or "import" statement.\n'
+           '\n'
+           '**CPython implementation detail:** The current implementation does '
+           'not\n'
+           'enforce the two restrictions, but programs should not abuse this\n'
+           'freedom, as future implementations may enforce them or silently '
+           'change\n'
+           'the meaning of the program.\n'
+           '\n'
+           '**Programmer\'s note:** the "global" is a directive to the '
+           'parser.  It\n'
+           'applies only to code parsed at the same time as the "global"\n'
+           'statement. In particular, a "global" statement contained in a '
+           'string\n'
+           'or code object supplied to the built-in "exec()" function does '
+           'not\n'
+           'affect the code block *containing* the function call, and code\n'
+           'contained in such a string is unaffected by "global" statements in '
+           'the\n'
+           'code containing the function call.  The same applies to the '
+           '"eval()"\n'
+           'and "compile()" functions.\n',
+ 'id-classes': '\n'
+               'Reserved classes of identifiers\n'
+               '*******************************\n'
+               '\n'
+               'Certain classes of identifiers (besides keywords) have '
+               'special\n'
+               'meanings.  These classes are identified by the patterns of '
+               'leading and\n'
+               'trailing underscore characters:\n'
+               '\n'
+               '"_*"\n'
+               '   Not imported by "from module import *".  The special '
+               'identifier "_"\n'
+               '   is used in the interactive interpreter to store the result '
+               'of the\n'
+               '   last evaluation; it is stored in the "builtins" module.  '
+               'When not\n'
+               '   in interactive mode, "_" has no special meaning and is not '
+               'defined.\n'
+               '   See section The import statement.\n'
+               '\n'
+               '   Note: The name "_" is often used in conjunction with\n'
+               '     internationalization; refer to the documentation for the\n'
+               '     "gettext" module for more information on this '
+               'convention.\n'
+               '\n'
+               '"__*__"\n'
+               '   System-defined names. These names are defined by the '
+               'interpreter\n'
+               '   and its implementation (including the standard library).  '
+               'Current\n'
+               '   system names are discussed in the Special method names '
+               'section and\n'
+               '   elsewhere.  More will likely be defined in future versions '
+               'of\n'
+               '   Python.  *Any* use of "__*__" names, in any context, that '
+               'does not\n'
+               '   follow explicitly documented use, is subject to breakage '
+               'without\n'
+               '   warning.\n'
+               '\n'
+               '"__*"\n'
+               '   Class-private names.  Names in this category, when used '
+               'within the\n'
+               '   context of a class definition, are re-written to use a '
+               'mangled form\n'
+               '   to help avoid name clashes between "private" attributes of '
+               'base and\n'
+               '   derived classes. See section Identifiers (Names).\n',
+ 'identifiers': '\n'
+                'Identifiers and keywords\n'
+                '************************\n'
+                '\n'
+                'Identifiers (also referred to as *names*) are described by '
+                'the\n'
+                'following lexical definitions.\n'
+                '\n'
+                'The syntax of identifiers in Python is based on the Unicode '
+                'standard\n'
+                'annex UAX-31, with elaboration and changes as defined below; '
+                'see also\n'
+                '**PEP 3131** for further details.\n'
+                '\n'
+                'Within the ASCII range (U+0001..U+007F), the valid characters '
+                'for\n'
+                'identifiers are the same as in Python 2.x: the uppercase and '
+                'lowercase\n'
+                'letters "A" through "Z", the underscore "_" and, except for '
+                'the first\n'
+                'character, the digits "0" through "9".\n'
+                '\n'
+                'Python 3.0 introduces additional characters from outside the '
+                'ASCII\n'
+                'range (see **PEP 3131**).  For these characters, the '
+                'classification\n'
+                'uses the version of the Unicode Character Database as '
+                'included in the\n'
+                '"unicodedata" module.\n'
+                '\n'
+                'Identifiers are unlimited in length.  Case is significant.\n'
+                '\n'
+                '   identifier   ::= xid_start xid_continue*\n'
+                '   id_start     ::= <all characters in general categories Lu, '
+                'Ll, Lt, Lm, Lo, Nl, the underscore, and characters with the '
+                'Other_ID_Start property>\n'
+                '   id_continue  ::= <all characters in id_start, plus '
+                'characters in the categories Mn, Mc, Nd, Pc and others with '
+                'the Other_ID_Continue property>\n'
+                '   xid_start    ::= <all characters in id_start whose NFKC '
+                'normalization is in "id_start xid_continue*">\n'
+                '   xid_continue ::= <all characters in id_continue whose NFKC '
+                'normalization is in "id_continue*">\n'
+                '\n'
+                'The Unicode category codes mentioned above stand for:\n'
+                '\n'
+                '* *Lu* - uppercase letters\n'
+                '\n'
+                '* *Ll* - lowercase letters\n'
+                '\n'
+                '* *Lt* - titlecase letters\n'
+                '\n'
+                '* *Lm* - modifier letters\n'
+                '\n'
+                '* *Lo* - other letters\n'
+                '\n'
+                '* *Nl* - letter numbers\n'
+                '\n'
+                '* *Mn* - nonspacing marks\n'
+                '\n'
+                '* *Mc* - spacing combining marks\n'
+                '\n'
+                '* *Nd* - decimal numbers\n'
+                '\n'
+                '* *Pc* - connector punctuations\n'
+                '\n'
+                '* *Other_ID_Start* - explicit list of characters in '
+                'PropList.txt to\n'
+                '  support backwards compatibility\n'
+                '\n'
+                '* *Other_ID_Continue* - likewise\n'
+                '\n'
+                'All identifiers are converted into the normal form NFKC while '
+                'parsing;\n'
+                'comparison of identifiers is based on NFKC.\n'
+                '\n'
+                'A non-normative HTML file listing all valid identifier '
+                'characters for\n'
+                'Unicode 4.1 can be found at https://www.dcl.hpi.uni-\n'
+                'potsdam.de/home/loewis/table-3131.html.\n'
+                '\n'
+                '\n'
+                'Keywords\n'
+                '========\n'
+                '\n'
+                'The following identifiers are used as reserved words, or '
+                '*keywords* of\n'
+                'the language, and cannot be used as ordinary identifiers.  '
+                'They must\n'
+                'be spelled exactly as written here:\n'
+                '\n'
+                '   False      class      finally    is         return\n'
+                '   None       continue   for        lambda     try\n'
+                '   True       def        from       nonlocal   while\n'
+                '   and        del        global     not        with\n'
+                '   as         elif       if         or         yield\n'
+                '   assert     else       import     pass\n'
+                '   break      except     in         raise\n'
+                '\n'
+                '\n'
+                'Reserved classes of identifiers\n'
+                '===============================\n'
+                '\n'
+                'Certain classes of identifiers (besides keywords) have '
+                'special\n'
+                'meanings.  These classes are identified by the patterns of '
+                'leading and\n'
+                'trailing underscore characters:\n'
+                '\n'
+                '"_*"\n'
+                '   Not imported by "from module import *".  The special '
+                'identifier "_"\n'
+                '   is used in the interactive interpreter to store the result '
+                'of the\n'
+                '   last evaluation; it is stored in the "builtins" module.  '
+                'When not\n'
+                '   in interactive mode, "_" has no special meaning and is not '
+                'defined.\n'
+                '   See section The import statement.\n'
+                '\n'
+                '   Note: The name "_" is often used in conjunction with\n'
+                '     internationalization; refer to the documentation for '
+                'the\n'
+                '     "gettext" module for more information on this '
+                'convention.\n'
+                '\n'
+                '"__*__"\n'
+                '   System-defined names. These names are defined by the '
+                'interpreter\n'
+                '   and its implementation (including the standard library).  '
+                'Current\n'
+                '   system names are discussed in the Special method names '
+                'section and\n'
+                '   elsewhere.  More will likely be defined in future versions '
+                'of\n'
+                '   Python.  *Any* use of "__*__" names, in any context, that '
+                'does not\n'
+                '   follow explicitly documented use, is subject to breakage '
+                'without\n'
+                '   warning.\n'
+                '\n'
+                '"__*"\n'
+                '   Class-private names.  Names in this category, when used '
+                'within the\n'
+                '   context of a class definition, are re-written to use a '
+                'mangled form\n'
+                '   to help avoid name clashes between "private" attributes of '
+                'base and\n'
+                '   derived classes. See section Identifiers (Names).\n',
+ 'if': '\n'
+       'The "if" statement\n'
+       '******************\n'
+       '\n'
+       'The "if" statement is used for conditional execution:\n'
+       '\n'
+       '   if_stmt ::= "if" expression ":" suite\n'
+       '               ( "elif" expression ":" suite )*\n'
+       '               ["else" ":" suite]\n'
+       '\n'
+       'It selects exactly one of the suites by evaluating the expressions '
+       'one\n'
+       'by one until one is found to be true (see section Boolean operations\n'
+       'for the definition of true and false); then that suite is executed\n'
+       '(and no other part of the "if" statement is executed or evaluated).\n'
+       'If all expressions are false, the suite of the "else" clause, if\n'
+       'present, is executed.\n',
+ 'imaginary': '\n'
+              'Imaginary literals\n'
+              '******************\n'
+              '\n'
+              'Imaginary literals are described by the following lexical '
+              'definitions:\n'
+              '\n'
+              '   imagnumber ::= (floatnumber | intpart) ("j" | "J")\n'
+              '\n'
+              'An imaginary literal yields a complex number with a real part '
+              'of 0.0.\n'
+              'Complex numbers are represented as a pair of floating point '
+              'numbers\n'
+              'and have the same restrictions on their range.  To create a '
+              'complex\n'
+              'number with a nonzero real part, add a floating point number to '
+              'it,\n'
+              'e.g., "(3+4j)".  Some examples of imaginary literals:\n'
+              '\n'
+              '   3.14j   10.j    10j     .001j   1e100j  3.14e-10j\n',
+ 'import': '\n'
+           'The "import" statement\n'
+           '**********************\n'
+           '\n'
+           '   import_stmt     ::= "import" module ["as" name] ( "," module '
+           '["as" name] )*\n'
+           '                   | "from" relative_module "import" identifier '
+           '["as" name]\n'
+           '                   ( "," identifier ["as" name] )*\n'
+           '                   | "from" relative_module "import" "(" '
+           'identifier ["as" name]\n'
+           '                   ( "," identifier ["as" name] )* [","] ")"\n'
+           '                   | "from" module "import" "*"\n'
+           '   module          ::= (identifier ".")* identifier\n'
+           '   relative_module ::= "."* module | "."+\n'
+           '   name            ::= identifier\n'
+           '\n'
+           'The basic import statement (no "from" clause) is executed in two\n'
+           'steps:\n'
+           '\n'
+           '1. find a module, loading and initializing it if necessary\n'
+           '\n'
+           '2. define a name or names in the local namespace for the scope\n'
+           '   where the "import" statement occurs.\n'
+           '\n'
+           'When the statement contains multiple clauses (separated by commas) '
+           'the\n'
+           'two steps are carried out separately for each clause, just as '
+           'though\n'
+           'the clauses had been separated out into individiual import '
+           'statements.\n'
+           '\n'
+           'The details of the first step, finding and loading modules are\n'
+           'described in greater detail in the section on the import system, '
+           'which\n'
+           'also describes the various types of packages and modules that can '
+           'be\n'
+           'imported, as well as all the hooks that can be used to customize '
+           'the\n'
+           'import system. Note that failures in this step may indicate '
+           'either\n'
+           'that the module could not be located, *or* that an error occurred\n'
+           'while initializing the module, which includes execution of the\n'
+           "module's code.\n"
+           '\n'
+           'If the requested module is retrieved successfully, it will be '
+           'made\n'
+           'available in the local namespace in one of three ways:\n'
+           '\n'
+           '* If the module name is followed by "as", then the name following\n'
+           '  "as" is bound directly to the imported module.\n'
+           '\n'
+           '* If no other name is specified, and the module being imported is '
+           'a\n'
+           "  top level module, the module's name is bound in the local "
+           'namespace\n'
+           '  as a reference to the imported module\n'
+           '\n'
+           '* If the module being imported is *not* a top level module, then '
+           'the\n'
+           '  name of the top level package that contains the module is bound '
+           'in\n'
+           '  the local namespace as a reference to the top level package. '
+           'The\n'
+           '  imported module must be accessed using its full qualified name\n'
+           '  rather than directly\n'
+           '\n'
+           'The "from" form uses a slightly more complex process:\n'
+           '\n'
+           '1. find the module specified in the "from" clause, loading and\n'
+           '   initializing it if necessary;\n'
+           '\n'
+           '2. for each of the identifiers specified in the "import" clauses:\n'
+           '\n'
+           '   1. check if the imported module has an attribute by that name\n'
+           '\n'
+           '   2. if not, attempt to import a submodule with that name and '
+           'then\n'
+           '      check the imported module again for that attribute\n'
+           '\n'
+           '   3. if the attribute is not found, "ImportError" is raised.\n'
+           '\n'
+           '   4. otherwise, a reference to that value is stored in the local\n'
+           '      namespace, using the name in the "as" clause if it is '
+           'present,\n'
+           '      otherwise using the attribute name\n'
+           '\n'
+           'Examples:\n'
+           '\n'
+           '   import foo                 # foo imported and bound locally\n'
+           '   import foo.bar.baz         # foo.bar.baz imported, foo bound '
+           'locally\n'
+           '   import foo.bar.baz as fbb  # foo.bar.baz imported and bound as '
+           'fbb\n'
+           '   from foo.bar import baz    # foo.bar.baz imported and bound as '
+           'baz\n'
+           '   from foo import attr       # foo imported and foo.attr bound as '
+           'attr\n'
+           '\n'
+           'If the list of identifiers is replaced by a star ("\'*\'"), all '
+           'public\n'
+           'names defined in the module are bound in the local namespace for '
+           'the\n'
+           'scope where the "import" statement occurs.\n'
+           '\n'
+           'The *public names* defined by a module are determined by checking '
+           'the\n'
+           'module\'s namespace for a variable named "__all__"; if defined, it '
+           'must\n'
+           'be a sequence of strings which are names defined or imported by '
+           'that\n'
+           'module.  The names given in "__all__" are all considered public '
+           'and\n'
+           'are required to exist.  If "__all__" is not defined, the set of '
+           'public\n'
+           "names includes all names found in the module's namespace which do "
+           'not\n'
+           'begin with an underscore character ("\'_\'").  "__all__" should '
+           'contain\n'
+           'the entire public API. It is intended to avoid accidentally '
+           'exporting\n'
+           'items that are not part of the API (such as library modules which '
+           'were\n'
+           'imported and used within the module).\n'
+           '\n'
+           'The wild card form of import --- "from module import *" --- is '
+           'only\n'
+           'allowed at the module level.  Attempting to use it in class or\n'
+           'function definitions will raise a "SyntaxError".\n'
+           '\n'
+           'When specifying what module to import you do not have to specify '
+           'the\n'
+           'absolute name of the module. When a module or package is '
+           'contained\n'
+           'within another package it is possible to make a relative import '
+           'within\n'
+           'the same top package without having to mention the package name. '
+           'By\n'
+           'using leading dots in the specified module or package after "from" '
+           'you\n'
+           'can specify how high to traverse up the current package hierarchy\n'
+           'without specifying exact names. One leading dot means the current\n'
+           'package where the module making the import exists. Two dots means '
+           'up\n'
+           'one package level. Three dots is up two levels, etc. So if you '
+           'execute\n'
+           '"from . import mod" from a module in the "pkg" package then you '
+           'will\n'
+           'end up importing "pkg.mod". If you execute "from ..subpkg2 import '
+           'mod"\n'
+           'from within "pkg.subpkg1" you will import "pkg.subpkg2.mod". The\n'
+           'specification for relative imports is contained within **PEP '
+           '328**.\n'
+           '\n'
+           '"importlib.import_module()" is provided to support applications '
+           'that\n'
+           'determine dynamically the modules to be loaded.\n'
+           '\n'
+           '\n'
+           'Future statements\n'
+           '=================\n'
+           '\n'
+           'A *future statement* is a directive to the compiler that a '
+           'particular\n'
+           'module should be compiled using syntax or semantics that will be\n'
+           'available in a specified future release of Python where the '
+           'feature\n'
+           'becomes standard.\n'
+           '\n'
+           'The future statement is intended to ease migration to future '
+           'versions\n'
+           'of Python that introduce incompatible changes to the language.  '
+           'It\n'
+           'allows use of the new features on a per-module basis before the\n'
+           'release in which the feature becomes standard.\n'
+           '\n'
+           '   future_statement ::= "from" "__future__" "import" feature ["as" '
+           'name]\n'
+           '                        ("," feature ["as" name])*\n'
+           '                        | "from" "__future__" "import" "(" feature '
+           '["as" name]\n'
+           '                        ("," feature ["as" name])* [","] ")"\n'
+           '   feature          ::= identifier\n'
+           '   name             ::= identifier\n'
+           '\n'
+           'A future statement must appear near the top of the module.  The '
+           'only\n'
+           'lines that can appear before a future statement are:\n'
+           '\n'
+           '* the module docstring (if any),\n'
+           '\n'
+           '* comments,\n'
+           '\n'
+           '* blank lines, and\n'
+           '\n'
+           '* other future statements.\n'
+           '\n'
+           'The features recognized by Python 3.0 are "absolute_import",\n'
+           '"division", "generators", "unicode_literals", "print_function",\n'
+           '"nested_scopes" and "with_statement".  They are all redundant '
+           'because\n'
+           'they are always enabled, and only kept for backwards '
+           'compatibility.\n'
+           '\n'
+           'A future statement is recognized and treated specially at compile\n'
+           'time: Changes to the semantics of core constructs are often\n'
+           'implemented by generating different code.  It may even be the '
+           'case\n'
+           'that a new feature introduces new incompatible syntax (such as a '
+           'new\n'
+           'reserved word), in which case the compiler may need to parse the\n'
+           'module differently.  Such decisions cannot be pushed off until\n'
+           'runtime.\n'
+           '\n'
+           'For any given release, the compiler knows which feature names '
+           'have\n'
+           'been defined, and raises a compile-time error if a future '
+           'statement\n'
+           'contains a feature not known to it.\n'
+           '\n'
+           'The direct runtime semantics are the same as for any import '
+           'statement:\n'
+           'there is a standard module "__future__", described later, and it '
+           'will\n'
+           'be imported in the usual way at the time the future statement is\n'
+           'executed.\n'
+           '\n'
+           'The interesting runtime semantics depend on the specific feature\n'
+           'enabled by the future statement.\n'
+           '\n'
+           'Note that there is nothing special about the statement:\n'
+           '\n'
+           '   import __future__ [as name]\n'
+           '\n'
+           "That is not a future statement; it's an ordinary import statement "
+           'with\n'
+           'no special semantics or syntax restrictions.\n'
+           '\n'
+           'Code compiled by calls to the built-in functions "exec()" and\n'
+           '"compile()" that occur in a module "M" containing a future '
+           'statement\n'
+           'will, by default, use the new syntax or semantics associated with '
+           'the\n'
+           'future statement.  This can be controlled by optional arguments '
+           'to\n'
+           '"compile()" --- see the documentation of that function for '
+           'details.\n'
+           '\n'
+           'A future statement typed at an interactive interpreter prompt '
+           'will\n'
+           'take effect for the rest of the interpreter session.  If an\n'
+           'interpreter is started with the "-i" option, is passed a script '
+           'name\n'
+           'to execute, and the script includes a future statement, it will be '
+           'in\n'
+           'effect in the interactive session started after the script is\n'
+           'executed.\n'
+           '\n'
+           'See also:\n'
+           '\n'
+           '  **PEP 236** - Back to the __future__\n'
+           '     The original proposal for the __future__ mechanism.\n',
+ 'in': '\n'
+       'Membership test operations\n'
+       '**************************\n'
+       '\n'
+       'The operators "in" and "not in" test for membership.  "x in s"\n'
+       'evaluates to true if *x* is a member of *s*, and false otherwise.  "x\n'
+       'not in s" returns the negation of "x in s".  All built-in sequences\n'
+       'and set types support this as well as dictionary, for which "in" '
+       'tests\n'
+       'whether the dictionary has a given key. For container types such as\n'
+       'list, tuple, set, frozenset, dict, or collections.deque, the\n'
+       'expression "x in y" is equivalent to "any(x is e or x == e for e in\n'
+       'y)".\n'
+       '\n'
+       'For the string and bytes types, "x in y" is true if and only if *x* '
+       'is\n'
+       'a substring of *y*.  An equivalent test is "y.find(x) != -1".  Empty\n'
+       'strings are always considered to be a substring of any other string,\n'
+       'so """ in "abc"" will return "True".\n'
+       '\n'
+       'For user-defined classes which define the "__contains__()" method, "x\n'
+       'in y" is true if and only if "y.__contains__(x)" is true.\n'
+       '\n'
+       'For user-defined classes which do not define "__contains__()" but do\n'
+       'define "__iter__()", "x in y" is true if some value "z" with "x == z"\n'
+       'is produced while iterating over "y".  If an exception is raised\n'
+       'during the iteration, it is as if "in" raised that exception.\n'
+       '\n'
+       'Lastly, the old-style iteration protocol is tried: if a class defines\n'
+       '"__getitem__()", "x in y" is true if and only if there is a non-\n'
+       'negative integer index *i* such that "x == y[i]", and all lower\n'
+       'integer indices do not raise "IndexError" exception.  (If any other\n'
+       'exception is raised, it is as if "in" raised that exception).\n'
+       '\n'
+       'The operator "not in" is defined to have the inverse true value of\n'
+       '"in".\n',
+ 'integers': '\n'
+             'Integer literals\n'
+             '****************\n'
+             '\n'
+             'Integer literals are described by the following lexical '
+             'definitions:\n'
+             '\n'
+             '   integer        ::= decimalinteger | octinteger | hexinteger | '
+             'bininteger\n'
+             '   decimalinteger ::= nonzerodigit digit* | "0"+\n'
+             '   nonzerodigit   ::= "1"..."9"\n'
+             '   digit          ::= "0"..."9"\n'
+             '   octinteger     ::= "0" ("o" | "O") octdigit+\n'
+             '   hexinteger     ::= "0" ("x" | "X") hexdigit+\n'
+             '   bininteger     ::= "0" ("b" | "B") bindigit+\n'
+             '   octdigit       ::= "0"..."7"\n'
+             '   hexdigit       ::= digit | "a"..."f" | "A"..."F"\n'
+             '   bindigit       ::= "0" | "1"\n'
+             '\n'
+             'There is no limit for the length of integer literals apart from '
+             'what\n'
+             'can be stored in available memory.\n'
+             '\n'
+             'Note that leading zeros in a non-zero decimal number are not '
+             'allowed.\n'
+             'This is for disambiguation with C-style octal literals, which '
+             'Python\n'
+             'used before version 3.0.\n'
+             '\n'
+             'Some examples of integer literals:\n'
+             '\n'
+             '   7     2147483647                        0o177    0b100110111\n'
+             '   3     79228162514264337593543950336     0o377    0xdeadbeef\n',
+ 'lambda': '\n'
+           'Lambdas\n'
+           '*******\n'
+           '\n'
+           '   lambda_expr        ::= "lambda" [parameter_list]: expression\n'
+           '   lambda_expr_nocond ::= "lambda" [parameter_list]: '
+           'expression_nocond\n'
+           '\n'
+           'Lambda expressions (sometimes called lambda forms) are used to '
+           'create\n'
+           'anonymous functions. The expression "lambda arguments: '
+           'expression"\n'
+           'yields a function object.  The unnamed object behaves like a '
+           'function\n'
+           'object defined with\n'
+           '\n'
+           '   def <lambda>(arguments):\n'
+           '       return expression\n'
+           '\n'
+           'See section Function definitions for the syntax of parameter '
+           'lists.\n'
+           'Note that functions created with lambda expressions cannot '
+           'contain\n'
+           'statements or annotations.\n',
+ 'lists': '\n'
+          'List displays\n'
+          '*************\n'
+          '\n'
+          'A list display is a possibly empty series of expressions enclosed '
+          'in\n'
+          'square brackets:\n'
+          '\n'
+          '   list_display ::= "[" [expression_list | comprehension] "]"\n'
+          '\n'
+          'A list display yields a new list object, the contents being '
+          'specified\n'
+          'by either a list of expressions or a comprehension.  When a comma-\n'
+          'separated list of expressions is supplied, its elements are '
+          'evaluated\n'
+          'from left to right and placed into the list object in that order.\n'
+          'When a comprehension is supplied, the list is constructed from the\n'
+          'elements resulting from the comprehension.\n',
+ 'naming': '\n'
+           'Naming and binding\n'
+           '******************\n'
+           '\n'
+           '\n'
+           'Binding of names\n'
+           '================\n'
+           '\n'
+           '*Names* refer to objects.  Names are introduced by name binding\n'
+           'operations.\n'
+           '\n'
+           'The following constructs bind names: formal parameters to '
+           'functions,\n'
+           '"import" statements, class and function definitions (these bind '
+           'the\n'
+           'class or function name in the defining block), and targets that '
+           'are\n'
+           'identifiers if occurring in an assignment, "for" loop header, or '
+           'after\n'
+           '"as" in a "with" statement or "except" clause. The "import" '
+           'statement\n'
+           'of the form "from ... import *" binds all names defined in the\n'
+           'imported module, except those beginning with an underscore.  This '
+           'form\n'
+           'may only be used at the module level.\n'
+           '\n'
+           'A target occurring in a "del" statement is also considered bound '
+           'for\n'
+           'this purpose (though the actual semantics are to unbind the '
+           'name).\n'
+           '\n'
+           'Each assignment or import statement occurs within a block defined '
+           'by a\n'
+           'class or function definition or at the module level (the '
+           'top-level\n'
+           'code block).\n'
+           '\n'
+           'If a name is bound in a block, it is a local variable of that '
+           'block,\n'
+           'unless declared as "nonlocal" or "global".  If a name is bound at '
+           'the\n'
+           'module level, it is a global variable.  (The variables of the '
+           'module\n'
+           'code block are local and global.)  If a variable is used in a '
+           'code\n'
+           'block but not defined there, it is a *free variable*.\n'
+           '\n'
+           'Each occurrence of a name in the program text refers to the '
+           '*binding*\n'
+           'of that name established by the following name resolution rules.\n'
+           '\n'
+           '\n'
+           'Resolution of names\n'
+           '===================\n'
+           '\n'
+           'A *scope* defines the visibility of a name within a block.  If a '
+           'local\n'
+           'variable is defined in a block, its scope includes that block.  If '
+           'the\n'
+           'definition occurs in a function block, the scope extends to any '
+           'blocks\n'
+           'contained within the defining one, unless a contained block '
+           'introduces\n'
+           'a different binding for the name.\n'
+           '\n'
+           'When a name is used in a code block, it is resolved using the '
+           'nearest\n'
+           'enclosing scope.  The set of all such scopes visible to a code '
+           'block\n'
+           "is called the block's *environment*.\n"
+           '\n'
+           'When a name is not found at all, a "NameError" exception is '
+           'raised. If\n'
+           'the current scope is a function scope, and the name refers to a '
+           'local\n'
+           'variable that has not yet been bound to a value at the point where '
+           'the\n'
+           'name is used, an "UnboundLocalError" exception is raised.\n'
+           '"UnboundLocalError" is a subclass of "NameError".\n'
+           '\n'
+           'If a name binding operation occurs anywhere within a code block, '
+           'all\n'
+           'uses of the name within the block are treated as references to '
+           'the\n'
+           'current block.  This can lead to errors when a name is used within '
+           'a\n'
+           'block before it is bound.  This rule is subtle.  Python lacks\n'
+           'declarations and allows name binding operations to occur anywhere\n'
+           'within a code block.  The local variables of a code block can be\n'
+           'determined by scanning the entire text of the block for name '
+           'binding\n'
+           'operations.\n'
+           '\n'
+           'If the "global" statement occurs within a block, all uses of the '
+           'name\n'
+           'specified in the statement refer to the binding of that name in '
+           'the\n'
+           'top-level namespace.  Names are resolved in the top-level '
+           'namespace by\n'
+           'searching the global namespace, i.e. the namespace of the module\n'
+           'containing the code block, and the builtins namespace, the '
+           'namespace\n'
+           'of the module "builtins".  The global namespace is searched '
+           'first.  If\n'
+           'the name is not found there, the builtins namespace is searched.  '
+           'The\n'
+           '"global" statement must precede all uses of the name.\n'
+           '\n'
+           'The "global" statement has the same scope as a name binding '
+           'operation\n'
+           'in the same block.  If the nearest enclosing scope for a free '
+           'variable\n'
+           'contains a global statement, the free variable is treated as a '
+           'global.\n'
+           '\n'
+           'The "nonlocal" statement causes corresponding names to refer to\n'
+           'previously bound variables in the nearest enclosing function '
+           'scope.\n'
+           '"SyntaxError" is raised at compile time if the given name does '
+           'not\n'
+           'exist in any enclosing function scope.\n'
+           '\n'
+           'The namespace for a module is automatically created the first time '
+           'a\n'
+           'module is imported.  The main module for a script is always '
+           'called\n'
+           '"__main__".\n'
+           '\n'
+           'Class definition blocks and arguments to "exec()" and "eval()" '
+           'are\n'
+           'special in the context of name resolution. A class definition is '
+           'an\n'
+           'executable statement that may use and define names. These '
+           'references\n'
+           'follow the normal rules for name resolution with an exception '
+           'that\n'
+           'unbound local variables are looked up in the global namespace. '
+           'The\n'
+           'namespace of the class definition becomes the attribute dictionary '
+           'of\n'
+           'the class. The scope of names defined in a class block is limited '
+           'to\n'
+           'the class block; it does not extend to the code blocks of methods '
+           '--\n'
+           'this includes comprehensions and generator expressions since they '
+           'are\n'
+           'implemented using a function scope.  This means that the '
+           'following\n'
+           'will fail:\n'
+           '\n'
+           '   class A:\n'
+           '       a = 42\n'
+           '       b = list(a + i for i in range(10))\n'
+           '\n'
+           '\n'
+           'Builtins and restricted execution\n'
+           '=================================\n'
+           '\n'
+           'The builtins namespace associated with the execution of a code '
+           'block\n'
+           'is actually found by looking up the name "__builtins__" in its '
+           'global\n'
+           'namespace; this should be a dictionary or a module (in the latter '
+           'case\n'
+           "the module's dictionary is used).  By default, when in the "
+           '"__main__"\n'
+           'module, "__builtins__" is the built-in module "builtins"; when in '
+           'any\n'
+           'other module, "__builtins__" is an alias for the dictionary of '
+           'the\n'
+           '"builtins" module itself.  "__builtins__" can be set to a '
+           'user-created\n'
+           'dictionary to create a weak form of restricted execution.\n'
+           '\n'
+           '**CPython implementation detail:** Users should not touch\n'
+           '"__builtins__"; it is strictly an implementation detail.  Users\n'
+           'wanting to override values in the builtins namespace should '
+           '"import"\n'
+           'the "builtins" module and modify its attributes appropriately.\n'
+           '\n'
+           '\n'
+           'Interaction with dynamic features\n'
+           '=================================\n'
+           '\n'
+           'Name resolution of free variables occurs at runtime, not at '
+           'compile\n'
+           'time. This means that the following code will print 42:\n'
+           '\n'
+           '   i = 10\n'
+           '   def f():\n'
+           '       print(i)\n'
+           '   i = 42\n'
+           '   f()\n'
+           '\n'
+           'There are several cases where Python statements are illegal when '
+           'used\n'
+           'in conjunction with nested scopes that contain free variables.\n'
+           '\n'
+           'If a variable is referenced in an enclosing scope, it is illegal '
+           'to\n'
+           'delete the name.  An error will be reported at compile time.\n'
+           '\n'
+           'The "eval()" and "exec()" functions do not have access to the '
+           'full\n'
+           'environment for resolving names.  Names may be resolved in the '
+           'local\n'
+           'and global namespaces of the caller.  Free variables are not '
+           'resolved\n'
+           'in the nearest enclosing namespace, but in the global namespace.  '
+           '[1]\n'
+           'The "exec()" and "eval()" functions have optional arguments to\n'
+           'override the global and local namespace.  If only one namespace '
+           'is\n'
+           'specified, it is used for both.\n',
+ 'nonlocal': '\n'
+             'The "nonlocal" statement\n'
+             '************************\n'
+             '\n'
+             '   nonlocal_stmt ::= "nonlocal" identifier ("," identifier)*\n'
+             '\n'
+             'The "nonlocal" statement causes the listed identifiers to refer '
+             'to\n'
+             'previously bound variables in the nearest enclosing scope '
+             'excluding\n'
+             'globals. This is important because the default behavior for '
+             'binding is\n'
+             'to search the local namespace first.  The statement allows\n'
+             'encapsulated code to rebind variables outside of the local '
+             'scope\n'
+             'besides the global (module) scope.\n'
+             '\n'
+             'Names listed in a "nonlocal" statement, unlike those listed in '
+             'a\n'
+             '"global" statement, must refer to pre-existing bindings in an\n'
+             'enclosing scope (the scope in which a new binding should be '
+             'created\n'
+             'cannot be determined unambiguously).\n'
+             '\n'
+             'Names listed in a "nonlocal" statement must not collide with '
+             'pre-\n'
+             'existing bindings in the local scope.\n'
+             '\n'
+             'See also:\n'
+             '\n'
+             '  **PEP 3104** - Access to Names in Outer Scopes\n'
+             '     The specification for the "nonlocal" statement.\n',
+ 'numbers': '\n'
+            'Numeric literals\n'
+            '****************\n'
+            '\n'
+            'There are three types of numeric literals: integers, floating '
+            'point\n'
+            'numbers, and imaginary numbers.  There are no complex literals\n'
+            '(complex numbers can be formed by adding a real number and an\n'
+            'imaginary number).\n'
+            '\n'
+            'Note that numeric literals do not include a sign; a phrase like '
+            '"-1"\n'
+            'is actually an expression composed of the unary operator \'"-"\' '
+            'and the\n'
+            'literal "1".\n',
+ 'numeric-types': '\n'
+                  'Emulating numeric types\n'
+                  '***********************\n'
+                  '\n'
+                  'The following methods can be defined to emulate numeric '
+                  'objects.\n'
+                  'Methods corresponding to operations that are not supported '
+                  'by the\n'
+                  'particular kind of number implemented (e.g., bitwise '
+                  'operations for\n'
+                  'non-integral numbers) should be left undefined.\n'
+                  '\n'
+                  'object.__add__(self, other)\n'
+                  'object.__sub__(self, other)\n'
+                  'object.__mul__(self, other)\n'
+                  'object.__matmul__(self, other)\n'
+                  'object.__truediv__(self, other)\n'
+                  'object.__floordiv__(self, other)\n'
+                  'object.__mod__(self, other)\n'
+                  'object.__divmod__(self, other)\n'
+                  'object.__pow__(self, other[, modulo])\n'
+                  'object.__lshift__(self, other)\n'
+                  'object.__rshift__(self, other)\n'
+                  'object.__and__(self, other)\n'
+                  'object.__xor__(self, other)\n'
+                  'object.__or__(self, other)\n'
+                  '\n'
+                  '   These methods are called to implement the binary '
+                  'arithmetic\n'
+                  '   operations ("+", "-", "*", "@", "/", "//", "%", '
+                  '"divmod()",\n'
+                  '   "pow()", "**", "<<", ">>", "&", "^", "|").  For '
+                  'instance, to\n'
+                  '   evaluate the expression "x + y", where *x* is an '
+                  'instance of a\n'
+                  '   class that has an "__add__()" method, "x.__add__(y)" is '
+                  'called.\n'
+                  '   The "__divmod__()" method should be the equivalent to '
+                  'using\n'
+                  '   "__floordiv__()" and "__mod__()"; it should not be '
+                  'related to\n'
+                  '   "__truediv__()".  Note that "__pow__()" should be '
+                  'defined to accept\n'
+                  '   an optional third argument if the ternary version of the '
+                  'built-in\n'
+                  '   "pow()" function is to be supported.\n'
+                  '\n'
+                  '   If one of those methods does not support the operation '
+                  'with the\n'
+                  '   supplied arguments, it should return "NotImplemented".\n'
+                  '\n'
+                  'object.__radd__(self, other)\n'
+                  'object.__rsub__(self, other)\n'
+                  'object.__rmul__(self, other)\n'
+                  'object.__rmatmul__(self, other)\n'
+                  'object.__rtruediv__(self, other)\n'
+                  'object.__rfloordiv__(self, other)\n'
+                  'object.__rmod__(self, other)\n'
+                  'object.__rdivmod__(self, other)\n'
+                  'object.__rpow__(self, other)\n'
+                  'object.__rlshift__(self, other)\n'
+                  'object.__rrshift__(self, other)\n'
+                  'object.__rand__(self, other)\n'
+                  'object.__rxor__(self, other)\n'
+                  'object.__ror__(self, other)\n'
+                  '\n'
+                  '   These methods are called to implement the binary '
+                  'arithmetic\n'
+                  '   operations ("+", "-", "*", "@", "/", "//", "%", '
+                  '"divmod()",\n'
+                  '   "pow()", "**", "<<", ">>", "&", "^", "|") with reflected '
+                  '(swapped)\n'
+                  '   operands.  These functions are only called if the left '
+                  'operand does\n'
+                  '   not support the corresponding operation and the operands '
+                  'are of\n'
+                  '   different types. [2] For instance, to evaluate the '
+                  'expression "x -\n'
+                  '   y", where *y* is an instance of a class that has an '
+                  '"__rsub__()"\n'
+                  '   method, "y.__rsub__(x)" is called if "x.__sub__(y)" '
+                  'returns\n'
+                  '   *NotImplemented*.\n'
+                  '\n'
+                  '   Note that ternary "pow()" will not try calling '
+                  '"__rpow__()" (the\n'
+                  '   coercion rules would become too complicated).\n'
+                  '\n'
+                  "   Note: If the right operand's type is a subclass of the "
+                  'left\n'
+                  "     operand's type and that subclass provides the "
+                  'reflected method\n'
+                  '     for the operation, this method will be called before '
+                  'the left\n'
+                  "     operand's non-reflected method.  This behavior allows "
+                  'subclasses\n'
+                  "     to override their ancestors' operations.\n"
+                  '\n'
+                  'object.__iadd__(self, other)\n'
+                  'object.__isub__(self, other)\n'
+                  'object.__imul__(self, other)\n'
+                  'object.__imatmul__(self, other)\n'
+                  'object.__itruediv__(self, other)\n'
+                  'object.__ifloordiv__(self, other)\n'
+                  'object.__imod__(self, other)\n'
+                  'object.__ipow__(self, other[, modulo])\n'
+                  'object.__ilshift__(self, other)\n'
+                  'object.__irshift__(self, other)\n'
+                  'object.__iand__(self, other)\n'
+                  'object.__ixor__(self, other)\n'
+                  'object.__ior__(self, other)\n'
+                  '\n'
+                  '   These methods are called to implement the augmented '
+                  'arithmetic\n'
+                  '   assignments ("+=", "-=", "*=", "@=", "/=", "//=", "%=", '
+                  '"**=",\n'
+                  '   "<<=", ">>=", "&=", "^=", "|=").  These methods should '
+                  'attempt to\n'
+                  '   do the operation in-place (modifying *self*) and return '
+                  'the result\n'
+                  '   (which could be, but does not have to be, *self*).  If a '
+                  'specific\n'
+                  '   method is not defined, the augmented assignment falls '
+                  'back to the\n'
+                  '   normal methods.  For instance, if *x* is an instance of '
+                  'a class\n'
+                  '   with an "__iadd__()" method, "x += y" is equivalent to '
+                  '"x =\n'
+                  '   x.__iadd__(y)" . Otherwise, "x.__add__(y)" and '
+                  '"y.__radd__(x)" are\n'
+                  '   considered, as with the evaluation of "x + y". In '
+                  'certain\n'
+                  '   situations, augmented assignment can result in '
+                  'unexpected errors\n'
+                  "   (see Why does a_tuple[i] += ['item'] raise an exception "
+                  'when the\n'
+                  '   addition works?), but this behavior is in fact part of '
+                  'the data\n'
+                  '   model.\n'
+                  '\n'
+                  'object.__neg__(self)\n'
+                  'object.__pos__(self)\n'
+                  'object.__abs__(self)\n'
+                  'object.__invert__(self)\n'
+                  '\n'
+                  '   Called to implement the unary arithmetic operations '
+                  '("-", "+",\n'
+                  '   "abs()" and "~").\n'
+                  '\n'
+                  'object.__complex__(self)\n'
+                  'object.__int__(self)\n'
+                  'object.__float__(self)\n'
+                  'object.__round__(self[, n])\n'
+                  '\n'
+                  '   Called to implement the built-in functions "complex()", '
+                  '"int()",\n'
+                  '   "float()" and "round()".  Should return a value of the '
+                  'appropriate\n'
+                  '   type.\n'
+                  '\n'
+                  'object.__index__(self)\n'
+                  '\n'
+                  '   Called to implement "operator.index()", and whenever '
+                  'Python needs\n'
+                  '   to losslessly convert the numeric object to an integer '
+                  'object (such\n'
+                  '   as in slicing, or in the built-in "bin()", "hex()" and '
+                  '"oct()"\n'
+                  '   functions). Presence of this method indicates that the '
+                  'numeric\n'
+                  '   object is an integer type.  Must return an integer.\n'
+                  '\n'
+                  '   Note: In order to have a coherent integer type class, '
+                  'when\n'
+                  '     "__index__()" is defined "__int__()" should also be '
+                  'defined, and\n'
+                  '     both should return the same value.\n',
+ 'objects': '\n'
+            'Objects, values and types\n'
+            '*************************\n'
+            '\n'
+            "*Objects* are Python's abstraction for data.  All data in a "
+            'Python\n'
+            'program is represented by objects or by relations between '
+            'objects. (In\n'
+            'a sense, and in conformance to Von Neumann\'s model of a "stored\n'
+            'program computer," code is also represented by objects.)\n'
+            '\n'
+            "Every object has an identity, a type and a value.  An object's\n"
+            '*identity* never changes once it has been created; you may think '
+            'of it\n'
+            'as the object\'s address in memory.  The \'"is"\' operator '
+            'compares the\n'
+            'identity of two objects; the "id()" function returns an integer\n'
+            'representing its identity.\n'
+            '\n'
+            '**CPython implementation detail:** For CPython, "id(x)" is the '
+            'memory\n'
+            'address where "x" is stored.\n'
+            '\n'
+            "An object's type determines the operations that the object "
+            'supports\n'
+            '(e.g., "does it have a length?") and also defines the possible '
+            'values\n'
+            'for objects of that type.  The "type()" function returns an '
+            "object's\n"
+            'type (which is an object itself).  Like its identity, an '
+            "object's\n"
+            '*type* is also unchangeable. [1]\n'
+            '\n'
+            'The *value* of some objects can change.  Objects whose value can\n'
+            'change are said to be *mutable*; objects whose value is '
+            'unchangeable\n'
+            'once they are created are called *immutable*. (The value of an\n'
+            'immutable container object that contains a reference to a '
+            'mutable\n'
+            "object can change when the latter's value is changed; however "
+            'the\n'
+            'container is still considered immutable, because the collection '
+            'of\n'
+            'objects it contains cannot be changed.  So, immutability is not\n'
+            'strictly the same as having an unchangeable value, it is more '
+            'subtle.)\n'
+            "An object's mutability is determined by its type; for instance,\n"
+            'numbers, strings and tuples are immutable, while dictionaries '
+            'and\n'
+            'lists are mutable.\n'
+            '\n'
+            'Objects are never explicitly destroyed; however, when they '
+            'become\n'
+            'unreachable they may be garbage-collected.  An implementation is\n'
+            'allowed to postpone garbage collection or omit it altogether --- '
+            'it is\n'
+            'a matter of implementation quality how garbage collection is\n'
+            'implemented, as long as no objects are collected that are still\n'
+            'reachable.\n'
+            '\n'
+            '**CPython implementation detail:** CPython currently uses a '
+            'reference-\n'
+            'counting scheme with (optional) delayed detection of cyclically '
+            'linked\n'
+            'garbage, which collects most objects as soon as they become\n'
+            'unreachable, but is not guaranteed to collect garbage containing\n'
+            'circular references.  See the documentation of the "gc" module '
+            'for\n'
+            'information on controlling the collection of cyclic garbage. '
+            'Other\n'
+            'implementations act differently and CPython may change. Do not '
+            'depend\n'
+            'on immediate finalization of objects when they become unreachable '
+            '(so\n'
+            'you should always close files explicitly).\n'
+            '\n'
+            "Note that the use of the implementation's tracing or debugging\n"
+            'facilities may keep objects alive that would normally be '
+            'collectable.\n'
+            'Also note that catching an exception with a \'"try"..."except"\'\n'
+            'statement may keep objects alive.\n'
+            '\n'
+            'Some objects contain references to "external" resources such as '
+            'open\n'
+            'files or windows.  It is understood that these resources are '
+            'freed\n'
+            'when the object is garbage-collected, but since garbage '
+            'collection is\n'
+            'not guaranteed to happen, such objects also provide an explicit '
+            'way to\n'
+            'release the external resource, usually a "close()" method. '
+            'Programs\n'
+            'are strongly recommended to explicitly close such objects.  The\n'
+            '\'"try"..."finally"\' statement and the \'"with"\' statement '
+            'provide\n'
+            'convenient ways to do this.\n'
+            '\n'
+            'Some objects contain references to other objects; these are '
+            'called\n'
+            '*containers*. Examples of containers are tuples, lists and\n'
+            "dictionaries.  The references are part of a container's value.  "
+            'In\n'
+            'most cases, when we talk about the value of a container, we imply '
+            'the\n'
+            'values, not the identities of the contained objects; however, '
+            'when we\n'
+            'talk about the mutability of a container, only the identities of '
+            'the\n'
+            'immediately contained objects are implied.  So, if an immutable\n'
+            'container (like a tuple) contains a reference to a mutable '
+            'object, its\n'
+            'value changes if that mutable object is changed.\n'
+            '\n'
+            'Types affect almost all aspects of object behavior.  Even the\n'
+            'importance of object identity is affected in some sense: for '
+            'immutable\n'
+            'types, operations that compute new values may actually return a\n'
+            'reference to any existing object with the same type and value, '
+            'while\n'
+            'for mutable objects this is not allowed.  E.g., after "a = 1; b = '
+            '1",\n'
+            '"a" and "b" may or may not refer to the same object with the '
+            'value\n'
+            'one, depending on the implementation, but after "c = []; d = []", '
+            '"c"\n'
+            'and "d" are guaranteed to refer to two different, unique, newly\n'
+            'created empty lists. (Note that "c = d = []" assigns the same '
+            'object\n'
+            'to both "c" and "d".)\n',
+ 'operator-summary': '\n'
+                     'Operator precedence\n'
+                     '*******************\n'
+                     '\n'
+                     'The following table summarizes the operator precedence '
+                     'in Python, from\n'
+                     'lowest precedence (least binding) to highest precedence '
+                     '(most\n'
+                     'binding).  Operators in the same box have the same '
+                     'precedence.  Unless\n'
+                     'the syntax is explicitly given, operators are binary.  '
+                     'Operators in\n'
+                     'the same box group left to right (except for '
+                     'exponentiation, which\n'
+                     'groups from right to left).\n'
+                     '\n'
+                     'Note that comparisons, membership tests, and identity '
+                     'tests, all have\n'
+                     'the same precedence and have a left-to-right chaining '
+                     'feature as\n'
+                     'described in the Comparisons section.\n'
+                     '\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| Operator                                        | '
+                     'Description                           |\n'
+                     '+=================================================+=======================================+\n'
+                     '| "lambda"                                        | '
+                     'Lambda expression                     |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| "if" -- "else"                                  | '
+                     'Conditional expression                |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| "or"                                            | '
+                     'Boolean OR                            |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| "and"                                           | '
+                     'Boolean AND                           |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| "not" "x"                                       | '
+                     'Boolean NOT                           |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| "in", "not in", "is", "is not", "<", "<=", ">", | '
+                     'Comparisons, including membership     |\n'
+                     '| ">=", "!=", "=="                                | '
+                     'tests and identity tests              |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| "|"                                             | '
+                     'Bitwise OR                            |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| "^"                                             | '
+                     'Bitwise XOR                           |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| "&"                                             | '
+                     'Bitwise AND                           |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| "<<", ">>"                                      | '
+                     'Shifts                                |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| "+", "-"                                        | '
+                     'Addition and subtraction              |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| "*", "@", "/", "//", "%"                        | '
+                     'Multiplication, matrix multiplication |\n'
+                     '|                                                 | '
+                     'division, remainder [5]               |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| "+x", "-x", "~x"                                | '
+                     'Positive, negative, bitwise NOT       |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| "**"                                            | '
+                     'Exponentiation [6]                    |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| "await" "x"                                     | '
+                     'Await expression                      |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| "x[index]", "x[index:index]",                   | '
+                     'Subscription, slicing, call,          |\n'
+                     '| "x(arguments...)", "x.attribute"                | '
+                     'attribute reference                   |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '| "(expressions...)", "[expressions...]", "{key:  | '
+                     'Binding or tuple display, list        |\n'
+                     '| value...}", "{expressions...}"                  | '
+                     'display, dictionary display, set      |\n'
+                     '|                                                 | '
+                     'display                               |\n'
+                     '+-------------------------------------------------+---------------------------------------+\n'
+                     '\n'
+                     '-[ Footnotes ]-\n'
+                     '\n'
+                     '[1] While "abs(x%y) < abs(y)" is true mathematically, '
+                     'for floats\n'
+                     '    it may not be true numerically due to roundoff.  For '
+                     'example, and\n'
+                     '    assuming a platform on which a Python float is an '
+                     'IEEE 754 double-\n'
+                     '    precision number, in order that "-1e-100 % 1e100" '
+                     'have the same\n'
+                     '    sign as "1e100", the computed result is "-1e-100 + '
+                     '1e100", which\n'
+                     '    is numerically exactly equal to "1e100".  The '
+                     'function\n'
+                     '    "math.fmod()" returns a result whose sign matches '
+                     'the sign of the\n'
+                     '    first argument instead, and so returns "-1e-100" in '
+                     'this case.\n'
+                     '    Which approach is more appropriate depends on the '
+                     'application.\n'
+                     '\n'
+                     '[2] If x is very close to an exact integer multiple of '
+                     "y, it's\n"
+                     '    possible for "x//y" to be one larger than '
+                     '"(x-x%y)//y" due to\n'
+                     '    rounding.  In such cases, Python returns the latter '
+                     'result, in\n'
+                     '    order to preserve that "divmod(x,y)[0] * y + x % y" '
+                     'be very close\n'
+                     '    to "x".\n'
+                     '\n'
+                     '[3] The Unicode standard distinguishes between *code '
+                     'points* (e.g.\n'
+                     '    U+0041) and *abstract characters* (e.g. "LATIN '
+                     'CAPITAL LETTER A").\n'
+                     '    While most abstract characters in Unicode are only '
+                     'represented\n'
+                     '    using one code point, there is a number of abstract '
+                     'characters\n'
+                     '    that can in addition be represented using a sequence '
+                     'of more than\n'
+                     '    one code point.  For example, the abstract character '
+                     '"LATIN\n'
+                     '    CAPITAL LETTER C WITH CEDILLA" can be represented as '
+                     'a single\n'
+                     '    *precomposed character* at code position U+00C7, or '
+                     'as a sequence\n'
+                     '    of a *base character* at code position U+0043 (LATIN '
+                     'CAPITAL\n'
+                     '    LETTER C), followed by a *combining character* at '
+                     'code position\n'
+                     '    U+0327 (COMBINING CEDILLA).\n'
+                     '\n'
+                     '    The comparison operators on strings compare at the '
+                     'level of\n'
+                     '    Unicode code points. This may be counter-intuitive '
+                     'to humans.  For\n'
+                     '    example, ""\\u00C7" == "\\u0043\\u0327"" is "False", '
+                     'even though both\n'
+                     '    strings represent the same abstract character "LATIN '
+                     'CAPITAL\n'
+                     '    LETTER C WITH CEDILLA".\n'
+                     '\n'
+                     '    To compare strings at the level of abstract '
+                     'characters (that is,\n'
+                     '    in a way intuitive to humans), use '
+                     '"unicodedata.normalize()".\n'
+                     '\n'
+                     '[4] Due to automatic garbage-collection, free lists, and '
+                     'the\n'
+                     '    dynamic nature of descriptors, you may notice '
+                     'seemingly unusual\n'
+                     '    behaviour in certain uses of the "is" operator, like '
+                     'those\n'
+                     '    involving comparisons between instance methods, or '
+                     'constants.\n'
+                     '    Check their documentation for more info.\n'
+                     '\n'
+                     '[5] The "%" operator is also used for string formatting; '
+                     'the same\n'
+                     '    precedence applies.\n'
+                     '\n'
+                     '[6] The power operator "**" binds less tightly than an '
+                     'arithmetic\n'
+                     '    or bitwise unary operator on its right, that is, '
+                     '"2**-1" is "0.5".\n',
+ 'pass': '\n'
+         'The "pass" statement\n'
+         '********************\n'
+         '\n'
+         '   pass_stmt ::= "pass"\n'
+         '\n'
+         '"pass" is a null operation --- when it is executed, nothing '
+         'happens.\n'
+         'It is useful as a placeholder when a statement is required\n'
+         'syntactically, but no code needs to be executed, for example:\n'
+         '\n'
+         '   def f(arg): pass    # a function that does nothing (yet)\n'
+         '\n'
+         '   class C: pass       # a class with no methods (yet)\n',
+ 'power': '\n'
+          'The power operator\n'
+          '******************\n'
+          '\n'
+          'The power operator binds more tightly than unary operators on its\n'
+          'left; it binds less tightly than unary operators on its right.  '
+          'The\n'
+          'syntax is:\n'
+          '\n'
+          '   power ::= ( await_expr | primary ) ["**" u_expr]\n'
+          '\n'
+          'Thus, in an unparenthesized sequence of power and unary operators, '
+          'the\n'
+          'operators are evaluated from right to left (this does not '
+          'constrain\n'
+          'the evaluation order for the operands): "-1**2" results in "-1".\n'
+          '\n'
+          'The power operator has the same semantics as the built-in "pow()"\n'
+          'function, when called with two arguments: it yields its left '
+          'argument\n'
+          'raised to the power of its right argument.  The numeric arguments '
+          'are\n'
+          'first converted to a common type, and the result is of that type.\n'
+          '\n'
+          'For int operands, the result has the same type as the operands '
+          'unless\n'
+          'the second argument is negative; in that case, all arguments are\n'
+          'converted to float and a float result is delivered. For example,\n'
+          '"10**2" returns "100", but "10**-2" returns "0.01".\n'
+          '\n'
+          'Raising "0.0" to a negative power results in a '
+          '"ZeroDivisionError".\n'
+          'Raising a negative number to a fractional power results in a '
+          '"complex"\n'
+          'number. (In earlier versions it raised a "ValueError".)\n',
+ 'raise': '\n'
+          'The "raise" statement\n'
+          '*********************\n'
+          '\n'
+          '   raise_stmt ::= "raise" [expression ["from" expression]]\n'
+          '\n'
+          'If no expressions are present, "raise" re-raises the last '
+          'exception\n'
+          'that was active in the current scope.  If no exception is active '
+          'in\n'
+          'the current scope, a "RuntimeError" exception is raised indicating\n'
+          'that this is an error.\n'
+          '\n'
+          'Otherwise, "raise" evaluates the first expression as the exception\n'
+          'object.  It must be either a subclass or an instance of\n'
+          '"BaseException". If it is a class, the exception instance will be\n'
+          'obtained when needed by instantiating the class with no arguments.\n'
+          '\n'
+          "The *type* of the exception is the exception instance's class, the\n"
+          '*value* is the instance itself.\n'
+          '\n'
+          'A traceback object is normally created automatically when an '
+          'exception\n'
+          'is raised and attached to it as the "__traceback__" attribute, '
+          'which\n'
+          'is writable. You can create an exception and set your own traceback '
+          'in\n'
+          'one step using the "with_traceback()" exception method (which '
+          'returns\n'
+          'the same exception instance, with its traceback set to its '
+          'argument),\n'
+          'like so:\n'
+          '\n'
+          '   raise Exception("foo occurred").with_traceback(tracebackobj)\n'
+          '\n'
+          'The "from" clause is used for exception chaining: if given, the '
+          'second\n'
+          '*expression* must be another exception class or instance, which '
+          'will\n'
+          'then be attached to the raised exception as the "__cause__" '
+          'attribute\n'
+          '(which is writable).  If the raised exception is not handled, both\n'
+          'exceptions will be printed:\n'
+          '\n'
+          '   >>> try:\n'
+          '   ...     print(1 / 0)\n'
+          '   ... except Exception as exc:\n'
+          '   ...     raise RuntimeError("Something bad happened") from exc\n'
+          '   ...\n'
+          '   Traceback (most recent call last):\n'
+          '     File "<stdin>", line 2, in <module>\n'
+          '   ZeroDivisionError: int division or modulo by zero\n'
+          '\n'
+          '   The above exception was the direct cause of the following '
+          'exception:\n'
+          '\n'
+          '   Traceback (most recent call last):\n'
+          '     File "<stdin>", line 4, in <module>\n'
+          '   RuntimeError: Something bad happened\n'
+          '\n'
+          'A similar mechanism works implicitly if an exception is raised '
+          'inside\n'
+          'an exception handler or a "finally" clause: the previous exception '
+          'is\n'
+          'then attached as the new exception\'s "__context__" attribute:\n'
+          '\n'
+          '   >>> try:\n'
+          '   ...     print(1 / 0)\n'
+          '   ... except:\n'
+          '   ...     raise RuntimeError("Something bad happened")\n'
+          '   ...\n'
+          '   Traceback (most recent call last):\n'
+          '     File "<stdin>", line 2, in <module>\n'
+          '   ZeroDivisionError: int division or modulo by zero\n'
+          '\n'
+          '   During handling of the above exception, another exception '
+          'occurred:\n'
+          '\n'
+          '   Traceback (most recent call last):\n'
+          '     File "<stdin>", line 4, in <module>\n'
+          '   RuntimeError: Something bad happened\n'
+          '\n'
+          'Additional information on exceptions can be found in section\n'
+          'Exceptions, and information about handling exceptions is in '
+          'section\n'
+          'The try statement.\n',
+ 'return': '\n'
+           'The "return" statement\n'
+           '**********************\n'
+           '\n'
+           '   return_stmt ::= "return" [expression_list]\n'
+           '\n'
+           '"return" may only occur syntactically nested in a function '
+           'definition,\n'
+           'not within a nested class definition.\n'
+           '\n'
+           'If an expression list is present, it is evaluated, else "None" is\n'
+           'substituted.\n'
+           '\n'
+           '"return" leaves the current function call with the expression list '
+           '(or\n'
+           '"None") as return value.\n'
+           '\n'
+           'When "return" passes control out of a "try" statement with a '
+           '"finally"\n'
+           'clause, that "finally" clause is executed before really leaving '
+           'the\n'
+           'function.\n'
+           '\n'
+           'In a generator function, the "return" statement indicates that '
+           'the\n'
+           'generator is done and will cause "StopIteration" to be raised. '
+           'The\n'
+           'returned value (if any) is used as an argument to construct\n'
+           '"StopIteration" and becomes the "StopIteration.value" attribute.\n',
+ 'sequence-types': '\n'
+                   'Emulating container types\n'
+                   '*************************\n'
+                   '\n'
+                   'The following methods can be defined to implement '
+                   'container objects.\n'
+                   'Containers usually are sequences (such as lists or tuples) '
+                   'or mappings\n'
+                   '(like dictionaries), but can represent other containers as '
+                   'well.  The\n'
+                   'first set of methods is used either to emulate a sequence '
+                   'or to\n'
+                   'emulate a mapping; the difference is that for a sequence, '
+                   'the\n'
+                   'allowable keys should be the integers *k* for which "0 <= '
+                   'k < N" where\n'
+                   '*N* is the length of the sequence, or slice objects, which '
+                   'define a\n'
+                   'range of items.  It is also recommended that mappings '
+                   'provide the\n'
+                   'methods "keys()", "values()", "items()", "get()", '
+                   '"clear()",\n'
+                   '"setdefault()", "pop()", "popitem()", "copy()", and '
+                   '"update()"\n'
+                   "behaving similar to those for Python's standard dictionary "
+                   'objects.\n'
+                   'The "collections" module provides a "MutableMapping" '
+                   'abstract base\n'
+                   'class to help create those methods from a base set of '
+                   '"__getitem__()",\n'
+                   '"__setitem__()", "__delitem__()", and "keys()". Mutable '
+                   'sequences\n'
+                   'should provide methods "append()", "count()", "index()", '
+                   '"extend()",\n'
+                   '"insert()", "pop()", "remove()", "reverse()" and "sort()", '
+                   'like Python\n'
+                   'standard list objects.  Finally, sequence types should '
+                   'implement\n'
+                   'addition (meaning concatenation) and multiplication '
+                   '(meaning\n'
+                   'repetition) by defining the methods "__add__()", '
+                   '"__radd__()",\n'
+                   '"__iadd__()", "__mul__()", "__rmul__()" and "__imul__()" '
+                   'described\n'
+                   'below; they should not define other numerical operators.  '
+                   'It is\n'
+                   'recommended that both mappings and sequences implement '
+                   'the\n'
+                   '"__contains__()" method to allow efficient use of the "in" '
+                   'operator;\n'
+                   'for mappings, "in" should search the mapping\'s keys; for '
+                   'sequences, it\n'
+                   'should search through the values.  It is further '
+                   'recommended that both\n'
+                   'mappings and sequences implement the "__iter__()" method '
+                   'to allow\n'
+                   'efficient iteration through the container; for mappings, '
+                   '"__iter__()"\n'
+                   'should be the same as "keys()"; for sequences, it should '
+                   'iterate\n'
+                   'through the values.\n'
+                   '\n'
+                   'object.__len__(self)\n'
+                   '\n'
+                   '   Called to implement the built-in function "len()".  '
+                   'Should return\n'
+                   '   the length of the object, an integer ">=" 0.  Also, an '
+                   'object that\n'
+                   '   doesn\'t define a "__bool__()" method and whose '
+                   '"__len__()" method\n'
+                   '   returns zero is considered to be false in a Boolean '
+                   'context.\n'
+                   '\n'
+                   'object.__length_hint__(self)\n'
+                   '\n'
+                   '   Called to implement "operator.length_hint()". Should '
+                   'return an\n'
+                   '   estimated length for the object (which may be greater '
+                   'or less than\n'
+                   '   the actual length). The length must be an integer ">=" '
+                   '0. This\n'
+                   '   method is purely an optimization and is never required '
+                   'for\n'
+                   '   correctness.\n'
+                   '\n'
+                   '   New in version 3.4.\n'
+                   '\n'
+                   'Note: Slicing is done exclusively with the following three '
+                   'methods.\n'
+                   '  A call like\n'
+                   '\n'
+                   '     a[1:2] = b\n'
+                   '\n'
+                   '  is translated to\n'
+                   '\n'
+                   '     a[slice(1, 2, None)] = b\n'
+                   '\n'
+                   '  and so forth.  Missing slice items are always filled in '
+                   'with "None".\n'
+                   '\n'
+                   'object.__getitem__(self, key)\n'
+                   '\n'
+                   '   Called to implement evaluation of "self[key]". For '
+                   'sequence types,\n'
+                   '   the accepted keys should be integers and slice '
+                   'objects.  Note that\n'
+                   '   the special interpretation of negative indexes (if the '
+                   'class wishes\n'
+                   '   to emulate a sequence type) is up to the '
+                   '"__getitem__()" method. If\n'
+                   '   *key* is of an inappropriate type, "TypeError" may be '
+                   'raised; if of\n'
+                   '   a value outside the set of indexes for the sequence '
+                   '(after any\n'
+                   '   special interpretation of negative values), '
+                   '"IndexError" should be\n'
+                   '   raised. For mapping types, if *key* is missing (not in '
+                   'the\n'
+                   '   container), "KeyError" should be raised.\n'
+                   '\n'
+                   '   Note: "for" loops expect that an "IndexError" will be '
+                   'raised for\n'
+                   '     illegal indexes to allow proper detection of the end '
+                   'of the\n'
+                   '     sequence.\n'
+                   '\n'
+                   'object.__missing__(self, key)\n'
+                   '\n'
+                   '   Called by "dict"."__getitem__()" to implement '
+                   '"self[key]" for dict\n'
+                   '   subclasses when key is not in the dictionary.\n'
+                   '\n'
+                   'object.__setitem__(self, key, value)\n'
+                   '\n'
+                   '   Called to implement assignment to "self[key]".  Same '
+                   'note as for\n'
+                   '   "__getitem__()".  This should only be implemented for '
+                   'mappings if\n'
+                   '   the objects support changes to the values for keys, or '
+                   'if new keys\n'
+                   '   can be added, or for sequences if elements can be '
+                   'replaced.  The\n'
+                   '   same exceptions should be raised for improper *key* '
+                   'values as for\n'
+                   '   the "__getitem__()" method.\n'
+                   '\n'
+                   'object.__delitem__(self, key)\n'
+                   '\n'
+                   '   Called to implement deletion of "self[key]".  Same note '
+                   'as for\n'
+                   '   "__getitem__()".  This should only be implemented for '
+                   'mappings if\n'
+                   '   the objects support removal of keys, or for sequences '
+                   'if elements\n'
+                   '   can be removed from the sequence.  The same exceptions '
+                   'should be\n'
+                   '   raised for improper *key* values as for the '
+                   '"__getitem__()" method.\n'
+                   '\n'
+                   'object.__iter__(self)\n'
+                   '\n'
+                   '   This method is called when an iterator is required for '
+                   'a container.\n'
+                   '   This method should return a new iterator object that '
+                   'can iterate\n'
+                   '   over all the objects in the container.  For mappings, '
+                   'it should\n'
+                   '   iterate over the keys of the container.\n'
+                   '\n'
+                   '   Iterator objects also need to implement this method; '
+                   'they are\n'
+                   '   required to return themselves.  For more information on '
+                   'iterator\n'
+                   '   objects, see Iterator Types.\n'
+                   '\n'
+                   'object.__reversed__(self)\n'
+                   '\n'
+                   '   Called (if present) by the "reversed()" built-in to '
+                   'implement\n'
+                   '   reverse iteration.  It should return a new iterator '
+                   'object that\n'
+                   '   iterates over all the objects in the container in '
+                   'reverse order.\n'
+                   '\n'
+                   '   If the "__reversed__()" method is not provided, the '
+                   '"reversed()"\n'
+                   '   built-in will fall back to using the sequence protocol '
+                   '("__len__()"\n'
+                   '   and "__getitem__()").  Objects that support the '
+                   'sequence protocol\n'
+                   '   should only provide "__reversed__()" if they can '
+                   'provide an\n'
+                   '   implementation that is more efficient than the one '
+                   'provided by\n'
+                   '   "reversed()".\n'
+                   '\n'
+                   'The membership test operators ("in" and "not in") are '
+                   'normally\n'
+                   'implemented as an iteration through a sequence.  However, '
+                   'container\n'
+                   'objects can supply the following special method with a '
+                   'more efficient\n'
+                   'implementation, which also does not require the object be '
+                   'a sequence.\n'
+                   '\n'
+                   'object.__contains__(self, item)\n'
+                   '\n'
+                   '   Called to implement membership test operators.  Should '
+                   'return true\n'
+                   '   if *item* is in *self*, false otherwise.  For mapping '
+                   'objects, this\n'
+                   '   should consider the keys of the mapping rather than the '
+                   'values or\n'
+                   '   the key-item pairs.\n'
+                   '\n'
+                   '   For objects that don\'t define "__contains__()", the '
+                   'membership test\n'
+                   '   first tries iteration via "__iter__()", then the old '
+                   'sequence\n'
+                   '   iteration protocol via "__getitem__()", see this '
+                   'section in the\n'
+                   '   language reference.\n',
+ 'shifting': '\n'
+             'Shifting operations\n'
+             '*******************\n'
+             '\n'
+             'The shifting operations have lower priority than the arithmetic\n'
+             'operations:\n'
+             '\n'
+             '   shift_expr ::= a_expr | shift_expr ( "<<" | ">>" ) a_expr\n'
+             '\n'
+             'These operators accept integers as arguments.  They shift the '
+             'first\n'
+             'argument to the left or right by the number of bits given by '
+             'the\n'
+             'second argument.\n'
+             '\n'
+             'A right shift by *n* bits is defined as floor division by '
+             '"pow(2,n)".\n'
+             'A left shift by *n* bits is defined as multiplication with '
+             '"pow(2,n)".\n'
+             '\n'
+             'Note: In the current implementation, the right-hand operand is\n'
+             '  required to be at most "sys.maxsize".  If the right-hand '
+             'operand is\n'
+             '  larger than "sys.maxsize" an "OverflowError" exception is '
+             'raised.\n',
+ 'slicings': '\n'
+             'Slicings\n'
+             '********\n'
+             '\n'
+             'A slicing selects a range of items in a sequence object (e.g., '
+             'a\n'
+             'string, tuple or list).  Slicings may be used as expressions or '
+             'as\n'
+             'targets in assignment or "del" statements.  The syntax for a '
+             'slicing:\n'
+             '\n'
+             '   slicing      ::= primary "[" slice_list "]"\n'
+             '   slice_list   ::= slice_item ("," slice_item)* [","]\n'
+             '   slice_item   ::= expression | proper_slice\n'
+             '   proper_slice ::= [lower_bound] ":" [upper_bound] [ ":" '
+             '[stride] ]\n'
+             '   lower_bound  ::= expression\n'
+             '   upper_bound  ::= expression\n'
+             '   stride       ::= expression\n'
+             '\n'
+             'There is ambiguity in the formal syntax here: anything that '
+             'looks like\n'
+             'an expression list also looks like a slice list, so any '
+             'subscription\n'
+             'can be interpreted as a slicing.  Rather than further '
+             'complicating the\n'
+             'syntax, this is disambiguated by defining that in this case the\n'
+             'interpretation as a subscription takes priority over the\n'
+             'interpretation as a slicing (this is the case if the slice list\n'
+             'contains no proper slice).\n'
+             '\n'
+             'The semantics for a slicing are as follows.  The primary is '
+             'indexed\n'
+             '(using the same "__getitem__()" method as normal subscription) '
+             'with a\n'
+             'key that is constructed from the slice list, as follows.  If the '
+             'slice\n'
+             'list contains at least one comma, the key is a tuple containing '
+             'the\n'
+             'conversion of the slice items; otherwise, the conversion of the '
+             'lone\n'
+             'slice item is the key.  The conversion of a slice item that is '
+             'an\n'
+             'expression is that expression.  The conversion of a proper slice '
+             'is a\n'
+             'slice object (see section The standard type hierarchy) whose '
+             '"start",\n'
+             '"stop" and "step" attributes are the values of the expressions '
+             'given\n'
+             'as lower bound, upper bound and stride, respectively, '
+             'substituting\n'
+             '"None" for missing expressions.\n',
+ 'specialattrs': '\n'
+                 'Special Attributes\n'
+                 '******************\n'
+                 '\n'
+                 'The implementation adds a few special read-only attributes '
+                 'to several\n'
+                 'object types, where they are relevant.  Some of these are '
+                 'not reported\n'
+                 'by the "dir()" built-in function.\n'
+                 '\n'
+                 'object.__dict__\n'
+                 '\n'
+                 '   A dictionary or other mapping object used to store an '
+                 "object's\n"
+                 '   (writable) attributes.\n'
+                 '\n'
+                 'instance.__class__\n'
+                 '\n'
+                 '   The class to which a class instance belongs.\n'
+                 '\n'
+                 'class.__bases__\n'
+                 '\n'
+                 '   The tuple of base classes of a class object.\n'
+                 '\n'
+                 'class.__name__\n'
+                 '\n'
+                 '   The name of the class or type.\n'
+                 '\n'
+                 'class.__qualname__\n'
+                 '\n'
+                 '   The *qualified name* of the class or type.\n'
+                 '\n'
+                 '   New in version 3.3.\n'
+                 '\n'
+                 'class.__mro__\n'
+                 '\n'
+                 '   This attribute is a tuple of classes that are considered '
+                 'when\n'
+                 '   looking for base classes during method resolution.\n'
+                 '\n'
+                 'class.mro()\n'
+                 '\n'
+                 '   This method can be overridden by a metaclass to customize '
+                 'the\n'
+                 '   method resolution order for its instances.  It is called '
+                 'at class\n'
+                 '   instantiation, and its result is stored in "__mro__".\n'
+                 '\n'
+                 'class.__subclasses__()\n'
+                 '\n'
+                 '   Each class keeps a list of weak references to its '
+                 'immediate\n'
+                 '   subclasses.  This method returns a list of all those '
+                 'references\n'
+                 '   still alive. Example:\n'
+                 '\n'
+                 '      >>> int.__subclasses__()\n'
+                 "      [<class 'bool'>]\n"
+                 '\n'
+                 '-[ Footnotes ]-\n'
+                 '\n'
+                 '[1] Additional information on these special methods may be '
+                 'found\n'
+                 '    in the Python Reference Manual (Basic customization).\n'
+                 '\n'
+                 '[2] As a consequence, the list "[1, 2]" is considered equal '
+                 'to\n'
+                 '    "[1.0, 2.0]", and similarly for tuples.\n'
+                 '\n'
+                 "[3] They must have since the parser can't tell the type of "
+                 'the\n'
+                 '    operands.\n'
+                 '\n'
+                 '[4] Cased characters are those with general category '
+                 'property\n'
+                 '    being one of "Lu" (Letter, uppercase), "Ll" (Letter, '
+                 'lowercase),\n'
+                 '    or "Lt" (Letter, titlecase).\n'
+                 '\n'
+                 '[5] To format only a tuple you should therefore provide a\n'
+                 '    singleton tuple whose only element is the tuple to be '
+                 'formatted.\n',
+ 'specialnames': '\n'
+                 'Special method names\n'
+                 '********************\n'
+                 '\n'
+                 'A class can implement certain operations that are invoked by '
+                 'special\n'
+                 'syntax (such as arithmetic operations or subscripting and '
+                 'slicing) by\n'
+                 "defining methods with special names. This is Python's "
+                 'approach to\n'
+                 '*operator overloading*, allowing classes to define their own '
+                 'behavior\n'
+                 'with respect to language operators.  For instance, if a '
+                 'class defines\n'
+                 'a method named "__getitem__()", and "x" is an instance of '
+                 'this class,\n'
+                 'then "x[i]" is roughly equivalent to "type(x).__getitem__(x, '
+                 'i)".\n'
+                 'Except where mentioned, attempts to execute an operation '
+                 'raise an\n'
+                 'exception when no appropriate method is defined (typically\n'
+                 '"AttributeError" or "TypeError").\n'
+                 '\n'
+                 'When implementing a class that emulates any built-in type, '
+                 'it is\n'
+                 'important that the emulation only be implemented to the '
+                 'degree that it\n'
+                 'makes sense for the object being modelled.  For example, '
+                 'some\n'
+                 'sequences may work well with retrieval of individual '
+                 'elements, but\n'
+                 'extracting a slice may not make sense.  (One example of this '
+                 'is the\n'
+                 '"NodeList" interface in the W3C\'s Document Object Model.)\n'
+                 '\n'
+                 '\n'
+                 'Basic customization\n'
+                 '===================\n'
+                 '\n'
+                 'object.__new__(cls[, ...])\n'
+                 '\n'
+                 '   Called to create a new instance of class *cls*.  '
+                 '"__new__()" is a\n'
+                 '   static method (special-cased so you need not declare it '
+                 'as such)\n'
+                 '   that takes the class of which an instance was requested '
+                 'as its\n'
+                 '   first argument.  The remaining arguments are those passed '
+                 'to the\n'
+                 '   object constructor expression (the call to the class).  '
+                 'The return\n'
+                 '   value of "__new__()" should be the new object instance '
+                 '(usually an\n'
+                 '   instance of *cls*).\n'
+                 '\n'
+                 '   Typical implementations create a new instance of the '
+                 'class by\n'
+                 '   invoking the superclass\'s "__new__()" method using\n'
+                 '   "super(currentclass, cls).__new__(cls[, ...])" with '
+                 'appropriate\n'
+                 '   arguments and then modifying the newly-created instance '
+                 'as\n'
+                 '   necessary before returning it.\n'
+                 '\n'
+                 '   If "__new__()" returns an instance of *cls*, then the '
+                 'new\n'
+                 '   instance\'s "__init__()" method will be invoked like\n'
+                 '   "__init__(self[, ...])", where *self* is the new instance '
+                 'and the\n'
+                 '   remaining arguments are the same as were passed to '
+                 '"__new__()".\n'
+                 '\n'
+                 '   If "__new__()" does not return an instance of *cls*, then '
+                 'the new\n'
+                 '   instance\'s "__init__()" method will not be invoked.\n'
+                 '\n'
+                 '   "__new__()" is intended mainly to allow subclasses of '
+                 'immutable\n'
+                 '   types (like int, str, or tuple) to customize instance '
+                 'creation.  It\n'
+                 '   is also commonly overridden in custom metaclasses in '
+                 'order to\n'
+                 '   customize class creation.\n'
+                 '\n'
+                 'object.__init__(self[, ...])\n'
+                 '\n'
+                 '   Called after the instance has been created (by '
+                 '"__new__()"), but\n'
+                 '   before it is returned to the caller.  The arguments are '
+                 'those\n'
+                 '   passed to the class constructor expression.  If a base '
+                 'class has an\n'
+                 '   "__init__()" method, the derived class\'s "__init__()" '
+                 'method, if\n'
+                 '   any, must explicitly call it to ensure proper '
+                 'initialization of the\n'
+                 '   base class part of the instance; for example:\n'
+                 '   "BaseClass.__init__(self, [args...])".\n'
+                 '\n'
+                 '   Because "__new__()" and "__init__()" work together in '
+                 'constructing\n'
+                 '   objects ("__new__()" to create it, and "__init__()" to '
+                 'customise\n'
+                 '   it), no non-"None" value may be returned by "__init__()"; '
+                 'doing so\n'
+                 '   will cause a "TypeError" to be raised at runtime.\n'
+                 '\n'
+                 'object.__del__(self)\n'
+                 '\n'
+                 '   Called when the instance is about to be destroyed.  This '
+                 'is also\n'
+                 '   called a destructor.  If a base class has a "__del__()" '
+                 'method, the\n'
+                 '   derived class\'s "__del__()" method, if any, must '
+                 'explicitly call it\n'
+                 '   to ensure proper deletion of the base class part of the '
+                 'instance.\n'
+                 '   Note that it is possible (though not recommended!) for '
+                 'the\n'
+                 '   "__del__()" method to postpone destruction of the '
+                 'instance by\n'
+                 '   creating a new reference to it.  It may then be called at '
+                 'a later\n'
+                 '   time when this new reference is deleted.  It is not '
+                 'guaranteed that\n'
+                 '   "__del__()" methods are called for objects that still '
+                 'exist when\n'
+                 '   the interpreter exits.\n'
+                 '\n'
+                 '   Note: "del x" doesn\'t directly call "x.__del__()" --- '
+                 'the former\n'
+                 '     decrements the reference count for "x" by one, and the '
+                 'latter is\n'
+                 '     only called when "x"\'s reference count reaches zero.  '
+                 'Some common\n'
+                 '     situations that may prevent the reference count of an '
+                 'object from\n'
+                 '     going to zero include: circular references between '
+                 'objects (e.g.,\n'
+                 '     a doubly-linked list or a tree data structure with '
+                 'parent and\n'
+                 '     child pointers); a reference to the object on the stack '
+                 'frame of\n'
+                 '     a function that caught an exception (the traceback '
+                 'stored in\n'
+                 '     "sys.exc_info()[2]" keeps the stack frame alive); or a '
+                 'reference\n'
+                 '     to the object on the stack frame that raised an '
+                 'unhandled\n'
+                 '     exception in interactive mode (the traceback stored in\n'
+                 '     "sys.last_traceback" keeps the stack frame alive).  The '
+                 'first\n'
+                 '     situation can only be remedied by explicitly breaking '
+                 'the cycles;\n'
+                 '     the second can be resolved by freeing the reference to '
+                 'the\n'
+                 '     traceback object when it is no longer useful, and the '
+                 'third can\n'
+                 '     be resolved by storing "None" in "sys.last_traceback". '
+                 'Circular\n'
+                 '     references which are garbage are detected and cleaned '
+                 'up when the\n'
+                 "     cyclic garbage collector is enabled (it's on by "
+                 'default). Refer\n'
+                 '     to the documentation for the "gc" module for more '
+                 'information\n'
+                 '     about this topic.\n'
+                 '\n'
+                 '   Warning: Due to the precarious circumstances under which\n'
+                 '     "__del__()" methods are invoked, exceptions that occur '
+                 'during\n'
+                 '     their execution are ignored, and a warning is printed '
+                 'to\n'
+                 '     "sys.stderr" instead. Also, when "__del__()" is invoked '
+                 'in\n'
+                 '     response to a module being deleted (e.g., when '
+                 'execution of the\n'
+                 '     program is done), other globals referenced by the '
+                 '"__del__()"\n'
+                 '     method may already have been deleted or in the process '
+                 'of being\n'
+                 '     torn down (e.g. the import machinery shutting down).  '
+                 'For this\n'
+                 '     reason, "__del__()" methods should do the absolute '
+                 'minimum needed\n'
+                 '     to maintain external invariants.  Starting with version '
+                 '1.5,\n'
+                 '     Python guarantees that globals whose name begins with a '
+                 'single\n'
+                 '     underscore are deleted from their module before other '
+                 'globals are\n'
+                 '     deleted; if no other references to such globals exist, '
+                 'this may\n'
+                 '     help in assuring that imported modules are still '
+                 'available at the\n'
+                 '     time when the "__del__()" method is called.\n'
+                 '\n'
+                 'object.__repr__(self)\n'
+                 '\n'
+                 '   Called by the "repr()" built-in function to compute the '
+                 '"official"\n'
+                 '   string representation of an object.  If at all possible, '
+                 'this\n'
+                 '   should look like a valid Python expression that could be '
+                 'used to\n'
+                 '   recreate an object with the same value (given an '
+                 'appropriate\n'
+                 '   environment).  If this is not possible, a string of the '
+                 'form\n'
+                 '   "<...some useful description...>" should be returned. The '
+                 'return\n'
+                 '   value must be a string object. If a class defines '
+                 '"__repr__()" but\n'
+                 '   not "__str__()", then "__repr__()" is also used when an '
+                 '"informal"\n'
+                 '   string representation of instances of that class is '
+                 'required.\n'
+                 '\n'
+                 '   This is typically used for debugging, so it is important '
+                 'that the\n'
+                 '   representation is information-rich and unambiguous.\n'
+                 '\n'
+                 'object.__str__(self)\n'
+                 '\n'
+                 '   Called by "str(object)" and the built-in functions '
+                 '"format()" and\n'
+                 '   "print()" to compute the "informal" or nicely printable '
+                 'string\n'
+                 '   representation of an object.  The return value must be a '
+                 'string\n'
+                 '   object.\n'
+                 '\n'
+                 '   This method differs from "object.__repr__()" in that '
+                 'there is no\n'
+                 '   expectation that "__str__()" return a valid Python '
+                 'expression: a\n'
+                 '   more convenient or concise representation can be used.\n'
+                 '\n'
+                 '   The default implementation defined by the built-in type '
+                 '"object"\n'
+                 '   calls "object.__repr__()".\n'
+                 '\n'
+                 'object.__bytes__(self)\n'
+                 '\n'
+                 '   Called by "bytes()" to compute a byte-string '
+                 'representation of an\n'
+                 '   object. This should return a "bytes" object.\n'
+                 '\n'
+                 'object.__format__(self, format_spec)\n'
+                 '\n'
+                 '   Called by the "format()" built-in function, and by '
+                 'extension,\n'
+                 '   evaluation of formatted string literals and the '
+                 '"str.format()"\n'
+                 '   method, to produce a "formatted" string representation of '
+                 'an\n'
+                 '   object. The "format_spec" argument is a string that '
+                 'contains a\n'
+                 '   description of the formatting options desired. The '
+                 'interpretation\n'
+                 '   of the "format_spec" argument is up to the type '
+                 'implementing\n'
+                 '   "__format__()", however most classes will either '
+                 'delegate\n'
+                 '   formatting to one of the built-in types, or use a '
+                 'similar\n'
+                 '   formatting option syntax.\n'
+                 '\n'
+                 '   See Format Specification Mini-Language for a description '
+                 'of the\n'
+                 '   standard formatting syntax.\n'
+                 '\n'
+                 '   The return value must be a string object.\n'
+                 '\n'
+                 '   Changed in version 3.4: The __format__ method of "object" '
+                 'itself\n'
+                 '   raises a "TypeError" if passed any non-empty string.\n'
+                 '\n'
+                 'object.__lt__(self, other)\n'
+                 'object.__le__(self, other)\n'
+                 'object.__eq__(self, other)\n'
+                 'object.__ne__(self, other)\n'
+                 'object.__gt__(self, other)\n'
+                 'object.__ge__(self, other)\n'
+                 '\n'
+                 '   These are the so-called "rich comparison" methods. The\n'
+                 '   correspondence between operator symbols and method names '
+                 'is as\n'
+                 '   follows: "x<y" calls "x.__lt__(y)", "x<=y" calls '
+                 '"x.__le__(y)",\n'
+                 '   "x==y" calls "x.__eq__(y)", "x!=y" calls "x.__ne__(y)", '
+                 '"x>y" calls\n'
+                 '   "x.__gt__(y)", and "x>=y" calls "x.__ge__(y)".\n'
+                 '\n'
+                 '   A rich comparison method may return the singleton '
+                 '"NotImplemented"\n'
+                 '   if it does not implement the operation for a given pair '
+                 'of\n'
+                 '   arguments. By convention, "False" and "True" are returned '
+                 'for a\n'
+                 '   successful comparison. However, these methods can return '
+                 'any value,\n'
+                 '   so if the comparison operator is used in a Boolean '
+                 'context (e.g.,\n'
+                 '   in the condition of an "if" statement), Python will call '
+                 '"bool()"\n'
+                 '   on the value to determine if the result is true or '
+                 'false.\n'
+                 '\n'
+                 '   By default, "__ne__()" delegates to "__eq__()" and '
+                 'inverts the\n'
+                 '   result unless it is "NotImplemented".  There are no other '
+                 'implied\n'
+                 '   relationships among the comparison operators, for '
+                 'example, the\n'
+                 '   truth of "(x<y or x==y)" does not imply "x<=y". To '
+                 'automatically\n'
+                 '   generate ordering operations from a single root '
+                 'operation, see\n'
+                 '   "functools.total_ordering()".\n'
+                 '\n'
+                 '   See the paragraph on "__hash__()" for some important '
+                 'notes on\n'
+                 '   creating *hashable* objects which support custom '
+                 'comparison\n'
+                 '   operations and are usable as dictionary keys.\n'
+                 '\n'
+                 '   There are no swapped-argument versions of these methods '
+                 '(to be used\n'
+                 '   when the left argument does not support the operation but '
+                 'the right\n'
+                 '   argument does); rather, "__lt__()" and "__gt__()" are '
+                 "each other's\n"
+                 '   reflection, "__le__()" and "__ge__()" are each other\'s '
+                 'reflection,\n'
+                 '   and "__eq__()" and "__ne__()" are their own reflection. '
+                 'If the\n'
+                 "   operands are of different types, and right operand's type "
+                 'is a\n'
+                 "   direct or indirect subclass of the left operand's type, "
+                 'the\n'
+                 '   reflected method of the right operand has priority, '
+                 'otherwise the\n'
+                 "   left operand's method has priority.  Virtual subclassing "
+                 'is not\n'
+                 '   considered.\n'
+                 '\n'
+                 'object.__hash__(self)\n'
+                 '\n'
+                 '   Called by built-in function "hash()" and for operations '
+                 'on members\n'
+                 '   of hashed collections including "set", "frozenset", and '
+                 '"dict".\n'
+                 '   "__hash__()" should return an integer.  The only required '
+                 'property\n'
+                 '   is that objects which compare equal have the same hash '
+                 'value; it is\n'
+                 '   advised to somehow mix together (e.g. using exclusive or) '
+                 'the hash\n'
+                 '   values for the components of the object that also play a '
+                 'part in\n'
+                 '   comparison of objects.\n'
+                 '\n'
+                 '   Note: "hash()" truncates the value returned from an '
+                 "object's\n"
+                 '     custom "__hash__()" method to the size of a '
+                 '"Py_ssize_t".  This\n'
+                 '     is typically 8 bytes on 64-bit builds and 4 bytes on '
+                 '32-bit\n'
+                 '     builds. If an object\'s   "__hash__()" must '
+                 'interoperate on builds\n'
+                 '     of different bit sizes, be sure to check the width on '
+                 'all\n'
+                 '     supported builds.  An easy way to do this is with '
+                 '"python -c\n'
+                 '     "import sys; print(sys.hash_info.width)"".\n'
+                 '\n'
+                 '   If a class does not define an "__eq__()" method it should '
+                 'not\n'
+                 '   define a "__hash__()" operation either; if it defines '
+                 '"__eq__()"\n'
+                 '   but not "__hash__()", its instances will not be usable as '
+                 'items in\n'
+                 '   hashable collections.  If a class defines mutable objects '
+                 'and\n'
+                 '   implements an "__eq__()" method, it should not implement\n'
+                 '   "__hash__()", since the implementation of hashable '
+                 'collections\n'
+                 "   requires that a key's hash value is immutable (if the "
+                 "object's hash\n"
+                 '   value changes, it will be in the wrong hash bucket).\n'
+                 '\n'
+                 '   User-defined classes have "__eq__()" and "__hash__()" '
+                 'methods by\n'
+                 '   default; with them, all objects compare unequal (except '
+                 'with\n'
+                 '   themselves) and "x.__hash__()" returns an appropriate '
+                 'value such\n'
+                 '   that "x == y" implies both that "x is y" and "hash(x) == '
+                 'hash(y)".\n'
+                 '\n'
+                 '   A class that overrides "__eq__()" and does not define '
+                 '"__hash__()"\n'
+                 '   will have its "__hash__()" implicitly set to "None".  '
+                 'When the\n'
+                 '   "__hash__()" method of a class is "None", instances of '
+                 'the class\n'
+                 '   will raise an appropriate "TypeError" when a program '
+                 'attempts to\n'
+                 '   retrieve their hash value, and will also be correctly '
+                 'identified as\n'
+                 '   unhashable when checking "isinstance(obj, '
+                 'collections.Hashable)".\n'
+                 '\n'
+                 '   If a class that overrides "__eq__()" needs to retain the\n'
+                 '   implementation of "__hash__()" from a parent class, the '
+                 'interpreter\n'
+                 '   must be told this explicitly by setting "__hash__ =\n'
+                 '   <ParentClass>.__hash__".\n'
+                 '\n'
+                 '   If a class that does not override "__eq__()" wishes to '
+                 'suppress\n'
+                 '   hash support, it should include "__hash__ = None" in the '
+                 'class\n'
+                 '   definition. A class which defines its own "__hash__()" '
+                 'that\n'
+                 '   explicitly raises a "TypeError" would be incorrectly '
+                 'identified as\n'
+                 '   hashable by an "isinstance(obj, collections.Hashable)" '
+                 'call.\n'
+                 '\n'
+                 '   Note: By default, the "__hash__()" values of str, bytes '
+                 'and\n'
+                 '     datetime objects are "salted" with an unpredictable '
+                 'random value.\n'
+                 '     Although they remain constant within an individual '
+                 'Python\n'
+                 '     process, they are not predictable between repeated '
+                 'invocations of\n'
+                 '     Python.This is intended to provide protection against a '
+                 'denial-\n'
+                 '     of-service caused by carefully-chosen inputs that '
+                 'exploit the\n'
+                 '     worst case performance of a dict insertion, O(n^2) '
+                 'complexity.\n'
+                 '     See http://www.ocert.org/advisories/ocert-2011-003.html '
+                 'for\n'
+                 '     details.Changing hash values affects the iteration '
+                 'order of\n'
+                 '     dicts, sets and other mappings.  Python has never made '
+                 'guarantees\n'
+                 '     about this ordering (and it typically varies between '
+                 '32-bit and\n'
+                 '     64-bit builds).See also "PYTHONHASHSEED".\n'
+                 '\n'
+                 '   Changed in version 3.3: Hash randomization is enabled by '
+                 'default.\n'
+                 '\n'
+                 'object.__bool__(self)\n'
+                 '\n'
+                 '   Called to implement truth value testing and the built-in '
+                 'operation\n'
+                 '   "bool()"; should return "False" or "True".  When this '
+                 'method is not\n'
+                 '   defined, "__len__()" is called, if it is defined, and the '
+                 'object is\n'
+                 '   considered true if its result is nonzero.  If a class '
+                 'defines\n'
+                 '   neither "__len__()" nor "__bool__()", all its instances '
+                 'are\n'
+                 '   considered true.\n'
+                 '\n'
+                 '\n'
+                 'Customizing attribute access\n'
+                 '============================\n'
+                 '\n'
+                 'The following methods can be defined to customize the '
+                 'meaning of\n'
+                 'attribute access (use of, assignment to, or deletion of '
+                 '"x.name") for\n'
+                 'class instances.\n'
+                 '\n'
+                 'object.__getattr__(self, name)\n'
+                 '\n'
+                 '   Called when an attribute lookup has not found the '
+                 'attribute in the\n'
+                 '   usual places (i.e. it is not an instance attribute nor is '
+                 'it found\n'
+                 '   in the class tree for "self").  "name" is the attribute '
+                 'name. This\n'
+                 '   method should return the (computed) attribute value or '
+                 'raise an\n'
+                 '   "AttributeError" exception.\n'
+                 '\n'
+                 '   Note that if the attribute is found through the normal '
+                 'mechanism,\n'
+                 '   "__getattr__()" is not called.  (This is an intentional '
+                 'asymmetry\n'
+                 '   between "__getattr__()" and "__setattr__()".) This is '
+                 'done both for\n'
+                 '   efficiency reasons and because otherwise "__getattr__()" '
+                 'would have\n'
+                 '   no way to access other attributes of the instance.  Note '
+                 'that at\n'
+                 '   least for instance variables, you can fake total control '
+                 'by not\n'
+                 '   inserting any values in the instance attribute dictionary '
+                 '(but\n'
+                 '   instead inserting them in another object).  See the\n'
+                 '   "__getattribute__()" method below for a way to actually '
+                 'get total\n'
+                 '   control over attribute access.\n'
+                 '\n'
+                 'object.__getattribute__(self, name)\n'
+                 '\n'
+                 '   Called unconditionally to implement attribute accesses '
+                 'for\n'
+                 '   instances of the class. If the class also defines '
+                 '"__getattr__()",\n'
+                 '   the latter will not be called unless "__getattribute__()" '
+                 'either\n'
+                 '   calls it explicitly or raises an "AttributeError". This '
+                 'method\n'
+                 '   should return the (computed) attribute value or raise an\n'
+                 '   "AttributeError" exception. In order to avoid infinite '
+                 'recursion in\n'
+                 '   this method, its implementation should always call the '
+                 'base class\n'
+                 '   method with the same name to access any attributes it '
+                 'needs, for\n'
+                 '   example, "object.__getattribute__(self, name)".\n'
+                 '\n'
+                 '   Note: This method may still be bypassed when looking up '
+                 'special\n'
+                 '     methods as the result of implicit invocation via '
+                 'language syntax\n'
+                 '     or built-in functions. See Special method lookup.\n'
+                 '\n'
+                 'object.__setattr__(self, name, value)\n'
+                 '\n'
+                 '   Called when an attribute assignment is attempted.  This '
+                 'is called\n'
+                 '   instead of the normal mechanism (i.e. store the value in '
+                 'the\n'
+                 '   instance dictionary). *name* is the attribute name, '
+                 '*value* is the\n'
+                 '   value to be assigned to it.\n'
+                 '\n'
+                 '   If "__setattr__()" wants to assign to an instance '
+                 'attribute, it\n'
+                 '   should call the base class method with the same name, for '
+                 'example,\n'
+                 '   "object.__setattr__(self, name, value)".\n'
+                 '\n'
+                 'object.__delattr__(self, name)\n'
+                 '\n'
+                 '   Like "__setattr__()" but for attribute deletion instead '
+                 'of\n'
+                 '   assignment.  This should only be implemented if "del '
+                 'obj.name" is\n'
+                 '   meaningful for the object.\n'
+                 '\n'
+                 'object.__dir__(self)\n'
+                 '\n'
+                 '   Called when "dir()" is called on the object. A sequence '
+                 'must be\n'
+                 '   returned. "dir()" converts the returned sequence to a '
+                 'list and\n'
+                 '   sorts it.\n'
+                 '\n'
+                 '\n'
+                 'Implementing Descriptors\n'
+                 '------------------------\n'
+                 '\n'
+                 'The following methods only apply when an instance of the '
+                 'class\n'
+                 'containing the method (a so-called *descriptor* class) '
+                 'appears in an\n'
+                 "*owner* class (the descriptor must be in either the owner's "
+                 'class\n'
+                 'dictionary or in the class dictionary for one of its '
+                 'parents).  In the\n'
+                 'examples below, "the attribute" refers to the attribute '
+                 'whose name is\n'
+                 'the key of the property in the owner class\' "__dict__".\n'
+                 '\n'
+                 'object.__get__(self, instance, owner)\n'
+                 '\n'
+                 '   Called to get the attribute of the owner class (class '
+                 'attribute\n'
+                 '   access) or of an instance of that class (instance '
+                 'attribute\n'
+                 '   access). *owner* is always the owner class, while '
+                 '*instance* is the\n'
+                 '   instance that the attribute was accessed through, or '
+                 '"None" when\n'
+                 '   the attribute is accessed through the *owner*.  This '
+                 'method should\n'
+                 '   return the (computed) attribute value or raise an '
+                 '"AttributeError"\n'
+                 '   exception.\n'
+                 '\n'
+                 'object.__set__(self, instance, value)\n'
+                 '\n'
+                 '   Called to set the attribute on an instance *instance* of '
+                 'the owner\n'
+                 '   class to a new value, *value*.\n'
+                 '\n'
+                 'object.__delete__(self, instance)\n'
+                 '\n'
+                 '   Called to delete the attribute on an instance *instance* '
+                 'of the\n'
+                 '   owner class.\n'
+                 '\n'
+                 'The attribute "__objclass__" is interpreted by the "inspect" '
+                 'module as\n'
+                 'specifying the class where this object was defined (setting '
+                 'this\n'
+                 'appropriately can assist in runtime introspection of dynamic '
+                 'class\n'
+                 'attributes). For callables, it may indicate that an instance '
+                 'of the\n'
+                 'given type (or a subclass) is expected or required as the '
+                 'first\n'
+                 'positional argument (for example, CPython sets this '
+                 'attribute for\n'
+                 'unbound methods that are implemented in C).\n'
+                 '\n'
+                 '\n'
+                 'Invoking Descriptors\n'
+                 '--------------------\n'
+                 '\n'
+                 'In general, a descriptor is an object attribute with '
+                 '"binding\n'
+                 'behavior", one whose attribute access has been overridden by '
+                 'methods\n'
+                 'in the descriptor protocol:  "__get__()", "__set__()", and\n'
+                 '"__delete__()". If any of those methods are defined for an '
+                 'object, it\n'
+                 'is said to be a descriptor.\n'
+                 '\n'
+                 'The default behavior for attribute access is to get, set, or '
+                 'delete\n'
+                 "the attribute from an object's dictionary. For instance, "
+                 '"a.x" has a\n'
+                 'lookup chain starting with "a.__dict__[\'x\']", then\n'
+                 '"type(a).__dict__[\'x\']", and continuing through the base '
+                 'classes of\n'
+                 '"type(a)" excluding metaclasses.\n'
+                 '\n'
+                 'However, if the looked-up value is an object defining one of '
+                 'the\n'
+                 'descriptor methods, then Python may override the default '
+                 'behavior and\n'
+                 'invoke the descriptor method instead.  Where this occurs in '
+                 'the\n'
+                 'precedence chain depends on which descriptor methods were '
+                 'defined and\n'
+                 'how they were called.\n'
+                 '\n'
+                 'The starting point for descriptor invocation is a binding, '
+                 '"a.x". How\n'
+                 'the arguments are assembled depends on "a":\n'
+                 '\n'
+                 'Direct Call\n'
+                 '   The simplest and least common call is when user code '
+                 'directly\n'
+                 '   invokes a descriptor method:    "x.__get__(a)".\n'
+                 '\n'
+                 'Instance Binding\n'
+                 '   If binding to an object instance, "a.x" is transformed '
+                 'into the\n'
+                 '   call: "type(a).__dict__[\'x\'].__get__(a, type(a))".\n'
+                 '\n'
+                 'Class Binding\n'
+                 '   If binding to a class, "A.x" is transformed into the '
+                 'call:\n'
+                 '   "A.__dict__[\'x\'].__get__(None, A)".\n'
+                 '\n'
+                 'Super Binding\n'
+                 '   If "a" is an instance of "super", then the binding '
+                 '"super(B,\n'
+                 '   obj).m()" searches "obj.__class__.__mro__" for the base '
+                 'class "A"\n'
+                 '   immediately preceding "B" and then invokes the descriptor '
+                 'with the\n'
+                 '   call: "A.__dict__[\'m\'].__get__(obj, obj.__class__)".\n'
+                 '\n'
+                 'For instance bindings, the precedence of descriptor '
+                 'invocation depends\n'
+                 'on the which descriptor methods are defined.  A descriptor '
+                 'can define\n'
+                 'any combination of "__get__()", "__set__()" and '
+                 '"__delete__()".  If it\n'
+                 'does not define "__get__()", then accessing the attribute '
+                 'will return\n'
+                 'the descriptor object itself unless there is a value in the '
+                 "object's\n"
+                 'instance dictionary.  If the descriptor defines "__set__()" '
+                 'and/or\n'
+                 '"__delete__()", it is a data descriptor; if it defines '
+                 'neither, it is\n'
+                 'a non-data descriptor.  Normally, data descriptors define '
+                 'both\n'
+                 '"__get__()" and "__set__()", while non-data descriptors have '
+                 'just the\n'
+                 '"__get__()" method.  Data descriptors with "__set__()" and '
+                 '"__get__()"\n'
+                 'defined always override a redefinition in an instance '
+                 'dictionary.  In\n'
+                 'contrast, non-data descriptors can be overridden by '
+                 'instances.\n'
+                 '\n'
+                 'Python methods (including "staticmethod()" and '
+                 '"classmethod()") are\n'
+                 'implemented as non-data descriptors.  Accordingly, instances '
+                 'can\n'
+                 'redefine and override methods.  This allows individual '
+                 'instances to\n'
+                 'acquire behaviors that differ from other instances of the '
+                 'same class.\n'
+                 '\n'
+                 'The "property()" function is implemented as a data '
+                 'descriptor.\n'
+                 'Accordingly, instances cannot override the behavior of a '
+                 'property.\n'
+                 '\n'
+                 '\n'
+                 '__slots__\n'
+                 '---------\n'
+                 '\n'
+                 'By default, instances of classes have a dictionary for '
+                 'attribute\n'
+                 'storage.  This wastes space for objects having very few '
+                 'instance\n'
+                 'variables.  The space consumption can become acute when '
+                 'creating large\n'
+                 'numbers of instances.\n'
+                 '\n'
+                 'The default can be overridden by defining *__slots__* in a '
+                 'class\n'
+                 'definition. The *__slots__* declaration takes a sequence of '
+                 'instance\n'
+                 'variables and reserves just enough space in each instance to '
+                 'hold a\n'
+                 'value for each variable.  Space is saved because *__dict__* '
+                 'is not\n'
+                 'created for each instance.\n'
+                 '\n'
+                 'object.__slots__\n'
+                 '\n'
+                 '   This class variable can be assigned a string, iterable, '
+                 'or sequence\n'
+                 '   of strings with variable names used by instances.  '
+                 '*__slots__*\n'
+                 '   reserves space for the declared variables and prevents '
+                 'the\n'
+                 '   automatic creation of *__dict__* and *__weakref__* for '
+                 'each\n'
+                 '   instance.\n'
+                 '\n'
+                 '\n'
+                 'Notes on using *__slots__*\n'
+                 '~~~~~~~~~~~~~~~~~~~~~~~~~~\n'
+                 '\n'
+                 '* When inheriting from a class without *__slots__*, the '
+                 '*__dict__*\n'
+                 '  attribute of that class will always be accessible, so a '
+                 '*__slots__*\n'
+                 '  definition in the subclass is meaningless.\n'
+                 '\n'
+                 '* Without a *__dict__* variable, instances cannot be '
+                 'assigned new\n'
+                 '  variables not listed in the *__slots__* definition.  '
+                 'Attempts to\n'
+                 '  assign to an unlisted variable name raises '
+                 '"AttributeError". If\n'
+                 '  dynamic assignment of new variables is desired, then add\n'
+                 '  "\'__dict__\'" to the sequence of strings in the '
+                 '*__slots__*\n'
+                 '  declaration.\n'
+                 '\n'
+                 '* Without a *__weakref__* variable for each instance, '
+                 'classes\n'
+                 '  defining *__slots__* do not support weak references to '
+                 'its\n'
+                 '  instances. If weak reference support is needed, then add\n'
+                 '  "\'__weakref__\'" to the sequence of strings in the '
+                 '*__slots__*\n'
+                 '  declaration.\n'
+                 '\n'
+                 '* *__slots__* are implemented at the class level by '
+                 'creating\n'
+                 '  descriptors (Implementing Descriptors) for each variable '
+                 'name.  As a\n'
+                 '  result, class attributes cannot be used to set default '
+                 'values for\n'
+                 '  instance variables defined by *__slots__*; otherwise, the '
+                 'class\n'
+                 '  attribute would overwrite the descriptor assignment.\n'
+                 '\n'
+                 '* The action of a *__slots__* declaration is limited to the '
+                 'class\n'
+                 '  where it is defined.  As a result, subclasses will have a '
+                 '*__dict__*\n'
+                 '  unless they also define *__slots__* (which must only '
+                 'contain names\n'
+                 '  of any *additional* slots).\n'
+                 '\n'
+                 '* If a class defines a slot also defined in a base class, '
+                 'the\n'
+                 '  instance variable defined by the base class slot is '
+                 'inaccessible\n'
+                 '  (except by retrieving its descriptor directly from the '
+                 'base class).\n'
+                 '  This renders the meaning of the program undefined.  In the '
+                 'future, a\n'
+                 '  check may be added to prevent this.\n'
+                 '\n'
+                 '* Nonempty *__slots__* does not work for classes derived '
+                 'from\n'
+                 '  "variable-length" built-in types such as "int", "bytes" '
+                 'and "tuple".\n'
+                 '\n'
+                 '* Any non-string iterable may be assigned to *__slots__*. '
+                 'Mappings\n'
+                 '  may also be used; however, in the future, special meaning '
+                 'may be\n'
+                 '  assigned to the values corresponding to each key.\n'
+                 '\n'
+                 '* *__class__* assignment works only if both classes have the '
+                 'same\n'
+                 '  *__slots__*.\n'
+                 '\n'
+                 '\n'
+                 'Customizing class creation\n'
+                 '==========================\n'
+                 '\n'
+                 'By default, classes are constructed using "type()". The '
+                 'class body is\n'
+                 'executed in a new namespace and the class name is bound '
+                 'locally to the\n'
+                 'result of "type(name, bases, namespace)".\n'
+                 '\n'
+                 'The class creation process can be customised by passing the\n'
+                 '"metaclass" keyword argument in the class definition line, '
+                 'or by\n'
+                 'inheriting from an existing class that included such an '
+                 'argument. In\n'
+                 'the following example, both "MyClass" and "MySubclass" are '
+                 'instances\n'
+                 'of "Meta":\n'
+                 '\n'
+                 '   class Meta(type):\n'
+                 '       pass\n'
+                 '\n'
+                 '   class MyClass(metaclass=Meta):\n'
+                 '       pass\n'
+                 '\n'
+                 '   class MySubclass(MyClass):\n'
+                 '       pass\n'
+                 '\n'
+                 'Any other keyword arguments that are specified in the class '
+                 'definition\n'
+                 'are passed through to all metaclass operations described '
+                 'below.\n'
+                 '\n'
+                 'When a class definition is executed, the following steps '
+                 'occur:\n'
+                 '\n'
+                 '* the appropriate metaclass is determined\n'
+                 '\n'
+                 '* the class namespace is prepared\n'
+                 '\n'
+                 '* the class body is executed\n'
+                 '\n'
+                 '* the class object is created\n'
+                 '\n'
+                 '\n'
+                 'Determining the appropriate metaclass\n'
+                 '-------------------------------------\n'
+                 '\n'
+                 'The appropriate metaclass for a class definition is '
+                 'determined as\n'
+                 'follows:\n'
+                 '\n'
+                 '* if no bases and no explicit metaclass are given, then '
+                 '"type()" is\n'
+                 '  used\n'
+                 '\n'
+                 '* if an explicit metaclass is given and it is *not* an '
+                 'instance of\n'
+                 '  "type()", then it is used directly as the metaclass\n'
+                 '\n'
+                 '* if an instance of "type()" is given as the explicit '
+                 'metaclass, or\n'
+                 '  bases are defined, then the most derived metaclass is '
+                 'used\n'
+                 '\n'
+                 'The most derived metaclass is selected from the explicitly '
+                 'specified\n'
+                 'metaclass (if any) and the metaclasses (i.e. "type(cls)") of '
+                 'all\n'
+                 'specified base classes. The most derived metaclass is one '
+                 'which is a\n'
+                 'subtype of *all* of these candidate metaclasses. If none of '
+                 'the\n'
+                 'candidate metaclasses meets that criterion, then the class '
+                 'definition\n'
+                 'will fail with "TypeError".\n'
+                 '\n'
+                 '\n'
+                 'Preparing the class namespace\n'
+                 '-----------------------------\n'
+                 '\n'
+                 'Once the appropriate metaclass has been identified, then the '
+                 'class\n'
+                 'namespace is prepared. If the metaclass has a "__prepare__" '
+                 'attribute,\n'
+                 'it is called as "namespace = metaclass.__prepare__(name, '
+                 'bases,\n'
+                 '**kwds)" (where the additional keyword arguments, if any, '
+                 'come from\n'
+                 'the class definition).\n'
+                 '\n'
+                 'If the metaclass has no "__prepare__" attribute, then the '
+                 'class\n'
+                 'namespace is initialised as an empty "dict()" instance.\n'
+                 '\n'
+                 'See also:\n'
+                 '\n'
+                 '  **PEP 3115** - Metaclasses in Python 3000\n'
+                 '     Introduced the "__prepare__" namespace hook\n'
+                 '\n'
+                 '\n'
+                 'Executing the class body\n'
+                 '------------------------\n'
+                 '\n'
+                 'The class body is executed (approximately) as "exec(body, '
+                 'globals(),\n'
+                 'namespace)". The key difference from a normal call to '
+                 '"exec()" is that\n'
+                 'lexical scoping allows the class body (including any '
+                 'methods) to\n'
+                 'reference names from the current and outer scopes when the '
+                 'class\n'
+                 'definition occurs inside a function.\n'
+                 '\n'
+                 'However, even when the class definition occurs inside the '
+                 'function,\n'
+                 'methods defined inside the class still cannot see names '
+                 'defined at the\n'
+                 'class scope. Class variables must be accessed through the '
+                 'first\n'
+                 'parameter of instance or class methods, and cannot be '
+                 'accessed at all\n'
+                 'from static methods.\n'
+                 '\n'
+                 '\n'
+                 'Creating the class object\n'
+                 '-------------------------\n'
+                 '\n'
+                 'Once the class namespace has been populated by executing the '
+                 'class\n'
+                 'body, the class object is created by calling '
+                 '"metaclass(name, bases,\n'
+                 'namespace, **kwds)" (the additional keywords passed here are '
+                 'the same\n'
+                 'as those passed to "__prepare__").\n'
+                 '\n'
+                 'This class object is the one that will be referenced by the '
+                 'zero-\n'
+                 'argument form of "super()". "__class__" is an implicit '
+                 'closure\n'
+                 'reference created by the compiler if any methods in a class '
+                 'body refer\n'
+                 'to either "__class__" or "super". This allows the zero '
+                 'argument form\n'
+                 'of "super()" to correctly identify the class being defined '
+                 'based on\n'
+                 'lexical scoping, while the class or instance that was used '
+                 'to make the\n'
+                 'current call is identified based on the first argument '
+                 'passed to the\n'
+                 'method.\n'
+                 '\n'
+                 'After the class object is created, it is passed to the '
+                 'class\n'
+                 'decorators included in the class definition (if any) and the '
+                 'resulting\n'
+                 'object is bound in the local namespace as the defined '
+                 'class.\n'
+                 '\n'
+                 'See also:\n'
+                 '\n'
+                 '  **PEP 3135** - New super\n'
+                 '     Describes the implicit "__class__" closure reference\n'
+                 '\n'
+                 '\n'
+                 'Metaclass example\n'
+                 '-----------------\n'
+                 '\n'
+                 'The potential uses for metaclasses are boundless. Some ideas '
+                 'that have\n'
+                 'been explored include logging, interface checking, '
+                 'automatic\n'
+                 'delegation, automatic property creation, proxies, '
+                 'frameworks, and\n'
+                 'automatic resource locking/synchronization.\n'
+                 '\n'
+                 'Here is an example of a metaclass that uses an\n'
+                 '"collections.OrderedDict" to remember the order that class '
+                 'variables\n'
+                 'are defined:\n'
+                 '\n'
+                 '   class OrderedClass(type):\n'
+                 '\n'
+                 '       @classmethod\n'
+                 '       def __prepare__(metacls, name, bases, **kwds):\n'
+                 '           return collections.OrderedDict()\n'
+                 '\n'
+                 '       def __new__(cls, name, bases, namespace, **kwds):\n'
+                 '           result = type.__new__(cls, name, bases, '
+                 'dict(namespace))\n'
+                 '           result.members = tuple(namespace)\n'
+                 '           return result\n'
+                 '\n'
+                 '   class A(metaclass=OrderedClass):\n'
+                 '       def one(self): pass\n'
+                 '       def two(self): pass\n'
+                 '       def three(self): pass\n'
+                 '       def four(self): pass\n'
+                 '\n'
+                 '   >>> A.members\n'
+                 "   ('__module__', 'one', 'two', 'three', 'four')\n"
+                 '\n'
+                 'When the class definition for *A* gets executed, the process '
+                 'begins\n'
+                 'with calling the metaclass\'s "__prepare__()" method which '
+                 'returns an\n'
+                 'empty "collections.OrderedDict".  That mapping records the '
+                 'methods and\n'
+                 'attributes of *A* as they are defined within the body of the '
+                 'class\n'
+                 'statement. Once those definitions are executed, the ordered '
+                 'dictionary\n'
+                 'is fully populated and the metaclass\'s "__new__()" method '
+                 'gets\n'
+                 'invoked.  That method builds the new type and it saves the '
+                 'ordered\n'
+                 'dictionary keys in an attribute called "members".\n'
+                 '\n'
+                 '\n'
+                 'Customizing instance and subclass checks\n'
+                 '========================================\n'
+                 '\n'
+                 'The following methods are used to override the default '
+                 'behavior of the\n'
+                 '"isinstance()" and "issubclass()" built-in functions.\n'
+                 '\n'
+                 'In particular, the metaclass "abc.ABCMeta" implements these '
+                 'methods in\n'
+                 'order to allow the addition of Abstract Base Classes (ABCs) '
+                 'as\n'
+                 '"virtual base classes" to any class or type (including '
+                 'built-in\n'
+                 'types), including other ABCs.\n'
+                 '\n'
+                 'class.__instancecheck__(self, instance)\n'
+                 '\n'
+                 '   Return true if *instance* should be considered a (direct '
+                 'or\n'
+                 '   indirect) instance of *class*. If defined, called to '
+                 'implement\n'
+                 '   "isinstance(instance, class)".\n'
+                 '\n'
+                 'class.__subclasscheck__(self, subclass)\n'
+                 '\n'
+                 '   Return true if *subclass* should be considered a (direct '
+                 'or\n'
+                 '   indirect) subclass of *class*.  If defined, called to '
+                 'implement\n'
+                 '   "issubclass(subclass, class)".\n'
+                 '\n'
+                 'Note that these methods are looked up on the type '
+                 '(metaclass) of a\n'
+                 'class.  They cannot be defined as class methods in the '
+                 'actual class.\n'
+                 'This is consistent with the lookup of special methods that '
+                 'are called\n'
+                 'on instances, only in this case the instance is itself a '
+                 'class.\n'
+                 '\n'
+                 'See also:\n'
+                 '\n'
+                 '  **PEP 3119** - Introducing Abstract Base Classes\n'
+                 '     Includes the specification for customizing '
+                 '"isinstance()" and\n'
+                 '     "issubclass()" behavior through "__instancecheck__()" '
+                 'and\n'
+                 '     "__subclasscheck__()", with motivation for this '
+                 'functionality in\n'
+                 '     the context of adding Abstract Base Classes (see the '
+                 '"abc"\n'
+                 '     module) to the language.\n'
+                 '\n'
+                 '\n'
+                 'Emulating callable objects\n'
+                 '==========================\n'
+                 '\n'
+                 'object.__call__(self[, args...])\n'
+                 '\n'
+                 '   Called when the instance is "called" as a function; if '
+                 'this method\n'
+                 '   is defined, "x(arg1, arg2, ...)" is a shorthand for\n'
+                 '   "x.__call__(arg1, arg2, ...)".\n'
+                 '\n'
+                 '\n'
+                 'Emulating container types\n'
+                 '=========================\n'
+                 '\n'
+                 'The following methods can be defined to implement container '
+                 'objects.\n'
+                 'Containers usually are sequences (such as lists or tuples) '
+                 'or mappings\n'
+                 '(like dictionaries), but can represent other containers as '
+                 'well.  The\n'
+                 'first set of methods is used either to emulate a sequence or '
+                 'to\n'
+                 'emulate a mapping; the difference is that for a sequence, '
+                 'the\n'
+                 'allowable keys should be the integers *k* for which "0 <= k '
+                 '< N" where\n'
+                 '*N* is the length of the sequence, or slice objects, which '
+                 'define a\n'
+                 'range of items.  It is also recommended that mappings '
+                 'provide the\n'
+                 'methods "keys()", "values()", "items()", "get()", '
+                 '"clear()",\n'
+                 '"setdefault()", "pop()", "popitem()", "copy()", and '
+                 '"update()"\n'
+                 "behaving similar to those for Python's standard dictionary "
+                 'objects.\n'
+                 'The "collections" module provides a "MutableMapping" '
+                 'abstract base\n'
+                 'class to help create those methods from a base set of '
+                 '"__getitem__()",\n'
+                 '"__setitem__()", "__delitem__()", and "keys()". Mutable '
+                 'sequences\n'
+                 'should provide methods "append()", "count()", "index()", '
+                 '"extend()",\n'
+                 '"insert()", "pop()", "remove()", "reverse()" and "sort()", '
+                 'like Python\n'
+                 'standard list objects.  Finally, sequence types should '
+                 'implement\n'
+                 'addition (meaning concatenation) and multiplication '
+                 '(meaning\n'
+                 'repetition) by defining the methods "__add__()", '
+                 '"__radd__()",\n'
+                 '"__iadd__()", "__mul__()", "__rmul__()" and "__imul__()" '
+                 'described\n'
+                 'below; they should not define other numerical operators.  It '
+                 'is\n'
+                 'recommended that both mappings and sequences implement the\n'
+                 '"__contains__()" method to allow efficient use of the "in" '
+                 'operator;\n'
+                 'for mappings, "in" should search the mapping\'s keys; for '
+                 'sequences, it\n'
+                 'should search through the values.  It is further recommended '
+                 'that both\n'
+                 'mappings and sequences implement the "__iter__()" method to '
+                 'allow\n'
+                 'efficient iteration through the container; for mappings, '
+                 '"__iter__()"\n'
+                 'should be the same as "keys()"; for sequences, it should '
+                 'iterate\n'
+                 'through the values.\n'
+                 '\n'
+                 'object.__len__(self)\n'
+                 '\n'
+                 '   Called to implement the built-in function "len()".  '
+                 'Should return\n'
+                 '   the length of the object, an integer ">=" 0.  Also, an '
+                 'object that\n'
+                 '   doesn\'t define a "__bool__()" method and whose '
+                 '"__len__()" method\n'
+                 '   returns zero is considered to be false in a Boolean '
+                 'context.\n'
+                 '\n'
+                 'object.__length_hint__(self)\n'
+                 '\n'
+                 '   Called to implement "operator.length_hint()". Should '
+                 'return an\n'
+                 '   estimated length for the object (which may be greater or '
+                 'less than\n'
+                 '   the actual length). The length must be an integer ">=" 0. '
+                 'This\n'
+                 '   method is purely an optimization and is never required '
+                 'for\n'
+                 '   correctness.\n'
+                 '\n'
+                 '   New in version 3.4.\n'
+                 '\n'
+                 'Note: Slicing is done exclusively with the following three '
+                 'methods.\n'
+                 '  A call like\n'
+                 '\n'
+                 '     a[1:2] = b\n'
+                 '\n'
+                 '  is translated to\n'
+                 '\n'
+                 '     a[slice(1, 2, None)] = b\n'
+                 '\n'
+                 '  and so forth.  Missing slice items are always filled in '
+                 'with "None".\n'
+                 '\n'
+                 'object.__getitem__(self, key)\n'
+                 '\n'
+                 '   Called to implement evaluation of "self[key]". For '
+                 'sequence types,\n'
+                 '   the accepted keys should be integers and slice objects.  '
+                 'Note that\n'
+                 '   the special interpretation of negative indexes (if the '
+                 'class wishes\n'
+                 '   to emulate a sequence type) is up to the "__getitem__()" '
+                 'method. If\n'
+                 '   *key* is of an inappropriate type, "TypeError" may be '
+                 'raised; if of\n'
+                 '   a value outside the set of indexes for the sequence '
+                 '(after any\n'
+                 '   special interpretation of negative values), "IndexError" '
+                 'should be\n'
+                 '   raised. For mapping types, if *key* is missing (not in '
+                 'the\n'
+                 '   container), "KeyError" should be raised.\n'
+                 '\n'
+                 '   Note: "for" loops expect that an "IndexError" will be '
+                 'raised for\n'
+                 '     illegal indexes to allow proper detection of the end of '
+                 'the\n'
+                 '     sequence.\n'
+                 '\n'
+                 'object.__missing__(self, key)\n'
+                 '\n'
+                 '   Called by "dict"."__getitem__()" to implement "self[key]" '
+                 'for dict\n'
+                 '   subclasses when key is not in the dictionary.\n'
+                 '\n'
+                 'object.__setitem__(self, key, value)\n'
+                 '\n'
+                 '   Called to implement assignment to "self[key]".  Same note '
+                 'as for\n'
+                 '   "__getitem__()".  This should only be implemented for '
+                 'mappings if\n'
+                 '   the objects support changes to the values for keys, or if '
+                 'new keys\n'
+                 '   can be added, or for sequences if elements can be '
+                 'replaced.  The\n'
+                 '   same exceptions should be raised for improper *key* '
+                 'values as for\n'
+                 '   the "__getitem__()" method.\n'
+                 '\n'
+                 'object.__delitem__(self, key)\n'
+                 '\n'
+                 '   Called to implement deletion of "self[key]".  Same note '
+                 'as for\n'
+                 '   "__getitem__()".  This should only be implemented for '
+                 'mappings if\n'
+                 '   the objects support removal of keys, or for sequences if '
+                 'elements\n'
+                 '   can be removed from the sequence.  The same exceptions '
+                 'should be\n'
+                 '   raised for improper *key* values as for the '
+                 '"__getitem__()" method.\n'
+                 '\n'
+                 'object.__iter__(self)\n'
+                 '\n'
+                 '   This method is called when an iterator is required for a '
+                 'container.\n'
+                 '   This method should return a new iterator object that can '
+                 'iterate\n'
+                 '   over all the objects in the container.  For mappings, it '
+                 'should\n'
+                 '   iterate over the keys of the container.\n'
+                 '\n'
+                 '   Iterator objects also need to implement this method; they '
+                 'are\n'
+                 '   required to return themselves.  For more information on '
+                 'iterator\n'
+                 '   objects, see Iterator Types.\n'
+                 '\n'
+                 'object.__reversed__(self)\n'
+                 '\n'
+                 '   Called (if present) by the "reversed()" built-in to '
+                 'implement\n'
+                 '   reverse iteration.  It should return a new iterator '
+                 'object that\n'
+                 '   iterates over all the objects in the container in reverse '
+                 'order.\n'
+                 '\n'
+                 '   If the "__reversed__()" method is not provided, the '
+                 '"reversed()"\n'
+                 '   built-in will fall back to using the sequence protocol '
+                 '("__len__()"\n'
+                 '   and "__getitem__()").  Objects that support the sequence '
+                 'protocol\n'
+                 '   should only provide "__reversed__()" if they can provide '
+                 'an\n'
+                 '   implementation that is more efficient than the one '
+                 'provided by\n'
+                 '   "reversed()".\n'
+                 '\n'
+                 'The membership test operators ("in" and "not in") are '
+                 'normally\n'
+                 'implemented as an iteration through a sequence.  However, '
+                 'container\n'
+                 'objects can supply the following special method with a more '
+                 'efficient\n'
+                 'implementation, which also does not require the object be a '
+                 'sequence.\n'
+                 '\n'
+                 'object.__contains__(self, item)\n'
+                 '\n'
+                 '   Called to implement membership test operators.  Should '
+                 'return true\n'
+                 '   if *item* is in *self*, false otherwise.  For mapping '
+                 'objects, this\n'
+                 '   should consider the keys of the mapping rather than the '
+                 'values or\n'
+                 '   the key-item pairs.\n'
+                 '\n'
+                 '   For objects that don\'t define "__contains__()", the '
+                 'membership test\n'
+                 '   first tries iteration via "__iter__()", then the old '
+                 'sequence\n'
+                 '   iteration protocol via "__getitem__()", see this section '
+                 'in the\n'
+                 '   language reference.\n'
+                 '\n'
+                 '\n'
+                 'Emulating numeric types\n'
+                 '=======================\n'
+                 '\n'
+                 'The following methods can be defined to emulate numeric '
+                 'objects.\n'
+                 'Methods corresponding to operations that are not supported '
+                 'by the\n'
+                 'particular kind of number implemented (e.g., bitwise '
+                 'operations for\n'
+                 'non-integral numbers) should be left undefined.\n'
+                 '\n'
+                 'object.__add__(self, other)\n'
+                 'object.__sub__(self, other)\n'
+                 'object.__mul__(self, other)\n'
+                 'object.__matmul__(self, other)\n'
+                 'object.__truediv__(self, other)\n'
+                 'object.__floordiv__(self, other)\n'
+                 'object.__mod__(self, other)\n'
+                 'object.__divmod__(self, other)\n'
+                 'object.__pow__(self, other[, modulo])\n'
+                 'object.__lshift__(self, other)\n'
+                 'object.__rshift__(self, other)\n'
+                 'object.__and__(self, other)\n'
+                 'object.__xor__(self, other)\n'
+                 'object.__or__(self, other)\n'
+                 '\n'
+                 '   These methods are called to implement the binary '
+                 'arithmetic\n'
+                 '   operations ("+", "-", "*", "@", "/", "//", "%", '
+                 '"divmod()",\n'
+                 '   "pow()", "**", "<<", ">>", "&", "^", "|").  For instance, '
+                 'to\n'
+                 '   evaluate the expression "x + y", where *x* is an instance '
+                 'of a\n'
+                 '   class that has an "__add__()" method, "x.__add__(y)" is '
+                 'called.\n'
+                 '   The "__divmod__()" method should be the equivalent to '
+                 'using\n'
+                 '   "__floordiv__()" and "__mod__()"; it should not be '
+                 'related to\n'
+                 '   "__truediv__()".  Note that "__pow__()" should be defined '
+                 'to accept\n'
+                 '   an optional third argument if the ternary version of the '
+                 'built-in\n'
+                 '   "pow()" function is to be supported.\n'
+                 '\n'
+                 '   If one of those methods does not support the operation '
+                 'with the\n'
+                 '   supplied arguments, it should return "NotImplemented".\n'
+                 '\n'
+                 'object.__radd__(self, other)\n'
+                 'object.__rsub__(self, other)\n'
+                 'object.__rmul__(self, other)\n'
+                 'object.__rmatmul__(self, other)\n'
+                 'object.__rtruediv__(self, other)\n'
+                 'object.__rfloordiv__(self, other)\n'
+                 'object.__rmod__(self, other)\n'
+                 'object.__rdivmod__(self, other)\n'
+                 'object.__rpow__(self, other)\n'
+                 'object.__rlshift__(self, other)\n'
+                 'object.__rrshift__(self, other)\n'
+                 'object.__rand__(self, other)\n'
+                 'object.__rxor__(self, other)\n'
+                 'object.__ror__(self, other)\n'
+                 '\n'
+                 '   These methods are called to implement the binary '
+                 'arithmetic\n'
+                 '   operations ("+", "-", "*", "@", "/", "//", "%", '
+                 '"divmod()",\n'
+                 '   "pow()", "**", "<<", ">>", "&", "^", "|") with reflected '
+                 '(swapped)\n'
+                 '   operands.  These functions are only called if the left '
+                 'operand does\n'
+                 '   not support the corresponding operation and the operands '
+                 'are of\n'
+                 '   different types. [2] For instance, to evaluate the '
+                 'expression "x -\n'
+                 '   y", where *y* is an instance of a class that has an '
+                 '"__rsub__()"\n'
+                 '   method, "y.__rsub__(x)" is called if "x.__sub__(y)" '
+                 'returns\n'
+                 '   *NotImplemented*.\n'
+                 '\n'
+                 '   Note that ternary "pow()" will not try calling '
+                 '"__rpow__()" (the\n'
+                 '   coercion rules would become too complicated).\n'
+                 '\n'
+                 "   Note: If the right operand's type is a subclass of the "
+                 'left\n'
+                 "     operand's type and that subclass provides the reflected "
+                 'method\n'
+                 '     for the operation, this method will be called before '
+                 'the left\n'
+                 "     operand's non-reflected method.  This behavior allows "
+                 'subclasses\n'
+                 "     to override their ancestors' operations.\n"
+                 '\n'
+                 'object.__iadd__(self, other)\n'
+                 'object.__isub__(self, other)\n'
+                 'object.__imul__(self, other)\n'
+                 'object.__imatmul__(self, other)\n'
+                 'object.__itruediv__(self, other)\n'
+                 'object.__ifloordiv__(self, other)\n'
+                 'object.__imod__(self, other)\n'
+                 'object.__ipow__(self, other[, modulo])\n'
+                 'object.__ilshift__(self, other)\n'
+                 'object.__irshift__(self, other)\n'
+                 'object.__iand__(self, other)\n'
+                 'object.__ixor__(self, other)\n'
+                 'object.__ior__(self, other)\n'
+                 '\n'
+                 '   These methods are called to implement the augmented '
+                 'arithmetic\n'
+                 '   assignments ("+=", "-=", "*=", "@=", "/=", "//=", "%=", '
+                 '"**=",\n'
+                 '   "<<=", ">>=", "&=", "^=", "|=").  These methods should '
+                 'attempt to\n'
+                 '   do the operation in-place (modifying *self*) and return '
+                 'the result\n'
+                 '   (which could be, but does not have to be, *self*).  If a '
+                 'specific\n'
+                 '   method is not defined, the augmented assignment falls '
+                 'back to the\n'
+                 '   normal methods.  For instance, if *x* is an instance of a '
+                 'class\n'
+                 '   with an "__iadd__()" method, "x += y" is equivalent to "x '
+                 '=\n'
+                 '   x.__iadd__(y)" . Otherwise, "x.__add__(y)" and '
+                 '"y.__radd__(x)" are\n'
+                 '   considered, as with the evaluation of "x + y". In '
+                 'certain\n'
+                 '   situations, augmented assignment can result in unexpected '
+                 'errors\n'
+                 "   (see Why does a_tuple[i] += ['item'] raise an exception "
+                 'when the\n'
+                 '   addition works?), but this behavior is in fact part of '
+                 'the data\n'
+                 '   model.\n'
+                 '\n'
+                 'object.__neg__(self)\n'
+                 'object.__pos__(self)\n'
+                 'object.__abs__(self)\n'
+                 'object.__invert__(self)\n'
+                 '\n'
+                 '   Called to implement the unary arithmetic operations ("-", '
+                 '"+",\n'
+                 '   "abs()" and "~").\n'
+                 '\n'
+                 'object.__complex__(self)\n'
+                 'object.__int__(self)\n'
+                 'object.__float__(self)\n'
+                 'object.__round__(self[, n])\n'
+                 '\n'
+                 '   Called to implement the built-in functions "complex()", '
+                 '"int()",\n'
+                 '   "float()" and "round()".  Should return a value of the '
+                 'appropriate\n'
+                 '   type.\n'
+                 '\n'
+                 'object.__index__(self)\n'
+                 '\n'
+                 '   Called to implement "operator.index()", and whenever '
+                 'Python needs\n'
+                 '   to losslessly convert the numeric object to an integer '
+                 'object (such\n'
+                 '   as in slicing, or in the built-in "bin()", "hex()" and '
+                 '"oct()"\n'
+                 '   functions). Presence of this method indicates that the '
+                 'numeric\n'
+                 '   object is an integer type.  Must return an integer.\n'
+                 '\n'
+                 '   Note: In order to have a coherent integer type class, '
+                 'when\n'
+                 '     "__index__()" is defined "__int__()" should also be '
+                 'defined, and\n'
+                 '     both should return the same value.\n'
+                 '\n'
+                 '\n'
+                 'With Statement Context Managers\n'
+                 '===============================\n'
+                 '\n'
+                 'A *context manager* is an object that defines the runtime '
+                 'context to\n'
+                 'be established when executing a "with" statement. The '
+                 'context manager\n'
+                 'handles the entry into, and the exit from, the desired '
+                 'runtime context\n'
+                 'for the execution of the block of code.  Context managers '
+                 'are normally\n'
+                 'invoked using the "with" statement (described in section The '
+                 'with\n'
+                 'statement), but can also be used by directly invoking their '
+                 'methods.\n'
+                 '\n'
+                 'Typical uses of context managers include saving and '
+                 'restoring various\n'
+                 'kinds of global state, locking and unlocking resources, '
+                 'closing opened\n'
+                 'files, etc.\n'
+                 '\n'
+                 'For more information on context managers, see Context '
+                 'Manager Types.\n'
+                 '\n'
+                 'object.__enter__(self)\n'
+                 '\n'
+                 '   Enter the runtime context related to this object. The '
+                 '"with"\n'
+                 "   statement will bind this method's return value to the "
+                 'target(s)\n'
+                 '   specified in the "as" clause of the statement, if any.\n'
+                 '\n'
+                 'object.__exit__(self, exc_type, exc_value, traceback)\n'
+                 '\n'
+                 '   Exit the runtime context related to this object. The '
+                 'parameters\n'
+                 '   describe the exception that caused the context to be '
+                 'exited. If the\n'
+                 '   context was exited without an exception, all three '
+                 'arguments will\n'
+                 '   be "None".\n'
+                 '\n'
+                 '   If an exception is supplied, and the method wishes to '
+                 'suppress the\n'
+                 '   exception (i.e., prevent it from being propagated), it '
+                 'should\n'
+                 '   return a true value. Otherwise, the exception will be '
+                 'processed\n'
+                 '   normally upon exit from this method.\n'
+                 '\n'
+                 '   Note that "__exit__()" methods should not reraise the '
+                 'passed-in\n'
+                 "   exception; this is the caller's responsibility.\n"
+                 '\n'
+                 'See also:\n'
+                 '\n'
+                 '  **PEP 343** - The "with" statement\n'
+                 '     The specification, background, and examples for the '
+                 'Python "with"\n'
+                 '     statement.\n'
+                 '\n'
+                 '\n'
+                 'Special method lookup\n'
+                 '=====================\n'
+                 '\n'
+                 'For custom classes, implicit invocations of special methods '
+                 'are only\n'
+                 "guaranteed to work correctly if defined on an object's type, "
+                 'not in\n'
+                 "the object's instance dictionary.  That behaviour is the "
+                 'reason why\n'
+                 'the following code raises an exception:\n'
+                 '\n'
+                 '   >>> class C:\n'
+                 '   ...     pass\n'
+                 '   ...\n'
+                 '   >>> c = C()\n'
+                 '   >>> c.__len__ = lambda: 5\n'
+                 '   >>> len(c)\n'
+                 '   Traceback (most recent call last):\n'
+                 '     File "<stdin>", line 1, in <module>\n'
+                 "   TypeError: object of type 'C' has no len()\n"
+                 '\n'
+                 'The rationale behind this behaviour lies with a number of '
+                 'special\n'
+                 'methods such as "__hash__()" and "__repr__()" that are '
+                 'implemented by\n'
+                 'all objects, including type objects. If the implicit lookup '
+                 'of these\n'
+                 'methods used the conventional lookup process, they would '
+                 'fail when\n'
+                 'invoked on the type object itself:\n'
+                 '\n'
+                 '   >>> 1 .__hash__() == hash(1)\n'
+                 '   True\n'
+                 '   >>> int.__hash__() == hash(int)\n'
+                 '   Traceback (most recent call last):\n'
+                 '     File "<stdin>", line 1, in <module>\n'
+                 "   TypeError: descriptor '__hash__' of 'int' object needs an "
+                 'argument\n'
+                 '\n'
+                 'Incorrectly attempting to invoke an unbound method of a '
+                 'class in this\n'
+                 "way is sometimes referred to as 'metaclass confusion', and "
+                 'is avoided\n'
+                 'by bypassing the instance when looking up special methods:\n'
+                 '\n'
+                 '   >>> type(1).__hash__(1) == hash(1)\n'
+                 '   True\n'
+                 '   >>> type(int).__hash__(int) == hash(int)\n'
+                 '   True\n'
+                 '\n'
+                 'In addition to bypassing any instance attributes in the '
+                 'interest of\n'
+                 'correctness, implicit special method lookup generally also '
+                 'bypasses\n'
+                 'the "__getattribute__()" method even of the object\'s '
+                 'metaclass:\n'
+                 '\n'
+                 '   >>> class Meta(type):\n'
+                 '   ...     def __getattribute__(*args):\n'
+                 '   ...         print("Metaclass getattribute invoked")\n'
+                 '   ...         return type.__getattribute__(*args)\n'
+                 '   ...\n'
+                 '   >>> class C(object, metaclass=Meta):\n'
+                 '   ...     def __len__(self):\n'
+                 '   ...         return 10\n'
+                 '   ...     def __getattribute__(*args):\n'
+                 '   ...         print("Class getattribute invoked")\n'
+                 '   ...         return object.__getattribute__(*args)\n'
+                 '   ...\n'
+                 '   >>> c = C()\n'
+                 '   >>> c.__len__()                 # Explicit lookup via '
+                 'instance\n'
+                 '   Class getattribute invoked\n'
+                 '   10\n'
+                 '   >>> type(c).__len__(c)          # Explicit lookup via '
+                 'type\n'
+                 '   Metaclass getattribute invoked\n'
+                 '   10\n'
+                 '   >>> len(c)                      # Implicit lookup\n'
+                 '   10\n'
+                 '\n'
+                 'Bypassing the "__getattribute__()" machinery in this fashion '
+                 'provides\n'
+                 'significant scope for speed optimisations within the '
+                 'interpreter, at\n'
+                 'the cost of some flexibility in the handling of special '
+                 'methods (the\n'
+                 'special method *must* be set on the class object itself in '
+                 'order to be\n'
+                 'consistently invoked by the interpreter).\n',
+ 'string-methods': '\n'
+                   'String Methods\n'
+                   '**************\n'
+                   '\n'
+                   'Strings implement all of the common sequence operations, '
+                   'along with\n'
+                   'the additional methods described below.\n'
+                   '\n'
+                   'Strings also support two styles of string formatting, one '
+                   'providing a\n'
+                   'large degree of flexibility and customization (see '
+                   '"str.format()",\n'
+                   'Format String Syntax and Custom String Formatting) and the '
+                   'other based\n'
+                   'on C "printf" style formatting that handles a narrower '
+                   'range of types\n'
+                   'and is slightly harder to use correctly, but is often '
+                   'faster for the\n'
+                   'cases it can handle (printf-style String Formatting).\n'
+                   '\n'
+                   'The Text Processing Services section of the standard '
+                   'library covers a\n'
+                   'number of other modules that provide various text related '
+                   'utilities\n'
+                   '(including regular expression support in the "re" '
+                   'module).\n'
+                   '\n'
+                   'str.capitalize()\n'
+                   '\n'
+                   '   Return a copy of the string with its first character '
+                   'capitalized\n'
+                   '   and the rest lowercased.\n'
+                   '\n'
+                   'str.casefold()\n'
+                   '\n'
+                   '   Return a casefolded copy of the string. Casefolded '
+                   'strings may be\n'
+                   '   used for caseless matching.\n'
+                   '\n'
+                   '   Casefolding is similar to lowercasing but more '
+                   'aggressive because\n'
+                   '   it is intended to remove all case distinctions in a '
+                   'string. For\n'
+                   '   example, the German lowercase letter "\'ß\'" is '
+                   'equivalent to ""ss"".\n'
+                   '   Since it is already lowercase, "lower()" would do '
+                   'nothing to "\'ß\'";\n'
+                   '   "casefold()" converts it to ""ss"".\n'
+                   '\n'
+                   '   The casefolding algorithm is described in section 3.13 '
+                   'of the\n'
+                   '   Unicode Standard.\n'
+                   '\n'
+                   '   New in version 3.3.\n'
+                   '\n'
+                   'str.center(width[, fillchar])\n'
+                   '\n'
+                   '   Return centered in a string of length *width*. Padding '
+                   'is done\n'
+                   '   using the specified *fillchar* (default is an ASCII '
+                   'space). The\n'
+                   '   original string is returned if *width* is less than or '
+                   'equal to\n'
+                   '   "len(s)".\n'
+                   '\n'
+                   'str.count(sub[, start[, end]])\n'
+                   '\n'
+                   '   Return the number of non-overlapping occurrences of '
+                   'substring *sub*\n'
+                   '   in the range [*start*, *end*].  Optional arguments '
+                   '*start* and\n'
+                   '   *end* are interpreted as in slice notation.\n'
+                   '\n'
+                   'str.encode(encoding="utf-8", errors="strict")\n'
+                   '\n'
+                   '   Return an encoded version of the string as a bytes '
+                   'object. Default\n'
+                   '   encoding is "\'utf-8\'". *errors* may be given to set a '
+                   'different\n'
+                   '   error handling scheme. The default for *errors* is '
+                   '"\'strict\'",\n'
+                   '   meaning that encoding errors raise a "UnicodeError". '
+                   'Other possible\n'
+                   '   values are "\'ignore\'", "\'replace\'", '
+                   '"\'xmlcharrefreplace\'",\n'
+                   '   "\'backslashreplace\'" and any other name registered '
+                   'via\n'
+                   '   "codecs.register_error()", see section Error Handlers. '
+                   'For a list\n'
+                   '   of possible encodings, see section Standard Encodings.\n'
+                   '\n'
+                   '   Changed in version 3.1: Support for keyword arguments '
+                   'added.\n'
+                   '\n'
+                   'str.endswith(suffix[, start[, end]])\n'
+                   '\n'
+                   '   Return "True" if the string ends with the specified '
+                   '*suffix*,\n'
+                   '   otherwise return "False".  *suffix* can also be a tuple '
+                   'of suffixes\n'
+                   '   to look for.  With optional *start*, test beginning at '
+                   'that\n'
+                   '   position.  With optional *end*, stop comparing at that '
+                   'position.\n'
+                   '\n'
+                   'str.expandtabs(tabsize=8)\n'
+                   '\n'
+                   '   Return a copy of the string where all tab characters '
+                   'are replaced\n'
+                   '   by one or more spaces, depending on the current column '
+                   'and the\n'
+                   '   given tab size.  Tab positions occur every *tabsize* '
+                   'characters\n'
+                   '   (default is 8, giving tab positions at columns 0, 8, 16 '
+                   'and so on).\n'
+                   '   To expand the string, the current column is set to zero '
+                   'and the\n'
+                   '   string is examined character by character.  If the '
+                   'character is a\n'
+                   '   tab ("\\t"), one or more space characters are inserted '
+                   'in the result\n'
+                   '   until the current column is equal to the next tab '
+                   'position. (The\n'
+                   '   tab character itself is not copied.)  If the character '
+                   'is a newline\n'
+                   '   ("\\n") or return ("\\r"), it is copied and the current '
+                   'column is\n'
+                   '   reset to zero.  Any other character is copied unchanged '
+                   'and the\n'
+                   '   current column is incremented by one regardless of how '
+                   'the\n'
+                   '   character is represented when printed.\n'
+                   '\n'
+                   "   >>> '01\\t012\\t0123\\t01234'.expandtabs()\n"
+                   "   '01      012     0123    01234'\n"
+                   "   >>> '01\\t012\\t0123\\t01234'.expandtabs(4)\n"
+                   "   '01  012 0123    01234'\n"
+                   '\n'
+                   'str.find(sub[, start[, end]])\n'
+                   '\n'
+                   '   Return the lowest index in the string where substring '
+                   '*sub* is\n'
+                   '   found within the slice "s[start:end]".  Optional '
+                   'arguments *start*\n'
+                   '   and *end* are interpreted as in slice notation.  Return '
+                   '"-1" if\n'
+                   '   *sub* is not found.\n'
+                   '\n'
+                   '   Note: The "find()" method should be used only if you '
+                   'need to know\n'
+                   '     the position of *sub*.  To check if *sub* is a '
+                   'substring or not,\n'
+                   '     use the "in" operator:\n'
+                   '\n'
+                   "        >>> 'Py' in 'Python'\n"
+                   '        True\n'
+                   '\n'
+                   'str.format(*args, **kwargs)\n'
+                   '\n'
+                   '   Perform a string formatting operation.  The string on '
+                   'which this\n'
+                   '   method is called can contain literal text or '
+                   'replacement fields\n'
+                   '   delimited by braces "{}".  Each replacement field '
+                   'contains either\n'
+                   '   the numeric index of a positional argument, or the name '
+                   'of a\n'
+                   '   keyword argument.  Returns a copy of the string where '
+                   'each\n'
+                   '   replacement field is replaced with the string value of '
+                   'the\n'
+                   '   corresponding argument.\n'
+                   '\n'
+                   '   >>> "The sum of 1 + 2 is {0}".format(1+2)\n'
+                   "   'The sum of 1 + 2 is 3'\n"
+                   '\n'
+                   '   See Format String Syntax for a description of the '
+                   'various\n'
+                   '   formatting options that can be specified in format '
+                   'strings.\n'
+                   '\n'
+                   'str.format_map(mapping)\n'
+                   '\n'
+                   '   Similar to "str.format(**mapping)", except that '
+                   '"mapping" is used\n'
+                   '   directly and not copied to a "dict".  This is useful if '
+                   'for example\n'
+                   '   "mapping" is a dict subclass:\n'
+                   '\n'
+                   '   >>> class Default(dict):\n'
+                   '   ...     def __missing__(self, key):\n'
+                   '   ...         return key\n'
+                   '   ...\n'
+                   "   >>> '{name} was born in "
+                   "{country}'.format_map(Default(name='Guido'))\n"
+                   "   'Guido was born in country'\n"
+                   '\n'
+                   '   New in version 3.2.\n'
+                   '\n'
+                   'str.index(sub[, start[, end]])\n'
+                   '\n'
+                   '   Like "find()", but raise "ValueError" when the '
+                   'substring is not\n'
+                   '   found.\n'
+                   '\n'
+                   'str.isalnum()\n'
+                   '\n'
+                   '   Return true if all characters in the string are '
+                   'alphanumeric and\n'
+                   '   there is at least one character, false otherwise.  A '
+                   'character "c"\n'
+                   '   is alphanumeric if one of the following returns '
+                   '"True":\n'
+                   '   "c.isalpha()", "c.isdecimal()", "c.isdigit()", or '
+                   '"c.isnumeric()".\n'
+                   '\n'
+                   'str.isalpha()\n'
+                   '\n'
+                   '   Return true if all characters in the string are '
+                   'alphabetic and\n'
+                   '   there is at least one character, false otherwise.  '
+                   'Alphabetic\n'
+                   '   characters are those characters defined in the Unicode '
+                   'character\n'
+                   '   database as "Letter", i.e., those with general category '
+                   'property\n'
+                   '   being one of "Lm", "Lt", "Lu", "Ll", or "Lo".  Note '
+                   'that this is\n'
+                   '   different from the "Alphabetic" property defined in the '
+                   'Unicode\n'
+                   '   Standard.\n'
+                   '\n'
+                   'str.isdecimal()\n'
+                   '\n'
+                   '   Return true if all characters in the string are decimal '
+                   'characters\n'
+                   '   and there is at least one character, false otherwise. '
+                   'Decimal\n'
+                   '   characters are those from general category "Nd". This '
+                   'category\n'
+                   '   includes digit characters, and all characters that can '
+                   'be used to\n'
+                   '   form decimal-radix numbers, e.g. U+0660, ARABIC-INDIC '
+                   'DIGIT ZERO.\n'
+                   '\n'
+                   'str.isdigit()\n'
+                   '\n'
+                   '   Return true if all characters in the string are digits '
+                   'and there is\n'
+                   '   at least one character, false otherwise.  Digits '
+                   'include decimal\n'
+                   '   characters and digits that need special handling, such '
+                   'as the\n'
+                   '   compatibility superscript digits.  Formally, a digit is '
+                   'a character\n'
+                   '   that has the property value Numeric_Type=Digit or\n'
+                   '   Numeric_Type=Decimal.\n'
+                   '\n'
+                   'str.isidentifier()\n'
+                   '\n'
+                   '   Return true if the string is a valid identifier '
+                   'according to the\n'
+                   '   language definition, section Identifiers and keywords.\n'
+                   '\n'
+                   '   Use "keyword.iskeyword()" to test for reserved '
+                   'identifiers such as\n'
+                   '   "def" and "class".\n'
+                   '\n'
+                   'str.islower()\n'
+                   '\n'
+                   '   Return true if all cased characters [4] in the string '
+                   'are lowercase\n'
+                   '   and there is at least one cased character, false '
+                   'otherwise.\n'
+                   '\n'
+                   'str.isnumeric()\n'
+                   '\n'
+                   '   Return true if all characters in the string are numeric '
+                   'characters,\n'
+                   '   and there is at least one character, false otherwise. '
+                   'Numeric\n'
+                   '   characters include digit characters, and all characters '
+                   'that have\n'
+                   '   the Unicode numeric value property, e.g. U+2155, VULGAR '
+                   'FRACTION\n'
+                   '   ONE FIFTH.  Formally, numeric characters are those with '
+                   'the\n'
+                   '   property value Numeric_Type=Digit, Numeric_Type=Decimal '
+                   'or\n'
+                   '   Numeric_Type=Numeric.\n'
+                   '\n'
+                   'str.isprintable()\n'
+                   '\n'
+                   '   Return true if all characters in the string are '
+                   'printable or the\n'
+                   '   string is empty, false otherwise.  Nonprintable '
+                   'characters are\n'
+                   '   those characters defined in the Unicode character '
+                   'database as\n'
+                   '   "Other" or "Separator", excepting the ASCII space '
+                   '(0x20) which is\n'
+                   '   considered printable.  (Note that printable characters '
+                   'in this\n'
+                   '   context are those which should not be escaped when '
+                   '"repr()" is\n'
+                   '   invoked on a string.  It has no bearing on the handling '
+                   'of strings\n'
+                   '   written to "sys.stdout" or "sys.stderr".)\n'
+                   '\n'
+                   'str.isspace()\n'
+                   '\n'
+                   '   Return true if there are only whitespace characters in '
+                   'the string\n'
+                   '   and there is at least one character, false otherwise.  '
+                   'Whitespace\n'
+                   '   characters  are those characters defined in the Unicode '
+                   'character\n'
+                   '   database as "Other" or "Separator" and those with '
+                   'bidirectional\n'
+                   '   property being one of "WS", "B", or "S".\n'
+                   '\n'
+                   'str.istitle()\n'
+                   '\n'
+                   '   Return true if the string is a titlecased string and '
+                   'there is at\n'
+                   '   least one character, for example uppercase characters '
+                   'may only\n'
+                   '   follow uncased characters and lowercase characters only '
+                   'cased ones.\n'
+                   '   Return false otherwise.\n'
+                   '\n'
+                   'str.isupper()\n'
+                   '\n'
+                   '   Return true if all cased characters [4] in the string '
+                   'are uppercase\n'
+                   '   and there is at least one cased character, false '
+                   'otherwise.\n'
+                   '\n'
+                   'str.join(iterable)\n'
+                   '\n'
+                   '   Return a string which is the concatenation of the '
+                   'strings in the\n'
+                   '   *iterable* *iterable*.  A "TypeError" will be raised if '
+                   'there are\n'
+                   '   any non-string values in *iterable*, including "bytes" '
+                   'objects.\n'
+                   '   The separator between elements is the string providing '
+                   'this method.\n'
+                   '\n'
+                   'str.ljust(width[, fillchar])\n'
+                   '\n'
+                   '   Return the string left justified in a string of length '
+                   '*width*.\n'
+                   '   Padding is done using the specified *fillchar* (default '
+                   'is an ASCII\n'
+                   '   space). The original string is returned if *width* is '
+                   'less than or\n'
+                   '   equal to "len(s)".\n'
+                   '\n'
+                   'str.lower()\n'
+                   '\n'
+                   '   Return a copy of the string with all the cased '
+                   'characters [4]\n'
+                   '   converted to lowercase.\n'
+                   '\n'
+                   '   The lowercasing algorithm used is described in section '
+                   '3.13 of the\n'
+                   '   Unicode Standard.\n'
+                   '\n'
+                   'str.lstrip([chars])\n'
+                   '\n'
+                   '   Return a copy of the string with leading characters '
+                   'removed.  The\n'
+                   '   *chars* argument is a string specifying the set of '
+                   'characters to be\n'
+                   '   removed.  If omitted or "None", the *chars* argument '
+                   'defaults to\n'
+                   '   removing whitespace.  The *chars* argument is not a '
+                   'prefix; rather,\n'
+                   '   all combinations of its values are stripped:\n'
+                   '\n'
+                   "      >>> '   spacious   '.lstrip()\n"
+                   "      'spacious   '\n"
+                   "      >>> 'www.example.com'.lstrip('cmowz.')\n"
+                   "      'example.com'\n"
+                   '\n'
+                   'static str.maketrans(x[, y[, z]])\n'
+                   '\n'
+                   '   This static method returns a translation table usable '
+                   'for\n'
+                   '   "str.translate()".\n'
+                   '\n'
+                   '   If there is only one argument, it must be a dictionary '
+                   'mapping\n'
+                   '   Unicode ordinals (integers) or characters (strings of '
+                   'length 1) to\n'
+                   '   Unicode ordinals, strings (of arbitrary lengths) or '
+                   'None.\n'
+                   '   Character keys will then be converted to ordinals.\n'
+                   '\n'
+                   '   If there are two arguments, they must be strings of '
+                   'equal length,\n'
+                   '   and in the resulting dictionary, each character in x '
+                   'will be mapped\n'
+                   '   to the character at the same position in y.  If there '
+                   'is a third\n'
+                   '   argument, it must be a string, whose characters will be '
+                   'mapped to\n'
+                   '   None in the result.\n'
+                   '\n'
+                   'str.partition(sep)\n'
+                   '\n'
+                   '   Split the string at the first occurrence of *sep*, and '
+                   'return a\n'
+                   '   3-tuple containing the part before the separator, the '
+                   'separator\n'
+                   '   itself, and the part after the separator.  If the '
+                   'separator is not\n'
+                   '   found, return a 3-tuple containing the string itself, '
+                   'followed by\n'
+                   '   two empty strings.\n'
+                   '\n'
+                   'str.replace(old, new[, count])\n'
+                   '\n'
+                   '   Return a copy of the string with all occurrences of '
+                   'substring *old*\n'
+                   '   replaced by *new*.  If the optional argument *count* is '
+                   'given, only\n'
+                   '   the first *count* occurrences are replaced.\n'
+                   '\n'
+                   'str.rfind(sub[, start[, end]])\n'
+                   '\n'
+                   '   Return the highest index in the string where substring '
+                   '*sub* is\n'
+                   '   found, such that *sub* is contained within '
+                   '"s[start:end]".\n'
+                   '   Optional arguments *start* and *end* are interpreted as '
+                   'in slice\n'
+                   '   notation.  Return "-1" on failure.\n'
+                   '\n'
+                   'str.rindex(sub[, start[, end]])\n'
+                   '\n'
+                   '   Like "rfind()" but raises "ValueError" when the '
+                   'substring *sub* is\n'
+                   '   not found.\n'
+                   '\n'
+                   'str.rjust(width[, fillchar])\n'
+                   '\n'
+                   '   Return the string right justified in a string of length '
+                   '*width*.\n'
+                   '   Padding is done using the specified *fillchar* (default '
+                   'is an ASCII\n'
+                   '   space). The original string is returned if *width* is '
+                   'less than or\n'
+                   '   equal to "len(s)".\n'
+                   '\n'
+                   'str.rpartition(sep)\n'
+                   '\n'
+                   '   Split the string at the last occurrence of *sep*, and '
+                   'return a\n'
+                   '   3-tuple containing the part before the separator, the '
+                   'separator\n'
+                   '   itself, and the part after the separator.  If the '
+                   'separator is not\n'
+                   '   found, return a 3-tuple containing two empty strings, '
+                   'followed by\n'
+                   '   the string itself.\n'
+                   '\n'
+                   'str.rsplit(sep=None, maxsplit=-1)\n'
+                   '\n'
+                   '   Return a list of the words in the string, using *sep* '
+                   'as the\n'
+                   '   delimiter string. If *maxsplit* is given, at most '
+                   '*maxsplit* splits\n'
+                   '   are done, the *rightmost* ones.  If *sep* is not '
+                   'specified or\n'
+                   '   "None", any whitespace string is a separator.  Except '
+                   'for splitting\n'
+                   '   from the right, "rsplit()" behaves like "split()" which '
+                   'is\n'
+                   '   described in detail below.\n'
+                   '\n'
+                   'str.rstrip([chars])\n'
+                   '\n'
+                   '   Return a copy of the string with trailing characters '
+                   'removed.  The\n'
+                   '   *chars* argument is a string specifying the set of '
+                   'characters to be\n'
+                   '   removed.  If omitted or "None", the *chars* argument '
+                   'defaults to\n'
+                   '   removing whitespace.  The *chars* argument is not a '
+                   'suffix; rather,\n'
+                   '   all combinations of its values are stripped:\n'
+                   '\n'
+                   "      >>> '   spacious   '.rstrip()\n"
+                   "      '   spacious'\n"
+                   "      >>> 'mississippi'.rstrip('ipz')\n"
+                   "      'mississ'\n"
+                   '\n'
+                   'str.split(sep=None, maxsplit=-1)\n'
+                   '\n'
+                   '   Return a list of the words in the string, using *sep* '
+                   'as the\n'
+                   '   delimiter string.  If *maxsplit* is given, at most '
+                   '*maxsplit*\n'
+                   '   splits are done (thus, the list will have at most '
+                   '"maxsplit+1"\n'
+                   '   elements).  If *maxsplit* is not specified or "-1", '
+                   'then there is\n'
+                   '   no limit on the number of splits (all possible splits '
+                   'are made).\n'
+                   '\n'
+                   '   If *sep* is given, consecutive delimiters are not '
+                   'grouped together\n'
+                   '   and are deemed to delimit empty strings (for example,\n'
+                   '   "\'1,,2\'.split(\',\')" returns "[\'1\', \'\', '
+                   '\'2\']").  The *sep* argument\n'
+                   '   may consist of multiple characters (for example,\n'
+                   '   "\'1<>2<>3\'.split(\'<>\')" returns "[\'1\', \'2\', '
+                   '\'3\']"). Splitting an\n'
+                   '   empty string with a specified separator returns '
+                   '"[\'\']".\n'
+                   '\n'
+                   '   For example:\n'
+                   '\n'
+                   "      >>> '1,2,3'.split(',')\n"
+                   "      ['1', '2', '3']\n"
+                   "      >>> '1,2,3'.split(',', maxsplit=1)\n"
+                   "      ['1', '2,3']\n"
+                   "      >>> '1,2,,3,'.split(',')\n"
+                   "      ['1', '2', '', '3', '']\n"
+                   '\n'
+                   '   If *sep* is not specified or is "None", a different '
+                   'splitting\n'
+                   '   algorithm is applied: runs of consecutive whitespace '
+                   'are regarded\n'
+                   '   as a single separator, and the result will contain no '
+                   'empty strings\n'
+                   '   at the start or end if the string has leading or '
+                   'trailing\n'
+                   '   whitespace.  Consequently, splitting an empty string or '
+                   'a string\n'
+                   '   consisting of just whitespace with a "None" separator '
+                   'returns "[]".\n'
+                   '\n'
+                   '   For example:\n'
+                   '\n'
+                   "      >>> '1 2 3'.split()\n"
+                   "      ['1', '2', '3']\n"
+                   "      >>> '1 2 3'.split(maxsplit=1)\n"
+                   "      ['1', '2 3']\n"
+                   "      >>> '   1   2   3   '.split()\n"
+                   "      ['1', '2', '3']\n"
+                   '\n'
+                   'str.splitlines([keepends])\n'
+                   '\n'
+                   '   Return a list of the lines in the string, breaking at '
+                   'line\n'
+                   '   boundaries.  Line breaks are not included in the '
+                   'resulting list\n'
+                   '   unless *keepends* is given and true.\n'
+                   '\n'
+                   '   This method splits on the following line boundaries.  '
+                   'In\n'
+                   '   particular, the boundaries are a superset of *universal '
+                   'newlines*.\n'
+                   '\n'
+                   '   '
+                   '+-------------------------+-------------------------------+\n'
+                   '   | Representation          | '
+                   'Description                   |\n'
+                   '   '
+                   '+=========================+===============================+\n'
+                   '   | "\\n"                    | Line '
+                   'Feed                     |\n'
+                   '   '
+                   '+-------------------------+-------------------------------+\n'
+                   '   | "\\r"                    | Carriage '
+                   'Return               |\n'
+                   '   '
+                   '+-------------------------+-------------------------------+\n'
+                   '   | "\\r\\n"                  | Carriage Return + Line '
+                   'Feed   |\n'
+                   '   '
+                   '+-------------------------+-------------------------------+\n'
+                   '   | "\\v" or "\\x0b"          | Line '
+                   'Tabulation               |\n'
+                   '   '
+                   '+-------------------------+-------------------------------+\n'
+                   '   | "\\f" or "\\x0c"          | Form '
+                   'Feed                     |\n'
+                   '   '
+                   '+-------------------------+-------------------------------+\n'
+                   '   | "\\x1c"                  | File '
+                   'Separator                |\n'
+                   '   '
+                   '+-------------------------+-------------------------------+\n'
+                   '   | "\\x1d"                  | Group '
+                   'Separator               |\n'
+                   '   '
+                   '+-------------------------+-------------------------------+\n'
+                   '   | "\\x1e"                  | Record '
+                   'Separator              |\n'
+                   '   '
+                   '+-------------------------+-------------------------------+\n'
+                   '   | "\\x85"                  | Next Line (C1 Control '
+                   'Code)   |\n'
+                   '   '
+                   '+-------------------------+-------------------------------+\n'
+                   '   | "\\u2028"                | Line '
+                   'Separator                |\n'
+                   '   '
+                   '+-------------------------+-------------------------------+\n'
+                   '   | "\\u2029"                | Paragraph '
+                   'Separator           |\n'
+                   '   '
+                   '+-------------------------+-------------------------------+\n'
+                   '\n'
+                   '   Changed in version 3.2: "\\v" and "\\f" added to list '
+                   'of line\n'
+                   '   boundaries.\n'
+                   '\n'
+                   '   For example:\n'
+                   '\n'
+                   "      >>> 'ab c\\n\\nde fg\\rkl\\r\\n'.splitlines()\n"
+                   "      ['ab c', '', 'de fg', 'kl']\n"
+                   "      >>> 'ab c\\n\\nde "
+                   "fg\\rkl\\r\\n'.splitlines(keepends=True)\n"
+                   "      ['ab c\\n', '\\n', 'de fg\\r', 'kl\\r\\n']\n"
+                   '\n'
+                   '   Unlike "split()" when a delimiter string *sep* is '
+                   'given, this\n'
+                   '   method returns an empty list for the empty string, and '
+                   'a terminal\n'
+                   '   line break does not result in an extra line:\n'
+                   '\n'
+                   '      >>> "".splitlines()\n'
+                   '      []\n'
+                   '      >>> "One line\\n".splitlines()\n'
+                   "      ['One line']\n"
+                   '\n'
+                   '   For comparison, "split(\'\\n\')" gives:\n'
+                   '\n'
+                   "      >>> ''.split('\\n')\n"
+                   "      ['']\n"
+                   "      >>> 'Two lines\\n'.split('\\n')\n"
+                   "      ['Two lines', '']\n"
+                   '\n'
+                   'str.startswith(prefix[, start[, end]])\n'
+                   '\n'
+                   '   Return "True" if string starts with the *prefix*, '
+                   'otherwise return\n'
+                   '   "False". *prefix* can also be a tuple of prefixes to '
+                   'look for.\n'
+                   '   With optional *start*, test string beginning at that '
+                   'position.\n'
+                   '   With optional *end*, stop comparing string at that '
+                   'position.\n'
+                   '\n'
+                   'str.strip([chars])\n'
+                   '\n'
+                   '   Return a copy of the string with the leading and '
+                   'trailing\n'
+                   '   characters removed. The *chars* argument is a string '
+                   'specifying the\n'
+                   '   set of characters to be removed. If omitted or "None", '
+                   'the *chars*\n'
+                   '   argument defaults to removing whitespace. The *chars* '
+                   'argument is\n'
+                   '   not a prefix or suffix; rather, all combinations of its '
+                   'values are\n'
+                   '   stripped:\n'
+                   '\n'
+                   "      >>> '   spacious   '.strip()\n"
+                   "      'spacious'\n"
+                   "      >>> 'www.example.com'.strip('cmowz.')\n"
+                   "      'example'\n"
+                   '\n'
+                   '   The outermost leading and trailing *chars* argument '
+                   'values are\n'
+                   '   stripped from the string. Characters are removed from '
+                   'the leading\n'
+                   '   end until reaching a string character that is not '
+                   'contained in the\n'
+                   '   set of characters in *chars*. A similar action takes '
+                   'place on the\n'
+                   '   trailing end. For example:\n'
+                   '\n'
+                   "      >>> comment_string = '#....... Section 3.2.1 Issue "
+                   "#32 .......'\n"
+                   "      >>> comment_string.strip('.#! ')\n"
+                   "      'Section 3.2.1 Issue #32'\n"
+                   '\n'
+                   'str.swapcase()\n'
+                   '\n'
+                   '   Return a copy of the string with uppercase characters '
+                   'converted to\n'
+                   '   lowercase and vice versa. Note that it is not '
+                   'necessarily true that\n'
+                   '   "s.swapcase().swapcase() == s".\n'
+                   '\n'
+                   'str.title()\n'
+                   '\n'
+                   '   Return a titlecased version of the string where words '
+                   'start with an\n'
+                   '   uppercase character and the remaining characters are '
+                   'lowercase.\n'
+                   '\n'
+                   '   For example:\n'
+                   '\n'
+                   "      >>> 'Hello world'.title()\n"
+                   "      'Hello World'\n"
+                   '\n'
+                   '   The algorithm uses a simple language-independent '
+                   'definition of a\n'
+                   '   word as groups of consecutive letters.  The definition '
+                   'works in\n'
+                   '   many contexts but it means that apostrophes in '
+                   'contractions and\n'
+                   '   possessives form word boundaries, which may not be the '
+                   'desired\n'
+                   '   result:\n'
+                   '\n'
+                   '      >>> "they\'re bill\'s friends from the UK".title()\n'
+                   '      "They\'Re Bill\'S Friends From The Uk"\n'
+                   '\n'
+                   '   A workaround for apostrophes can be constructed using '
+                   'regular\n'
+                   '   expressions:\n'
+                   '\n'
+                   '      >>> import re\n'
+                   '      >>> def titlecase(s):\n'
+                   '      ...     return re.sub(r"[A-Za-z]+(\'[A-Za-z]+)?",\n'
+                   '      ...                   lambda mo: '
+                   'mo.group(0)[0].upper() +\n'
+                   '      ...                              '
+                   'mo.group(0)[1:].lower(),\n'
+                   '      ...                   s)\n'
+                   '      ...\n'
+                   '      >>> titlecase("they\'re bill\'s friends.")\n'
+                   '      "They\'re Bill\'s Friends."\n'
+                   '\n'
+                   'str.translate(table)\n'
+                   '\n'
+                   '   Return a copy of the string in which each character has '
+                   'been mapped\n'
+                   '   through the given translation table.  The table must be '
+                   'an object\n'
+                   '   that implements indexing via "__getitem__()", typically '
+                   'a *mapping*\n'
+                   '   or *sequence*.  When indexed by a Unicode ordinal (an '
+                   'integer), the\n'
+                   '   table object can do any of the following: return a '
+                   'Unicode ordinal\n'
+                   '   or a string, to map the character to one or more other '
+                   'characters;\n'
+                   '   return "None", to delete the character from the return '
+                   'string; or\n'
+                   '   raise a "LookupError" exception, to map the character '
+                   'to itself.\n'
+                   '\n'
+                   '   You can use "str.maketrans()" to create a translation '
+                   'map from\n'
+                   '   character-to-character mappings in different formats.\n'
+                   '\n'
+                   '   See also the "codecs" module for a more flexible '
+                   'approach to custom\n'
+                   '   character mappings.\n'
+                   '\n'
+                   'str.upper()\n'
+                   '\n'
+                   '   Return a copy of the string with all the cased '
+                   'characters [4]\n'
+                   '   converted to uppercase.  Note that '
+                   '"str.upper().isupper()" might be\n'
+                   '   "False" if "s" contains uncased characters or if the '
+                   'Unicode\n'
+                   '   category of the resulting character(s) is not "Lu" '
+                   '(Letter,\n'
+                   '   uppercase), but e.g. "Lt" (Letter, titlecase).\n'
+                   '\n'
+                   '   The uppercasing algorithm used is described in section '
+                   '3.13 of the\n'
+                   '   Unicode Standard.\n'
+                   '\n'
+                   'str.zfill(width)\n'
+                   '\n'
+                   '   Return a copy of the string left filled with ASCII '
+                   '"\'0\'" digits to\n'
+                   '   make a string of length *width*. A leading sign prefix\n'
+                   '   ("\'+\'"/"\'-\'") is handled by inserting the padding '
+                   '*after* the sign\n'
+                   '   character rather than before. The original string is '
+                   'returned if\n'
+                   '   *width* is less than or equal to "len(s)".\n'
+                   '\n'
+                   '   For example:\n'
+                   '\n'
+                   '      >>> "42".zfill(5)\n'
+                   "      '00042'\n"
+                   '      >>> "-42".zfill(5)\n'
+                   "      '-0042'\n",
+ 'strings': '\n'
+            'String and Bytes literals\n'
+            '*************************\n'
+            '\n'
+            'String literals are described by the following lexical '
+            'definitions:\n'
+            '\n'
+            '   stringliteral   ::= [stringprefix](shortstring | longstring)\n'
+            '   stringprefix    ::= "r" | "u" | "R" | "U" | "f" | "F"\n'
+            '                    | "fr" | "Fr" | "fR" | "FR" | "rf" | "rF" | '
+            '"Rf" | "RF"\n'
+            '   shortstring     ::= "\'" shortstringitem* "\'" | \'"\' '
+            'shortstringitem* \'"\'\n'
+            '   longstring      ::= "\'\'\'" longstringitem* "\'\'\'" | '
+            '\'"""\' longstringitem* \'"""\'\n'
+            '   shortstringitem ::= shortstringchar | stringescapeseq\n'
+            '   longstringitem  ::= longstringchar | stringescapeseq\n'
+            '   shortstringchar ::= <any source character except "\\" or '
+            'newline or the quote>\n'
+            '   longstringchar  ::= <any source character except "\\">\n'
+            '   stringescapeseq ::= "\\" <any source character>\n'
+            '\n'
+            '   bytesliteral   ::= bytesprefix(shortbytes | longbytes)\n'
+            '   bytesprefix    ::= "b" | "B" | "br" | "Br" | "bR" | "BR" | '
+            '"rb" | "rB" | "Rb" | "RB"\n'
+            '   shortbytes     ::= "\'" shortbytesitem* "\'" | \'"\' '
+            'shortbytesitem* \'"\'\n'
+            '   longbytes      ::= "\'\'\'" longbytesitem* "\'\'\'" | \'"""\' '
+            'longbytesitem* \'"""\'\n'
+            '   shortbytesitem ::= shortbyteschar | bytesescapeseq\n'
+            '   longbytesitem  ::= longbyteschar | bytesescapeseq\n'
+            '   shortbyteschar ::= <any ASCII character except "\\" or newline '
+            'or the quote>\n'
+            '   longbyteschar  ::= <any ASCII character except "\\">\n'
+            '   bytesescapeseq ::= "\\" <any ASCII character>\n'
+            '\n'
+            'One syntactic restriction not indicated by these productions is '
+            'that\n'
+            'whitespace is not allowed between the "stringprefix" or '
+            '"bytesprefix"\n'
+            'and the rest of the literal. The source character set is defined '
+            'by\n'
+            'the encoding declaration; it is UTF-8 if no encoding declaration '
+            'is\n'
+            'given in the source file; see section Encoding declarations.\n'
+            '\n'
+            'In plain English: Both types of literals can be enclosed in '
+            'matching\n'
+            'single quotes ("\'") or double quotes (""").  They can also be '
+            'enclosed\n'
+            'in matching groups of three single or double quotes (these are\n'
+            'generally referred to as *triple-quoted strings*).  The '
+            'backslash\n'
+            '("\\") character is used to escape characters that otherwise have '
+            'a\n'
+            'special meaning, such as newline, backslash itself, or the quote\n'
+            'character.\n'
+            '\n'
+            'Bytes literals are always prefixed with "\'b\'" or "\'B\'"; they '
+            'produce\n'
+            'an instance of the "bytes" type instead of the "str" type.  They '
+            'may\n'
+            'only contain ASCII characters; bytes with a numeric value of 128 '
+            'or\n'
+            'greater must be expressed with escapes.\n'
+            '\n'
+            'As of Python 3.3 it is possible again to prefix string literals '
+            'with a\n'
+            '"u" prefix to simplify maintenance of dual 2.x and 3.x '
+            'codebases.\n'
+            '\n'
+            'Both string and bytes literals may optionally be prefixed with a\n'
+            'letter "\'r\'" or "\'R\'"; such strings are called *raw strings* '
+            'and treat\n'
+            'backslashes as literal characters.  As a result, in string '
+            'literals,\n'
+            '"\'\\U\'" and "\'\\u\'" escapes in raw strings are not treated '
+            'specially.\n'
+            "Given that Python 2.x's raw unicode literals behave differently "
+            'than\n'
+            'Python 3.x\'s the "\'ur\'" syntax is not supported.\n'
+            '\n'
+            'New in version 3.3: The "\'rb\'" prefix of raw bytes literals has '
+            'been\n'
+            'added as a synonym of "\'br\'".\n'
+            '\n'
+            'New in version 3.3: Support for the unicode legacy literal\n'
+            '("u\'value\'") was reintroduced to simplify the maintenance of '
+            'dual\n'
+            'Python 2.x and 3.x codebases. See **PEP 414** for more '
+            'information.\n'
+            '\n'
+            'A string literal with "\'f\'" or "\'F\'" in its prefix is a '
+            '*formatted\n'
+            'string literal*; see Formatted string literals.  The "\'f\'" may '
+            'be\n'
+            'combined with "\'r\'", but not with "\'b\'" or "\'u\'", therefore '
+            'raw\n'
+            'formatted strings are possible, but formatted bytes literals are '
+            'not.\n'
+            '\n'
+            'In triple-quoted literals, unescaped newlines and quotes are '
+            'allowed\n'
+            '(and are retained), except that three unescaped quotes in a row\n'
+            'terminate the literal.  (A "quote" is the character used to open '
+            'the\n'
+            'literal, i.e. either "\'" or """.)\n'
+            '\n'
+            'Unless an "\'r\'" or "\'R\'" prefix is present, escape sequences '
+            'in string\n'
+            'and bytes literals are interpreted according to rules similar to '
+            'those\n'
+            'used by Standard C.  The recognized escape sequences are:\n'
+            '\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '| Escape Sequence   | Meaning                           | Notes   '
+            '|\n'
+            '+===================+===================================+=========+\n'
+            '| "\\newline"        | Backslash and newline ignored     '
+            '|         |\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '| "\\\\"              | Backslash ("\\")                   '
+            '|         |\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '| "\\\'"              | Single quote ("\'")                '
+            '|         |\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '| "\\""              | Double quote (""")                '
+            '|         |\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '| "\\a"              | ASCII Bell (BEL)                  '
+            '|         |\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '| "\\b"              | ASCII Backspace (BS)              '
+            '|         |\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '| "\\f"              | ASCII Formfeed (FF)               '
+            '|         |\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '| "\\n"              | ASCII Linefeed (LF)               '
+            '|         |\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '| "\\r"              | ASCII Carriage Return (CR)        '
+            '|         |\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '| "\\t"              | ASCII Horizontal Tab (TAB)        '
+            '|         |\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '| "\\v"              | ASCII Vertical Tab (VT)           '
+            '|         |\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '| "\\ooo"            | Character with octal value *ooo*  | '
+            '(1,3)   |\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '| "\\xhh"            | Character with hex value *hh*     | '
+            '(2,3)   |\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '\n'
+            'Escape sequences only recognized in string literals are:\n'
+            '\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '| Escape Sequence   | Meaning                           | Notes   '
+            '|\n'
+            '+===================+===================================+=========+\n'
+            '| "\\N{name}"        | Character named *name* in the     | '
+            '(4)     |\n'
+            '|                   | Unicode database                  |         '
+            '|\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '| "\\uxxxx"          | Character with 16-bit hex value   | '
+            '(5)     |\n'
+            '|                   | *xxxx*                            |         '
+            '|\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '| "\\Uxxxxxxxx"      | Character with 32-bit hex value   | '
+            '(6)     |\n'
+            '|                   | *xxxxxxxx*                        |         '
+            '|\n'
+            '+-------------------+-----------------------------------+---------+\n'
+            '\n'
+            'Notes:\n'
+            '\n'
+            '1. As in Standard C, up to three octal digits are accepted.\n'
+            '\n'
+            '2. Unlike in Standard C, exactly two hex digits are required.\n'
+            '\n'
+            '3. In a bytes literal, hexadecimal and octal escapes denote the\n'
+            '   byte with the given value. In a string literal, these escapes\n'
+            '   denote a Unicode character with the given value.\n'
+            '\n'
+            '4. Changed in version 3.3: Support for name aliases [1] has been\n'
+            '   added.\n'
+            '\n'
+            '5. Exactly four hex digits are required.\n'
+            '\n'
+            '6. Any Unicode character can be encoded this way.  Exactly eight\n'
+            '   hex digits are required.\n'
+            '\n'
+            'Unlike Standard C, all unrecognized escape sequences are left in '
+            'the\n'
+            'string unchanged, i.e., *the backslash is left in the result*.  '
+            '(This\n'
+            'behavior is useful when debugging: if an escape sequence is '
+            'mistyped,\n'
+            'the resulting output is more easily recognized as broken.)  It is '
+            'also\n'
+            'important to note that the escape sequences only recognized in '
+            'string\n'
+            'literals fall into the category of unrecognized escapes for '
+            'bytes\n'
+            'literals.\n'
+            '\n'
+            'Even in a raw literal, quotes can be escaped with a backslash, '
+            'but the\n'
+            'backslash remains in the result; for example, "r"\\""" is a '
+            'valid\n'
+            'string literal consisting of two characters: a backslash and a '
+            'double\n'
+            'quote; "r"\\"" is not a valid string literal (even a raw string '
+            'cannot\n'
+            'end in an odd number of backslashes).  Specifically, *a raw '
+            'literal\n'
+            'cannot end in a single backslash* (since the backslash would '
+            'escape\n'
+            'the following quote character).  Note also that a single '
+            'backslash\n'
+            'followed by a newline is interpreted as those two characters as '
+            'part\n'
+            'of the literal, *not* as a line continuation.\n',
+ 'subscriptions': '\n'
+                  'Subscriptions\n'
+                  '*************\n'
+                  '\n'
+                  'A subscription selects an item of a sequence (string, tuple '
+                  'or list)\n'
+                  'or mapping (dictionary) object:\n'
+                  '\n'
+                  '   subscription ::= primary "[" expression_list "]"\n'
+                  '\n'
+                  'The primary must evaluate to an object that supports '
+                  'subscription\n'
+                  '(lists or dictionaries for example).  User-defined objects '
+                  'can support\n'
+                  'subscription by defining a "__getitem__()" method.\n'
+                  '\n'
+                  'For built-in objects, there are two types of objects that '
+                  'support\n'
+                  'subscription:\n'
+                  '\n'
+                  'If the primary is a mapping, the expression list must '
+                  'evaluate to an\n'
+                  'object whose value is one of the keys of the mapping, and '
+                  'the\n'
+                  'subscription selects the value in the mapping that '
+                  'corresponds to that\n'
+                  'key.  (The expression list is a tuple except if it has '
+                  'exactly one\n'
+                  'item.)\n'
+                  '\n'
+                  'If the primary is a sequence, the expression (list) must '
+                  'evaluate to\n'
+                  'an integer or a slice (as discussed in the following '
+                  'section).\n'
+                  '\n'
+                  'The formal syntax makes no special provision for negative '
+                  'indices in\n'
+                  'sequences; however, built-in sequences all provide a '
+                  '"__getitem__()"\n'
+                  'method that interprets negative indices by adding the '
+                  'length of the\n'
+                  'sequence to the index (so that "x[-1]" selects the last '
+                  'item of "x").\n'
+                  'The resulting value must be a nonnegative integer less than '
+                  'the number\n'
+                  'of items in the sequence, and the subscription selects the '
+                  'item whose\n'
+                  'index is that value (counting from zero). Since the support '
+                  'for\n'
+                  "negative indices and slicing occurs in the object's "
+                  '"__getitem__()"\n'
+                  'method, subclasses overriding this method will need to '
+                  'explicitly add\n'
+                  'that support.\n'
+                  '\n'
+                  "A string's items are characters.  A character is not a "
+                  'separate data\n'
+                  'type but a string of exactly one character.\n',
+ 'truth': '\n'
+          'Truth Value Testing\n'
+          '*******************\n'
+          '\n'
+          'Any object can be tested for truth value, for use in an "if" or\n'
+          '"while" condition or as operand of the Boolean operations below. '
+          'The\n'
+          'following values are considered false:\n'
+          '\n'
+          '* "None"\n'
+          '\n'
+          '* "False"\n'
+          '\n'
+          '* zero of any numeric type, for example, "0", "0.0", "0j".\n'
+          '\n'
+          '* any empty sequence, for example, "\'\'", "()", "[]".\n'
+          '\n'
+          '* any empty mapping, for example, "{}".\n'
+          '\n'
+          '* instances of user-defined classes, if the class defines a\n'
+          '  "__bool__()" or "__len__()" method, when that method returns the\n'
+          '  integer zero or "bool" value "False". [1]\n'
+          '\n'
+          'All other values are considered true --- so objects of many types '
+          'are\n'
+          'always true.\n'
+          '\n'
+          'Operations and built-in functions that have a Boolean result '
+          'always\n'
+          'return "0" or "False" for false and "1" or "True" for true, unless\n'
+          'otherwise stated. (Important exception: the Boolean operations '
+          '"or"\n'
+          'and "and" always return one of their operands.)\n',
+ 'try': '\n'
+        'The "try" statement\n'
+        '*******************\n'
+        '\n'
+        'The "try" statement specifies exception handlers and/or cleanup code\n'
+        'for a group of statements:\n'
+        '\n'
+        '   try_stmt  ::= try1_stmt | try2_stmt\n'
+        '   try1_stmt ::= "try" ":" suite\n'
+        '                 ("except" [expression ["as" identifier]] ":" '
+        'suite)+\n'
+        '                 ["else" ":" suite]\n'
+        '                 ["finally" ":" suite]\n'
+        '   try2_stmt ::= "try" ":" suite\n'
+        '                 "finally" ":" suite\n'
+        '\n'
+        'The "except" clause(s) specify one or more exception handlers. When '
+        'no\n'
+        'exception occurs in the "try" clause, no exception handler is\n'
+        'executed. When an exception occurs in the "try" suite, a search for '
+        'an\n'
+        'exception handler is started.  This search inspects the except '
+        'clauses\n'
+        'in turn until one is found that matches the exception.  An '
+        'expression-\n'
+        'less except clause, if present, must be last; it matches any\n'
+        'exception.  For an except clause with an expression, that expression\n'
+        'is evaluated, and the clause matches the exception if the resulting\n'
+        'object is "compatible" with the exception.  An object is compatible\n'
+        'with an exception if it is the class or a base class of the '
+        'exception\n'
+        'object or a tuple containing an item compatible with the exception.\n'
+        '\n'
+        'If no except clause matches the exception, the search for an '
+        'exception\n'
+        'handler continues in the surrounding code and on the invocation '
+        'stack.\n'
+        '[1]\n'
+        '\n'
+        'If the evaluation of an expression in the header of an except clause\n'
+        'raises an exception, the original search for a handler is canceled '
+        'and\n'
+        'a search starts for the new exception in the surrounding code and on\n'
+        'the call stack (it is treated as if the entire "try" statement '
+        'raised\n'
+        'the exception).\n'
+        '\n'
+        'When a matching except clause is found, the exception is assigned to\n'
+        'the target specified after the "as" keyword in that except clause, '
+        'if\n'
+        "present, and the except clause's suite is executed.  All except\n"
+        'clauses must have an executable block.  When the end of this block '
+        'is\n'
+        'reached, execution continues normally after the entire try '
+        'statement.\n'
+        '(This means that if two nested handlers exist for the same '
+        'exception,\n'
+        'and the exception occurs in the try clause of the inner handler, the\n'
+        'outer handler will not handle the exception.)\n'
+        '\n'
+        'When an exception has been assigned using "as target", it is cleared\n'
+        'at the end of the except clause.  This is as if\n'
+        '\n'
+        '   except E as N:\n'
+        '       foo\n'
+        '\n'
+        'was translated to\n'
+        '\n'
+        '   except E as N:\n'
+        '       try:\n'
+        '           foo\n'
+        '       finally:\n'
+        '           del N\n'
+        '\n'
+        'This means the exception must be assigned to a different name to be\n'
+        'able to refer to it after the except clause.  Exceptions are cleared\n'
+        'because with the traceback attached to them, they form a reference\n'
+        'cycle with the stack frame, keeping all locals in that frame alive\n'
+        'until the next garbage collection occurs.\n'
+        '\n'
+        "Before an except clause's suite is executed, details about the\n"
+        'exception are stored in the "sys" module and can be accessed via\n'
+        '"sys.exc_info()". "sys.exc_info()" returns a 3-tuple consisting of '
+        'the\n'
+        'exception class, the exception instance and a traceback object (see\n'
+        'section The standard type hierarchy) identifying the point in the\n'
+        'program where the exception occurred.  "sys.exc_info()" values are\n'
+        'restored to their previous values (before the call) when returning\n'
+        'from a function that handled an exception.\n'
+        '\n'
+        'The optional "else" clause is executed if and when control flows off\n'
+        'the end of the "try" clause. [2] Exceptions in the "else" clause are\n'
+        'not handled by the preceding "except" clauses.\n'
+        '\n'
+        'If "finally" is present, it specifies a \'cleanup\' handler.  The '
+        '"try"\n'
+        'clause is executed, including any "except" and "else" clauses.  If '
+        'an\n'
+        'exception occurs in any of the clauses and is not handled, the\n'
+        'exception is temporarily saved. The "finally" clause is executed.  '
+        'If\n'
+        'there is a saved exception it is re-raised at the end of the '
+        '"finally"\n'
+        'clause.  If the "finally" clause raises another exception, the saved\n'
+        'exception is set as the context of the new exception. If the '
+        '"finally"\n'
+        'clause executes a "return" or "break" statement, the saved exception\n'
+        'is discarded:\n'
+        '\n'
+        '   >>> def f():\n'
+        '   ...     try:\n'
+        '   ...         1/0\n'
+        '   ...     finally:\n'
+        '   ...         return 42\n'
+        '   ...\n'
+        '   >>> f()\n'
+        '   42\n'
+        '\n'
+        'The exception information is not available to the program during\n'
+        'execution of the "finally" clause.\n'
+        '\n'
+        'When a "return", "break" or "continue" statement is executed in the\n'
+        '"try" suite of a "try"..."finally" statement, the "finally" clause '
+        'is\n'
+        'also executed \'on the way out.\' A "continue" statement is illegal '
+        'in\n'
+        'the "finally" clause. (The reason is a problem with the current\n'
+        'implementation --- this restriction may be lifted in the future).\n'
+        '\n'
+        'The return value of a function is determined by the last "return"\n'
+        'statement executed.  Since the "finally" clause always executes, a\n'
+        '"return" statement executed in the "finally" clause will always be '
+        'the\n'
+        'last one executed:\n'
+        '\n'
+        '   >>> def foo():\n'
+        '   ...     try:\n'
+        "   ...         return 'try'\n"
+        '   ...     finally:\n'
+        "   ...         return 'finally'\n"
+        '   ...\n'
+        '   >>> foo()\n'
+        "   'finally'\n"
+        '\n'
+        'Additional information on exceptions can be found in section\n'
+        'Exceptions, and information on using the "raise" statement to '
+        'generate\n'
+        'exceptions may be found in section The raise statement.\n',
+ 'types': '\n'
+          'The standard type hierarchy\n'
+          '***************************\n'
+          '\n'
+          'Below is a list of the types that are built into Python.  '
+          'Extension\n'
+          'modules (written in C, Java, or other languages, depending on the\n'
+          'implementation) can define additional types.  Future versions of\n'
+          'Python may add types to the type hierarchy (e.g., rational '
+          'numbers,\n'
+          'efficiently stored arrays of integers, etc.), although such '
+          'additions\n'
+          'will often be provided via the standard library instead.\n'
+          '\n'
+          'Some of the type descriptions below contain a paragraph listing\n'
+          "'special attributes.'  These are attributes that provide access to "
+          'the\n'
+          'implementation and are not intended for general use.  Their '
+          'definition\n'
+          'may change in the future.\n'
+          '\n'
+          'None\n'
+          '   This type has a single value.  There is a single object with '
+          'this\n'
+          '   value. This object is accessed through the built-in name "None". '
+          'It\n'
+          '   is used to signify the absence of a value in many situations, '
+          'e.g.,\n'
+          "   it is returned from functions that don't explicitly return\n"
+          '   anything. Its truth value is false.\n'
+          '\n'
+          'NotImplemented\n'
+          '   This type has a single value.  There is a single object with '
+          'this\n'
+          '   value. This object is accessed through the built-in name\n'
+          '   "NotImplemented". Numeric methods and rich comparison methods\n'
+          '   should return this value if they do not implement the operation '
+          'for\n'
+          '   the operands provided.  (The interpreter will then try the\n'
+          '   reflected operation, or some other fallback, depending on the\n'
+          '   operator.)  Its truth value is true.\n'
+          '\n'
+          '   See Implementing the arithmetic operations for more details.\n'
+          '\n'
+          'Ellipsis\n'
+          '   This type has a single value.  There is a single object with '
+          'this\n'
+          '   value. This object is accessed through the literal "..." or the\n'
+          '   built-in name "Ellipsis".  Its truth value is true.\n'
+          '\n'
+          '"numbers.Number"\n'
+          '   These are created by numeric literals and returned as results '
+          'by\n'
+          '   arithmetic operators and arithmetic built-in functions.  '
+          'Numeric\n'
+          '   objects are immutable; once created their value never changes.\n'
+          '   Python numbers are of course strongly related to mathematical\n'
+          '   numbers, but subject to the limitations of numerical '
+          'representation\n'
+          '   in computers.\n'
+          '\n'
+          '   Python distinguishes between integers, floating point numbers, '
+          'and\n'
+          '   complex numbers:\n'
+          '\n'
+          '   "numbers.Integral"\n'
+          '      These represent elements from the mathematical set of '
+          'integers\n'
+          '      (positive and negative).\n'
+          '\n'
+          '      There are two types of integers:\n'
+          '\n'
+          '      Integers ("int")\n'
+          '\n'
+          '         These represent numbers in an unlimited range, subject to\n'
+          '         available (virtual) memory only.  For the purpose of '
+          'shift\n'
+          '         and mask operations, a binary representation is assumed, '
+          'and\n'
+          "         negative numbers are represented in a variant of 2's\n"
+          '         complement which gives the illusion of an infinite string '
+          'of\n'
+          '         sign bits extending to the left.\n'
+          '\n'
+          '      Booleans ("bool")\n'
+          '         These represent the truth values False and True.  The two\n'
+          '         objects representing the values "False" and "True" are '
+          'the\n'
+          '         only Boolean objects. The Boolean type is a subtype of '
+          'the\n'
+          '         integer type, and Boolean values behave like the values 0 '
+          'and\n'
+          '         1, respectively, in almost all contexts, the exception '
+          'being\n'
+          '         that when converted to a string, the strings ""False"" or\n'
+          '         ""True"" are returned, respectively.\n'
+          '\n'
+          '      The rules for integer representation are intended to give '
+          'the\n'
+          '      most meaningful interpretation of shift and mask operations\n'
+          '      involving negative integers.\n'
+          '\n'
+          '   "numbers.Real" ("float")\n'
+          '      These represent machine-level double precision floating '
+          'point\n'
+          '      numbers. You are at the mercy of the underlying machine\n'
+          '      architecture (and C or Java implementation) for the accepted\n'
+          '      range and handling of overflow. Python does not support '
+          'single-\n'
+          '      precision floating point numbers; the savings in processor '
+          'and\n'
+          '      memory usage that are usually the reason for using these are\n'
+          '      dwarfed by the overhead of using objects in Python, so there '
+          'is\n'
+          '      no reason to complicate the language with two kinds of '
+          'floating\n'
+          '      point numbers.\n'
+          '\n'
+          '   "numbers.Complex" ("complex")\n'
+          '      These represent complex numbers as a pair of machine-level\n'
+          '      double precision floating point numbers.  The same caveats '
+          'apply\n'
+          '      as for floating point numbers. The real and imaginary parts '
+          'of a\n'
+          '      complex number "z" can be retrieved through the read-only\n'
+          '      attributes "z.real" and "z.imag".\n'
+          '\n'
+          'Sequences\n'
+          '   These represent finite ordered sets indexed by non-negative\n'
+          '   numbers. The built-in function "len()" returns the number of '
+          'items\n'
+          '   of a sequence. When the length of a sequence is *n*, the index '
+          'set\n'
+          '   contains the numbers 0, 1, ..., *n*-1.  Item *i* of sequence *a* '
+          'is\n'
+          '   selected by "a[i]".\n'
+          '\n'
+          '   Sequences also support slicing: "a[i:j]" selects all items with\n'
+          '   index *k* such that *i* "<=" *k* "<" *j*.  When used as an\n'
+          '   expression, a slice is a sequence of the same type.  This '
+          'implies\n'
+          '   that the index set is renumbered so that it starts at 0.\n'
+          '\n'
+          '   Some sequences also support "extended slicing" with a third '
+          '"step"\n'
+          '   parameter: "a[i:j:k]" selects all items of *a* with index *x* '
+          'where\n'
+          '   "x = i + n*k", *n* ">=" "0" and *i* "<=" *x* "<" *j*.\n'
+          '\n'
+          '   Sequences are distinguished according to their mutability:\n'
+          '\n'
+          '   Immutable sequences\n'
+          '      An object of an immutable sequence type cannot change once it '
+          'is\n'
+          '      created.  (If the object contains references to other '
+          'objects,\n'
+          '      these other objects may be mutable and may be changed; '
+          'however,\n'
+          '      the collection of objects directly referenced by an '
+          'immutable\n'
+          '      object cannot change.)\n'
+          '\n'
+          '      The following types are immutable sequences:\n'
+          '\n'
+          '      Strings\n'
+          '         A string is a sequence of values that represent Unicode '
+          'code\n'
+          '         points. All the code points in the range "U+0000 - '
+          'U+10FFFF"\n'
+          "         can be represented in a string.  Python doesn't have a "
+          '"char"\n'
+          '         type; instead, every code point in the string is '
+          'represented\n'
+          '         as a string object with length "1".  The built-in '
+          'function\n'
+          '         "ord()" converts a code point from its string form to an\n'
+          '         integer in the range "0 - 10FFFF"; "chr()" converts an\n'
+          '         integer in the range "0 - 10FFFF" to the corresponding '
+          'length\n'
+          '         "1" string object. "str.encode()" can be used to convert '
+          'a\n'
+          '         "str" to "bytes" using the given text encoding, and\n'
+          '         "bytes.decode()" can be used to achieve the opposite.\n'
+          '\n'
+          '      Tuples\n'
+          '         The items of a tuple are arbitrary Python objects. Tuples '
+          'of\n'
+          '         two or more items are formed by comma-separated lists of\n'
+          "         expressions.  A tuple of one item (a 'singleton') can be\n"
+          '         formed by affixing a comma to an expression (an expression '
+          'by\n'
+          '         itself does not create a tuple, since parentheses must be\n'
+          '         usable for grouping of expressions).  An empty tuple can '
+          'be\n'
+          '         formed by an empty pair of parentheses.\n'
+          '\n'
+          '      Bytes\n'
+          '         A bytes object is an immutable array.  The items are '
+          '8-bit\n'
+          '         bytes, represented by integers in the range 0 <= x < 256.\n'
+          '         Bytes literals (like "b\'abc\'") and the built-in '
+          'function\n'
+          '         "bytes()" can be used to construct bytes objects.  Also,\n'
+          '         bytes objects can be decoded to strings via the '
+          '"decode()"\n'
+          '         method.\n'
+          '\n'
+          '   Mutable sequences\n'
+          '      Mutable sequences can be changed after they are created.  '
+          'The\n'
+          '      subscription and slicing notations can be used as the target '
+          'of\n'
+          '      assignment and "del" (delete) statements.\n'
+          '\n'
+          '      There are currently two intrinsic mutable sequence types:\n'
+          '\n'
+          '      Lists\n'
+          '         The items of a list are arbitrary Python objects.  Lists '
+          'are\n'
+          '         formed by placing a comma-separated list of expressions '
+          'in\n'
+          '         square brackets. (Note that there are no special cases '
+          'needed\n'
+          '         to form lists of length 0 or 1.)\n'
+          '\n'
+          '      Byte Arrays\n'
+          '         A bytearray object is a mutable array. They are created '
+          'by\n'
+          '         the built-in "bytearray()" constructor.  Aside from being\n'
+          '         mutable (and hence unhashable), byte arrays otherwise '
+          'provide\n'
+          '         the same interface and functionality as immutable bytes\n'
+          '         objects.\n'
+          '\n'
+          '      The extension module "array" provides an additional example '
+          'of a\n'
+          '      mutable sequence type, as does the "collections" module.\n'
+          '\n'
+          'Set types\n'
+          '   These represent unordered, finite sets of unique, immutable\n'
+          '   objects. As such, they cannot be indexed by any subscript. '
+          'However,\n'
+          '   they can be iterated over, and the built-in function "len()"\n'
+          '   returns the number of items in a set. Common uses for sets are '
+          'fast\n'
+          '   membership testing, removing duplicates from a sequence, and\n'
+          '   computing mathematical operations such as intersection, union,\n'
+          '   difference, and symmetric difference.\n'
+          '\n'
+          '   For set elements, the same immutability rules apply as for\n'
+          '   dictionary keys. Note that numeric types obey the normal rules '
+          'for\n'
+          '   numeric comparison: if two numbers compare equal (e.g., "1" and\n'
+          '   "1.0"), only one of them can be contained in a set.\n'
+          '\n'
+          '   There are currently two intrinsic set types:\n'
+          '\n'
+          '   Sets\n'
+          '      These represent a mutable set. They are created by the '
+          'built-in\n'
+          '      "set()" constructor and can be modified afterwards by '
+          'several\n'
+          '      methods, such as "add()".\n'
+          '\n'
+          '   Frozen sets\n'
+          '      These represent an immutable set.  They are created by the\n'
+          '      built-in "frozenset()" constructor.  As a frozenset is '
+          'immutable\n'
+          '      and *hashable*, it can be used again as an element of '
+          'another\n'
+          '      set, or as a dictionary key.\n'
+          '\n'
+          'Mappings\n'
+          '   These represent finite sets of objects indexed by arbitrary '
+          'index\n'
+          '   sets. The subscript notation "a[k]" selects the item indexed by '
+          '"k"\n'
+          '   from the mapping "a"; this can be used in expressions and as '
+          'the\n'
+          '   target of assignments or "del" statements. The built-in '
+          'function\n'
+          '   "len()" returns the number of items in a mapping.\n'
+          '\n'
+          '   There is currently a single intrinsic mapping type:\n'
+          '\n'
+          '   Dictionaries\n'
+          '      These represent finite sets of objects indexed by nearly\n'
+          '      arbitrary values.  The only types of values not acceptable '
+          'as\n'
+          '      keys are values containing lists or dictionaries or other\n'
+          '      mutable types that are compared by value rather than by '
+          'object\n'
+          '      identity, the reason being that the efficient implementation '
+          'of\n'
+          "      dictionaries requires a key's hash value to remain constant.\n"
+          '      Numeric types used for keys obey the normal rules for '
+          'numeric\n'
+          '      comparison: if two numbers compare equal (e.g., "1" and '
+          '"1.0")\n'
+          '      then they can be used interchangeably to index the same\n'
+          '      dictionary entry.\n'
+          '\n'
+          '      Dictionaries are mutable; they can be created by the "{...}"\n'
+          '      notation (see section Dictionary displays).\n'
+          '\n'
+          '      The extension modules "dbm.ndbm" and "dbm.gnu" provide\n'
+          '      additional examples of mapping types, as does the '
+          '"collections"\n'
+          '      module.\n'
+          '\n'
+          'Callable types\n'
+          '   These are the types to which the function call operation (see\n'
+          '   section Calls) can be applied:\n'
+          '\n'
+          '   User-defined functions\n'
+          '      A user-defined function object is created by a function\n'
+          '      definition (see section Function definitions).  It should be\n'
+          '      called with an argument list containing the same number of '
+          'items\n'
+          "      as the function's formal parameter list.\n"
+          '\n'
+          '      Special attributes:\n'
+          '\n'
+          '      '
+          '+---------------------------+---------------------------------+-------------+\n'
+          '      | Attribute                 | Meaning                         '
+          '|             |\n'
+          '      '
+          '+===========================+=================================+=============+\n'
+          '      | "__doc__"                 | The function\'s '
+          'documentation    | Writable    |\n'
+          '      |                           | string, or "None" if            '
+          '|             |\n'
+          '      |                           | unavailable; not inherited by   '
+          '|             |\n'
+          '      |                           | subclasses                      '
+          '|             |\n'
+          '      '
+          '+---------------------------+---------------------------------+-------------+\n'
+          '      | "__name__"                | The function\'s '
+          'name             | Writable    |\n'
+          '      '
+          '+---------------------------+---------------------------------+-------------+\n'
+          '      | "__qualname__"            | The function\'s *qualified '
+          'name* | Writable    |\n'
+          '      |                           | New in version 3.3.             '
+          '|             |\n'
+          '      '
+          '+---------------------------+---------------------------------+-------------+\n'
+          '      | "__module__"              | The name of the module the      '
+          '| Writable    |\n'
+          '      |                           | function was defined in, or     '
+          '|             |\n'
+          '      |                           | "None" if unavailable.          '
+          '|             |\n'
+          '      '
+          '+---------------------------+---------------------------------+-------------+\n'
+          '      | "__defaults__"            | A tuple containing default      '
+          '| Writable    |\n'
+          '      |                           | argument values for those       '
+          '|             |\n'
+          '      |                           | arguments that have defaults,   '
+          '|             |\n'
+          '      |                           | or "None" if no arguments have  '
+          '|             |\n'
+          '      |                           | a default value                 '
+          '|             |\n'
+          '      '
+          '+---------------------------+---------------------------------+-------------+\n'
+          '      | "__code__"                | The code object representing    '
+          '| Writable    |\n'
+          '      |                           | the compiled function body.     '
+          '|             |\n'
+          '      '
+          '+---------------------------+---------------------------------+-------------+\n'
+          '      | "__globals__"             | A reference to the dictionary   '
+          '| Read-only   |\n'
+          "      |                           | that holds the function's       "
+          '|             |\n'
+          '      |                           | global variables --- the global '
+          '|             |\n'
+          '      |                           | namespace of the module in      '
+          '|             |\n'
+          '      |                           | which the function was defined. '
+          '|             |\n'
+          '      '
+          '+---------------------------+---------------------------------+-------------+\n'
+          '      | "__dict__"                | The namespace supporting        '
+          '| Writable    |\n'
+          '      |                           | arbitrary function attributes.  '
+          '|             |\n'
+          '      '
+          '+---------------------------+---------------------------------+-------------+\n'
+          '      | "__closure__"             | "None" or a tuple of cells that '
+          '| Read-only   |\n'
+          '      |                           | contain bindings for the        '
+          '|             |\n'
+          "      |                           | function's free variables.      "
+          '|             |\n'
+          '      '
+          '+---------------------------+---------------------------------+-------------+\n'
+          '      | "__annotations__"         | A dict containing annotations   '
+          '| Writable    |\n'
+          '      |                           | of parameters.  The keys of the '
+          '|             |\n'
+          '      |                           | dict are the parameter names,   '
+          '|             |\n'
+          '      |                           | and "\'return\'" for the '
+          'return   |             |\n'
+          '      |                           | annotation, if provided.        '
+          '|             |\n'
+          '      '
+          '+---------------------------+---------------------------------+-------------+\n'
+          '      | "__kwdefaults__"          | A dict containing defaults for  '
+          '| Writable    |\n'
+          '      |                           | keyword-only parameters.        '
+          '|             |\n'
+          '      '
+          '+---------------------------+---------------------------------+-------------+\n'
+          '\n'
+          '      Most of the attributes labelled "Writable" check the type of '
+          'the\n'
+          '      assigned value.\n'
+          '\n'
+          '      Function objects also support getting and setting arbitrary\n'
+          '      attributes, which can be used, for example, to attach '
+          'metadata\n'
+          '      to functions.  Regular attribute dot-notation is used to get '
+          'and\n'
+          '      set such attributes. *Note that the current implementation '
+          'only\n'
+          '      supports function attributes on user-defined functions. '
+          'Function\n'
+          '      attributes on built-in functions may be supported in the\n'
+          '      future.*\n'
+          '\n'
+          "      Additional information about a function's definition can be\n"
+          '      retrieved from its code object; see the description of '
+          'internal\n'
+          '      types below.\n'
+          '\n'
+          '   Instance methods\n'
+          '      An instance method object combines a class, a class instance '
+          'and\n'
+          '      any callable object (normally a user-defined function).\n'
+          '\n'
+          '      Special read-only attributes: "__self__" is the class '
+          'instance\n'
+          '      object, "__func__" is the function object; "__doc__" is the\n'
+          '      method\'s documentation (same as "__func__.__doc__"); '
+          '"__name__"\n'
+          '      is the method name (same as "__func__.__name__"); '
+          '"__module__"\n'
+          '      is the name of the module the method was defined in, or '
+          '"None"\n'
+          '      if unavailable.\n'
+          '\n'
+          '      Methods also support accessing (but not setting) the '
+          'arbitrary\n'
+          '      function attributes on the underlying function object.\n'
+          '\n'
+          '      User-defined method objects may be created when getting an\n'
+          '      attribute of a class (perhaps via an instance of that class), '
+          'if\n'
+          '      that attribute is a user-defined function object or a class\n'
+          '      method object.\n'
+          '\n'
+          '      When an instance method object is created by retrieving a '
+          'user-\n'
+          '      defined function object from a class via one of its '
+          'instances,\n'
+          '      its "__self__" attribute is the instance, and the method '
+          'object\n'
+          '      is said to be bound.  The new method\'s "__func__" attribute '
+          'is\n'
+          '      the original function object.\n'
+          '\n'
+          '      When a user-defined method object is created by retrieving\n'
+          '      another method object from a class or instance, the behaviour '
+          'is\n'
+          '      the same as for a function object, except that the '
+          '"__func__"\n'
+          '      attribute of the new instance is not the original method '
+          'object\n'
+          '      but its "__func__" attribute.\n'
+          '\n'
+          '      When an instance method object is created by retrieving a '
+          'class\n'
+          '      method object from a class or instance, its "__self__" '
+          'attribute\n'
+          '      is the class itself, and its "__func__" attribute is the\n'
+          '      function object underlying the class method.\n'
+          '\n'
+          '      When an instance method object is called, the underlying\n'
+          '      function ("__func__") is called, inserting the class '
+          'instance\n'
+          '      ("__self__") in front of the argument list.  For instance, '
+          'when\n'
+          '      "C" is a class which contains a definition for a function '
+          '"f()",\n'
+          '      and "x" is an instance of "C", calling "x.f(1)" is equivalent '
+          'to\n'
+          '      calling "C.f(x, 1)".\n'
+          '\n'
+          '      When an instance method object is derived from a class '
+          'method\n'
+          '      object, the "class instance" stored in "__self__" will '
+          'actually\n'
+          '      be the class itself, so that calling either "x.f(1)" or '
+          '"C.f(1)"\n'
+          '      is equivalent to calling "f(C,1)" where "f" is the '
+          'underlying\n'
+          '      function.\n'
+          '\n'
+          '      Note that the transformation from function object to '
+          'instance\n'
+          '      method object happens each time the attribute is retrieved '
+          'from\n'
+          '      the instance.  In some cases, a fruitful optimization is to\n'
+          '      assign the attribute to a local variable and call that local\n'
+          '      variable. Also notice that this transformation only happens '
+          'for\n'
+          '      user-defined functions; other callable objects (and all non-\n'
+          '      callable objects) are retrieved without transformation.  It '
+          'is\n'
+          '      also important to note that user-defined functions which are\n'
+          '      attributes of a class instance are not converted to bound\n'
+          '      methods; this *only* happens when the function is an '
+          'attribute\n'
+          '      of the class.\n'
+          '\n'
+          '   Generator functions\n'
+          '      A function or method which uses the "yield" statement (see\n'
+          '      section The yield statement) is called a *generator '
+          'function*.\n'
+          '      Such a function, when called, always returns an iterator '
+          'object\n'
+          '      which can be used to execute the body of the function:  '
+          'calling\n'
+          '      the iterator\'s "iterator.__next__()" method will cause the\n'
+          '      function to execute until it provides a value using the '
+          '"yield"\n'
+          '      statement.  When the function executes a "return" statement '
+          'or\n'
+          '      falls off the end, a "StopIteration" exception is raised and '
+          'the\n'
+          '      iterator will have reached the end of the set of values to '
+          'be\n'
+          '      returned.\n'
+          '\n'
+          '   Coroutine functions\n'
+          '      A function or method which is defined using "async def" is\n'
+          '      called a *coroutine function*.  Such a function, when '
+          'called,\n'
+          '      returns a *coroutine* object.  It may contain "await"\n'
+          '      expressions, as well as "async with" and "async for" '
+          'statements.\n'
+          '      See also the Coroutine Objects section.\n'
+          '\n'
+          '   Built-in functions\n'
+          '      A built-in function object is a wrapper around a C function.\n'
+          '      Examples of built-in functions are "len()" and "math.sin()"\n'
+          '      ("math" is a standard built-in module). The number and type '
+          'of\n'
+          '      the arguments are determined by the C function. Special '
+          'read-\n'
+          '      only attributes: "__doc__" is the function\'s documentation\n'
+          '      string, or "None" if unavailable; "__name__" is the '
+          "function's\n"
+          '      name; "__self__" is set to "None" (but see the next item);\n'
+          '      "__module__" is the name of the module the function was '
+          'defined\n'
+          '      in or "None" if unavailable.\n'
+          '\n'
+          '   Built-in methods\n'
+          '      This is really a different disguise of a built-in function, '
+          'this\n'
+          '      time containing an object passed to the C function as an\n'
+          '      implicit extra argument.  An example of a built-in method is\n'
+          '      "alist.append()", assuming *alist* is a list object. In this\n'
+          '      case, the special read-only attribute "__self__" is set to '
+          'the\n'
+          '      object denoted by *alist*.\n'
+          '\n'
+          '   Classes\n'
+          '      Classes are callable.  These objects normally act as '
+          'factories\n'
+          '      for new instances of themselves, but variations are possible '
+          'for\n'
+          '      class types that override "__new__()".  The arguments of the\n'
+          '      call are passed to "__new__()" and, in the typical case, to\n'
+          '      "__init__()" to initialize the new instance.\n'
+          '\n'
+          '   Class Instances\n'
+          '      Instances of arbitrary classes can be made callable by '
+          'defining\n'
+          '      a "__call__()" method in their class.\n'
+          '\n'
+          'Modules\n'
+          '   Modules are a basic organizational unit of Python code, and are\n'
+          '   created by the import system as invoked either by the "import"\n'
+          '   statement (see "import"), or by calling functions such as\n'
+          '   "importlib.import_module()" and built-in "__import__()".  A '
+          'module\n'
+          '   object has a namespace implemented by a dictionary object (this '
+          'is\n'
+          '   the dictionary referenced by the "__globals__" attribute of\n'
+          '   functions defined in the module).  Attribute references are\n'
+          '   translated to lookups in this dictionary, e.g., "m.x" is '
+          'equivalent\n'
+          '   to "m.__dict__["x"]". A module object does not contain the code\n'
+          "   object used to initialize the module (since it isn't needed "
+          'once\n'
+          '   the initialization is done).\n'
+          '\n'
+          "   Attribute assignment updates the module's namespace dictionary,\n"
+          '   e.g., "m.x = 1" is equivalent to "m.__dict__["x"] = 1".\n'
+          '\n'
+          '   Special read-only attribute: "__dict__" is the module\'s '
+          'namespace\n'
+          '   as a dictionary object.\n'
+          '\n'
+          '   **CPython implementation detail:** Because of the way CPython\n'
+          '   clears module dictionaries, the module dictionary will be '
+          'cleared\n'
+          '   when the module falls out of scope even if the dictionary still '
+          'has\n'
+          '   live references.  To avoid this, copy the dictionary or keep '
+          'the\n'
+          '   module around while using its dictionary directly.\n'
+          '\n'
+          '   Predefined (writable) attributes: "__name__" is the module\'s '
+          'name;\n'
+          '   "__doc__" is the module\'s documentation string, or "None" if\n'
+          '   unavailable; "__file__" is the pathname of the file from which '
+          'the\n'
+          '   module was loaded, if it was loaded from a file. The "__file__"\n'
+          '   attribute may be missing for certain types of modules, such as '
+          'C\n'
+          '   modules that are statically linked into the interpreter; for\n'
+          '   extension modules loaded dynamically from a shared library, it '
+          'is\n'
+          '   the pathname of the shared library file.\n'
+          '\n'
+          'Custom classes\n'
+          '   Custom class types are typically created by class definitions '
+          '(see\n'
+          '   section Class definitions).  A class has a namespace implemented '
+          'by\n'
+          '   a dictionary object. Class attribute references are translated '
+          'to\n'
+          '   lookups in this dictionary, e.g., "C.x" is translated to\n'
+          '   "C.__dict__["x"]" (although there are a number of hooks which '
+          'allow\n'
+          '   for other means of locating attributes). When the attribute name '
+          'is\n'
+          '   not found there, the attribute search continues in the base\n'
+          '   classes. This search of the base classes uses the C3 method\n'
+          '   resolution order which behaves correctly even in the presence '
+          'of\n'
+          "   'diamond' inheritance structures where there are multiple\n"
+          '   inheritance paths leading back to a common ancestor. Additional\n'
+          '   details on the C3 MRO used by Python can be found in the\n'
+          '   documentation accompanying the 2.3 release at\n'
+          '   https://www.python.org/download/releases/2.3/mro/.\n'
+          '\n'
+          '   When a class attribute reference (for class "C", say) would '
+          'yield a\n'
+          '   class method object, it is transformed into an instance method\n'
+          '   object whose "__self__" attributes is "C".  When it would yield '
+          'a\n'
+          '   static method object, it is transformed into the object wrapped '
+          'by\n'
+          '   the static method object. See section Implementing Descriptors '
+          'for\n'
+          '   another way in which attributes retrieved from a class may '
+          'differ\n'
+          '   from those actually contained in its "__dict__".\n'
+          '\n'
+          "   Class attribute assignments update the class's dictionary, "
+          'never\n'
+          '   the dictionary of a base class.\n'
+          '\n'
+          '   A class object can be called (see above) to yield a class '
+          'instance\n'
+          '   (see below).\n'
+          '\n'
+          '   Special attributes: "__name__" is the class name; "__module__" '
+          'is\n'
+          '   the module name in which the class was defined; "__dict__" is '
+          'the\n'
+          '   dictionary containing the class\'s namespace; "__bases__" is a '
+          'tuple\n'
+          '   (possibly empty or a singleton) containing the base classes, in '
+          'the\n'
+          '   order of their occurrence in the base class list; "__doc__" is '
+          'the\n'
+          "   class's documentation string, or None if undefined.\n"
+          '\n'
+          'Class instances\n'
+          '   A class instance is created by calling a class object (see '
+          'above).\n'
+          '   A class instance has a namespace implemented as a dictionary '
+          'which\n'
+          '   is the first place in which attribute references are searched.\n'
+          "   When an attribute is not found there, and the instance's class "
+          'has\n'
+          '   an attribute by that name, the search continues with the class\n'
+          '   attributes.  If a class attribute is found that is a '
+          'user-defined\n'
+          '   function object, it is transformed into an instance method '
+          'object\n'
+          '   whose "__self__" attribute is the instance.  Static method and\n'
+          '   class method objects are also transformed; see above under\n'
+          '   "Classes".  See section Implementing Descriptors for another way '
+          'in\n'
+          '   which attributes of a class retrieved via its instances may '
+          'differ\n'
+          '   from the objects actually stored in the class\'s "__dict__".  If '
+          'no\n'
+          "   class attribute is found, and the object's class has a\n"
+          '   "__getattr__()" method, that is called to satisfy the lookup.\n'
+          '\n'
+          "   Attribute assignments and deletions update the instance's\n"
+          "   dictionary, never a class's dictionary.  If the class has a\n"
+          '   "__setattr__()" or "__delattr__()" method, this is called '
+          'instead\n'
+          '   of updating the instance dictionary directly.\n'
+          '\n'
+          '   Class instances can pretend to be numbers, sequences, or '
+          'mappings\n'
+          '   if they have methods with certain special names.  See section\n'
+          '   Special method names.\n'
+          '\n'
+          '   Special attributes: "__dict__" is the attribute dictionary;\n'
+          '   "__class__" is the instance\'s class.\n'
+          '\n'
+          'I/O objects (also known as file objects)\n'
+          '   A *file object* represents an open file.  Various shortcuts are\n'
+          '   available to create file objects: the "open()" built-in '
+          'function,\n'
+          '   and also "os.popen()", "os.fdopen()", and the "makefile()" '
+          'method\n'
+          '   of socket objects (and perhaps by other functions or methods\n'
+          '   provided by extension modules).\n'
+          '\n'
+          '   The objects "sys.stdin", "sys.stdout" and "sys.stderr" are\n'
+          "   initialized to file objects corresponding to the interpreter's\n"
+          '   standard input, output and error streams; they are all open in '
+          'text\n'
+          '   mode and therefore follow the interface defined by the\n'
+          '   "io.TextIOBase" abstract class.\n'
+          '\n'
+          'Internal types\n'
+          '   A few types used internally by the interpreter are exposed to '
+          'the\n'
+          '   user. Their definitions may change with future versions of the\n'
+          '   interpreter, but they are mentioned here for completeness.\n'
+          '\n'
+          '   Code objects\n'
+          '      Code objects represent *byte-compiled* executable Python '
+          'code,\n'
+          '      or *bytecode*. The difference between a code object and a\n'
+          '      function object is that the function object contains an '
+          'explicit\n'
+          "      reference to the function's globals (the module in which it "
+          'was\n'
+          '      defined), while a code object contains no context; also the\n'
+          '      default argument values are stored in the function object, '
+          'not\n'
+          '      in the code object (because they represent values calculated '
+          'at\n'
+          '      run-time).  Unlike function objects, code objects are '
+          'immutable\n'
+          '      and contain no references (directly or indirectly) to '
+          'mutable\n'
+          '      objects.\n'
+          '\n'
+          '      Special read-only attributes: "co_name" gives the function '
+          'name;\n'
+          '      "co_argcount" is the number of positional arguments '
+          '(including\n'
+          '      arguments with default values); "co_nlocals" is the number '
+          'of\n'
+          '      local variables used by the function (including arguments);\n'
+          '      "co_varnames" is a tuple containing the names of the local\n'
+          '      variables (starting with the argument names); "co_cellvars" '
+          'is a\n'
+          '      tuple containing the names of local variables that are\n'
+          '      referenced by nested functions; "co_freevars" is a tuple\n'
+          '      containing the names of free variables; "co_code" is a '
+          'string\n'
+          '      representing the sequence of bytecode instructions; '
+          '"co_consts"\n'
+          '      is a tuple containing the literals used by the bytecode;\n'
+          '      "co_names" is a tuple containing the names used by the '
+          'bytecode;\n'
+          '      "co_filename" is the filename from which the code was '
+          'compiled;\n'
+          '      "co_firstlineno" is the first line number of the function;\n'
+          '      "co_lnotab" is a string encoding the mapping from bytecode\n'
+          '      offsets to line numbers (for details see the source code of '
+          'the\n'
+          '      interpreter); "co_stacksize" is the required stack size\n'
+          '      (including local variables); "co_flags" is an integer '
+          'encoding a\n'
+          '      number of flags for the interpreter.\n'
+          '\n'
+          '      The following flag bits are defined for "co_flags": bit '
+          '"0x04"\n'
+          '      is set if the function uses the "*arguments" syntax to accept '
+          'an\n'
+          '      arbitrary number of positional arguments; bit "0x08" is set '
+          'if\n'
+          '      the function uses the "**keywords" syntax to accept '
+          'arbitrary\n'
+          '      keyword arguments; bit "0x20" is set if the function is a\n'
+          '      generator.\n'
+          '\n'
+          '      Future feature declarations ("from __future__ import '
+          'division")\n'
+          '      also use bits in "co_flags" to indicate whether a code '
+          'object\n'
+          '      was compiled with a particular feature enabled: bit "0x2000" '
+          'is\n'
+          '      set if the function was compiled with future division '
+          'enabled;\n'
+          '      bits "0x10" and "0x1000" were used in earlier versions of\n'
+          '      Python.\n'
+          '\n'
+          '      Other bits in "co_flags" are reserved for internal use.\n'
+          '\n'
+          '      If a code object represents a function, the first item in\n'
+          '      "co_consts" is the documentation string of the function, or\n'
+          '      "None" if undefined.\n'
+          '\n'
+          '   Frame objects\n'
+          '      Frame objects represent execution frames.  They may occur in\n'
+          '      traceback objects (see below).\n'
+          '\n'
+          '      Special read-only attributes: "f_back" is to the previous '
+          'stack\n'
+          '      frame (towards the caller), or "None" if this is the bottom\n'
+          '      stack frame; "f_code" is the code object being executed in '
+          'this\n'
+          '      frame; "f_locals" is the dictionary used to look up local\n'
+          '      variables; "f_globals" is used for global variables;\n'
+          '      "f_builtins" is used for built-in (intrinsic) names; '
+          '"f_lasti"\n'
+          '      gives the precise instruction (this is an index into the\n'
+          '      bytecode string of the code object).\n'
+          '\n'
+          '      Special writable attributes: "f_trace", if not "None", is a\n'
+          '      function called at the start of each source code line (this '
+          'is\n'
+          '      used by the debugger); "f_lineno" is the current line number '
+          'of\n'
+          '      the frame --- writing to this from within a trace function '
+          'jumps\n'
+          '      to the given line (only for the bottom-most frame).  A '
+          'debugger\n'
+          '      can implement a Jump command (aka Set Next Statement) by '
+          'writing\n'
+          '      to f_lineno.\n'
+          '\n'
+          '      Frame objects support one method:\n'
+          '\n'
+          '      frame.clear()\n'
+          '\n'
+          '         This method clears all references to local variables held '
+          'by\n'
+          '         the frame.  Also, if the frame belonged to a generator, '
+          'the\n'
+          '         generator is finalized.  This helps break reference '
+          'cycles\n'
+          '         involving frame objects (for example when catching an\n'
+          '         exception and storing its traceback for later use).\n'
+          '\n'
+          '         "RuntimeError" is raised if the frame is currently '
+          'executing.\n'
+          '\n'
+          '         New in version 3.4.\n'
+          '\n'
+          '   Traceback objects\n'
+          '      Traceback objects represent a stack trace of an exception.  '
+          'A\n'
+          '      traceback object is created when an exception occurs.  When '
+          'the\n'
+          '      search for an exception handler unwinds the execution stack, '
+          'at\n'
+          '      each unwound level a traceback object is inserted in front '
+          'of\n'
+          '      the current traceback.  When an exception handler is '
+          'entered,\n'
+          '      the stack trace is made available to the program. (See '
+          'section\n'
+          '      The try statement.) It is accessible as the third item of '
+          'the\n'
+          '      tuple returned by "sys.exc_info()". When the program contains '
+          'no\n'
+          '      suitable handler, the stack trace is written (nicely '
+          'formatted)\n'
+          '      to the standard error stream; if the interpreter is '
+          'interactive,\n'
+          '      it is also made available to the user as '
+          '"sys.last_traceback".\n'
+          '\n'
+          '      Special read-only attributes: "tb_next" is the next level in '
+          'the\n'
+          '      stack trace (towards the frame where the exception occurred), '
+          'or\n'
+          '      "None" if there is no next level; "tb_frame" points to the\n'
+          '      execution frame of the current level; "tb_lineno" gives the '
+          'line\n'
+          '      number where the exception occurred; "tb_lasti" indicates '
+          'the\n'
+          '      precise instruction.  The line number and last instruction '
+          'in\n'
+          '      the traceback may differ from the line number of its frame\n'
+          '      object if the exception occurred in a "try" statement with '
+          'no\n'
+          '      matching except clause or with a finally clause.\n'
+          '\n'
+          '   Slice objects\n'
+          '      Slice objects are used to represent slices for '
+          '"__getitem__()"\n'
+          '      methods.  They are also created by the built-in "slice()"\n'
+          '      function.\n'
+          '\n'
+          '      Special read-only attributes: "start" is the lower bound; '
+          '"stop"\n'
+          '      is the upper bound; "step" is the step value; each is "None" '
+          'if\n'
+          '      omitted.  These attributes can have any type.\n'
+          '\n'
+          '      Slice objects support one method:\n'
+          '\n'
+          '      slice.indices(self, length)\n'
+          '\n'
+          '         This method takes a single integer argument *length* and\n'
+          '         computes information about the slice that the slice '
+          'object\n'
+          '         would describe if applied to a sequence of *length* '
+          'items.\n'
+          '         It returns a tuple of three integers; respectively these '
+          'are\n'
+          '         the *start* and *stop* indices and the *step* or stride\n'
+          '         length of the slice. Missing or out-of-bounds indices are\n'
+          '         handled in a manner consistent with regular slices.\n'
+          '\n'
+          '   Static method objects\n'
+          '      Static method objects provide a way of defeating the\n'
+          '      transformation of function objects to method objects '
+          'described\n'
+          '      above. A static method object is a wrapper around any other\n'
+          '      object, usually a user-defined method object. When a static\n'
+          '      method object is retrieved from a class or a class instance, '
+          'the\n'
+          '      object actually returned is the wrapped object, which is not\n'
+          '      subject to any further transformation. Static method objects '
+          'are\n'
+          '      not themselves callable, although the objects they wrap '
+          'usually\n'
+          '      are. Static method objects are created by the built-in\n'
+          '      "staticmethod()" constructor.\n'
+          '\n'
+          '   Class method objects\n'
+          '      A class method object, like a static method object, is a '
+          'wrapper\n'
+          '      around another object that alters the way in which that '
+          'object\n'
+          '      is retrieved from classes and class instances. The behaviour '
+          'of\n'
+          '      class method objects upon such retrieval is described above,\n'
+          '      under "User-defined methods". Class method objects are '
+          'created\n'
+          '      by the built-in "classmethod()" constructor.\n',
+ 'typesfunctions': '\n'
+                   'Functions\n'
+                   '*********\n'
+                   '\n'
+                   'Function objects are created by function definitions.  The '
+                   'only\n'
+                   'operation on a function object is to call it: '
+                   '"func(argument-list)".\n'
+                   '\n'
+                   'There are really two flavors of function objects: built-in '
+                   'functions\n'
+                   'and user-defined functions.  Both support the same '
+                   'operation (to call\n'
+                   'the function), but the implementation is different, hence '
+                   'the\n'
+                   'different object types.\n'
+                   '\n'
+                   'See Function definitions for more information.\n',
+ 'typesmapping': '\n'
+                 'Mapping Types --- "dict"\n'
+                 '************************\n'
+                 '\n'
+                 'A *mapping* object maps *hashable* values to arbitrary '
+                 'objects.\n'
+                 'Mappings are mutable objects.  There is currently only one '
+                 'standard\n'
+                 'mapping type, the *dictionary*.  (For other containers see '
+                 'the built-\n'
+                 'in "list", "set", and "tuple" classes, and the "collections" '
+                 'module.)\n'
+                 '\n'
+                 "A dictionary's keys are *almost* arbitrary values.  Values "
+                 'that are\n'
+                 'not *hashable*, that is, values containing lists, '
+                 'dictionaries or\n'
+                 'other mutable types (that are compared by value rather than '
+                 'by object\n'
+                 'identity) may not be used as keys.  Numeric types used for '
+                 'keys obey\n'
+                 'the normal rules for numeric comparison: if two numbers '
+                 'compare equal\n'
+                 '(such as "1" and "1.0") then they can be used '
+                 'interchangeably to index\n'
+                 'the same dictionary entry.  (Note however, that since '
+                 'computers store\n'
+                 'floating-point numbers as approximations it is usually '
+                 'unwise to use\n'
+                 'them as dictionary keys.)\n'
+                 '\n'
+                 'Dictionaries can be created by placing a comma-separated '
+                 'list of "key:\n'
+                 'value" pairs within braces, for example: "{\'jack\': 4098, '
+                 "'sjoerd':\n"
+                 '4127}" or "{4098: \'jack\', 4127: \'sjoerd\'}", or by the '
+                 '"dict"\n'
+                 'constructor.\n'
+                 '\n'
+                 'class dict(**kwarg)\n'
+                 'class dict(mapping, **kwarg)\n'
+                 'class dict(iterable, **kwarg)\n'
+                 '\n'
+                 '   Return a new dictionary initialized from an optional '
+                 'positional\n'
+                 '   argument and a possibly empty set of keyword arguments.\n'
+                 '\n'
+                 '   If no positional argument is given, an empty dictionary '
+                 'is created.\n'
+                 '   If a positional argument is given and it is a mapping '
+                 'object, a\n'
+                 '   dictionary is created with the same key-value pairs as '
+                 'the mapping\n'
+                 '   object.  Otherwise, the positional argument must be an '
+                 '*iterable*\n'
+                 '   object.  Each item in the iterable must itself be an '
+                 'iterable with\n'
+                 '   exactly two objects.  The first object of each item '
+                 'becomes a key\n'
+                 '   in the new dictionary, and the second object the '
+                 'corresponding\n'
+                 '   value.  If a key occurs more than once, the last value '
+                 'for that key\n'
+                 '   becomes the corresponding value in the new dictionary.\n'
+                 '\n'
+                 '   If keyword arguments are given, the keyword arguments and '
+                 'their\n'
+                 '   values are added to the dictionary created from the '
+                 'positional\n'
+                 '   argument.  If a key being added is already present, the '
+                 'value from\n'
+                 '   the keyword argument replaces the value from the '
+                 'positional\n'
+                 '   argument.\n'
+                 '\n'
+                 '   To illustrate, the following examples all return a '
+                 'dictionary equal\n'
+                 '   to "{"one": 1, "two": 2, "three": 3}":\n'
+                 '\n'
+                 '      >>> a = dict(one=1, two=2, three=3)\n'
+                 "      >>> b = {'one': 1, 'two': 2, 'three': 3}\n"
+                 "      >>> c = dict(zip(['one', 'two', 'three'], [1, 2, 3]))\n"
+                 "      >>> d = dict([('two', 2), ('one', 1), ('three', 3)])\n"
+                 "      >>> e = dict({'three': 3, 'one': 1, 'two': 2})\n"
+                 '      >>> a == b == c == d == e\n'
+                 '      True\n'
+                 '\n'
+                 '   Providing keyword arguments as in the first example only '
+                 'works for\n'
+                 '   keys that are valid Python identifiers.  Otherwise, any '
+                 'valid keys\n'
+                 '   can be used.\n'
+                 '\n'
+                 '   These are the operations that dictionaries support (and '
+                 'therefore,\n'
+                 '   custom mapping types should support too):\n'
+                 '\n'
+                 '   len(d)\n'
+                 '\n'
+                 '      Return the number of items in the dictionary *d*.\n'
+                 '\n'
+                 '   d[key]\n'
+                 '\n'
+                 '      Return the item of *d* with key *key*.  Raises a '
+                 '"KeyError" if\n'
+                 '      *key* is not in the map.\n'
+                 '\n'
+                 '      If a subclass of dict defines a method "__missing__()" '
+                 'and *key*\n'
+                 '      is not present, the "d[key]" operation calls that '
+                 'method with\n'
+                 '      the key *key* as argument.  The "d[key]" operation '
+                 'then returns\n'
+                 '      or raises whatever is returned or raised by the\n'
+                 '      "__missing__(key)" call. No other operations or '
+                 'methods invoke\n'
+                 '      "__missing__()". If "__missing__()" is not defined, '
+                 '"KeyError"\n'
+                 '      is raised. "__missing__()" must be a method; it cannot '
+                 'be an\n'
+                 '      instance variable:\n'
+                 '\n'
+                 '         >>> class Counter(dict):\n'
+                 '         ...     def __missing__(self, key):\n'
+                 '         ...         return 0\n'
+                 '         >>> c = Counter()\n'
+                 "         >>> c['red']\n"
+                 '         0\n'
+                 "         >>> c['red'] += 1\n"
+                 "         >>> c['red']\n"
+                 '         1\n'
+                 '\n'
+                 '      The example above shows part of the implementation of\n'
+                 '      "collections.Counter".  A different "__missing__" '
+                 'method is used\n'
+                 '      by "collections.defaultdict".\n'
+                 '\n'
+                 '   d[key] = value\n'
+                 '\n'
+                 '      Set "d[key]" to *value*.\n'
+                 '\n'
+                 '   del d[key]\n'
+                 '\n'
+                 '      Remove "d[key]" from *d*.  Raises a "KeyError" if '
+                 '*key* is not\n'
+                 '      in the map.\n'
+                 '\n'
+                 '   key in d\n'
+                 '\n'
+                 '      Return "True" if *d* has a key *key*, else "False".\n'
+                 '\n'
+                 '   key not in d\n'
+                 '\n'
+                 '      Equivalent to "not key in d".\n'
+                 '\n'
+                 '   iter(d)\n'
+                 '\n'
+                 '      Return an iterator over the keys of the dictionary.  '
+                 'This is a\n'
+                 '      shortcut for "iter(d.keys())".\n'
+                 '\n'
+                 '   clear()\n'
+                 '\n'
+                 '      Remove all items from the dictionary.\n'
+                 '\n'
+                 '   copy()\n'
+                 '\n'
+                 '      Return a shallow copy of the dictionary.\n'
+                 '\n'
+                 '   classmethod fromkeys(seq[, value])\n'
+                 '\n'
+                 '      Create a new dictionary with keys from *seq* and '
+                 'values set to\n'
+                 '      *value*.\n'
+                 '\n'
+                 '      "fromkeys()" is a class method that returns a new '
+                 'dictionary.\n'
+                 '      *value* defaults to "None".\n'
+                 '\n'
+                 '   get(key[, default])\n'
+                 '\n'
+                 '      Return the value for *key* if *key* is in the '
+                 'dictionary, else\n'
+                 '      *default*. If *default* is not given, it defaults to '
+                 '"None", so\n'
+                 '      that this method never raises a "KeyError".\n'
+                 '\n'
+                 '   items()\n'
+                 '\n'
+                 '      Return a new view of the dictionary\'s items ("(key, '
+                 'value)"\n'
+                 '      pairs). See the documentation of view objects.\n'
+                 '\n'
+                 '   keys()\n'
+                 '\n'
+                 "      Return a new view of the dictionary's keys.  See the\n"
+                 '      documentation of view objects.\n'
+                 '\n'
+                 '   pop(key[, default])\n'
+                 '\n'
+                 '      If *key* is in the dictionary, remove it and return '
+                 'its value,\n'
+                 '      else return *default*.  If *default* is not given and '
+                 '*key* is\n'
+                 '      not in the dictionary, a "KeyError" is raised.\n'
+                 '\n'
+                 '   popitem()\n'
+                 '\n'
+                 '      Remove and return an arbitrary "(key, value)" pair '
+                 'from the\n'
+                 '      dictionary.\n'
+                 '\n'
+                 '      "popitem()" is useful to destructively iterate over a\n'
+                 '      dictionary, as often used in set algorithms.  If the '
+                 'dictionary\n'
+                 '      is empty, calling "popitem()" raises a "KeyError".\n'
+                 '\n'
+                 '   setdefault(key[, default])\n'
+                 '\n'
+                 '      If *key* is in the dictionary, return its value.  If '
+                 'not, insert\n'
+                 '      *key* with a value of *default* and return *default*.  '
+                 '*default*\n'
+                 '      defaults to "None".\n'
+                 '\n'
+                 '   update([other])\n'
+                 '\n'
+                 '      Update the dictionary with the key/value pairs from '
+                 '*other*,\n'
+                 '      overwriting existing keys.  Return "None".\n'
+                 '\n'
+                 '      "update()" accepts either another dictionary object or '
+                 'an\n'
+                 '      iterable of key/value pairs (as tuples or other '
+                 'iterables of\n'
+                 '      length two).  If keyword arguments are specified, the '
+                 'dictionary\n'
+                 '      is then updated with those key/value pairs: '
+                 '"d.update(red=1,\n'
+                 '      blue=2)".\n'
+                 '\n'
+                 '   values()\n'
+                 '\n'
+                 "      Return a new view of the dictionary's values.  See "
+                 'the\n'
+                 '      documentation of view objects.\n'
+                 '\n'
+                 '   Dictionaries compare equal if and only if they have the '
+                 'same "(key,\n'
+                 '   value)" pairs. Order comparisons (\'<\', \'<=\', \'>=\', '
+                 "'>') raise\n"
+                 '   "TypeError".\n'
+                 '\n'
+                 'See also: "types.MappingProxyType" can be used to create a '
+                 'read-only\n'
+                 '  view of a "dict".\n'
+                 '\n'
+                 '\n'
+                 'Dictionary view objects\n'
+                 '=======================\n'
+                 '\n'
+                 'The objects returned by "dict.keys()", "dict.values()" and\n'
+                 '"dict.items()" are *view objects*.  They provide a dynamic '
+                 'view on the\n'
+                 "dictionary's entries, which means that when the dictionary "
+                 'changes,\n'
+                 'the view reflects these changes.\n'
+                 '\n'
+                 'Dictionary views can be iterated over to yield their '
+                 'respective data,\n'
+                 'and support membership tests:\n'
+                 '\n'
+                 'len(dictview)\n'
+                 '\n'
+                 '   Return the number of entries in the dictionary.\n'
+                 '\n'
+                 'iter(dictview)\n'
+                 '\n'
+                 '   Return an iterator over the keys, values or items '
+                 '(represented as\n'
+                 '   tuples of "(key, value)") in the dictionary.\n'
+                 '\n'
+                 '   Keys and values are iterated over in an arbitrary order '
+                 'which is\n'
+                 '   non-random, varies across Python implementations, and '
+                 'depends on\n'
+                 "   the dictionary's history of insertions and deletions. If "
+                 'keys,\n'
+                 '   values and items views are iterated over with no '
+                 'intervening\n'
+                 '   modifications to the dictionary, the order of items will '
+                 'directly\n'
+                 '   correspond.  This allows the creation of "(value, key)" '
+                 'pairs using\n'
+                 '   "zip()": "pairs = zip(d.values(), d.keys())".  Another '
+                 'way to\n'
+                 '   create the same list is "pairs = [(v, k) for (k, v) in '
+                 'd.items()]".\n'
+                 '\n'
+                 '   Iterating views while adding or deleting entries in the '
+                 'dictionary\n'
+                 '   may raise a "RuntimeError" or fail to iterate over all '
+                 'entries.\n'
+                 '\n'
+                 'x in dictview\n'
+                 '\n'
+                 '   Return "True" if *x* is in the underlying dictionary\'s '
+                 'keys, values\n'
+                 '   or items (in the latter case, *x* should be a "(key, '
+                 'value)"\n'
+                 '   tuple).\n'
+                 '\n'
+                 'Keys views are set-like since their entries are unique and '
+                 'hashable.\n'
+                 'If all values are hashable, so that "(key, value)" pairs are '
+                 'unique\n'
+                 'and hashable, then the items view is also set-like.  (Values '
+                 'views are\n'
+                 'not treated as set-like since the entries are generally not '
+                 'unique.)\n'
+                 'For set-like views, all of the operations defined for the '
+                 'abstract\n'
+                 'base class "collections.abc.Set" are available (for example, '
+                 '"==",\n'
+                 '"<", or "^").\n'
+                 '\n'
+                 'An example of dictionary view usage:\n'
+                 '\n'
+                 "   >>> dishes = {'eggs': 2, 'sausage': 1, 'bacon': 1, "
+                 "'spam': 500}\n"
+                 '   >>> keys = dishes.keys()\n'
+                 '   >>> values = dishes.values()\n'
+                 '\n'
+                 '   >>> # iteration\n'
+                 '   >>> n = 0\n'
+                 '   >>> for val in values:\n'
+                 '   ...     n += val\n'
+                 '   >>> print(n)\n'
+                 '   504\n'
+                 '\n'
+                 '   >>> # keys and values are iterated over in the same '
+                 'order\n'
+                 '   >>> list(keys)\n'
+                 "   ['eggs', 'bacon', 'sausage', 'spam']\n"
+                 '   >>> list(values)\n'
+                 '   [2, 1, 1, 500]\n'
+                 '\n'
+                 '   >>> # view objects are dynamic and reflect dict changes\n'
+                 "   >>> del dishes['eggs']\n"
+                 "   >>> del dishes['sausage']\n"
+                 '   >>> list(keys)\n'
+                 "   ['spam', 'bacon']\n"
+                 '\n'
+                 '   >>> # set operations\n'
+                 "   >>> keys & {'eggs', 'bacon', 'salad'}\n"
+                 "   {'bacon'}\n"
+                 "   >>> keys ^ {'sausage', 'juice'}\n"
+                 "   {'juice', 'sausage', 'bacon', 'spam'}\n",
+ 'typesmethods': '\n'
+                 'Methods\n'
+                 '*******\n'
+                 '\n'
+                 'Methods are functions that are called using the attribute '
+                 'notation.\n'
+                 'There are two flavors: built-in methods (such as "append()" '
+                 'on lists)\n'
+                 'and class instance methods.  Built-in methods are described '
+                 'with the\n'
+                 'types that support them.\n'
+                 '\n'
+                 'If you access a method (a function defined in a class '
+                 'namespace)\n'
+                 'through an instance, you get a special object: a *bound '
+                 'method* (also\n'
+                 'called *instance method*) object. When called, it will add '
+                 'the "self"\n'
+                 'argument to the argument list.  Bound methods have two '
+                 'special read-\n'
+                 'only attributes: "m.__self__" is the object on which the '
+                 'method\n'
+                 'operates, and "m.__func__" is the function implementing the '
+                 'method.\n'
+                 'Calling "m(arg-1, arg-2, ..., arg-n)" is completely '
+                 'equivalent to\n'
+                 'calling "m.__func__(m.__self__, arg-1, arg-2, ..., arg-n)".\n'
+                 '\n'
+                 'Like function objects, bound method objects support getting '
+                 'arbitrary\n'
+                 'attributes.  However, since method attributes are actually '
+                 'stored on\n'
+                 'the underlying function object ("meth.__func__"), setting '
+                 'method\n'
+                 'attributes on bound methods is disallowed.  Attempting to '
+                 'set an\n'
+                 'attribute on a method results in an "AttributeError" being '
+                 'raised.  In\n'
+                 'order to set a method attribute, you need to explicitly set '
+                 'it on the\n'
+                 'underlying function object:\n'
+                 '\n'
+                 '   >>> class C:\n'
+                 '   ...     def method(self):\n'
+                 '   ...         pass\n'
+                 '   ...\n'
+                 '   >>> c = C()\n'
+                 "   >>> c.method.whoami = 'my name is method'  # can't set on "
+                 'the method\n'
+                 '   Traceback (most recent call last):\n'
+                 '     File "<stdin>", line 1, in <module>\n'
+                 "   AttributeError: 'method' object has no attribute "
+                 "'whoami'\n"
+                 "   >>> c.method.__func__.whoami = 'my name is method'\n"
+                 '   >>> c.method.whoami\n'
+                 "   'my name is method'\n"
+                 '\n'
+                 'See The standard type hierarchy for more information.\n',
+ 'typesmodules': '\n'
+                 'Modules\n'
+                 '*******\n'
+                 '\n'
+                 'The only special operation on a module is attribute access: '
+                 '"m.name",\n'
+                 'where *m* is a module and *name* accesses a name defined in '
+                 "*m*'s\n"
+                 'symbol table. Module attributes can be assigned to.  (Note '
+                 'that the\n'
+                 '"import" statement is not, strictly speaking, an operation '
+                 'on a module\n'
+                 'object; "import foo" does not require a module object named '
+                 '*foo* to\n'
+                 'exist, rather it requires an (external) *definition* for a '
+                 'module\n'
+                 'named *foo* somewhere.)\n'
+                 '\n'
+                 'A special attribute of every module is "__dict__". This is '
+                 'the\n'
+                 "dictionary containing the module's symbol table. Modifying "
+                 'this\n'
+                 "dictionary will actually change the module's symbol table, "
+                 'but direct\n'
+                 'assignment to the "__dict__" attribute is not possible (you '
+                 'can write\n'
+                 '"m.__dict__[\'a\'] = 1", which defines "m.a" to be "1", but '
+                 "you can't\n"
+                 'write "m.__dict__ = {}").  Modifying "__dict__" directly is '
+                 'not\n'
+                 'recommended.\n'
+                 '\n'
+                 'Modules built into the interpreter are written like this: '
+                 '"<module\n'
+                 '\'sys\' (built-in)>".  If loaded from a file, they are '
+                 'written as\n'
+                 '"<module \'os\' from '
+                 '\'/usr/local/lib/pythonX.Y/os.pyc\'>".\n',
+ 'typesseq': '\n'
+             'Sequence Types --- "list", "tuple", "range"\n'
+             '*******************************************\n'
+             '\n'
+             'There are three basic sequence types: lists, tuples, and range\n'
+             'objects. Additional sequence types tailored for processing of '
+             'binary\n'
+             'data and text strings are described in dedicated sections.\n'
+             '\n'
+             '\n'
+             'Common Sequence Operations\n'
+             '==========================\n'
+             '\n'
+             'The operations in the following table are supported by most '
+             'sequence\n'
+             'types, both mutable and immutable. The '
+             '"collections.abc.Sequence" ABC\n'
+             'is provided to make it easier to correctly implement these '
+             'operations\n'
+             'on custom sequence types.\n'
+             '\n'
+             'This table lists the sequence operations sorted in ascending '
+             'priority.\n'
+             'In the table, *s* and *t* are sequences of the same type, *n*, '
+             '*i*,\n'
+             '*j* and *k* are integers and *x* is an arbitrary object that '
+             'meets any\n'
+             'type and value restrictions imposed by *s*.\n'
+             '\n'
+             'The "in" and "not in" operations have the same priorities as '
+             'the\n'
+             'comparison operations. The "+" (concatenation) and "*" '
+             '(repetition)\n'
+             'operations have the same priority as the corresponding numeric\n'
+             'operations.\n'
+             '\n'
+             '+----------------------------+----------------------------------+------------+\n'
+             '| Operation                  | Result                           '
+             '| Notes      |\n'
+             '+============================+==================================+============+\n'
+             '| "x in s"                   | "True" if an item of *s* is      '
+             '| (1)        |\n'
+             '|                            | equal to *x*, else "False"       '
+             '|            |\n'
+             '+----------------------------+----------------------------------+------------+\n'
+             '| "x not in s"               | "False" if an item of *s* is     '
+             '| (1)        |\n'
+             '|                            | equal to *x*, else "True"        '
+             '|            |\n'
+             '+----------------------------+----------------------------------+------------+\n'
+             '| "s + t"                    | the concatenation of *s* and *t* '
+             '| (6)(7)     |\n'
+             '+----------------------------+----------------------------------+------------+\n'
+             '| "s * n" or "n * s"         | equivalent to adding *s* to      '
+             '| (2)(7)     |\n'
+             '|                            | itself *n* times                 '
+             '|            |\n'
+             '+----------------------------+----------------------------------+------------+\n'
+             '| "s[i]"                     | *i*th item of *s*, origin 0      '
+             '| (3)        |\n'
+             '+----------------------------+----------------------------------+------------+\n'
+             '| "s[i:j]"                   | slice of *s* from *i* to *j*     '
+             '| (3)(4)     |\n'
+             '+----------------------------+----------------------------------+------------+\n'
+             '| "s[i:j:k]"                 | slice of *s* from *i* to *j*     '
+             '| (3)(5)     |\n'
+             '|                            | with step *k*                    '
+             '|            |\n'
+             '+----------------------------+----------------------------------+------------+\n'
+             '| "len(s)"                   | length of *s*                    '
+             '|            |\n'
+             '+----------------------------+----------------------------------+------------+\n'
+             '| "min(s)"                   | smallest item of *s*             '
+             '|            |\n'
+             '+----------------------------+----------------------------------+------------+\n'
+             '| "max(s)"                   | largest item of *s*              '
+             '|            |\n'
+             '+----------------------------+----------------------------------+------------+\n'
+             '| "s.index(x[, i[, j]])"     | index of the first occurrence of '
+             '| (8)        |\n'
+             '|                            | *x* in *s* (at or after index    '
+             '|            |\n'
+             '|                            | *i* and before index *j*)        '
+             '|            |\n'
+             '+----------------------------+----------------------------------+------------+\n'
+             '| "s.count(x)"               | total number of occurrences of   '
+             '|            |\n'
+             '|                            | *x* in *s*                       '
+             '|            |\n'
+             '+----------------------------+----------------------------------+------------+\n'
+             '\n'
+             'Sequences of the same type also support comparisons.  In '
+             'particular,\n'
+             'tuples and lists are compared lexicographically by comparing\n'
+             'corresponding elements. This means that to compare equal, every\n'
+             'element must compare equal and the two sequences must be of the '
+             'same\n'
+             'type and have the same length.  (For full details see '
+             'Comparisons in\n'
+             'the language reference.)\n'
+             '\n'
+             'Notes:\n'
+             '\n'
+             '1. While the "in" and "not in" operations are used only for '
+             'simple\n'
+             '   containment testing in the general case, some specialised '
+             'sequences\n'
+             '   (such as "str", "bytes" and "bytearray") also use them for\n'
+             '   subsequence testing:\n'
+             '\n'
+             '      >>> "gg" in "eggs"\n'
+             '      True\n'
+             '\n'
+             '2. Values of *n* less than "0" are treated as "0" (which yields '
+             'an\n'
+             '   empty sequence of the same type as *s*).  Note that items in '
+             'the\n'
+             '   sequence *s* are not copied; they are referenced multiple '
+             'times.\n'
+             '   This often haunts new Python programmers; consider:\n'
+             '\n'
+             '      >>> lists = [[]] * 3\n'
+             '      >>> lists\n'
+             '      [[], [], []]\n'
+             '      >>> lists[0].append(3)\n'
+             '      >>> lists\n'
+             '      [[3], [3], [3]]\n'
+             '\n'
+             '   What has happened is that "[[]]" is a one-element list '
+             'containing\n'
+             '   an empty list, so all three elements of "[[]] * 3" are '
+             'references\n'
+             '   to this single empty list.  Modifying any of the elements of\n'
+             '   "lists" modifies this single list. You can create a list of\n'
+             '   different lists this way:\n'
+             '\n'
+             '      >>> lists = [[] for i in range(3)]\n'
+             '      >>> lists[0].append(3)\n'
+             '      >>> lists[1].append(5)\n'
+             '      >>> lists[2].append(7)\n'
+             '      >>> lists\n'
+             '      [[3], [5], [7]]\n'
+             '\n'
+             '   Further explanation is available in the FAQ entry How do I '
+             'create a\n'
+             '   multidimensional list?.\n'
+             '\n'
+             '3. If *i* or *j* is negative, the index is relative to the end '
+             'of\n'
+             '   the string: "len(s) + i" or "len(s) + j" is substituted.  But '
+             'note\n'
+             '   that "-0" is still "0".\n'
+             '\n'
+             '4. The slice of *s* from *i* to *j* is defined as the sequence '
+             'of\n'
+             '   items with index *k* such that "i <= k < j".  If *i* or *j* '
+             'is\n'
+             '   greater than "len(s)", use "len(s)".  If *i* is omitted or '
+             '"None",\n'
+             '   use "0".  If *j* is omitted or "None", use "len(s)".  If *i* '
+             'is\n'
+             '   greater than or equal to *j*, the slice is empty.\n'
+             '\n'
+             '5. The slice of *s* from *i* to *j* with step *k* is defined as '
+             'the\n'
+             '   sequence of items with index  "x = i + n*k" such that "0 <= n '
+             '<\n'
+             '   (j-i)/k".  In other words, the indices are "i", "i+k", '
+             '"i+2*k",\n'
+             '   "i+3*k" and so on, stopping when *j* is reached (but never\n'
+             '   including *j*).  If *i* or *j* is greater than "len(s)", use\n'
+             '   "len(s)".  If *i* or *j* are omitted or "None", they become '
+             '"end"\n'
+             '   values (which end depends on the sign of *k*).  Note, *k* '
+             'cannot be\n'
+             '   zero. If *k* is "None", it is treated like "1".\n'
+             '\n'
+             '6. Concatenating immutable sequences always results in a new\n'
+             '   object. This means that building up a sequence by repeated\n'
+             '   concatenation will have a quadratic runtime cost in the '
+             'total\n'
+             '   sequence length. To get a linear runtime cost, you must '
+             'switch to\n'
+             '   one of the alternatives below:\n'
+             '\n'
+             '   * if concatenating "str" objects, you can build a list and '
+             'use\n'
+             '     "str.join()" at the end or else write to an "io.StringIO"\n'
+             '     instance and retrieve its value when complete\n'
+             '\n'
+             '   * if concatenating "bytes" objects, you can similarly use\n'
+             '     "bytes.join()" or "io.BytesIO", or you can do in-place\n'
+             '     concatenation with a "bytearray" object.  "bytearray" '
+             'objects are\n'
+             '     mutable and have an efficient overallocation mechanism\n'
+             '\n'
+             '   * if concatenating "tuple" objects, extend a "list" instead\n'
+             '\n'
+             '   * for other types, investigate the relevant class '
+             'documentation\n'
+             '\n'
+             '7. Some sequence types (such as "range") only support item\n'
+             "   sequences that follow specific patterns, and hence don't "
+             'support\n'
+             '   sequence concatenation or repetition.\n'
+             '\n'
+             '8. "index" raises "ValueError" when *x* is not found in *s*. '
+             'When\n'
+             '   supported, the additional arguments to the index method '
+             'allow\n'
+             '   efficient searching of subsections of the sequence. Passing '
+             'the\n'
+             '   extra arguments is roughly equivalent to using '
+             '"s[i:j].index(x)",\n'
+             '   only without copying any data and with the returned index '
+             'being\n'
+             '   relative to the start of the sequence rather than the start '
+             'of the\n'
+             '   slice.\n'
+             '\n'
+             '\n'
+             'Immutable Sequence Types\n'
+             '========================\n'
+             '\n'
+             'The only operation that immutable sequence types generally '
+             'implement\n'
+             'that is not also implemented by mutable sequence types is '
+             'support for\n'
+             'the "hash()" built-in.\n'
+             '\n'
+             'This support allows immutable sequences, such as "tuple" '
+             'instances, to\n'
+             'be used as "dict" keys and stored in "set" and "frozenset" '
+             'instances.\n'
+             '\n'
+             'Attempting to hash an immutable sequence that contains '
+             'unhashable\n'
+             'values will result in "TypeError".\n'
+             '\n'
+             '\n'
+             'Mutable Sequence Types\n'
+             '======================\n'
+             '\n'
+             'The operations in the following table are defined on mutable '
+             'sequence\n'
+             'types. The "collections.abc.MutableSequence" ABC is provided to '
+             'make\n'
+             'it easier to correctly implement these operations on custom '
+             'sequence\n'
+             'types.\n'
+             '\n'
+             'In the table *s* is an instance of a mutable sequence type, *t* '
+             'is any\n'
+             'iterable object and *x* is an arbitrary object that meets any '
+             'type and\n'
+             'value restrictions imposed by *s* (for example, "bytearray" '
+             'only\n'
+             'accepts integers that meet the value restriction "0 <= x <= '
+             '255").\n'
+             '\n'
+             '+--------------------------------+----------------------------------+-----------------------+\n'
+             '| Operation                      | '
+             'Result                           | Notes                 |\n'
+             '+================================+==================================+=======================+\n'
+             '| "s[i] = x"                     | item *i* of *s* is replaced '
+             'by   |                       |\n'
+             '|                                | '
+             '*x*                              |                       |\n'
+             '+--------------------------------+----------------------------------+-----------------------+\n'
+             '| "s[i:j] = t"                   | slice of *s* from *i* to *j* '
+             'is  |                       |\n'
+             '|                                | replaced by the contents of '
+             'the  |                       |\n'
+             '|                                | iterable '
+             '*t*                     |                       |\n'
+             '+--------------------------------+----------------------------------+-----------------------+\n'
+             '| "del s[i:j]"                   | same as "s[i:j] = '
+             '[]"            |                       |\n'
+             '+--------------------------------+----------------------------------+-----------------------+\n'
+             '| "s[i:j:k] = t"                 | the elements of "s[i:j:k]" '
+             'are   | (1)                   |\n'
+             '|                                | replaced by those of '
+             '*t*         |                       |\n'
+             '+--------------------------------+----------------------------------+-----------------------+\n'
+             '| "del s[i:j:k]"                 | removes the elements '
+             'of          |                       |\n'
+             '|                                | "s[i:j:k]" from the '
+             'list         |                       |\n'
+             '+--------------------------------+----------------------------------+-----------------------+\n'
+             '| "s.append(x)"                  | appends *x* to the end of '
+             'the    |                       |\n'
+             '|                                | sequence (same '
+             'as                |                       |\n'
+             '|                                | "s[len(s):len(s)] = '
+             '[x]")        |                       |\n'
+             '+--------------------------------+----------------------------------+-----------------------+\n'
+             '| "s.clear()"                    | removes all items from "s" '
+             '(same | (5)                   |\n'
+             '|                                | as "del '
+             's[:]")                   |                       |\n'
+             '+--------------------------------+----------------------------------+-----------------------+\n'
+             '| "s.copy()"                     | creates a shallow copy of '
+             '"s"    | (5)                   |\n'
+             '|                                | (same as '
+             '"s[:]")                 |                       |\n'
+             '+--------------------------------+----------------------------------+-----------------------+\n'
+             '| "s.extend(t)" or "s += t"      | extends *s* with the contents '
+             'of |                       |\n'
+             '|                                | *t* (for the most part the '
+             'same  |                       |\n'
+             '|                                | as "s[len(s):len(s)] = '
+             't")       |                       |\n'
+             '+--------------------------------+----------------------------------+-----------------------+\n'
+             '| "s *= n"                       | updates *s* with its '
+             'contents    | (6)                   |\n'
+             '|                                | repeated *n* '
+             'times               |                       |\n'
+             '+--------------------------------+----------------------------------+-----------------------+\n'
+             '| "s.insert(i, x)"               | inserts *x* into *s* at '
+             'the      |                       |\n'
+             '|                                | index given by *i* (same '
+             'as      |                       |\n'
+             '|                                | "s[i:i] = '
+             '[x]")                  |                       |\n'
+             '+--------------------------------+----------------------------------+-----------------------+\n'
+             '| "s.pop([i])"                   | retrieves the item at *i* '
+             'and    | (2)                   |\n'
+             '|                                | also removes it from '
+             '*s*         |                       |\n'
+             '+--------------------------------+----------------------------------+-----------------------+\n'
+             '| "s.remove(x)"                  | remove the first item from '
+             '*s*   | (3)                   |\n'
+             '|                                | where "s[i] == '
+             'x"                |                       |\n'
+             '+--------------------------------+----------------------------------+-----------------------+\n'
+             '| "s.reverse()"                  | reverses the items of *s* '
+             'in     | (4)                   |\n'
+             '|                                | '
+             'place                            |                       |\n'
+             '+--------------------------------+----------------------------------+-----------------------+\n'
+             '\n'
+             'Notes:\n'
+             '\n'
+             '1. *t* must have the same length as the slice it is replacing.\n'
+             '\n'
+             '2. The optional argument *i* defaults to "-1", so that by '
+             'default\n'
+             '   the last item is removed and returned.\n'
+             '\n'
+             '3. "remove" raises "ValueError" when *x* is not found in *s*.\n'
+             '\n'
+             '4. The "reverse()" method modifies the sequence in place for\n'
+             '   economy of space when reversing a large sequence.  To remind '
+             'users\n'
+             '   that it operates by side effect, it does not return the '
+             'reversed\n'
+             '   sequence.\n'
+             '\n'
+             '5. "clear()" and "copy()" are included for consistency with the\n'
+             "   interfaces of mutable containers that don't support slicing\n"
+             '   operations (such as "dict" and "set")\n'
+             '\n'
+             '   New in version 3.3: "clear()" and "copy()" methods.\n'
+             '\n'
+             '6. The value *n* is an integer, or an object implementing\n'
+             '   "__index__()".  Zero and negative values of *n* clear the '
+             'sequence.\n'
+             '   Items in the sequence are not copied; they are referenced '
+             'multiple\n'
+             '   times, as explained for "s * n" under Common Sequence '
+             'Operations.\n'
+             '\n'
+             '\n'
+             'Lists\n'
+             '=====\n'
+             '\n'
+             'Lists are mutable sequences, typically used to store collections '
+             'of\n'
+             'homogeneous items (where the precise degree of similarity will '
+             'vary by\n'
+             'application).\n'
+             '\n'
+             'class list([iterable])\n'
+             '\n'
+             '   Lists may be constructed in several ways:\n'
+             '\n'
+             '   * Using a pair of square brackets to denote the empty list: '
+             '"[]"\n'
+             '\n'
+             '   * Using square brackets, separating items with commas: '
+             '"[a]",\n'
+             '     "[a, b, c]"\n'
+             '\n'
+             '   * Using a list comprehension: "[x for x in iterable]"\n'
+             '\n'
+             '   * Using the type constructor: "list()" or "list(iterable)"\n'
+             '\n'
+             '   The constructor builds a list whose items are the same and in '
+             'the\n'
+             "   same order as *iterable*'s items.  *iterable* may be either "
+             'a\n'
+             '   sequence, a container that supports iteration, or an '
+             'iterator\n'
+             '   object.  If *iterable* is already a list, a copy is made and\n'
+             '   returned, similar to "iterable[:]". For example, '
+             '"list(\'abc\')"\n'
+             '   returns "[\'a\', \'b\', \'c\']" and "list( (1, 2, 3) )" '
+             'returns "[1, 2,\n'
+             '   3]". If no argument is given, the constructor creates a new '
+             'empty\n'
+             '   list, "[]".\n'
+             '\n'
+             '   Many other operations also produce lists, including the '
+             '"sorted()"\n'
+             '   built-in.\n'
+             '\n'
+             '   Lists implement all of the common and mutable sequence '
+             'operations.\n'
+             '   Lists also provide the following additional method:\n'
+             '\n'
+             '   sort(*, key=None, reverse=None)\n'
+             '\n'
+             '      This method sorts the list in place, using only "<" '
+             'comparisons\n'
+             '      between items. Exceptions are not suppressed - if any '
+             'comparison\n'
+             '      operations fail, the entire sort operation will fail (and '
+             'the\n'
+             '      list will likely be left in a partially modified state).\n'
+             '\n'
+             '      "sort()" accepts two arguments that can only be passed by\n'
+             '      keyword (keyword-only arguments):\n'
+             '\n'
+             '      *key* specifies a function of one argument that is used '
+             'to\n'
+             '      extract a comparison key from each list element (for '
+             'example,\n'
+             '      "key=str.lower"). The key corresponding to each item in '
+             'the list\n'
+             '      is calculated once and then used for the entire sorting '
+             'process.\n'
+             '      The default value of "None" means that list items are '
+             'sorted\n'
+             '      directly without calculating a separate key value.\n'
+             '\n'
+             '      The "functools.cmp_to_key()" utility is available to '
+             'convert a\n'
+             '      2.x style *cmp* function to a *key* function.\n'
+             '\n'
+             '      *reverse* is a boolean value.  If set to "True", then the '
+             'list\n'
+             '      elements are sorted as if each comparison were reversed.\n'
+             '\n'
+             '      This method modifies the sequence in place for economy of '
+             'space\n'
+             '      when sorting a large sequence.  To remind users that it '
+             'operates\n'
+             '      by side effect, it does not return the sorted sequence '
+             '(use\n'
+             '      "sorted()" to explicitly request a new sorted list '
+             'instance).\n'
+             '\n'
+             '      The "sort()" method is guaranteed to be stable.  A sort '
+             'is\n'
+             '      stable if it guarantees not to change the relative order '
+             'of\n'
+             '      elements that compare equal --- this is helpful for '
+             'sorting in\n'
+             '      multiple passes (for example, sort by department, then by '
+             'salary\n'
+             '      grade).\n'
+             '\n'
+             '      **CPython implementation detail:** While a list is being '
+             'sorted,\n'
+             '      the effect of attempting to mutate, or even inspect, the '
+             'list is\n'
+             '      undefined.  The C implementation of Python makes the list '
+             'appear\n'
+             '      empty for the duration, and raises "ValueError" if it can '
+             'detect\n'
+             '      that the list has been mutated during a sort.\n'
+             '\n'
+             '\n'
+             'Tuples\n'
+             '======\n'
+             '\n'
+             'Tuples are immutable sequences, typically used to store '
+             'collections of\n'
+             'heterogeneous data (such as the 2-tuples produced by the '
+             '"enumerate()"\n'
+             'built-in). Tuples are also used for cases where an immutable '
+             'sequence\n'
+             'of homogeneous data is needed (such as allowing storage in a '
+             '"set" or\n'
+             '"dict" instance).\n'
+             '\n'
+             'class tuple([iterable])\n'
+             '\n'
+             '   Tuples may be constructed in a number of ways:\n'
+             '\n'
+             '   * Using a pair of parentheses to denote the empty tuple: '
+             '"()"\n'
+             '\n'
+             '   * Using a trailing comma for a singleton tuple: "a," or '
+             '"(a,)"\n'
+             '\n'
+             '   * Separating items with commas: "a, b, c" or "(a, b, c)"\n'
+             '\n'
+             '   * Using the "tuple()" built-in: "tuple()" or '
+             '"tuple(iterable)"\n'
+             '\n'
+             '   The constructor builds a tuple whose items are the same and '
+             'in the\n'
+             "   same order as *iterable*'s items.  *iterable* may be either "
+             'a\n'
+             '   sequence, a container that supports iteration, or an '
+             'iterator\n'
+             '   object.  If *iterable* is already a tuple, it is returned\n'
+             '   unchanged. For example, "tuple(\'abc\')" returns "(\'a\', '
+             '\'b\', \'c\')"\n'
+             '   and "tuple( [1, 2, 3] )" returns "(1, 2, 3)". If no argument '
+             'is\n'
+             '   given, the constructor creates a new empty tuple, "()".\n'
+             '\n'
+             '   Note that it is actually the comma which makes a tuple, not '
+             'the\n'
+             '   parentheses. The parentheses are optional, except in the '
+             'empty\n'
+             '   tuple case, or when they are needed to avoid syntactic '
+             'ambiguity.\n'
+             '   For example, "f(a, b, c)" is a function call with three '
+             'arguments,\n'
+             '   while "f((a, b, c))" is a function call with a 3-tuple as the '
+             'sole\n'
+             '   argument.\n'
+             '\n'
+             '   Tuples implement all of the common sequence operations.\n'
+             '\n'
+             'For heterogeneous collections of data where access by name is '
+             'clearer\n'
+             'than access by index, "collections.namedtuple()" may be a more\n'
+             'appropriate choice than a simple tuple object.\n'
+             '\n'
+             '\n'
+             'Ranges\n'
+             '======\n'
+             '\n'
+             'The "range" type represents an immutable sequence of numbers and '
+             'is\n'
+             'commonly used for looping a specific number of times in "for" '
+             'loops.\n'
+             '\n'
+             'class range(stop)\n'
+             'class range(start, stop[, step])\n'
+             '\n'
+             '   The arguments to the range constructor must be integers '
+             '(either\n'
+             '   built-in "int" or any object that implements the "__index__"\n'
+             '   special method).  If the *step* argument is omitted, it '
+             'defaults to\n'
+             '   "1". If the *start* argument is omitted, it defaults to "0". '
+             'If\n'
+             '   *step* is zero, "ValueError" is raised.\n'
+             '\n'
+             '   For a positive *step*, the contents of a range "r" are '
+             'determined\n'
+             '   by the formula "r[i] = start + step*i" where "i >= 0" and '
+             '"r[i] <\n'
+             '   stop".\n'
+             '\n'
+             '   For a negative *step*, the contents of the range are still\n'
+             '   determined by the formula "r[i] = start + step*i", but the\n'
+             '   constraints are "i >= 0" and "r[i] > stop".\n'
+             '\n'
+             '   A range object will be empty if "r[0]" does not meet the '
+             'value\n'
+             '   constraint. Ranges do support negative indices, but these '
+             'are\n'
+             '   interpreted as indexing from the end of the sequence '
+             'determined by\n'
+             '   the positive indices.\n'
+             '\n'
+             '   Ranges containing absolute values larger than "sys.maxsize" '
+             'are\n'
+             '   permitted but some features (such as "len()") may raise\n'
+             '   "OverflowError".\n'
+             '\n'
+             '   Range examples:\n'
+             '\n'
+             '      >>> list(range(10))\n'
+             '      [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]\n'
+             '      >>> list(range(1, 11))\n'
+             '      [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]\n'
+             '      >>> list(range(0, 30, 5))\n'
+             '      [0, 5, 10, 15, 20, 25]\n'
+             '      >>> list(range(0, 10, 3))\n'
+             '      [0, 3, 6, 9]\n'
+             '      >>> list(range(0, -10, -1))\n'
+             '      [0, -1, -2, -3, -4, -5, -6, -7, -8, -9]\n'
+             '      >>> list(range(0))\n'
+             '      []\n'
+             '      >>> list(range(1, 0))\n'
+             '      []\n'
+             '\n'
+             '   Ranges implement all of the common sequence operations '
+             'except\n'
+             '   concatenation and repetition (due to the fact that range '
+             'objects\n'
+             '   can only represent sequences that follow a strict pattern '
+             'and\n'
+             '   repetition and concatenation will usually violate that '
+             'pattern).\n'
+             '\n'
+             '   start\n'
+             '\n'
+             '      The value of the *start* parameter (or "0" if the '
+             'parameter was\n'
+             '      not supplied)\n'
+             '\n'
+             '   stop\n'
+             '\n'
+             '      The value of the *stop* parameter\n'
+             '\n'
+             '   step\n'
+             '\n'
+             '      The value of the *step* parameter (or "1" if the parameter '
+             'was\n'
+             '      not supplied)\n'
+             '\n'
+             'The advantage of the "range" type over a regular "list" or '
+             '"tuple" is\n'
+             'that a "range" object will always take the same (small) amount '
+             'of\n'
+             'memory, no matter the size of the range it represents (as it '
+             'only\n'
+             'stores the "start", "stop" and "step" values, calculating '
+             'individual\n'
+             'items and subranges as needed).\n'
+             '\n'
+             'Range objects implement the "collections.abc.Sequence" ABC, and\n'
+             'provide features such as containment tests, element index '
+             'lookup,\n'
+             'slicing and support for negative indices (see Sequence Types --- '
+             'list,\n'
+             'tuple, range):\n'
+             '\n'
+             '>>> r = range(0, 20, 2)\n'
+             '>>> r\n'
+             'range(0, 20, 2)\n'
+             '>>> 11 in r\n'
+             'False\n'
+             '>>> 10 in r\n'
+             'True\n'
+             '>>> r.index(10)\n'
+             '5\n'
+             '>>> r[5]\n'
+             '10\n'
+             '>>> r[:5]\n'
+             'range(0, 10, 2)\n'
+             '>>> r[-1]\n'
+             '18\n'
+             '\n'
+             'Testing range objects for equality with "==" and "!=" compares '
+             'them as\n'
+             'sequences.  That is, two range objects are considered equal if '
+             'they\n'
+             'represent the same sequence of values.  (Note that two range '
+             'objects\n'
+             'that compare equal might have different "start", "stop" and '
+             '"step"\n'
+             'attributes, for example "range(0) == range(2, 1, 3)" or '
+             '"range(0, 3,\n'
+             '2) == range(0, 4, 2)".)\n'
+             '\n'
+             'Changed in version 3.2: Implement the Sequence ABC. Support '
+             'slicing\n'
+             'and negative indices. Test "int" objects for membership in '
+             'constant\n'
+             'time instead of iterating through all items.\n'
+             '\n'
+             "Changed in version 3.3: Define '==' and '!=' to compare range "
+             'objects\n'
+             'based on the sequence of values they define (instead of '
+             'comparing\n'
+             'based on object identity).\n'
+             '\n'
+             'New in version 3.3: The "start", "stop" and "step" attributes.\n',
+ 'typesseq-mutable': '\n'
+                     'Mutable Sequence Types\n'
+                     '**********************\n'
+                     '\n'
+                     'The operations in the following table are defined on '
+                     'mutable sequence\n'
+                     'types. The "collections.abc.MutableSequence" ABC is '
+                     'provided to make\n'
+                     'it easier to correctly implement these operations on '
+                     'custom sequence\n'
+                     'types.\n'
+                     '\n'
+                     'In the table *s* is an instance of a mutable sequence '
+                     'type, *t* is any\n'
+                     'iterable object and *x* is an arbitrary object that '
+                     'meets any type and\n'
+                     'value restrictions imposed by *s* (for example, '
+                     '"bytearray" only\n'
+                     'accepts integers that meet the value restriction "0 <= x '
+                     '<= 255").\n'
+                     '\n'
+                     '+--------------------------------+----------------------------------+-----------------------+\n'
+                     '| Operation                      | '
+                     'Result                           | Notes                 '
+                     '|\n'
+                     '+================================+==================================+=======================+\n'
+                     '| "s[i] = x"                     | item *i* of *s* is '
+                     'replaced by   |                       |\n'
+                     '|                                | '
+                     '*x*                              |                       '
+                     '|\n'
+                     '+--------------------------------+----------------------------------+-----------------------+\n'
+                     '| "s[i:j] = t"                   | slice of *s* from *i* '
+                     'to *j* is  |                       |\n'
+                     '|                                | replaced by the '
+                     'contents of the  |                       |\n'
+                     '|                                | iterable '
+                     '*t*                     |                       |\n'
+                     '+--------------------------------+----------------------------------+-----------------------+\n'
+                     '| "del s[i:j]"                   | same as "s[i:j] = '
+                     '[]"            |                       |\n'
+                     '+--------------------------------+----------------------------------+-----------------------+\n'
+                     '| "s[i:j:k] = t"                 | the elements of '
+                     '"s[i:j:k]" are   | (1)                   |\n'
+                     '|                                | replaced by those of '
+                     '*t*         |                       |\n'
+                     '+--------------------------------+----------------------------------+-----------------------+\n'
+                     '| "del s[i:j:k]"                 | removes the elements '
+                     'of          |                       |\n'
+                     '|                                | "s[i:j:k]" from the '
+                     'list         |                       |\n'
+                     '+--------------------------------+----------------------------------+-----------------------+\n'
+                     '| "s.append(x)"                  | appends *x* to the '
+                     'end of the    |                       |\n'
+                     '|                                | sequence (same '
+                     'as                |                       |\n'
+                     '|                                | "s[len(s):len(s)] = '
+                     '[x]")        |                       |\n'
+                     '+--------------------------------+----------------------------------+-----------------------+\n'
+                     '| "s.clear()"                    | removes all items '
+                     'from "s" (same | (5)                   |\n'
+                     '|                                | as "del '
+                     's[:]")                   |                       |\n'
+                     '+--------------------------------+----------------------------------+-----------------------+\n'
+                     '| "s.copy()"                     | creates a shallow '
+                     'copy of "s"    | (5)                   |\n'
+                     '|                                | (same as '
+                     '"s[:]")                 |                       |\n'
+                     '+--------------------------------+----------------------------------+-----------------------+\n'
+                     '| "s.extend(t)" or "s += t"      | extends *s* with the '
+                     'contents of |                       |\n'
+                     '|                                | *t* (for the most '
+                     'part the same  |                       |\n'
+                     '|                                | as "s[len(s):len(s)] '
+                     '= t")       |                       |\n'
+                     '+--------------------------------+----------------------------------+-----------------------+\n'
+                     '| "s *= n"                       | updates *s* with its '
+                     'contents    | (6)                   |\n'
+                     '|                                | repeated *n* '
+                     'times               |                       |\n'
+                     '+--------------------------------+----------------------------------+-----------------------+\n'
+                     '| "s.insert(i, x)"               | inserts *x* into *s* '
+                     'at the      |                       |\n'
+                     '|                                | index given by *i* '
+                     '(same as      |                       |\n'
+                     '|                                | "s[i:i] = '
+                     '[x]")                  |                       |\n'
+                     '+--------------------------------+----------------------------------+-----------------------+\n'
+                     '| "s.pop([i])"                   | retrieves the item at '
+                     '*i* and    | (2)                   |\n'
+                     '|                                | also removes it from '
+                     '*s*         |                       |\n'
+                     '+--------------------------------+----------------------------------+-----------------------+\n'
+                     '| "s.remove(x)"                  | remove the first item '
+                     'from *s*   | (3)                   |\n'
+                     '|                                | where "s[i] == '
+                     'x"                |                       |\n'
+                     '+--------------------------------+----------------------------------+-----------------------+\n'
+                     '| "s.reverse()"                  | reverses the items of '
+                     '*s* in     | (4)                   |\n'
+                     '|                                | '
+                     'place                            |                       '
+                     '|\n'
+                     '+--------------------------------+----------------------------------+-----------------------+\n'
+                     '\n'
+                     'Notes:\n'
+                     '\n'
+                     '1. *t* must have the same length as the slice it is '
+                     'replacing.\n'
+                     '\n'
+                     '2. The optional argument *i* defaults to "-1", so that '
+                     'by default\n'
+                     '   the last item is removed and returned.\n'
+                     '\n'
+                     '3. "remove" raises "ValueError" when *x* is not found in '
+                     '*s*.\n'
+                     '\n'
+                     '4. The "reverse()" method modifies the sequence in place '
+                     'for\n'
+                     '   economy of space when reversing a large sequence.  To '
+                     'remind users\n'
+                     '   that it operates by side effect, it does not return '
+                     'the reversed\n'
+                     '   sequence.\n'
+                     '\n'
+                     '5. "clear()" and "copy()" are included for consistency '
+                     'with the\n'
+                     "   interfaces of mutable containers that don't support "
+                     'slicing\n'
+                     '   operations (such as "dict" and "set")\n'
+                     '\n'
+                     '   New in version 3.3: "clear()" and "copy()" methods.\n'
+                     '\n'
+                     '6. The value *n* is an integer, or an object '
+                     'implementing\n'
+                     '   "__index__()".  Zero and negative values of *n* clear '
+                     'the sequence.\n'
+                     '   Items in the sequence are not copied; they are '
+                     'referenced multiple\n'
+                     '   times, as explained for "s * n" under Common Sequence '
+                     'Operations.\n',
+ 'unary': '\n'
+          'Unary arithmetic and bitwise operations\n'
+          '***************************************\n'
+          '\n'
+          'All unary arithmetic and bitwise operations have the same '
+          'priority:\n'
+          '\n'
+          '   u_expr ::= power | "-" u_expr | "+" u_expr | "~" u_expr\n'
+          '\n'
+          'The unary "-" (minus) operator yields the negation of its numeric\n'
+          'argument.\n'
+          '\n'
+          'The unary "+" (plus) operator yields its numeric argument '
+          'unchanged.\n'
+          '\n'
+          'The unary "~" (invert) operator yields the bitwise inversion of '
+          'its\n'
+          'integer argument.  The bitwise inversion of "x" is defined as\n'
+          '"-(x+1)".  It only applies to integral numbers.\n'
+          '\n'
+          'In all three cases, if the argument does not have the proper type, '
+          'a\n'
+          '"TypeError" exception is raised.\n',
+ 'while': '\n'
+          'The "while" statement\n'
+          '*********************\n'
+          '\n'
+          'The "while" statement is used for repeated execution as long as an\n'
+          'expression is true:\n'
+          '\n'
+          '   while_stmt ::= "while" expression ":" suite\n'
+          '                  ["else" ":" suite]\n'
+          '\n'
+          'This repeatedly tests the expression and, if it is true, executes '
+          'the\n'
+          'first suite; if the expression is false (which may be the first '
+          'time\n'
+          'it is tested) the suite of the "else" clause, if present, is '
+          'executed\n'
+          'and the loop terminates.\n'
+          '\n'
+          'A "break" statement executed in the first suite terminates the '
+          'loop\n'
+          'without executing the "else" clause\'s suite.  A "continue" '
+          'statement\n'
+          'executed in the first suite skips the rest of the suite and goes '
+          'back\n'
+          'to testing the expression.\n',
+ 'with': '\n'
+         'The "with" statement\n'
+         '********************\n'
+         '\n'
+         'The "with" statement is used to wrap the execution of a block with\n'
+         'methods defined by a context manager (see section With Statement\n'
+         'Context Managers). This allows common "try"..."except"..."finally"\n'
+         'usage patterns to be encapsulated for convenient reuse.\n'
+         '\n'
+         '   with_stmt ::= "with" with_item ("," with_item)* ":" suite\n'
+         '   with_item ::= expression ["as" target]\n'
+         '\n'
+         'The execution of the "with" statement with one "item" proceeds as\n'
+         'follows:\n'
+         '\n'
+         '1. The context expression (the expression given in the "with_item")\n'
+         '   is evaluated to obtain a context manager.\n'
+         '\n'
+         '2. The context manager\'s "__exit__()" is loaded for later use.\n'
+         '\n'
+         '3. The context manager\'s "__enter__()" method is invoked.\n'
+         '\n'
+         '4. If a target was included in the "with" statement, the return\n'
+         '   value from "__enter__()" is assigned to it.\n'
+         '\n'
+         '   Note: The "with" statement guarantees that if the "__enter__()"\n'
+         '     method returns without an error, then "__exit__()" will always '
+         'be\n'
+         '     called. Thus, if an error occurs during the assignment to the\n'
+         '     target list, it will be treated the same as an error occurring\n'
+         '     within the suite would be. See step 6 below.\n'
+         '\n'
+         '5. The suite is executed.\n'
+         '\n'
+         '6. The context manager\'s "__exit__()" method is invoked.  If an\n'
+         '   exception caused the suite to be exited, its type, value, and\n'
+         '   traceback are passed as arguments to "__exit__()". Otherwise, '
+         'three\n'
+         '   "None" arguments are supplied.\n'
+         '\n'
+         '   If the suite was exited due to an exception, and the return '
+         'value\n'
+         '   from the "__exit__()" method was false, the exception is '
+         'reraised.\n'
+         '   If the return value was true, the exception is suppressed, and\n'
+         '   execution continues with the statement following the "with"\n'
+         '   statement.\n'
+         '\n'
+         '   If the suite was exited for any reason other than an exception, '
+         'the\n'
+         '   return value from "__exit__()" is ignored, and execution '
+         'proceeds\n'
+         '   at the normal location for the kind of exit that was taken.\n'
+         '\n'
+         'With more than one item, the context managers are processed as if\n'
+         'multiple "with" statements were nested:\n'
+         '\n'
+         '   with A() as a, B() as b:\n'
+         '       suite\n'
+         '\n'
+         'is equivalent to\n'
+         '\n'
+         '   with A() as a:\n'
+         '       with B() as b:\n'
+         '           suite\n'
+         '\n'
+         'Changed in version 3.1: Support for multiple context expressions.\n'
+         '\n'
+         'See also:\n'
+         '\n'
+         '  **PEP 343** - The "with" statement\n'
+         '     The specification, background, and examples for the Python '
+         '"with"\n'
+         '     statement.\n',
+ 'yield': '\n'
+          'The "yield" statement\n'
+          '*********************\n'
+          '\n'
+          '   yield_stmt ::= yield_expression\n'
+          '\n'
+          'A "yield" statement is semantically equivalent to a yield '
+          'expression.\n'
+          'The yield statement can be used to omit the parentheses that would\n'
+          'otherwise be required in the equivalent yield expression '
+          'statement.\n'
+          'For example, the yield statements\n'
+          '\n'
+          '   yield <expr>\n'
+          '   yield from <expr>\n'
+          '\n'
+          'are equivalent to the yield expression statements\n'
+          '\n'
+          '   (yield <expr>)\n'
+          '   (yield from <expr>)\n'
+          '\n'
+          'Yield expressions and statements are only used when defining a\n'
+          '*generator* function, and are only used in the body of the '
+          'generator\n'
+          'function.  Using yield in a function definition is sufficient to '
+          'cause\n'
+          'that definition to create a generator function instead of a normal\n'
+          'function.\n'
+          '\n'
+          'For full details of "yield" semantics, refer to the Yield '
+          'expressions\n'
+          'section.\n'}
diff --git a/Lib/re.py b/Lib/re.py
index dde8901c62..661929e76b 100644
--- a/Lib/re.py
+++ b/Lib/re.py
@@ -119,7 +119,6 @@ This module also defines an exception 'error'.
 
 """
 
-import sys
 import sre_compile
 import sre_parse
 try:
diff --git a/Lib/rlcompleter.py b/Lib/rlcompleter.py
index 401a626179..bca4a7bc52 100644
--- a/Lib/rlcompleter.py
+++ b/Lib/rlcompleter.py
@@ -113,6 +113,12 @@ class Completer:
         for word in keyword.kwlist:
             if word[:n] == text:
                 seen.add(word)
+                if word in {'finally', 'try'}:
+                    word = word + ':'
+                elif word not in {'False', 'None', 'True',
+                                  'break', 'continue', 'pass',
+                                  'else'}:
+                    word = word + ' '
                 matches.append(word)
         for nspace in [self.namespace, builtins.__dict__]:
             for word, val in nspace.items():
@@ -152,14 +158,30 @@ class Completer:
             words.update(get_class_members(thisobject.__class__))
         matches = []
         n = len(attr)
-        for word in words:
-            if word[:n] == attr:
-                try:
-                    val = getattr(thisobject, word)
-                except Exception:
-                    continue  # Exclude properties that are not set
-                word = self._callable_postfix(val, "%s.%s" % (expr, word))
-                matches.append(word)
+        if attr == '':
+            noprefix = '_'
+        elif attr == '_':
+            noprefix = '__'
+        else:
+            noprefix = None
+        while True:
+            for word in words:
+                if (word[:n] == attr and
+                    not (noprefix and word[:n+1] == noprefix)):
+                    match = "%s.%s" % (expr, word)
+                    try:
+                        val = getattr(thisobject, word)
+                    except Exception:
+                        pass  # Include even if attribute not set
+                    else:
+                        match = self._callable_postfix(val, match)
+                    matches.append(match)
+            if matches or not noprefix:
+                break
+            if noprefix == '_':
+                noprefix = '__'
+            else:
+                noprefix = None
         matches.sort()
         return matches
 
diff --git a/Lib/sched.py b/Lib/sched.py
index b47648d973..bd7c0f1b6f 100644
--- a/Lib/sched.py
+++ b/Lib/sched.py
@@ -46,6 +46,17 @@ class Event(namedtuple('Event', 'time, priority, action, argument, kwargs')):
     def __gt__(s, o): return (s.time, s.priority) >  (o.time, o.priority)
     def __ge__(s, o): return (s.time, s.priority) >= (o.time, o.priority)
 
+Event.time.__doc__ = ('''Numeric type compatible with the return value of the
+timefunc function passed to the constructor.''')
+Event.priority.__doc__ = ('''Events scheduled for the same time will be executed
+in the order of their priority.''')
+Event.action.__doc__ = ('''Executing the event means executing
+action(*argument, **kwargs)''')
+Event.argument.__doc__ = ('''argument is a sequence holding the positional
+arguments for the action.''')
+Event.kwargs.__doc__ = ('''kwargs is a dictionary holding the keyword
+arguments for the action.''')
+
 _sentinel = object()
 
 class scheduler:
diff --git a/Lib/secrets.py b/Lib/secrets.py
new file mode 100644
index 0000000000..27fa4503d7
--- /dev/null
+++ b/Lib/secrets.py
@@ -0,0 +1,71 @@
+"""Generate cryptographically strong pseudo-random numbers suitable for
+managing secrets such as account authentication, tokens, and similar.
+
+See PEP 506 for more information.
+https://www.python.org/dev/peps/pep-0506/
+
+"""
+
+__all__ = ['choice', 'randbelow', 'randbits', 'SystemRandom',
+           'token_bytes', 'token_hex', 'token_urlsafe',
+           'compare_digest',
+           ]
+
+
+import base64
+import binascii
+import os
+
+from hmac import compare_digest
+from random import SystemRandom
+
+_sysrand = SystemRandom()
+
+randbits = _sysrand.getrandbits
+choice = _sysrand.choice
+
+def randbelow(exclusive_upper_bound):
+    """Return a random int in the range [0, n)."""
+    return _sysrand._randbelow(exclusive_upper_bound)
+
+DEFAULT_ENTROPY = 32  # number of bytes to return by default
+
+def token_bytes(nbytes=None):
+    """Return a random byte string containing *nbytes* bytes.
+
+    If *nbytes* is ``None`` or not supplied, a reasonable
+    default is used.
+
+    >>> token_bytes(16)  #doctest:+SKIP
+    b'\\xebr\\x17D*t\\xae\\xd4\\xe3S\\xb6\\xe2\\xebP1\\x8b'
+
+    """
+    if nbytes is None:
+        nbytes = DEFAULT_ENTROPY
+    return os.urandom(nbytes)
+
+def token_hex(nbytes=None):
+    """Return a random text string, in hexadecimal.
+
+    The string has *nbytes* random bytes, each byte converted to two
+    hex digits.  If *nbytes* is ``None`` or not supplied, a reasonable
+    default is used.
+
+    >>> token_hex(16)  #doctest:+SKIP
+    'f9bf78b9a18ce6d46a0cd2b0b86df9da'
+
+    """
+    return binascii.hexlify(token_bytes(nbytes)).decode('ascii')
+
+def token_urlsafe(nbytes=None):
+    """Return a random URL-safe text string, in Base64 encoding.
+
+    The string has *nbytes* random bytes.  If *nbytes* is ``None``
+    or not supplied, a reasonable default is used.
+
+    >>> token_urlsafe(16)  #doctest:+SKIP
+    'Drmhze6EPcv0fN_81Bj-nA'
+
+    """
+    tok = token_bytes(nbytes)
+    return base64.urlsafe_b64encode(tok).rstrip(b'=').decode('ascii')
diff --git a/Lib/shutil.py b/Lib/shutil.py
index 37124a0c98..b1953cc570 100644
--- a/Lib/shutil.py
+++ b/Lib/shutil.py
@@ -974,6 +974,9 @@ if hasattr(os, 'statvfs'):
 
     __all__.append('disk_usage')
     _ntuple_diskusage = collections.namedtuple('usage', 'total used free')
+    _ntuple_diskusage.total.__doc__ = 'Total space in bytes'
+    _ntuple_diskusage.used.__doc__ = 'Used space in bytes'
+    _ntuple_diskusage.free.__doc__ = 'Free space in bytes'
 
     def disk_usage(path):
         """Return disk usage statistics about the given path.
diff --git a/Lib/site-packages/README.txt b/Lib/site-packages/README.txt
new file mode 100644
index 0000000000..273f6251a7
--- /dev/null
+++ b/Lib/site-packages/README.txt
@@ -0,0 +1,2 @@
+This directory exists so that 3rd party packages can be installed
+here.  Read the source for site.py for more details.
diff --git a/Lib/site.py b/Lib/site.py
index 3f78ef5b88..a84e3bb7c5 100644
--- a/Lib/site.py
+++ b/Lib/site.py
@@ -131,13 +131,13 @@ def removeduppaths():
 
 
 def _init_pathinfo():
-    """Return a set containing all existing directory entries from sys.path"""
+    """Return a set containing all existing file system items from sys.path."""
     d = set()
-    for dir in sys.path:
+    for item in sys.path:
         try:
-            if os.path.isdir(dir):
-                dir, dircase = makepath(dir)
-                d.add(dircase)
+            if os.path.exists(item):
+                _, itemcase = makepath(item)
+                d.add(itemcase)
         except TypeError:
             continue
     return d
@@ -150,9 +150,9 @@ def addpackage(sitedir, name, known_paths):
     """
     if known_paths is None:
         known_paths = _init_pathinfo()
-        reset = 1
+        reset = True
     else:
-        reset = 0
+        reset = False
     fullname = os.path.join(sitedir, name)
     try:
         f = open(fullname, "r")
@@ -190,9 +190,9 @@ def addsitedir(sitedir, known_paths=None):
     'sitedir'"""
     if known_paths is None:
         known_paths = _init_pathinfo()
-        reset = 1
+        reset = True
     else:
-        reset = 0
+        reset = False
     sitedir, sitedircase = makepath(sitedir)
     if not sitedircase in known_paths:
         sys.path.append(sitedir)        # Add path component
@@ -304,7 +304,7 @@ def getsitepackages(prefixes=None):
 
         if os.sep == '/':
             sitepackages.append(os.path.join(prefix, "lib",
-                                        "python" + sys.version[:3],
+                                        "python%d.%d" % sys.version_info[:2],
                                         "site-packages"))
         else:
             sitepackages.append(prefix)
@@ -317,7 +317,7 @@ def getsitepackages(prefixes=None):
             if framework:
                 sitepackages.append(
                         os.path.join("/Library", framework,
-                            sys.version[:3], "site-packages"))
+                            '%d.%d' % sys.version_info[:2], "site-packages"))
     return sitepackages
 
 def addsitepackages(known_paths, prefixes=None):
@@ -504,9 +504,13 @@ def venv(known_paths):
 def execsitecustomize():
     """Run custom site specific code, if available."""
     try:
-        import sitecustomize
-    except ImportError:
-        pass
+        try:
+            import sitecustomize
+        except ImportError as exc:
+            if exc.name == 'sitecustomize':
+                pass
+            else:
+                raise
     except Exception as err:
         if os.environ.get("PYTHONVERBOSE"):
             sys.excepthook(*sys.exc_info())
@@ -520,9 +524,13 @@ def execsitecustomize():
 def execusercustomize():
     """Run custom user specific code, if available."""
     try:
-        import usercustomize
-    except ImportError:
-        pass
+        try:
+            import usercustomize
+        except ImportError as exc:
+            if exc.name == 'usercustomize':
+                pass
+            else:
+                raise
     except Exception as err:
         if os.environ.get("PYTHONVERBOSE"):
             sys.excepthook(*sys.exc_info())
diff --git a/Lib/smtpd.py b/Lib/smtpd.py
index 732066ef9a..8103ca9af0 100755
--- a/Lib/smtpd.py
+++ b/Lib/smtpd.py
@@ -89,7 +89,10 @@ import collections
 from warnings import warn
 from email._header_value_parser import get_addr_spec, get_angle_addr
 
-__all__ = ["SMTPServer","DebuggingServer","PureProxy","MailmanProxy"]
+__all__ = [
+    "SMTPChannel", "SMTPServer", "DebuggingServer", "PureProxy",
+    "MailmanProxy",
+]
 
 program = sys.argv[0]
 __version__ = 'Python SMTP proxy version 0.3'
@@ -128,24 +131,17 @@ class SMTPChannel(asynchat.async_chat):
             return self.command_size_limit
 
     def __init__(self, server, conn, addr, data_size_limit=DATA_SIZE_DEFAULT,
-                 map=None, enable_SMTPUTF8=False, decode_data=None):
+                 map=None, enable_SMTPUTF8=False, decode_data=False):
         asynchat.async_chat.__init__(self, conn, map=map)
         self.smtp_server = server
         self.conn = conn
         self.addr = addr
         self.data_size_limit = data_size_limit
         self.enable_SMTPUTF8 = enable_SMTPUTF8
-        if enable_SMTPUTF8:
-            if decode_data:
-                raise ValueError("decode_data and enable_SMTPUTF8 cannot"
-                                 " be set to True at the same time")
-            decode_data = False
-        if decode_data is None:
-            warn("The decode_data default of True will change to False in 3.6;"
-                 " specify an explicit value for this keyword",
-                 DeprecationWarning, 2)
-            decode_data = True
         self._decode_data = decode_data
+        if enable_SMTPUTF8 and decode_data:
+            raise ValueError("decode_data and enable_SMTPUTF8 cannot"
+                             " be set to True at the same time")
         if decode_data:
             self._emptystring = ''
             self._linesep = '\r\n'
@@ -635,23 +631,15 @@ class SMTPServer(asyncore.dispatcher):
 
     def __init__(self, localaddr, remoteaddr,
                  data_size_limit=DATA_SIZE_DEFAULT, map=None,
-                 enable_SMTPUTF8=False, decode_data=None):
+                 enable_SMTPUTF8=False, decode_data=False):
         self._localaddr = localaddr
         self._remoteaddr = remoteaddr
         self.data_size_limit = data_size_limit
         self.enable_SMTPUTF8 = enable_SMTPUTF8
-        if enable_SMTPUTF8:
-            if decode_data:
-                raise ValueError("The decode_data and enable_SMTPUTF8"
-                                 " parameters cannot be set to True at the"
-                                 " same time.")
-            decode_data = False
-        if decode_data is None:
-            warn("The decode_data default of True will change to False in 3.6;"
-                 " specify an explicit value for this keyword",
-                 DeprecationWarning, 2)
-            decode_data = True
         self._decode_data = decode_data
+        if enable_SMTPUTF8 and decode_data:
+            raise ValueError("decode_data and enable_SMTPUTF8 cannot"
+                             " be set to True at the same time")
         asyncore.dispatcher.__init__(self, map=map)
         try:
             gai_results = socket.getaddrinfo(*localaddr,
@@ -698,9 +686,9 @@ class SMTPServer(asyncore.dispatcher):
         containing a `.' followed by other text has had the leading dot
         removed.
 
-        kwargs is a dictionary containing additional information. It is empty
-        unless decode_data=False or enable_SMTPUTF8=True was given as init
-        parameter, in which case ut will contain the following keys:
+        kwargs is a dictionary containing additional information.  It is
+        empty if decode_data=True was given as init parameter, otherwise
+        it will contain the following keys:
             'mail_options': list of parameters to the mail command.  All
                             elements are uppercase strings.  Example:
                             ['BODY=8BITMIME', 'SMTPUTF8'].
diff --git a/Lib/sndhdr.py b/Lib/sndhdr.py
index e5901ec583..7ecafb40e8 100644
--- a/Lib/sndhdr.py
+++ b/Lib/sndhdr.py
@@ -37,6 +37,18 @@ from collections import namedtuple
 SndHeaders = namedtuple('SndHeaders',
                         'filetype framerate nchannels nframes sampwidth')
 
+SndHeaders.filetype.__doc__ = ("""The value for type indicates the data type
+and will be one of the strings 'aifc', 'aiff', 'au','hcom',
+'sndr', 'sndt', 'voc', 'wav', '8svx', 'sb', 'ub', or 'ul'.""")
+SndHeaders.framerate.__doc__ = ("""The sampling_rate will be either the actual
+value or 0 if unknown or difficult to decode.""")
+SndHeaders.nchannels.__doc__ = ("""The number of channels or 0 if it cannot be
+determined or if the value is difficult to decode.""")
+SndHeaders.nframes.__doc__ = ("""The value for frames will be either the number
+of frames or -1.""")
+SndHeaders.sampwidth.__doc__ = ("""Either the sample size in bits or
+'A' for A-LAW or 'U' for u-LAW.""")
+
 def what(filename):
     """Guess the type of a sound file."""
     res = whathdr(filename)
diff --git a/Lib/socketserver.py b/Lib/socketserver.py
index 88088130ee..c6d38c775a 100644
--- a/Lib/socketserver.py
+++ b/Lib/socketserver.py
@@ -127,16 +127,19 @@ import socket
 import selectors
 import os
 import errno
+import sys
 try:
     import threading
 except ImportError:
     import dummy_threading as threading
 from time import monotonic as time
 
-__all__ = ["BaseServer", "TCPServer", "UDPServer", "ForkingUDPServer",
-           "ForkingTCPServer", "ThreadingUDPServer", "ThreadingTCPServer",
+__all__ = ["BaseServer", "TCPServer", "UDPServer",
+           "ThreadingUDPServer", "ThreadingTCPServer",
            "BaseRequestHandler", "StreamRequestHandler",
-           "DatagramRequestHandler", "ThreadingMixIn", "ForkingMixIn"]
+           "DatagramRequestHandler", "ThreadingMixIn"]
+if hasattr(os, "fork"):
+    __all__.extend(["ForkingUDPServer","ForkingTCPServer", "ForkingMixIn"])
 if hasattr(socket, "AF_UNIX"):
     __all__.extend(["UnixStreamServer","UnixDatagramServer",
                     "ThreadingUnixStreamServer",
@@ -311,9 +314,12 @@ class BaseServer:
         if self.verify_request(request, client_address):
             try:
                 self.process_request(request, client_address)
-            except:
+            except Exception:
                 self.handle_error(request, client_address)
                 self.shutdown_request(request)
+            except:
+                self.shutdown_request(request)
+                raise
         else:
             self.shutdown_request(request)
 
@@ -367,12 +373,18 @@ class BaseServer:
         The default is to print a traceback and continue.
 
         """
-        print('-'*40)
-        print('Exception happened during processing of request from', end=' ')
-        print(client_address)
+        print('-'*40, file=sys.stderr)
+        print('Exception happened during processing of request from',
+            client_address, file=sys.stderr)
         import traceback
-        traceback.print_exc() # XXX But this goes to stderr!
-        print('-'*40)
+        traceback.print_exc()
+        print('-'*40, file=sys.stderr)
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *args):
+        self.server_close()
 
 
 class TCPServer(BaseServer):
@@ -527,85 +539,86 @@ class UDPServer(TCPServer):
         # No need to close anything.
         pass
 
-class ForkingMixIn:
-
-    """Mix-in class to handle each request in a new process."""
-
-    timeout = 300
-    active_children = None
-    max_children = 40
+if hasattr(os, "fork"):
+    class ForkingMixIn:
+        """Mix-in class to handle each request in a new process."""
 
-    def collect_children(self):
-        """Internal routine to wait for children that have exited."""
-        if self.active_children is None:
-            return
-
-        # If we're above the max number of children, wait and reap them until
-        # we go back below threshold. Note that we use waitpid(-1) below to be
-        # able to collect children in size(<defunct children>) syscalls instead
-        # of size(<children>): the downside is that this might reap children
-        # which we didn't spawn, which is why we only resort to this when we're
-        # above max_children.
-        while len(self.active_children) >= self.max_children:
-            try:
-                pid, _ = os.waitpid(-1, 0)
-                self.active_children.discard(pid)
-            except ChildProcessError:
-                # we don't have any children, we're done
-                self.active_children.clear()
-            except OSError:
-                break
-
-        # Now reap all defunct children.
-        for pid in self.active_children.copy():
-            try:
-                pid, _ = os.waitpid(pid, os.WNOHANG)
-                # if the child hasn't exited yet, pid will be 0 and ignored by
-                # discard() below
-                self.active_children.discard(pid)
-            except ChildProcessError:
-                # someone else reaped it
-                self.active_children.discard(pid)
-            except OSError:
-                pass
-
-    def handle_timeout(self):
-        """Wait for zombies after self.timeout seconds of inactivity.
+        timeout = 300
+        active_children = None
+        max_children = 40
 
-        May be extended, do not override.
-        """
-        self.collect_children()
-
-    def service_actions(self):
-        """Collect the zombie child processes regularly in the ForkingMixIn.
-
-        service_actions is called in the BaseServer's serve_forver loop.
-        """
-        self.collect_children()
-
-    def process_request(self, request, client_address):
-        """Fork a new subprocess to process the request."""
-        pid = os.fork()
-        if pid:
-            # Parent process
+        def collect_children(self):
+            """Internal routine to wait for children that have exited."""
             if self.active_children is None:
-                self.active_children = set()
-            self.active_children.add(pid)
-            self.close_request(request)
-            return
-        else:
-            # Child process.
-            # This must never return, hence os._exit()!
-            try:
-                self.finish_request(request, client_address)
-                self.shutdown_request(request)
-                os._exit(0)
-            except:
+                return
+
+            # If we're above the max number of children, wait and reap them until
+            # we go back below threshold. Note that we use waitpid(-1) below to be
+            # able to collect children in size(<defunct children>) syscalls instead
+            # of size(<children>): the downside is that this might reap children
+            # which we didn't spawn, which is why we only resort to this when we're
+            # above max_children.
+            while len(self.active_children) >= self.max_children:
+                try:
+                    pid, _ = os.waitpid(-1, 0)
+                    self.active_children.discard(pid)
+                except ChildProcessError:
+                    # we don't have any children, we're done
+                    self.active_children.clear()
+                except OSError:
+                    break
+
+            # Now reap all defunct children.
+            for pid in self.active_children.copy():
                 try:
+                    pid, _ = os.waitpid(pid, os.WNOHANG)
+                    # if the child hasn't exited yet, pid will be 0 and ignored by
+                    # discard() below
+                    self.active_children.discard(pid)
+                except ChildProcessError:
+                    # someone else reaped it
+                    self.active_children.discard(pid)
+                except OSError:
+                    pass
+
+        def handle_timeout(self):
+            """Wait for zombies after self.timeout seconds of inactivity.
+
+            May be extended, do not override.
+            """
+            self.collect_children()
+
+        def service_actions(self):
+            """Collect the zombie child processes regularly in the ForkingMixIn.
+
+            service_actions is called in the BaseServer's serve_forver loop.
+            """
+            self.collect_children()
+
+        def process_request(self, request, client_address):
+            """Fork a new subprocess to process the request."""
+            pid = os.fork()
+            if pid:
+                # Parent process
+                if self.active_children is None:
+                    self.active_children = set()
+                self.active_children.add(pid)
+                self.close_request(request)
+                return
+            else:
+                # Child process.
+                # This must never return, hence os._exit()!
+                status = 1
+                try:
+                    self.finish_request(request, client_address)
+                    status = 0
+                except Exception:
                     self.handle_error(request, client_address)
-                    self.shutdown_request(request)
                 finally:
-                    os._exit(1)
+                    try:
+                        self.shutdown_request(request)
+                    finally:
+                        os._exit(status)
 
 
 class ThreadingMixIn:
@@ -623,9 +636,9 @@ class ThreadingMixIn:
         """
         try:
             self.finish_request(request, client_address)
-            self.shutdown_request(request)
-        except:
+        except Exception:
             self.handle_error(request, client_address)
+        finally:
             self.shutdown_request(request)
 
     def process_request(self, request, client_address):
@@ -636,8 +649,9 @@ class ThreadingMixIn:
         t.start()
 
 
-class ForkingUDPServer(ForkingMixIn, UDPServer): pass
-class ForkingTCPServer(ForkingMixIn, TCPServer): pass
+if hasattr(os, "fork"):
+    class ForkingUDPServer(ForkingMixIn, UDPServer): pass
+    class ForkingTCPServer(ForkingMixIn, TCPServer): pass
 
 class ThreadingUDPServer(ThreadingMixIn, UDPServer): pass
 class ThreadingTCPServer(ThreadingMixIn, TCPServer): pass
diff --git a/Lib/sre_compile.py b/Lib/sre_compile.py
index 502b0616c6..4edb03fa30 100644
--- a/Lib/sre_compile.py
+++ b/Lib/sre_compile.py
@@ -409,57 +409,39 @@ def _generate_overlap_table(prefix):
             table[i] = idx + 1
     return table
 
-def _compile_info(code, pattern, flags):
-    # internal: compile an info block.  in the current version,
-    # this contains min/max pattern width, and an optional literal
-    # prefix or a character map
-    lo, hi = pattern.getwidth()
-    if hi > MAXCODE:
-        hi = MAXCODE
-    if lo == 0:
-        code.extend([INFO, 4, 0, lo, hi])
-        return
-    # look for a literal prefix
+def _get_literal_prefix(pattern):
+    # look for literal prefix
     prefix = []
     prefixappend = prefix.append
-    prefix_skip = 0
+    prefix_skip = None
+    got_all = True
+    for op, av in pattern.data:
+        if op is LITERAL:
+            prefixappend(av)
+        elif op is SUBPATTERN:
+            prefix1, prefix_skip1, got_all = _get_literal_prefix(av[1])
+            if prefix_skip is None:
+                if av[0] is not None:
+                    prefix_skip = len(prefix)
+                elif prefix_skip1 is not None:
+                    prefix_skip = len(prefix) + prefix_skip1
+            prefix.extend(prefix1)
+            if not got_all:
+                break
+        else:
+            got_all = False
+            break
+    return prefix, prefix_skip, got_all
+
+def _get_charset_prefix(pattern):
     charset = [] # not used
     charsetappend = charset.append
-    if not (flags & SRE_FLAG_IGNORECASE):
-        # look for literal prefix
-        for op, av in pattern.data:
+    if pattern.data:
+        op, av = pattern.data[0]
+        if op is SUBPATTERN and av[1]:
+            op, av = av[1][0]
             if op is LITERAL:
-                if len(prefix) == prefix_skip:
-                    prefix_skip = prefix_skip + 1
-                prefixappend(av)
-            elif op is SUBPATTERN and len(av[1]) == 1:
-                op, av = av[1][0]
-                if op is LITERAL:
-                    prefixappend(av)
-                else:
-                    break
-            else:
-                break
-        # if no prefix, look for charset prefix
-        if not prefix and pattern.data:
-            op, av = pattern.data[0]
-            if op is SUBPATTERN and av[1]:
-                op, av = av[1][0]
-                if op is LITERAL:
-                    charsetappend((op, av))
-                elif op is BRANCH:
-                    c = []
-                    cappend = c.append
-                    for p in av[1]:
-                        if not p:
-                            break
-                        op, av = p[0]
-                        if op is LITERAL:
-                            cappend((op, av))
-                        else:
-                            break
-                    else:
-                        charset = c
+                charsetappend((op, av))
             elif op is BRANCH:
                 c = []
                 cappend = c.append
@@ -473,8 +455,43 @@ def _compile_info(code, pattern, flags):
                         break
                 else:
                     charset = c
-            elif op is IN:
-                charset = av
+        elif op is BRANCH:
+            c = []
+            cappend = c.append
+            for p in av[1]:
+                if not p:
+                    break
+                op, av = p[0]
+                if op is LITERAL:
+                    cappend((op, av))
+                else:
+                    break
+            else:
+                charset = c
+        elif op is IN:
+            charset = av
+    return charset
+
+def _compile_info(code, pattern, flags):
+    # internal: compile an info block.  in the current version,
+    # this contains min/max pattern width, and an optional literal
+    # prefix or a character map
+    lo, hi = pattern.getwidth()
+    if hi > MAXCODE:
+        hi = MAXCODE
+    if lo == 0:
+        code.extend([INFO, 4, 0, lo, hi])
+        return
+    # look for a literal prefix
+    prefix = []
+    prefix_skip = 0
+    charset = [] # not used
+    if not (flags & SRE_FLAG_IGNORECASE):
+        # look for literal prefix
+        prefix, prefix_skip, got_all = _get_literal_prefix(pattern)
+        # if no prefix, look for charset prefix
+        if not prefix:
+            charset = _get_charset_prefix(pattern)
 ##     if prefix:
 ##         print("*** PREFIX", prefix, prefix_skip)
 ##     if charset:
@@ -487,7 +504,7 @@ def _compile_info(code, pattern, flags):
     mask = 0
     if prefix:
         mask = SRE_INFO_PREFIX
-        if len(prefix) == prefix_skip == len(pattern.data):
+        if prefix_skip is None and got_all:
             mask = mask | SRE_INFO_LITERAL
     elif charset:
         mask = mask | SRE_INFO_CHARSET
@@ -502,6 +519,8 @@ def _compile_info(code, pattern, flags):
     # add literal prefix
     if prefix:
         emit(len(prefix)) # length
+        if prefix_skip is None:
+            prefix_skip =  len(prefix)
         emit(prefix_skip) # skip
         code.extend(prefix)
         # generate overlap table
diff --git a/Lib/ssl.py b/Lib/ssl.py
index 3f5c3c4d07..560cfef776 100644
--- a/Lib/ssl.py
+++ b/Lib/ssl.py
@@ -890,7 +890,6 @@ class SSLSocket(socket):
             while (count < amount):
                 v = self.send(data[count:])
                 count += v
-            return amount
         else:
             return socket.sendall(self, data, flags)
 
diff --git a/Lib/statistics.py b/Lib/statistics.py
index 4f5c1c164a..63adc1a44f 100644
--- a/Lib/statistics.py
+++ b/Lib/statistics.py
@@ -105,6 +105,7 @@ import math
 from fractions import Fraction
 from decimal import Decimal
 from itertools import groupby
+from bisect import bisect_left, bisect_right
 
 
 
@@ -130,23 +131,23 @@ def _sum(data, start=0):
     --------
 
     >>> _sum([3, 2.25, 4.5, -0.5, 1.0], 0.75)
-    (<class 'float'>, Fraction(11, 1), 5)
+    (<class 'float' ...>, Fraction(11, 1), 5)
 
     Some sources of round-off error will be avoided:
 
     >>> _sum([1e50, 1, -1e50] * 1000)  # Built-in sum returns zero.
-    (<class 'float'>, Fraction(1000, 1), 3000)
+    (<class 'float' ...>, Fraction(1000, 1), 3000)
 
     Fractions and Decimals are also supported:
 
     >>> from fractions import Fraction as F
     >>> _sum([F(2, 3), F(7, 5), F(1, 4), F(5, 6)])
-    (<class 'fractions.Fraction'>, Fraction(63, 20), 4)
+    (<class 'fractions.Fraction' ...>, Fraction(63, 20), 4)
 
     >>> from decimal import Decimal as D
     >>> data = [D("0.1375"), D("0.2108"), D("0.3061"), D("0.0419")]
     >>> _sum(data)
-    (<class 'decimal.Decimal'>, Fraction(6963, 10000), 4)
+    (<class 'decimal.Decimal' ...>, Fraction(6963, 10000), 4)
 
     Mixed types are currently treated as an error, except that int is
     allowed.
@@ -223,56 +224,26 @@ def _exact_ratio(x):
         # Optimise the common case of floats. We expect that the most often
         # used numeric type will be builtin floats, so try to make this as
         # fast as possible.
-        if type(x) is float:
+        if type(x) is float or type(x) is Decimal:
             return x.as_integer_ratio()
         try:
             # x may be an int, Fraction, or Integral ABC.
             return (x.numerator, x.denominator)
         except AttributeError:
             try:
-                # x may be a float subclass.
+                # x may be a float or Decimal subclass.
                 return x.as_integer_ratio()
             except AttributeError:
-                try:
-                    # x may be a Decimal.
-                    return _decimal_to_ratio(x)
-                except AttributeError:
-                    # Just give up?
-                    pass
+                # Just give up?
+                pass
     except (OverflowError, ValueError):
         # float NAN or INF.
-        assert not math.isfinite(x)
+        assert not _isfinite(x)
         return (x, None)
     msg = "can't convert type '{}' to numerator/denominator"
     raise TypeError(msg.format(type(x).__name__))
 
 
-# FIXME This is faster than Fraction.from_decimal, but still too slow.
-def _decimal_to_ratio(d):
-    """Convert Decimal d to exact integer ratio (numerator, denominator).
-
-    >>> from decimal import Decimal
-    >>> _decimal_to_ratio(Decimal("2.6"))
-    (26, 10)
-
-    """
-    sign, digits, exp = d.as_tuple()
-    if exp in ('F', 'n', 'N'):  # INF, NAN, sNAN
-        assert not d.is_finite()
-        return (d, None)
-    num = 0
-    for digit in digits:
-        num = num*10 + digit
-    if exp < 0:
-        den = 10**-exp
-    else:
-        num *= 10**exp
-        den = 1
-    if sign:
-        num = -num
-    return (num, den)
-
-
 def _convert(value, T):
     """Convert value to given numeric type T."""
     if type(value) is T:
@@ -305,6 +276,21 @@ def _counts(data):
     return table
 
 
+def _find_lteq(a, x):
+    'Locate the leftmost value exactly equal to x'
+    i = bisect_left(a, x)
+    if i != len(a) and a[i] == x:
+        return i
+    raise ValueError
+
+
+def _find_rteq(a, l, x):
+    'Locate the rightmost value exactly equal to x'
+    i = bisect_right(a, x, lo=l)
+    if i != (len(a)+1) and a[i-1] == x:
+        return i-1
+    raise ValueError
+
 # === Measures of central tendency (averages) ===
 
 def mean(data):
@@ -442,9 +428,15 @@ def median_grouped(data, interval=1):
     except TypeError:
         # Mixed type. For now we just coerce to float.
         L = float(x) - float(interval)/2
-    cf = data.index(x)  # Number of values below the median interval.
-    # FIXME The following line could be more efficient for big lists.
-    f = data.count(x)  # Number of data points in the median interval.
+
+    # Uses bisection search to search for x in data with log(n) time complexity
+    # Find the position of leftmost occurrence of x in data
+    l1 = _find_lteq(data, x)
+    # Find the position of rightmost occurrence of x in data[l1...len(data)]
+    # Assuming always l1 <= l2
+    l2 = _find_rteq(data, l1, x)
+    cf = l1
+    f = l2 - l1 + 1
     return L + interval*(n/2 - cf)/f
 
 
diff --git a/Lib/string.py b/Lib/string.py
index 89287c4c0a..7298c89087 100644
--- a/Lib/string.py
+++ b/Lib/string.py
@@ -116,10 +116,7 @@ class Template(metaclass=_TemplateMetaclass):
             # Check the most common path first.
             named = mo.group('named') or mo.group('braced')
             if named is not None:
-                val = mapping[named]
-                # We use this idiom instead of str() because the latter will
-                # fail if val is a Unicode containing non-ASCII characters.
-                return '%s' % (val,)
+                return str(mapping[named])
             if mo.group('escaped') is not None:
                 return self.delimiter
             if mo.group('invalid') is not None:
@@ -146,9 +143,7 @@ class Template(metaclass=_TemplateMetaclass):
             named = mo.group('named') or mo.group('braced')
             if named is not None:
                 try:
-                    # We use this idiom instead of str() because the latter
-                    # will fail if val is a Unicode containing non-ASCII
-                    return '%s' % (mapping[named],)
+                    return str(mapping[named])
                 except KeyError:
                     return mo.group()
             if mo.group('escaped') is not None:
diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index d8d6ab2274..98f339ee5c 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -372,9 +372,11 @@ class SubprocessError(Exception): pass
 
 
 class CalledProcessError(SubprocessError):
-    """This exception is raised when a process run by check_call() or
-    check_output() returns a non-zero exit status.
-    The exit status will be stored in the returncode attribute;
+    """Raised when a check_call() or check_output() process returns non-zero.
+
+    The exit status will be stored in the returncode attribute, negative
+    if it represents a signal number.
+
     check_output() will also store the output in the output attribute.
     """
     def __init__(self, returncode, cmd, output=None, stderr=None):
@@ -384,7 +386,16 @@ class CalledProcessError(SubprocessError):
         self.stderr = stderr
 
     def __str__(self):
-        return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode)
+        if self.returncode and self.returncode < 0:
+            try:
+                return "Command '%s' died with %r." % (
+                        self.cmd, signal.Signals(-self.returncode))
+            except ValueError:
+                return "Command '%s' died with unknown signal %d." % (
+                        self.cmd, -self.returncode)
+        else:
+            return "Command '%s' returned non-zero exit status %d." % (
+                    self.cmd, self.returncode)
 
     @property
     def stdout(self):
@@ -471,7 +482,8 @@ if _mswindows:
     __all__.extend(["CREATE_NEW_CONSOLE", "CREATE_NEW_PROCESS_GROUP",
                     "STD_INPUT_HANDLE", "STD_OUTPUT_HANDLE",
                     "STD_ERROR_HANDLE", "SW_HIDE",
-                    "STARTF_USESTDHANDLES", "STARTF_USESHOWWINDOW"])
+                    "STARTF_USESTDHANDLES", "STARTF_USESHOWWINDOW",
+                    "STARTUPINFO"])
 
     class Handle(int):
         closed = False
@@ -520,6 +532,16 @@ DEVNULL = -3
 # but it's here so that it can be imported when Python is compiled without
 # threads.
 
+def _optim_args_from_interpreter_flags():
+    """Return a list of command-line arguments reproducing the current
+    optimization settings in sys.flags."""
+    args = []
+    value = sys.flags.optimize
+    if value > 0:
+        args.append('-' + 'O' * value)
+    return args
+
+
 def _args_from_interpreter_flags():
     """Return a list of command-line arguments reproducing the current
     settings in sys.flags and sys.warnoptions."""
@@ -527,7 +549,6 @@ def _args_from_interpreter_flags():
         'debug': 'd',
         # 'inspect': 'i',
         # 'interactive': 'i',
-        'optimize': 'O',
         'dont_write_bytecode': 'B',
         'no_user_site': 's',
         'no_site': 'S',
@@ -535,8 +556,9 @@ def _args_from_interpreter_flags():
         'verbose': 'v',
         'bytes_warning': 'b',
         'quiet': 'q',
+        # -O is handled in _optim_args_from_interpreter_flags()
     }
-    args = []
+    args = _optim_args_from_interpreter_flags()
     for flag, opt in flag_opt_map.items():
         v = getattr(sys.flags, flag)
         if v > 0:
@@ -995,6 +1017,9 @@ class Popen(object):
         if not self._child_created:
             # We didn't get to successfully create a child process.
             return
+        if self.returncode is None:
+            warnings.warn("running subprocess %r" % self, ResourceWarning,
+                          source=self)
         # In case the child hasn't been waited on, check if it's done.
         self._internal_poll(_deadstate=_maxsize)
         if self.returncode is None and _active is not None:
@@ -1520,9 +1545,14 @@ class Popen(object):
 
             if errpipe_data:
                 try:
-                    os.waitpid(self.pid, 0)
+                    pid, sts = os.waitpid(self.pid, 0)
+                    if pid == self.pid:
+                        self._handle_exitstatus(sts)
+                    else:
+                        self.returncode = sys.maxsize
                 except ChildProcessError:
                     pass
+
                 try:
                     exception_name, hex_errno, err_msg = (
                             errpipe_data.split(b':', 2))
diff --git a/Lib/sysconfig.py b/Lib/sysconfig.py
index 9c34be0a07..f18b1bc958 100644
--- a/Lib/sysconfig.py
+++ b/Lib/sysconfig.py
@@ -86,8 +86,8 @@ _SCHEME_KEYS = ('stdlib', 'platstdlib', 'purelib', 'platlib', 'include',
  # FIXME don't rely on sys.version here, its format is an implementation detail
  # of CPython, use sys.version_info or sys.hexversion
 _PY_VERSION = sys.version.split()[0]
-_PY_VERSION_SHORT = sys.version[:3]
-_PY_VERSION_SHORT_NO_DOT = _PY_VERSION[0] + _PY_VERSION[2]
+_PY_VERSION_SHORT = '%d.%d' % sys.version_info[:2]
+_PY_VERSION_SHORT_NO_DOT = '%d%d' % sys.version_info[:2]
 _PREFIX = os.path.normpath(sys.prefix)
 _BASE_PREFIX = os.path.normpath(sys.base_prefix)
 _EXEC_PREFIX = os.path.normpath(sys.exec_prefix)
@@ -386,7 +386,7 @@ def _generate_posix_vars():
         module.build_time_vars = vars
         sys.modules[name] = module
 
-    pybuilddir = 'build/lib.%s-%s' % (get_platform(), sys.version[:3])
+    pybuilddir = 'build/lib.%s-%s' % (get_platform(), _PY_VERSION_SHORT)
     if hasattr(sys, "gettotalrefcount"):
         pybuilddir += '-pydebug'
     os.makedirs(pybuilddir, exist_ok=True)
@@ -518,7 +518,7 @@ def get_config_vars(*args):
         _CONFIG_VARS['exec_prefix'] = _EXEC_PREFIX
         _CONFIG_VARS['py_version'] = _PY_VERSION
         _CONFIG_VARS['py_version_short'] = _PY_VERSION_SHORT
-        _CONFIG_VARS['py_version_nodot'] = _PY_VERSION[0] + _PY_VERSION[2]
+        _CONFIG_VARS['py_version_nodot'] = _PY_VERSION_SHORT_NO_DOT
         _CONFIG_VARS['installed_base'] = _BASE_PREFIX
         _CONFIG_VARS['base'] = _PREFIX
         _CONFIG_VARS['installed_platbase'] = _BASE_EXEC_PREFIX
diff --git a/Lib/tarfile.py b/Lib/tarfile.py
index 86e1cf9b89..8ed87c2f43 100755
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -64,7 +64,10 @@ except NameError:
     pass
 
 # from tarfile import *
-__all__ = ["TarFile", "TarInfo", "is_tarfile", "TarError"]
+__all__ = ["TarFile", "TarInfo", "is_tarfile", "TarError", "ReadError",
+           "CompressionError", "StreamError", "ExtractError", "HeaderError",
+           "ENCODING", "USTAR_FORMAT", "GNU_FORMAT", "PAX_FORMAT",
+           "DEFAULT_FORMAT", "open"]
 
 #---------------------------------------------------------
 # tar constants
@@ -2374,9 +2377,32 @@ class TarFile(object):
         """Provide an iterator object.
         """
         if self._loaded:
-            return iter(self.members)
-        else:
-            return TarIter(self)
+            yield from self.members
+            return
+
+        # Yield items using TarFile's next() method.
+        # When all members have been read, set TarFile as _loaded.
+        index = 0
+        # Fix for SF #1100429: Under rare circumstances it can
+        # happen that getmembers() is called during iteration,
+        # which will have already exhausted the next() method.
+        if self.firstmember is not None:
+            tarinfo = self.next()
+            index += 1
+            yield tarinfo
+
+        while True:
+            if index < len(self.members):
+                tarinfo = self.members[index]
+            elif not self._loaded:
+                tarinfo = self.next()
+                if not tarinfo:
+                    self._loaded = True
+                    return
+            else:
+                return
+            index += 1
+            yield tarinfo
 
     def _dbg(self, level, msg):
         """Write debugging output to sys.stderr.
@@ -2397,45 +2423,6 @@ class TarFile(object):
             if not self._extfileobj:
                 self.fileobj.close()
             self.closed = True
-# class TarFile
-
-class TarIter:
-    """Iterator Class.
-
-       for tarinfo in TarFile(...):
-           suite...
-    """
-
-    def __init__(self, tarfile):
-        """Construct a TarIter object.
-        """
-        self.tarfile = tarfile
-        self.index = 0
-    def __iter__(self):
-        """Return iterator object.
-        """
-        return self
-    def __next__(self):
-        """Return the next item using TarFile's next() method.
-           When all members have been read, set TarFile as _loaded.
-        """
-        # Fix for SF #1100429: Under rare circumstances it can
-        # happen that getmembers() is called during iteration,
-        # which will cause TarIter to stop prematurely.
-
-        if self.index == 0 and self.tarfile.firstmember is not None:
-            tarinfo = self.tarfile.next()
-        elif self.index < len(self.tarfile.members):
-            tarinfo = self.tarfile.members[self.index]
-        elif not self.tarfile._loaded:
-            tarinfo = self.tarfile.next()
-            if not tarinfo:
-                self.tarfile._loaded = True
-                raise StopIteration
-        else:
-            raise StopIteration
-        self.index += 1
-        return tarinfo
 
 #--------------------
 # exported functions
diff --git a/Lib/telnetlib.py b/Lib/telnetlib.py
index 72dabc76e0..b0863b1cbd 100644
--- a/Lib/telnetlib.py
+++ b/Lib/telnetlib.py
@@ -637,6 +637,12 @@ class Telnet:
             raise EOFError
         return (-1, None, text)
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, type, value, traceback):
+        self.close()
+
 
 def test():
     """Test program for telnetlib.
@@ -660,11 +666,10 @@ def test():
             port = int(portstr)
         except ValueError:
             port = socket.getservbyname(portstr, 'tcp')
-    tn = Telnet()
-    tn.set_debuglevel(debuglevel)
-    tn.open(host, port, timeout=0.5)
-    tn.interact()
-    tn.close()
+    with Telnet() as tn:
+        tn.set_debuglevel(debuglevel)
+        tn.open(host, port, timeout=0.5)
+        tn.interact()
 
 if __name__ == '__main__':
     test()
diff --git a/Lib/tempfile.py b/Lib/tempfile.py
index ad687b9a03..61462357c7 100644
--- a/Lib/tempfile.py
+++ b/Lib/tempfile.py
@@ -797,7 +797,6 @@ class TemporaryDirectory(object):
         _shutil.rmtree(name)
         _warnings.warn(warn_message, ResourceWarning)
 
-
     def __repr__(self):
         return "<{} {!r}>".format(self.__class__.__name__, self.name)
 
diff --git a/Lib/test/__main__.py b/Lib/test/__main__.py
index d5fbe159d7..19a6b2b890 100644
--- a/Lib/test/__main__.py
+++ b/Lib/test/__main__.py
@@ -1,3 +1,2 @@
-from test import regrtest
-
-regrtest.main_in_temp_cwd()
+from test.libregrtest import main
+main()
diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py
index 11a6310a76..16407db7b3 100644
--- a/Lib/test/_test_multiprocessing.py
+++ b/Lib/test/_test_multiprocessing.py
@@ -1668,6 +1668,10 @@ def sqr(x, wait=0.0):
 def mul(x, y):
     return x*y
 
+def raise_large_valuerror(wait):
+    time.sleep(wait)
+    raise ValueError("x" * 1024**2)
+
 class SayWhenError(ValueError): pass
 
 def exception_throwing_generator(total, when):
@@ -1910,6 +1914,26 @@ class _TestPool(BaseTestCase):
             with self.assertRaises(RuntimeError):
                 p.apply(self._test_wrapped_exception)
 
+    def test_map_no_failfast(self):
+        # Issue #23992: the fail-fast behaviour when an exception is raised
+        # during map() would make Pool.join() deadlock, because a worker
+        # process would fill the result queue (after the result handler thread
+        # terminated, hence not draining it anymore).
+
+        t_start = time.time()
+
+        with self.assertRaises(ValueError):
+            with self.Pool(2) as p:
+                try:
+                    p.map(raise_large_valuerror, [0, 1])
+                finally:
+                    time.sleep(0.5)
+                    p.close()
+                    p.join()
+
+        # check that we indeed waited for all jobs
+        self.assertGreater(time.time() - t_start, 0.9)
+
 
 def raising():
     raise KeyError("key")
diff --git a/Lib/test/audiotests.py b/Lib/test/audiotests.py
index 0ae2242851..d3e8e9ee44 100644
--- a/Lib/test/audiotests.py
+++ b/Lib/test/audiotests.py
@@ -1,9 +1,8 @@
 from test.support import findfile, TESTFN, unlink
-import unittest
 import array
 import io
 import pickle
-import sys
+
 
 class UnseekableIO(io.FileIO):
     def tell(self):
diff --git a/Lib/test/autotest.py b/Lib/test/autotest.py
index 41c2088727..fa85cc153a 100644
--- a/Lib/test/autotest.py
+++ b/Lib/test/autotest.py
@@ -1,6 +1,5 @@
 # This should be equivalent to running regrtest.py from the cmdline.
 # It can be especially handy if you're in an interactive shell, e.g.,
 # from test import autotest.
-
-from test import regrtest
-regrtest.main()
+from test.libregrtest import main
+main()
diff --git a/Lib/test/capath/0e4015b9.0 b/Lib/test/capath/0e4015b9.0
deleted file mode 100644
index b6d259bcb2..0000000000
--- a/Lib/test/capath/0e4015b9.0
+++ /dev/null
@@ -1,16 +0,0 @@
------BEGIN CERTIFICATE-----
-MIIClTCCAf6gAwIBAgIJAKGU95wKR8pTMA0GCSqGSIb3DQEBBQUAMHAxCzAJBgNV
-BAYTAlhZMRcwFQYDVQQHDA5DYXN0bGUgQW50aHJheDEjMCEGA1UECgwaUHl0aG9u
-IFNvZnR3YXJlIEZvdW5kYXRpb24xIzAhBgNVBAMMGnNlbGYtc2lnbmVkLnB5dGhv
-bnRlc3QubmV0MB4XDTE0MTEwMjE4MDkyOVoXDTI0MTAzMDE4MDkyOVowcDELMAkG
-A1UEBhMCWFkxFzAVBgNVBAcMDkNhc3RsZSBBbnRocmF4MSMwIQYDVQQKDBpQeXRo
-b24gU29mdHdhcmUgRm91bmRhdGlvbjEjMCEGA1UEAwwac2VsZi1zaWduZWQucHl0
-aG9udGVzdC5uZXQwgZ8wDQYJKoZIhvcNAQEBBQADgY0AMIGJAoGBANDXQXW9tjyZ
-Xt0Iv2tLL1+jinr4wGg36ioLDLFkMf+2Y1GL0v0BnKYG4N1OKlAU15LXGeGer8vm
-Sv/yIvmdrELvhAbbo3w4a9TMYQA4XkIVLdvu3mvNOAet+8PMJxn26dbDhG809ALv
-EHY57lQsBS3G59RZyBPVqAqmImWNJnVzAgMBAAGjNzA1MCUGA1UdEQQeMByCGnNl
-bGYtc2lnbmVkLnB5dGhvbnRlc3QubmV0MAwGA1UdEwQFMAMBAf8wDQYJKoZIhvcN
-AQEFBQADgYEAIuzAhgMouJpNdf3URCHIineyoSt6WK/9+eyUcjlKOrDoXNZaD72h
-TXMeKYoWvJyVcSLKL8ckPtDobgP2OTt0UkyAaj0n+ZHaqq1lH2yVfGUA1ILJv515
-C8BqbvVZuqm3i7ygmw3bqE/lYMgOrYtXXnqOrz6nvsE6Yc9V9rFflOM=
------END CERTIFICATE-----
diff --git a/Lib/test/capath/b1930218.0 b/Lib/test/capath/b1930218.0
new file mode 100644
index 0000000000..373349cae0
--- /dev/null
+++ b/Lib/test/capath/b1930218.0
@@ -0,0 +1,21 @@
+-----BEGIN CERTIFICATE-----
+MIIDbTCCAlWgAwIBAgIJALCSZLHy2iHQMA0GCSqGSIb3DQEBBQUAME0xCzAJBgNV
+BAYTAlhZMSYwJAYDVQQKDB1QeXRob24gU29mdHdhcmUgRm91bmRhdGlvbiBDQTEW
+MBQGA1UEAwwNb3VyLWNhLXNlcnZlcjAeFw0xMzAxMDQxOTQ3MDdaFw0yMzAxMDIx
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+f+/fNDY7L131hLIvxG2TlhpvMCjx2hKaZLRAMx293itTqOq+1rxOlvVE+zIYrtUf
+9mmvtk57HVjsO6lTo15YyJ4=
+-----END CERTIFICATE-----
diff --git a/Lib/test/capath/ce7b8643.0 b/Lib/test/capath/ce7b8643.0
deleted file mode 100644
index b6d259bcb2..0000000000
--- a/Lib/test/capath/ce7b8643.0
+++ /dev/null
@@ -1,16 +0,0 @@
------BEGIN CERTIFICATE-----
-MIIClTCCAf6gAwIBAgIJAKGU95wKR8pTMA0GCSqGSIb3DQEBBQUAMHAxCzAJBgNV
-BAYTAlhZMRcwFQYDVQQHDA5DYXN0bGUgQW50aHJheDEjMCEGA1UECgwaUHl0aG9u
-IFNvZnR3YXJlIEZvdW5kYXRpb24xIzAhBgNVBAMMGnNlbGYtc2lnbmVkLnB5dGhv
-bnRlc3QubmV0MB4XDTE0MTEwMjE4MDkyOVoXDTI0MTAzMDE4MDkyOVowcDELMAkG
-A1UEBhMCWFkxFzAVBgNVBAcMDkNhc3RsZSBBbnRocmF4MSMwIQYDVQQKDBpQeXRo
-b24gU29mdHdhcmUgRm91bmRhdGlvbjEjMCEGA1UEAwwac2VsZi1zaWduZWQucHl0
-aG9udGVzdC5uZXQwgZ8wDQYJKoZIhvcNAQEBBQADgY0AMIGJAoGBANDXQXW9tjyZ
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-C8BqbvVZuqm3i7ygmw3bqE/lYMgOrYtXXnqOrz6nvsE6Yc9V9rFflOM=
------END CERTIFICATE-----
diff --git a/Lib/test/capath/ceff1710.0 b/Lib/test/capath/ceff1710.0
new file mode 100644
index 0000000000..373349cae0
--- /dev/null
+++ b/Lib/test/capath/ceff1710.0
@@ -0,0 +1,21 @@
+-----BEGIN CERTIFICATE-----
+MIIDbTCCAlWgAwIBAgIJALCSZLHy2iHQMA0GCSqGSIb3DQEBBQUAME0xCzAJBgNV
+BAYTAlhZMSYwJAYDVQQKDB1QeXRob24gU29mdHdhcmUgRm91bmRhdGlvbiBDQTEW
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+9mmvtk57HVjsO6lTo15YyJ4=
+-----END CERTIFICATE-----
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index f5222c7e48..8fc01390b3 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -284,7 +284,8 @@ class TestTimeZone(unittest.TestCase):
         with self.assertRaises(TypeError): self.EST.dst(5)
 
     def test_tzname(self):
-        self.assertEqual('UTC+00:00', timezone(ZERO).tzname(None))
+        self.assertEqual('UTC', timezone.utc.tzname(None))
+        self.assertEqual('UTC', timezone(ZERO).tzname(None))
         self.assertEqual('UTC-05:00', timezone(-5 * HOUR).tzname(None))
         self.assertEqual('UTC+09:30', timezone(9.5 * HOUR).tzname(None))
         self.assertEqual('UTC-00:01', timezone(timedelta(minutes=-1)).tzname(None))
@@ -1558,13 +1559,32 @@ class TestDateTime(TestDate):
             self.assertEqual(dt, dt2)
 
     def test_isoformat(self):
-        t = self.theclass(2, 3, 2, 4, 5, 1, 123)
-        self.assertEqual(t.isoformat(),    "0002-03-02T04:05:01.000123")
-        self.assertEqual(t.isoformat('T'), "0002-03-02T04:05:01.000123")
-        self.assertEqual(t.isoformat(' '), "0002-03-02 04:05:01.000123")
-        self.assertEqual(t.isoformat('\x00'), "0002-03-02\x0004:05:01.000123")
+        t = self.theclass(1, 2, 3, 4, 5, 1, 123)
+        self.assertEqual(t.isoformat(),    "0001-02-03T04:05:01.000123")
+        self.assertEqual(t.isoformat('T'), "0001-02-03T04:05:01.000123")
+        self.assertEqual(t.isoformat(' '), "0001-02-03 04:05:01.000123")
+        self.assertEqual(t.isoformat('\x00'), "0001-02-03\x0004:05:01.000123")
+        self.assertEqual(t.isoformat(timespec='hours'), "0001-02-03T04")
+        self.assertEqual(t.isoformat(timespec='minutes'), "0001-02-03T04:05")
+        self.assertEqual(t.isoformat(timespec='seconds'), "0001-02-03T04:05:01")
+        self.assertEqual(t.isoformat(timespec='milliseconds'), "0001-02-03T04:05:01.000")
+        self.assertEqual(t.isoformat(timespec='microseconds'), "0001-02-03T04:05:01.000123")
+        self.assertEqual(t.isoformat(timespec='auto'), "0001-02-03T04:05:01.000123")
+        self.assertEqual(t.isoformat(sep=' ', timespec='minutes'), "0001-02-03 04:05")
+        self.assertRaises(ValueError, t.isoformat, timespec='foo')
         # str is ISO format with the separator forced to a blank.
-        self.assertEqual(str(t), "0002-03-02 04:05:01.000123")
+        self.assertEqual(str(t), "0001-02-03 04:05:01.000123")
+
+        t = self.theclass(1, 2, 3, 4, 5, 1, 999500, tzinfo=timezone.utc)
+        self.assertEqual(t.isoformat(timespec='milliseconds'), "0001-02-03T04:05:01.999+00:00")
+
+        t = self.theclass(1, 2, 3, 4, 5, 1, 999500)
+        self.assertEqual(t.isoformat(timespec='milliseconds'), "0001-02-03T04:05:01.999")
+
+        t = self.theclass(1, 2, 3, 4, 5, 1)
+        self.assertEqual(t.isoformat(timespec='auto'), "0001-02-03T04:05:01")
+        self.assertEqual(t.isoformat(timespec='milliseconds'), "0001-02-03T04:05:01.000")
+        self.assertEqual(t.isoformat(timespec='microseconds'), "0001-02-03T04:05:01.000000")
 
         t = self.theclass(2, 3, 2)
         self.assertEqual(t.isoformat(),    "0002-03-02T00:00:00")
@@ -2324,6 +2344,23 @@ class TestTime(HarmlessMixedComparison, unittest.TestCase):
         self.assertEqual(t.isoformat(), "00:00:00.100000")
         self.assertEqual(t.isoformat(), str(t))
 
+        t = self.theclass(hour=12, minute=34, second=56, microsecond=123456)
+        self.assertEqual(t.isoformat(timespec='hours'), "12")
+        self.assertEqual(t.isoformat(timespec='minutes'), "12:34")
+        self.assertEqual(t.isoformat(timespec='seconds'), "12:34:56")
+        self.assertEqual(t.isoformat(timespec='milliseconds'), "12:34:56.123")
+        self.assertEqual(t.isoformat(timespec='microseconds'), "12:34:56.123456")
+        self.assertEqual(t.isoformat(timespec='auto'), "12:34:56.123456")
+        self.assertRaises(ValueError, t.isoformat, timespec='monkey')
+
+        t = self.theclass(hour=12, minute=34, second=56, microsecond=999500)
+        self.assertEqual(t.isoformat(timespec='milliseconds'), "12:34:56.999")
+
+        t = self.theclass(hour=12, minute=34, second=56, microsecond=0)
+        self.assertEqual(t.isoformat(timespec='milliseconds'), "12:34:56.000")
+        self.assertEqual(t.isoformat(timespec='microseconds'), "12:34:56.000000")
+        self.assertEqual(t.isoformat(timespec='auto'), "12:34:56")
+
     def test_1653736(self):
         # verify it doesn't accept extra keyword arguments
         t = self.theclass(second=1)
diff --git a/Lib/test/eintrdata/eintr_tester.py b/Lib/test/eintrdata/eintr_tester.py
index 9931a5515b..ffcdb98605 100644
--- a/Lib/test/eintrdata/eintr_tester.py
+++ b/Lib/test/eintrdata/eintr_tester.py
@@ -9,7 +9,7 @@ sub-second periodicity (contrarily to signal()).
 """
 
 import contextlib
-import io
+import faulthandler
 import os
 import select
 import signal
@@ -50,6 +50,10 @@ class EINTRBaseTest(unittest.TestCase):
         signal.setitimer(signal.ITIMER_REAL, cls.signal_delay,
                          cls.signal_period)
 
+        # Issue #25277: Use faulthandler to try to debug a hang on FreeBSD
+        if hasattr(faulthandler, 'dump_traceback_later'):
+            faulthandler.dump_traceback_later(10 * 60, exit=True)
+
     @classmethod
     def stop_alarm(cls):
         signal.setitimer(signal.ITIMER_REAL, 0, 0)
@@ -58,6 +62,8 @@ class EINTRBaseTest(unittest.TestCase):
     def tearDownClass(cls):
         cls.stop_alarm()
         signal.signal(signal.SIGALRM, cls.orig_handler)
+        if hasattr(faulthandler, 'cancel_dump_traceback_later'):
+            faulthandler.cancel_dump_traceback_later()
 
     def subprocess(self, *args, **kw):
         cmd_args = (sys.executable, '-c') + args
diff --git a/Lib/test/libregrtest/__init__.py b/Lib/test/libregrtest/__init__.py
new file mode 100644
index 0000000000..7ba0e6e535
--- /dev/null
+++ b/Lib/test/libregrtest/__init__.py
@@ -0,0 +1,5 @@
+# We import importlib *ASAP* in order to test #15386
+import importlib
+
+from test.libregrtest.cmdline import _parse_args, RESOURCE_NAMES
+from test.libregrtest.main import main
diff --git a/Lib/test/libregrtest/cmdline.py b/Lib/test/libregrtest/cmdline.py
new file mode 100644
index 0000000000..de09a0122a
--- /dev/null
+++ b/Lib/test/libregrtest/cmdline.py
@@ -0,0 +1,342 @@
+import argparse
+import os
+import sys
+from test import support
+
+
+USAGE = """\
+python -m test [options] [test_name1 [test_name2 ...]]
+python path/to/Lib/test/regrtest.py [options] [test_name1 [test_name2 ...]]
+"""
+
+DESCRIPTION = """\
+Run Python regression tests.
+
+If no arguments or options are provided, finds all files matching
+the pattern "test_*" in the Lib/test subdirectory and runs
+them in alphabetical order (but see -M and -u, below, for exceptions).
+
+For more rigorous testing, it is useful to use the following
+command line:
+
+python -E -Wd -m test [options] [test_name1 ...]
+"""
+
+EPILOG = """\
+Additional option details:
+
+-r randomizes test execution order. You can use --randseed=int to provide an
+int seed value for the randomizer; this is useful for reproducing troublesome
+test orders.
+
+-s On the first invocation of regrtest using -s, the first test file found
+or the first test file given on the command line is run, and the name of
+the next test is recorded in a file named pynexttest.  If run from the
+Python build directory, pynexttest is located in the 'build' subdirectory,
+otherwise it is located in tempfile.gettempdir().  On subsequent runs,
+the test in pynexttest is run, and the next test is written to pynexttest.
+When the last test has been run, pynexttest is deleted.  In this way it
+is possible to single step through the test files.  This is useful when
+doing memory analysis on the Python interpreter, which process tends to
+consume too many resources to run the full regression test non-stop.
+
+-S is used to continue running tests after an aborted run.  It will
+maintain the order a standard run (ie, this assumes -r is not used).
+This is useful after the tests have prematurely stopped for some external
+reason and you want to start running from where you left off rather
+than starting from the beginning.
+
+-f reads the names of tests from the file given as f's argument, one
+or more test names per line.  Whitespace is ignored.  Blank lines and
+lines beginning with '#' are ignored.  This is especially useful for
+whittling down failures involving interactions among tests.
+
+-L causes the leaks(1) command to be run just before exit if it exists.
+leaks(1) is available on Mac OS X and presumably on some other
+FreeBSD-derived systems.
+
+-R runs each test several times and examines sys.gettotalrefcount() to
+see if the test appears to be leaking references.  The argument should
+be of the form stab:run:fname where 'stab' is the number of times the
+test is run to let gettotalrefcount settle down, 'run' is the number
+of times further it is run and 'fname' is the name of the file the
+reports are written to.  These parameters all have defaults (5, 4 and
+"reflog.txt" respectively), and the minimal invocation is '-R :'.
+
+-M runs tests that require an exorbitant amount of memory. These tests
+typically try to ascertain containers keep working when containing more than
+2 billion objects, which only works on 64-bit systems. There are also some
+tests that try to exhaust the address space of the process, which only makes
+sense on 32-bit systems with at least 2Gb of memory. The passed-in memlimit,
+which is a string in the form of '2.5Gb', determines howmuch memory the
+tests will limit themselves to (but they may go slightly over.) The number
+shouldn't be more memory than the machine has (including swap memory). You
+should also keep in mind that swap memory is generally much, much slower
+than RAM, and setting memlimit to all available RAM or higher will heavily
+tax the machine. On the other hand, it is no use running these tests with a
+limit of less than 2.5Gb, and many require more than 20Gb. Tests that expect
+to use more than memlimit memory will be skipped. The big-memory tests
+generally run very, very long.
+
+-u is used to specify which special resource intensive tests to run,
+such as those requiring large file support or network connectivity.
+The argument is a comma-separated list of words indicating the
+resources to test.  Currently only the following are defined:
+
+    all -       Enable all special resources.
+
+    none -      Disable all special resources (this is the default).
+
+    audio -     Tests that use the audio device.  (There are known
+                cases of broken audio drivers that can crash Python or
+                even the Linux kernel.)
+
+    curses -    Tests that use curses and will modify the terminal's
+                state and output modes.
+
+    largefile - It is okay to run some test that may create huge
+                files.  These tests can take a long time and may
+                consume >2GB of disk space temporarily.
+
+    network -   It is okay to run tests that use external network
+                resource, e.g. testing SSL support for sockets.
+
+    decimal -   Test the decimal module against a large suite that
+                verifies compliance with standards.
+
+    cpu -       Used for certain CPU-heavy tests.
+
+    subprocess  Run all tests for the subprocess module.
+
+    urlfetch -  It is okay to download files required on testing.
+
+    gui -       Run tests that require a running GUI.
+
+To enable all resources except one, use '-uall,-<resource>'.  For
+example, to run all the tests except for the gui tests, give the
+option '-uall,-gui'.
+"""
+
+
+RESOURCE_NAMES = ('audio', 'curses', 'largefile', 'network',
+                  'decimal', 'cpu', 'subprocess', 'urlfetch', 'gui')
+
+class _ArgParser(argparse.ArgumentParser):
+
+    def error(self, message):
+        super().error(message + "\nPass -h or --help for complete help.")
+
+
+def _create_parser():
+    # Set prog to prevent the uninformative "__main__.py" from displaying in
+    # error messages when using "python -m test ...".
+    parser = _ArgParser(prog='regrtest.py',
+                        usage=USAGE,
+                        description=DESCRIPTION,
+                        epilog=EPILOG,
+                        add_help=False,
+                        formatter_class=argparse.RawDescriptionHelpFormatter)
+
+    # Arguments with this clause added to its help are described further in
+    # the epilog's "Additional option details" section.
+    more_details = '  See the section at bottom for more details.'
+
+    group = parser.add_argument_group('General options')
+    # We add help explicitly to control what argument group it renders under.
+    group.add_argument('-h', '--help', action='help',
+                       help='show this help message and exit')
+    group.add_argument('--timeout', metavar='TIMEOUT', type=float,
+                        help='dump the traceback and exit if a test takes '
+                             'more than TIMEOUT seconds; disabled if TIMEOUT '
+                             'is negative or equals to zero')
+    group.add_argument('--wait', action='store_true',
+                       help='wait for user input, e.g., allow a debugger '
+                            'to be attached')
+    group.add_argument('--slaveargs', metavar='ARGS')
+    group.add_argument('-S', '--start', metavar='START',
+                       help='the name of the test at which to start.' +
+                            more_details)
+
+    group = parser.add_argument_group('Verbosity')
+    group.add_argument('-v', '--verbose', action='count',
+                       help='run tests in verbose mode with output to stdout')
+    group.add_argument('-w', '--verbose2', action='store_true',
+                       help='re-run failed tests in verbose mode')
+    group.add_argument('-W', '--verbose3', action='store_true',
+                       help='display test output on failure')
+    group.add_argument('-q', '--quiet', action='store_true',
+                       help='no output unless one or more tests fail')
+    group.add_argument('-o', '--slow', action='store_true', dest='print_slow',
+                       help='print the slowest 10 tests')
+    group.add_argument('--header', action='store_true',
+                       help='print header with interpreter info')
+
+    group = parser.add_argument_group('Selecting tests')
+    group.add_argument('-r', '--randomize', action='store_true',
+                       help='randomize test execution order.' + more_details)
+    group.add_argument('--randseed', metavar='SEED',
+                       dest='random_seed', type=int,
+                       help='pass a random seed to reproduce a previous '
+                            'random run')
+    group.add_argument('-f', '--fromfile', metavar='FILE',
+                       help='read names of tests to run from a file.' +
+                            more_details)
+    group.add_argument('-x', '--exclude', action='store_true',
+                       help='arguments are tests to *exclude*')
+    group.add_argument('-s', '--single', action='store_true',
+                       help='single step through a set of tests.' +
+                            more_details)
+    group.add_argument('-m', '--match', metavar='PAT',
+                       dest='match_tests',
+                       help='match test cases and methods with glob pattern PAT')
+    group.add_argument('-G', '--failfast', action='store_true',
+                       help='fail as soon as a test fails (only with -v or -W)')
+    group.add_argument('-u', '--use', metavar='RES1,RES2,...',
+                       action='append', type=resources_list,
+                       help='specify which special resource intensive tests '
+                            'to run.' + more_details)
+    group.add_argument('-M', '--memlimit', metavar='LIMIT',
+                       help='run very large memory-consuming tests.' +
+                            more_details)
+    group.add_argument('--testdir', metavar='DIR',
+                       type=relative_filename,
+                       help='execute test files in the specified directory '
+                            '(instead of the Python stdlib test suite)')
+
+    group = parser.add_argument_group('Special runs')
+    group.add_argument('-l', '--findleaks', action='store_true',
+                       help='if GC is available detect tests that leak memory')
+    group.add_argument('-L', '--runleaks', action='store_true',
+                       help='run the leaks(1) command just before exit.' +
+                            more_details)
+    group.add_argument('-R', '--huntrleaks', metavar='RUNCOUNTS',
+                       type=huntrleaks,
+                       help='search for reference leaks (needs debug build, '
+                            'very slow).' + more_details)
+    group.add_argument('-j', '--multiprocess', metavar='PROCESSES',
+                       dest='use_mp', type=int,
+                       help='run PROCESSES processes at once')
+    group.add_argument('-T', '--coverage', action='store_true',
+                       dest='trace',
+                       help='turn on code coverage tracing using the trace '
+                            'module')
+    group.add_argument('-D', '--coverdir', metavar='DIR',
+                       type=relative_filename,
+                       help='directory where coverage files are put')
+    group.add_argument('-N', '--nocoverdir',
+                       action='store_const', const=None, dest='coverdir',
+                       help='put coverage files alongside modules')
+    group.add_argument('-t', '--threshold', metavar='THRESHOLD',
+                       type=int,
+                       help='call gc.set_threshold(THRESHOLD)')
+    group.add_argument('-n', '--nowindows', action='store_true',
+                       help='suppress error message boxes on Windows')
+    group.add_argument('-F', '--forever', action='store_true',
+                       help='run the specified tests in a loop, until an '
+                            'error happens')
+    group.add_argument('--list-tests', action='store_true',
+                       help="only write the name of tests that will be run, "
+                            "don't execute them")
+    group.add_argument('-P', '--pgo', dest='pgo', action='store_true',
+                       help='enable Profile Guided Optimization training')
+
+    parser.add_argument('args', nargs=argparse.REMAINDER,
+                        help=argparse.SUPPRESS)
+
+    return parser
+
+
+def relative_filename(string):
+    # CWD is replaced with a temporary dir before calling main(), so we
+    # join it with the saved CWD so it ends up where the user expects.
+    return os.path.join(support.SAVEDCWD, string)
+
+
+def huntrleaks(string):
+    args = string.split(':')
+    if len(args) not in (2, 3):
+        raise argparse.ArgumentTypeError(
+            'needs 2 or 3 colon-separated arguments')
+    nwarmup = int(args[0]) if args[0] else 5
+    ntracked = int(args[1]) if args[1] else 4
+    fname = args[2] if len(args) > 2 and args[2] else 'reflog.txt'
+    return nwarmup, ntracked, fname
+
+
+def resources_list(string):
+    u = [x.lower() for x in string.split(',')]
+    for r in u:
+        if r == 'all' or r == 'none':
+            continue
+        if r[0] == '-':
+            r = r[1:]
+        if r not in RESOURCE_NAMES:
+            raise argparse.ArgumentTypeError('invalid resource: ' + r)
+    return u
+
+
+def _parse_args(args, **kwargs):
+    # Defaults
+    ns = argparse.Namespace(testdir=None, verbose=0, quiet=False,
+         exclude=False, single=False, randomize=False, fromfile=None,
+         findleaks=False, use_resources=None, trace=False, coverdir='coverage',
+         runleaks=False, huntrleaks=False, verbose2=False, print_slow=False,
+         random_seed=None, use_mp=None, verbose3=False, forever=False,
+         header=False, failfast=False, match_tests=None, pgo=False)
+    for k, v in kwargs.items():
+        if not hasattr(ns, k):
+            raise TypeError('%r is an invalid keyword argument '
+                            'for this function' % k)
+        setattr(ns, k, v)
+    if ns.use_resources is None:
+        ns.use_resources = []
+
+    parser = _create_parser()
+    parser.parse_args(args=args, namespace=ns)
+
+    if ns.single and ns.fromfile:
+        parser.error("-s and -f don't go together!")
+    if ns.use_mp and ns.trace:
+        parser.error("-T and -j don't go together!")
+    if ns.use_mp and ns.findleaks:
+        parser.error("-l and -j don't go together!")
+    if ns.failfast and not (ns.verbose or ns.verbose3):
+        parser.error("-G/--failfast needs either -v or -W")
+    if ns.pgo and (ns.verbose or ns.verbose2 or ns.verbose3):
+        parser.error("--pgo/-v don't go together!")
+
+    if ns.nowindows:
+        print("Warning: the --nowindows (-n) option is deprecated. "
+              "Use -vv to display assertions in stderr.", file=sys.stderr)
+
+    if ns.quiet:
+        ns.verbose = 0
+    if ns.timeout is not None:
+        if ns.timeout <= 0:
+            ns.timeout = None
+    if ns.use_mp is not None:
+        if ns.use_mp <= 0:
+            # Use all cores + extras for tests that like to sleep
+            ns.use_mp = 2 + (os.cpu_count() or 1)
+    if ns.use:
+        for a in ns.use:
+            for r in a:
+                if r == 'all':
+                    ns.use_resources[:] = RESOURCE_NAMES
+                    continue
+                if r == 'none':
+                    del ns.use_resources[:]
+                    continue
+                remove = False
+                if r[0] == '-':
+                    remove = True
+                    r = r[1:]
+                if remove:
+                    if r in ns.use_resources:
+                        ns.use_resources.remove(r)
+                elif r not in ns.use_resources:
+                    ns.use_resources.append(r)
+    if ns.random_seed is not None:
+        ns.randomize = True
+
+    return ns
diff --git a/Lib/test/libregrtest/main.py b/Lib/test/libregrtest/main.py
new file mode 100644
index 0000000000..e503c131ac
--- /dev/null
+++ b/Lib/test/libregrtest/main.py
@@ -0,0 +1,508 @@
+import datetime
+import faulthandler
+import math
+import os
+import platform
+import random
+import re
+import sys
+import sysconfig
+import tempfile
+import textwrap
+import time
+from test.libregrtest.cmdline import _parse_args
+from test.libregrtest.runtest import (
+    findtests, runtest,
+    STDTESTS, NOTTESTS, PASSED, FAILED, ENV_CHANGED, SKIPPED, RESOURCE_DENIED,
+    INTERRUPTED, CHILD_ERROR,
+    PROGRESS_MIN_TIME, format_test_result)
+from test.libregrtest.setup import setup_tests
+from test import support
+try:
+    import gc
+except ImportError:
+    gc = None
+
+
+# When tests are run from the Python build directory, it is best practice
+# to keep the test files in a subfolder.  This eases the cleanup of leftover
+# files using the "make distclean" command.
+if sysconfig.is_python_build():
+    TEMPDIR = os.path.join(sysconfig.get_config_var('srcdir'), 'build')
+else:
+    TEMPDIR = tempfile.gettempdir()
+TEMPDIR = os.path.abspath(TEMPDIR)
+
+
+class Regrtest:
+    """Execute a test suite.
+
+    This also parses command-line options and modifies its behavior
+    accordingly.
+
+    tests -- a list of strings containing test names (optional)
+    testdir -- the directory in which to look for tests (optional)
+
+    Users other than the Python test suite will certainly want to
+    specify testdir; if it's omitted, the directory containing the
+    Python test suite is searched for.
+
+    If the tests argument is omitted, the tests listed on the
+    command-line will be used.  If that's empty, too, then all *.py
+    files beginning with test_ will be used.
+
+    The other default arguments (verbose, quiet, exclude,
+    single, randomize, findleaks, use_resources, trace, coverdir,
+    print_slow, and random_seed) allow programmers calling main()
+    directly to set the values that would normally be set by flags
+    on the command line.
+    """
+    def __init__(self):
+        # Namespace of command line options
+        self.ns = None
+
+        # tests
+        self.tests = []
+        self.selected = []
+
+        # test results
+        self.good = []
+        self.bad = []
+        self.skipped = []
+        self.resource_denieds = []
+        self.environment_changed = []
+        self.interrupted = False
+
+        # used by --slow
+        self.test_times = []
+
+        # used by --coverage, trace.Trace instance
+        self.tracer = None
+
+        # used by --findleaks, store for gc.garbage
+        self.found_garbage = []
+
+        # used to display the progress bar "[ 3/100]"
+        self.start_time = time.monotonic()
+        self.test_count = ''
+        self.test_count_width = 1
+
+        # used by --single
+        self.next_single_test = None
+        self.next_single_filename = None
+
+    def accumulate_result(self, test, result):
+        ok, test_time = result
+        if ok not in (CHILD_ERROR, INTERRUPTED):
+            self.test_times.append((test_time, test))
+        if ok == PASSED:
+            self.good.append(test)
+        elif ok == FAILED:
+            self.bad.append(test)
+        elif ok == ENV_CHANGED:
+            self.environment_changed.append(test)
+        elif ok == SKIPPED:
+            self.skipped.append(test)
+        elif ok == RESOURCE_DENIED:
+            self.skipped.append(test)
+            self.resource_denieds.append(test)
+
+    def time_delta(self, ceil=False):
+        seconds = time.monotonic() - self.start_time
+        if ceil:
+            seconds = math.ceil(seconds)
+        else:
+            seconds = int(seconds)
+        return datetime.timedelta(seconds=seconds)
+
+    def display_progress(self, test_index, test):
+        if self.ns.quiet:
+            return
+        if self.bad and not self.ns.pgo:
+            fmt = "{time} [{test_index:{count_width}}{test_count}/{nbad}] {test_name}"
+        else:
+            fmt = "{time} [{test_index:{count_width}}{test_count}] {test_name}"
+        line = fmt.format(count_width=self.test_count_width,
+                          test_index=test_index,
+                          test_count=self.test_count,
+                          nbad=len(self.bad),
+                          test_name=test,
+                          time=self.time_delta())
+        print(line, flush=True)
+
+    def parse_args(self, kwargs):
+        ns = _parse_args(sys.argv[1:], **kwargs)
+
+        if ns.timeout and not hasattr(faulthandler, 'dump_traceback_later'):
+            print("Warning: The timeout option requires "
+                  "faulthandler.dump_traceback_later", file=sys.stderr)
+            ns.timeout = None
+
+        if ns.threshold is not None and gc is None:
+            print('No GC available, ignore --threshold.', file=sys.stderr)
+            ns.threshold = None
+
+        if ns.findleaks:
+            if gc is not None:
+                # Uncomment the line below to report garbage that is not
+                # freeable by reference counting alone.  By default only
+                # garbage that is not collectable by the GC is reported.
+                pass
+                #gc.set_debug(gc.DEBUG_SAVEALL)
+            else:
+                print('No GC available, disabling --findleaks',
+                      file=sys.stderr)
+                ns.findleaks = False
+
+        # Strip .py extensions.
+        removepy(ns.args)
+
+        return ns
+
+    def find_tests(self, tests):
+        self.tests = tests
+
+        if self.ns.single:
+            self.next_single_filename = os.path.join(TEMPDIR, 'pynexttest')
+            try:
+                with open(self.next_single_filename, 'r') as fp:
+                    next_test = fp.read().strip()
+                    self.tests = [next_test]
+            except OSError:
+                pass
+
+        if self.ns.fromfile:
+            self.tests = []
+            # regex to match 'test_builtin' in line:
+            # '0:00:00 [  4/400] test_builtin -- test_dict took 1 sec'
+            regex = (r'^(?:[0-9]+:[0-9]+:[0-9]+ *)?'
+                     r'(?:\[[0-9/ ]+\] *)?'
+                     r'(test_[a-zA-Z0-9_]+)')
+            regex = re.compile(regex)
+            with open(os.path.join(support.SAVEDCWD, self.ns.fromfile)) as fp:
+                for line in fp:
+                    line = line.strip()
+                    if line.startswith('#'):
+                        continue
+                    match = regex.match(line)
+                    if match is None:
+                        continue
+                    self.tests.append(match.group(1))
+
+        removepy(self.tests)
+
+        stdtests = STDTESTS[:]
+        nottests = NOTTESTS.copy()
+        if self.ns.exclude:
+            for arg in self.ns.args:
+                if arg in stdtests:
+                    stdtests.remove(arg)
+                nottests.add(arg)
+            self.ns.args = []
+
+        # if testdir is set, then we are not running the python tests suite, so
+        # don't add default tests to be executed or skipped (pass empty values)
+        if self.ns.testdir:
+            alltests = findtests(self.ns.testdir, list(), set())
+        else:
+            alltests = findtests(self.ns.testdir, stdtests, nottests)
+
+        if not self.ns.fromfile:
+            self.selected = self.tests or self.ns.args or alltests
+        else:
+            self.selected = self.tests
+        if self.ns.single:
+            self.selected = self.selected[:1]
+            try:
+                pos = alltests.index(self.selected[0])
+                self.next_single_test = alltests[pos + 1]
+            except IndexError:
+                pass
+
+        # Remove all the selected tests that precede start if it's set.
+        if self.ns.start:
+            try:
+                del self.selected[:self.selected.index(self.ns.start)]
+            except ValueError:
+                print("Couldn't find starting test (%s), using all tests"
+                      % self.ns.start, file=sys.stderr)
+
+        if self.ns.randomize:
+            if self.ns.random_seed is None:
+                self.ns.random_seed = random.randrange(10000000)
+            random.seed(self.ns.random_seed)
+            random.shuffle(self.selected)
+
+    def list_tests(self):
+        for name in self.selected:
+            print(name)
+
+    def rerun_failed_tests(self):
+        self.ns.verbose = True
+        self.ns.failfast = False
+        self.ns.verbose3 = False
+        self.ns.match_tests = None
+
+        print("Re-running failed tests in verbose mode")
+        for test in self.bad[:]:
+            print("Re-running test %r in verbose mode" % test, flush=True)
+            try:
+                self.ns.verbose = True
+                ok = runtest(self.ns, test)
+            except KeyboardInterrupt:
+                # print a newline separate from the ^C
+                print()
+                break
+            else:
+                if ok[0] in {PASSED, ENV_CHANGED, SKIPPED, RESOURCE_DENIED}:
+                    self.bad.remove(test)
+        else:
+            if self.bad:
+                print(count(len(self.bad), 'test'), "failed again:")
+                printlist(self.bad)
+
+    def display_result(self):
+        if self.interrupted:
+            # print a newline after ^C
+            print()
+            print("Test suite interrupted by signal SIGINT.")
+            executed = set(self.good) | set(self.bad) | set(self.skipped)
+            omitted = set(self.selected) - executed
+            print(count(len(omitted), "test"), "omitted:")
+            printlist(omitted)
+
+        # If running the test suite for PGO then no one cares about
+        # results.
+        if self.ns.pgo:
+            return
+
+        if self.good and not self.ns.quiet:
+            if (not self.bad
+                and not self.skipped
+                and not self.interrupted
+                and len(self.good) > 1):
+                print("All", end=' ')
+            print(count(len(self.good), "test"), "OK.")
+
+        if self.ns.print_slow:
+            self.test_times.sort(reverse=True)
+            print("10 slowest tests:")
+            for time, test in self.test_times[:10]:
+                print("%s: %.1fs" % (test, time))
+
+        if self.bad:
+            print(count(len(self.bad), "test"), "failed:")
+            printlist(self.bad)
+
+        if self.environment_changed:
+            print("{} altered the execution environment:".format(
+                     count(len(self.environment_changed), "test")))
+            printlist(self.environment_changed)
+
+        if self.skipped and not self.ns.quiet:
+            print(count(len(self.skipped), "test"), "skipped:")
+            printlist(self.skipped)
+
+    def run_tests_sequential(self):
+        if self.ns.trace:
+            import trace
+            self.tracer = trace.Trace(trace=False, count=True)
+
+        save_modules = sys.modules.keys()
+
+        print("Run tests sequentially")
+
+        previous_test = None
+        for test_index, test in enumerate(self.tests, 1):
+            start_time = time.monotonic()
+
+            text = test
+            if previous_test:
+                text = '%s -- %s' % (text, previous_test)
+            self.display_progress(test_index, text)
+
+            if self.tracer:
+                # If we're tracing code coverage, then we don't exit with status
+                # if on a false return value from main.
+                cmd = ('result = runtest(self.ns, test); '
+                       'self.accumulate_result(test, result)')
+                ns = dict(locals())
+                self.tracer.runctx(cmd, globals=globals(), locals=ns)
+                result = ns['result']
+            else:
+                try:
+                    result = runtest(self.ns, test)
+                except KeyboardInterrupt:
+                    self.accumulate_result(test, (INTERRUPTED, None))
+                    self.interrupted = True
+                    break
+                else:
+                    self.accumulate_result(test, result)
+
+            previous_test = format_test_result(test, result[0])
+            test_time = time.monotonic() - start_time
+            if test_time >= PROGRESS_MIN_TIME:
+                previous_test = "%s in %.0f sec" % (previous_test, test_time)
+            elif result[0] == PASSED:
+                # be quiet: say nothing if the test passed shortly
+                previous_test = None
+
+            if self.ns.findleaks:
+                gc.collect()
+                if gc.garbage:
+                    print("Warning: test created", len(gc.garbage), end=' ')
+                    print("uncollectable object(s).")
+                    # move the uncollectable objects somewhere so we don't see
+                    # them again
+                    self.found_garbage.extend(gc.garbage)
+                    del gc.garbage[:]
+
+            # Unload the newly imported modules (best effort finalization)
+            for module in sys.modules.keys():
+                if module not in save_modules and module.startswith("test."):
+                    support.unload(module)
+
+        if previous_test:
+            print(previous_test)
+
+    def _test_forever(self, tests):
+        while True:
+            for test in tests:
+                yield test
+                if self.bad:
+                    return
+
+    def run_tests(self):
+        # For a partial run, we do not need to clutter the output.
+        if (self.ns.verbose
+            or self.ns.header
+            or not (self.ns.pgo or self.ns.quiet or self.ns.single
+                    or self.tests or self.ns.args)):
+            # Print basic platform information
+            print("==", platform.python_implementation(), *sys.version.split())
+            print("==  ", platform.platform(aliased=True),
+                          "%s-endian" % sys.byteorder)
+            print("==  ", "hash algorithm:", sys.hash_info.algorithm,
+                  "64bit" if sys.maxsize > 2**32 else "32bit")
+            print("==  ", os.getcwd())
+            print("Testing with flags:", sys.flags)
+
+        if self.ns.randomize:
+            print("Using random seed", self.ns.random_seed)
+
+        if self.ns.forever:
+            self.tests = self._test_forever(list(self.selected))
+            self.test_count = ''
+            self.test_count_width = 3
+        else:
+            self.tests = iter(self.selected)
+            self.test_count = '/{}'.format(len(self.selected))
+            self.test_count_width = len(self.test_count) - 1
+
+        if self.ns.use_mp:
+            from test.libregrtest.runtest_mp import run_tests_multiprocess
+            run_tests_multiprocess(self)
+        else:
+            self.run_tests_sequential()
+
+    def finalize(self):
+        if self.next_single_filename:
+            if self.next_single_test:
+                with open(self.next_single_filename, 'w') as fp:
+                    fp.write(self.next_single_test + '\n')
+            else:
+                os.unlink(self.next_single_filename)
+
+        if self.tracer:
+            r = self.tracer.results()
+            r.write_results(show_missing=True, summary=True,
+                            coverdir=self.ns.coverdir)
+
+        print("Total duration: %s" % self.time_delta(ceil=True))
+
+        if self.ns.runleaks:
+            os.system("leaks %d" % os.getpid())
+
+    def main(self, tests=None, **kwargs):
+        global TEMPDIR
+
+        if sysconfig.is_python_build():
+            try:
+                os.mkdir(TEMPDIR)
+            except FileExistsError:
+                pass
+
+        # Define a writable temp dir that will be used as cwd while running
+        # the tests. The name of the dir includes the pid to allow parallel
+        # testing (see the -j option).
+        test_cwd = 'test_python_{}'.format(os.getpid())
+        test_cwd = os.path.join(TEMPDIR, test_cwd)
+
+        # Run the tests in a context manager that temporarily changes the CWD to a
+        # temporary and writable directory.  If it's not possible to create or
+        # change the CWD, the original CWD will be used.  The original CWD is
+        # available from support.SAVEDCWD.
+        with support.temp_cwd(test_cwd, quiet=True):
+            self._main(tests, kwargs)
+
+    def _main(self, tests, kwargs):
+        self.ns = self.parse_args(kwargs)
+
+        if self.ns.slaveargs is not None:
+            from test.libregrtest.runtest_mp import run_tests_slave
+            run_tests_slave(self.ns.slaveargs)
+
+        if self.ns.wait:
+            input("Press any key to continue...")
+
+        setup_tests(self.ns)
+
+        self.find_tests(tests)
+
+        if self.ns.list_tests:
+            self.list_tests()
+            sys.exit(0)
+
+        self.run_tests()
+        self.display_result()
+
+        if self.ns.verbose2 and self.bad:
+            self.rerun_failed_tests()
+
+        self.finalize()
+        sys.exit(len(self.bad) > 0 or self.interrupted)
+
+
+def removepy(names):
+    if not names:
+        return
+    for idx, name in enumerate(names):
+        basename, ext = os.path.splitext(name)
+        if ext == '.py':
+            names[idx] = basename
+
+
+def count(n, word):
+    if n == 1:
+        return "%d %s" % (n, word)
+    else:
+        return "%d %ss" % (n, word)
+
+
+def printlist(x, width=70, indent=4):
+    """Print the elements of iterable x to stdout.
+
+    Optional arg width (default 70) is the maximum line length.
+    Optional arg indent (default 4) is the number of blanks with which to
+    begin each line.
+    """
+
+    blanks = ' ' * indent
+    # Print the sorted list: 'x' may be a '--random' list or a set()
+    print(textwrap.fill(' '.join(str(elt) for elt in sorted(x)), width,
+                        initial_indent=blanks, subsequent_indent=blanks))
+
+
+def main(tests=None, **kwargs):
+    """Run the Python suite."""
+    Regrtest().main(tests=tests, **kwargs)
diff --git a/Lib/test/libregrtest/refleak.py b/Lib/test/libregrtest/refleak.py
new file mode 100644
index 0000000000..59dc49fe77
--- /dev/null
+++ b/Lib/test/libregrtest/refleak.py
@@ -0,0 +1,202 @@
+import errno
+import os
+import re
+import sys
+import warnings
+from inspect import isabstract
+from test import support
+
+
+try:
+    MAXFD = os.sysconf("SC_OPEN_MAX")
+except Exception:
+    MAXFD = 256
+
+
+def fd_count():
+    """Count the number of open file descriptors"""
+    if sys.platform.startswith(('linux', 'freebsd')):
+        try:
+            names = os.listdir("/proc/self/fd")
+            return len(names)
+        except FileNotFoundError:
+            pass
+
+    count = 0
+    for fd in range(MAXFD):
+        try:
+            # Prefer dup() over fstat(). fstat() can require input/output
+            # whereas dup() doesn't.
+            fd2 = os.dup(fd)
+        except OSError as e:
+            if e.errno != errno.EBADF:
+                raise
+        else:
+            os.close(fd2)
+            count += 1
+    return count
+
+
+def dash_R(the_module, test, indirect_test, huntrleaks):
+    """Run a test multiple times, looking for reference leaks.
+
+    Returns:
+        False if the test didn't leak references; True if we detected refleaks.
+    """
+    # This code is hackish and inelegant, but it seems to do the job.
+    import copyreg
+    import collections.abc
+
+    if not hasattr(sys, 'gettotalrefcount'):
+        raise Exception("Tracking reference leaks requires a debug build "
+                        "of Python")
+
+    # Save current values for dash_R_cleanup() to restore.
+    fs = warnings.filters[:]
+    ps = copyreg.dispatch_table.copy()
+    pic = sys.path_importer_cache.copy()
+    try:
+        import zipimport
+    except ImportError:
+        zdc = None # Run unmodified on platforms without zipimport support
+    else:
+        zdc = zipimport._zip_directory_cache.copy()
+    abcs = {}
+    for abc in [getattr(collections.abc, a) for a in collections.abc.__all__]:
+        if not isabstract(abc):
+            continue
+        for obj in abc.__subclasses__() + [abc]:
+            abcs[obj] = obj._abc_registry.copy()
+
+    nwarmup, ntracked, fname = huntrleaks
+    fname = os.path.join(support.SAVEDCWD, fname)
+    repcount = nwarmup + ntracked
+    rc_deltas = [0] * repcount
+    alloc_deltas = [0] * repcount
+    fd_deltas = [0] * repcount
+
+    print("beginning", repcount, "repetitions", file=sys.stderr)
+    print(("1234567890"*(repcount//10 + 1))[:repcount], file=sys.stderr,
+          flush=True)
+    # initialize variables to make pyflakes quiet
+    rc_before = alloc_before = fd_before = 0
+    for i in range(repcount):
+        indirect_test()
+        alloc_after, rc_after, fd_after = dash_R_cleanup(fs, ps, pic, zdc,
+                                                         abcs)
+        print('.', end='', flush=True)
+        if i >= nwarmup:
+            rc_deltas[i] = rc_after - rc_before
+            alloc_deltas[i] = alloc_after - alloc_before
+            fd_deltas[i] = fd_after - fd_before
+        alloc_before = alloc_after
+        rc_before = rc_after
+        fd_before = fd_after
+    print(file=sys.stderr)
+    # These checkers return False on success, True on failure
+    def check_rc_deltas(deltas):
+        return any(deltas)
+    def check_alloc_deltas(deltas):
+        # At least 1/3rd of 0s
+        if 3 * deltas.count(0) < len(deltas):
+            return True
+        # Nothing else than 1s, 0s and -1s
+        if not set(deltas) <= {1,0,-1}:
+            return True
+        return False
+    failed = False
+    for deltas, item_name, checker in [
+        (rc_deltas, 'references', check_rc_deltas),
+        (alloc_deltas, 'memory blocks', check_alloc_deltas),
+        (fd_deltas, 'file descriptors', check_rc_deltas)]:
+        if checker(deltas):
+            msg = '%s leaked %s %s, sum=%s' % (
+                test, deltas[nwarmup:], item_name, sum(deltas))
+            print(msg, file=sys.stderr, flush=True)
+            with open(fname, "a") as refrep:
+                print(msg, file=refrep)
+                refrep.flush()
+            failed = True
+    return failed
+
+
+def dash_R_cleanup(fs, ps, pic, zdc, abcs):
+    import gc, copyreg
+    import _strptime, linecache
+    import urllib.parse, urllib.request, mimetypes, doctest
+    import struct, filecmp, collections.abc
+    from distutils.dir_util import _path_created
+    from weakref import WeakSet
+
+    # Clear the warnings registry, so they can be displayed again
+    for mod in sys.modules.values():
+        if hasattr(mod, '__warningregistry__'):
+            del mod.__warningregistry__
+
+    # Restore some original values.
+    warnings.filters[:] = fs
+    copyreg.dispatch_table.clear()
+    copyreg.dispatch_table.update(ps)
+    sys.path_importer_cache.clear()
+    sys.path_importer_cache.update(pic)
+    try:
+        import zipimport
+    except ImportError:
+        pass # Run unmodified on platforms without zipimport support
+    else:
+        zipimport._zip_directory_cache.clear()
+        zipimport._zip_directory_cache.update(zdc)
+
+    # clear type cache
+    sys._clear_type_cache()
+
+    # Clear ABC registries, restoring previously saved ABC registries.
+    for abc in [getattr(collections.abc, a) for a in collections.abc.__all__]:
+        if not isabstract(abc):
+            continue
+        for obj in abc.__subclasses__() + [abc]:
+            obj._abc_registry = abcs.get(obj, WeakSet()).copy()
+            obj._abc_cache.clear()
+            obj._abc_negative_cache.clear()
+
+    # Flush standard output, so that buffered data is sent to the OS and
+    # associated Python objects are reclaimed.
+    for stream in (sys.stdout, sys.stderr, sys.__stdout__, sys.__stderr__):
+        if stream is not None:
+            stream.flush()
+
+    # Clear assorted module caches.
+    _path_created.clear()
+    re.purge()
+    _strptime._regex_cache.clear()
+    urllib.parse.clear_cache()
+    urllib.request.urlcleanup()
+    linecache.clearcache()
+    mimetypes._default_mime_types()
+    filecmp._cache.clear()
+    struct._clearcache()
+    doctest.master = None
+    try:
+        import ctypes
+    except ImportError:
+        # Don't worry about resetting the cache if ctypes is not supported
+        pass
+    else:
+        ctypes._reset_cache()
+
+    # Collect cyclic trash and read memory statistics immediately after.
+    func1 = sys.getallocatedblocks
+    func2 = sys.gettotalrefcount
+    gc.collect()
+    return func1(), func2(), fd_count()
+
+
+def warm_caches():
+    # char cache
+    s = bytes(range(256))
+    for i in range(256):
+        s[i:i+1]
+    # unicode cache
+    [chr(i) for i in range(256)]
+    # int cache
+    list(range(-5, 257))
diff --git a/Lib/test/libregrtest/runtest.py b/Lib/test/libregrtest/runtest.py
new file mode 100644
index 0000000000..ef1feb738a
--- /dev/null
+++ b/Lib/test/libregrtest/runtest.py
@@ -0,0 +1,260 @@
+import faulthandler
+import importlib
+import io
+import os
+import sys
+import time
+import traceback
+import unittest
+from test import support
+from test.libregrtest.refleak import dash_R
+from test.libregrtest.save_env import saved_test_environment
+
+
+# Test result constants.
+PASSED = 1
+FAILED = 0
+ENV_CHANGED = -1
+SKIPPED = -2
+RESOURCE_DENIED = -3
+INTERRUPTED = -4
+CHILD_ERROR = -5   # error in a child process
+
+_FORMAT_TEST_RESULT = {
+    PASSED: '%s passed',
+    FAILED: '%s failed',
+    ENV_CHANGED: '%s failed (env changed)',
+    SKIPPED: '%s skipped',
+    RESOURCE_DENIED: '%s skipped (resource denied)',
+    INTERRUPTED: '%s interrupted',
+    CHILD_ERROR: '%s crashed',
+}
+
+# Minimum duration of a test to display its duration or to mention that
+# the test is running in background
+PROGRESS_MIN_TIME = 30.0   # seconds
+
+# small set of tests to determine if we have a basically functioning interpreter
+# (i.e. if any of these fail, then anything else is likely to follow)
+STDTESTS = [
+    'test_grammar',
+    'test_opcodes',
+    'test_dict',
+    'test_builtin',
+    'test_exceptions',
+    'test_types',
+    'test_unittest',
+    'test_doctest',
+    'test_doctest2',
+    'test_support'
+]
+
+# set of tests that we don't want to be executed when using regrtest
+NOTTESTS = set()
+
+
+def format_test_result(test_name, result):
+    fmt = _FORMAT_TEST_RESULT.get(result, "%s")
+    return fmt % test_name
+
+
+def findtests(testdir=None, stdtests=STDTESTS, nottests=NOTTESTS):
+    """Return a list of all applicable test modules."""
+    testdir = findtestdir(testdir)
+    names = os.listdir(testdir)
+    tests = []
+    others = set(stdtests) | nottests
+    for name in names:
+        mod, ext = os.path.splitext(name)
+        if mod[:5] == "test_" and ext in (".py", "") and mod not in others:
+            tests.append(mod)
+    return stdtests + sorted(tests)
+
+
+def runtest(ns, test):
+    """Run a single test.
+
+    test -- the name of the test
+    verbose -- if true, print more messages
+    quiet -- if true, don't print 'skipped' messages (probably redundant)
+    huntrleaks -- run multiple times to test for leaks; requires a debug
+                  build; a triple corresponding to -R's three arguments
+    output_on_failure -- if true, display test output on failure
+    timeout -- dump the traceback and exit if a test takes more than
+               timeout seconds
+    failfast, match_tests -- See regrtest command-line flags for these.
+    pgo -- if true, suppress any info irrelevant to a generating a PGO build
+
+    Returns the tuple result, test_time, where result is one of the constants:
+        INTERRUPTED      KeyboardInterrupt when run under -j
+        RESOURCE_DENIED  test skipped because resource denied
+        SKIPPED          test skipped for some other reason
+        ENV_CHANGED      test failed because it changed the execution environment
+        FAILED           test failed
+        PASSED           test passed
+    """
+
+    verbose = ns.verbose
+    quiet = ns.quiet
+    huntrleaks = ns.huntrleaks
+    output_on_failure = ns.verbose3
+    failfast = ns.failfast
+    match_tests = ns.match_tests
+    timeout = ns.timeout
+    pgo = ns.pgo
+
+    use_timeout = (timeout is not None)
+    if use_timeout:
+        faulthandler.dump_traceback_later(timeout, exit=True)
+    try:
+        support.match_tests = match_tests
+        if failfast:
+            support.failfast = True
+        if output_on_failure:
+            support.verbose = True
+
+            # Reuse the same instance to all calls to runtest(). Some
+            # tests keep a reference to sys.stdout or sys.stderr
+            # (eg. test_argparse).
+            if runtest.stringio is None:
+                stream = io.StringIO()
+                runtest.stringio = stream
+            else:
+                stream = runtest.stringio
+                stream.seek(0)
+                stream.truncate()
+
+            orig_stdout = sys.stdout
+            orig_stderr = sys.stderr
+            try:
+                sys.stdout = stream
+                sys.stderr = stream
+                result = runtest_inner(ns, test, verbose, quiet, huntrleaks,
+                                       display_failure=False, pgo=pgo)
+                if result[0] == FAILED:
+                    output = stream.getvalue()
+                    orig_stderr.write(output)
+                    orig_stderr.flush()
+            finally:
+                sys.stdout = orig_stdout
+                sys.stderr = orig_stderr
+        else:
+            support.verbose = verbose  # Tell tests to be moderately quiet
+            result = runtest_inner(ns, test, verbose, quiet, huntrleaks,
+                                   display_failure=not verbose, pgo=pgo)
+        return result
+    finally:
+        if use_timeout:
+            faulthandler.cancel_dump_traceback_later()
+        cleanup_test_droppings(test, verbose)
+runtest.stringio = None
+
+
+def runtest_inner(ns, test, verbose, quiet,
+                  huntrleaks=False, display_failure=True, *, pgo=False):
+    support.unload(test)
+
+    test_time = 0.0
+    refleak = False  # True if the test leaked references.
+    try:
+        if test.startswith('test.') or ns.testdir:
+            abstest = test
+        else:
+            # Always import it from the test package
+            abstest = 'test.' + test
+        with saved_test_environment(test, verbose, quiet, pgo=pgo) as environment:
+            start_time = time.time()
+            the_module = importlib.import_module(abstest)
+            # If the test has a test_main, that will run the appropriate
+            # tests.  If not, use normal unittest test loading.
+            test_runner = getattr(the_module, "test_main", None)
+            if test_runner is None:
+                def test_runner():
+                    loader = unittest.TestLoader()
+                    tests = loader.loadTestsFromModule(the_module)
+                    for error in loader.errors:
+                        print(error, file=sys.stderr)
+                    if loader.errors:
+                        raise Exception("errors while loading tests")
+                    support.run_unittest(tests)
+            test_runner()
+            if huntrleaks:
+                refleak = dash_R(the_module, test, test_runner, huntrleaks)
+            test_time = time.time() - start_time
+    except support.ResourceDenied as msg:
+        if not quiet and not pgo:
+            print(test, "skipped --", msg, flush=True)
+        return RESOURCE_DENIED, test_time
+    except unittest.SkipTest as msg:
+        if not quiet and not pgo:
+            print(test, "skipped --", msg, flush=True)
+        return SKIPPED, test_time
+    except KeyboardInterrupt:
+        raise
+    except support.TestFailed as msg:
+        if not pgo:
+            if display_failure:
+                print("test", test, "failed --", msg, file=sys.stderr,
+                      flush=True)
+            else:
+                print("test", test, "failed", file=sys.stderr, flush=True)
+        return FAILED, test_time
+    except:
+        msg = traceback.format_exc()
+        if not pgo:
+            print("test", test, "crashed --", msg, file=sys.stderr,
+                  flush=True)
+        return FAILED, test_time
+    else:
+        if refleak:
+            return FAILED, test_time
+        if environment.changed:
+            return ENV_CHANGED, test_time
+        return PASSED, test_time
+
+
+def cleanup_test_droppings(testname, verbose):
+    import shutil
+    import stat
+    import gc
+
+    # First kill any dangling references to open files etc.
+    # This can also issue some ResourceWarnings which would otherwise get
+    # triggered during the following test run, and possibly produce failures.
+    gc.collect()
+
+    # Try to clean up junk commonly left behind.  While tests shouldn't leave
+    # any files or directories behind, when a test fails that can be tedious
+    # for it to arrange.  The consequences can be especially nasty on Windows,
+    # since if a test leaves a file open, it cannot be deleted by name (while
+    # there's nothing we can do about that here either, we can display the
+    # name of the offending test, which is a real help).
+    for name in (support.TESTFN,
+                 "db_home",
+                ):
+        if not os.path.exists(name):
+            continue
+
+        if os.path.isdir(name):
+            kind, nuker = "directory", shutil.rmtree
+        elif os.path.isfile(name):
+            kind, nuker = "file", os.unlink
+        else:
+            raise SystemError("os.path says %r exists but is neither "
+                              "directory nor file" % name)
+
+        if verbose:
+            print("%r left behind %s %r" % (testname, kind, name))
+        try:
+            # if we have chmod, fix possible permissions problems
+            # that might prevent cleanup
+            if (hasattr(os, 'chmod')):
+                os.chmod(name, stat.S_IRWXU | stat.S_IRWXG | stat.S_IRWXO)
+            nuker(name)
+        except Exception as msg:
+            print(("%r left behind %s %r and it couldn't be "
+                "removed: %s" % (testname, kind, name, msg)), file=sys.stderr)
+
+
+def findtestdir(path=None):
+    return path or os.path.dirname(os.path.dirname(__file__)) or os.curdir
diff --git a/Lib/test/libregrtest/runtest_mp.py b/Lib/test/libregrtest/runtest_mp.py
new file mode 100644
index 0000000000..9604c16600
--- /dev/null
+++ b/Lib/test/libregrtest/runtest_mp.py
@@ -0,0 +1,245 @@
+import faulthandler
+import json
+import os
+import queue
+import sys
+import time
+import traceback
+import types
+from test import support
+try:
+    import threading
+except ImportError:
+    print("Multiprocess option requires thread support")
+    sys.exit(2)
+
+from test.libregrtest.runtest import (
+    runtest, INTERRUPTED, CHILD_ERROR, PROGRESS_MIN_TIME,
+    format_test_result)
+from test.libregrtest.setup import setup_tests
+
+
+# Display the running tests if nothing happened last N seconds
+PROGRESS_UPDATE = 30.0   # seconds
+
+# If interrupted, display the wait progress every N seconds
+WAIT_PROGRESS = 2.0   # seconds
+
+
+def run_test_in_subprocess(testname, ns):
+    """Run the given test in a subprocess with --slaveargs.
+
+    ns is the option Namespace parsed from command-line arguments. regrtest
+    is invoked in a subprocess with the --slaveargs argument; when the
+    subprocess exits, its return code, stdout and stderr are returned as a
+    3-tuple.
+    """
+    from subprocess import Popen, PIPE
+
+    ns_dict = vars(ns)
+    slaveargs = (ns_dict, testname)
+    slaveargs = json.dumps(slaveargs)
+
+    cmd = [sys.executable, *support.args_from_interpreter_flags(),
+           '-X', 'faulthandler',
+           '-m', 'test.regrtest',
+           '--slaveargs', slaveargs]
+    if ns.pgo:
+        cmd += ['--pgo']
+
+    # Running the child from the same working directory as regrtest's original
+    # invocation ensures that TEMPDIR for the child is the same when
+    # sysconfig.is_python_build() is true. See issue 15300.
+    popen = Popen(cmd,
+                  stdout=PIPE, stderr=PIPE,
+                  universal_newlines=True,
+                  close_fds=(os.name != 'nt'),
+                  cwd=support.SAVEDCWD)
+    with popen:
+        stdout, stderr = popen.communicate()
+        retcode = popen.wait()
+    return retcode, stdout, stderr
+
+
+def run_tests_slave(slaveargs):
+    ns_dict, testname = json.loads(slaveargs)
+    ns = types.SimpleNamespace(**ns_dict)
+
+    setup_tests(ns)
+
+    try:
+        result = runtest(ns, testname)
+    except KeyboardInterrupt:
+        result = INTERRUPTED, ''
+    except BaseException as e:
+        traceback.print_exc()
+        result = CHILD_ERROR, str(e)
+
+    print()   # Force a newline (just in case)
+    print(json.dumps(result), flush=True)
+    sys.exit(0)
+
+
+# We do not use a generator so multiple threads can call next().
+class MultiprocessIterator:
+
+    """A thread-safe iterator over tests for multiprocess mode."""
+
+    def __init__(self, tests):
+        self.interrupted = False
+        self.lock = threading.Lock()
+        self.tests = tests
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        with self.lock:
+            if self.interrupted:
+                raise StopIteration('tests interrupted')
+            return next(self.tests)
+
+
+class MultiprocessThread(threading.Thread):
+    def __init__(self, pending, output, ns):
+        super().__init__()
+        self.pending = pending
+        self.output = output
+        self.ns = ns
+        self.current_test = None
+        self.start_time = None
+
+    def _runtest(self):
+        try:
+            test = next(self.pending)
+        except StopIteration:
+            self.output.put((None, None, None, None))
+            return True
+
+        try:
+            self.start_time = time.monotonic()
+            self.current_test = test
+
+            retcode, stdout, stderr = run_test_in_subprocess(test, self.ns)
+        finally:
+            self.current_test = None
+
+        stdout, _, result = stdout.strip().rpartition("\n")
+        if retcode != 0:
+            result = (CHILD_ERROR, "Exit code %s" % retcode)
+            self.output.put((test, stdout.rstrip(), stderr.rstrip(),
+                             result))
+            return True
+
+        if not result:
+            self.output.put((None, None, None, None))
+            return True
+
+        result = json.loads(result)
+        self.output.put((test, stdout.rstrip(), stderr.rstrip(),
+                         result))
+        return False
+
+    def run(self):
+        try:
+            stop = False
+            while not stop:
+                stop = self._runtest()
+        except BaseException:
+            self.output.put((None, None, None, None))
+            raise
+
+
+def run_tests_multiprocess(regrtest):
+    output = queue.Queue()
+    pending = MultiprocessIterator(regrtest.tests)
+    test_timeout = regrtest.ns.timeout
+    use_timeout = (test_timeout is not None)
+
+    workers = [MultiprocessThread(pending, output, regrtest.ns)
+               for i in range(regrtest.ns.use_mp)]
+    print("Run tests in parallel using %s child processes"
+          % len(workers))
+    for worker in workers:
+        worker.start()
+
+    def get_running(workers):
+        running = []
+        for worker in workers:
+            current_test = worker.current_test
+            if not current_test:
+                continue
+            dt = time.monotonic() - worker.start_time
+            if dt >= PROGRESS_MIN_TIME:
+                running.append('%s (%.0f sec)' % (current_test, dt))
+        return running
+
+    finished = 0
+    test_index = 1
+    get_timeout = max(PROGRESS_UPDATE, PROGRESS_MIN_TIME)
+    try:
+        while finished < regrtest.ns.use_mp:
+            if use_timeout:
+                faulthandler.dump_traceback_later(test_timeout, exit=True)
+
+            try:
+                item = output.get(timeout=get_timeout)
+            except queue.Empty:
+                running = get_running(workers)
+                if running and not regrtest.ns.pgo:
+                    print('running: %s' % ', '.join(running))
+                continue
+
+            test, stdout, stderr, result = item
+            if test is None:
+                finished += 1
+                continue
+            regrtest.accumulate_result(test, result)
+
+            # Display progress
+            ok, test_time = result
+            text = format_test_result(test, ok)
+            if (ok not in (CHILD_ERROR, INTERRUPTED)
+                and test_time >= PROGRESS_MIN_TIME
+                and not regrtest.ns.pgo):
+                text += ' (%.0f sec)' % test_time
+            running = get_running(workers)
+            if running and not regrtest.ns.pgo:
+                text += ' -- running: %s' % ', '.join(running)
+            regrtest.display_progress(test_index, text)
+
+            # Copy stdout and stderr from the child process
+            if stdout:
+                print(stdout, flush=True)
+            if stderr and not regrtest.ns.pgo:
+                print(stderr, file=sys.stderr, flush=True)
+
+            if result[0] == INTERRUPTED:
+                raise KeyboardInterrupt
+            if result[0] == CHILD_ERROR:
+                msg = "Child error on {}: {}".format(test, result[1])
+                raise Exception(msg)
+            test_index += 1
+    except KeyboardInterrupt:
+        regrtest.interrupted = True
+        pending.interrupted = True
+        print()
+    finally:
+        if use_timeout:
+            faulthandler.cancel_dump_traceback_later()
+
+    # If tests are interrupted, wait until tests complete
+    wait_start = time.monotonic()
+    while True:
+        running = [worker.current_test for worker in workers]
+        running = list(filter(bool, running))
+        if not running:
+            break
+
+        dt = time.monotonic() - wait_start
+        line = "Waiting for %s (%s tests)" % (', '.join(running), len(running))
+        if dt >= WAIT_PROGRESS:
+            line = "%s since %.0f sec" % (line, dt)
+        print(line)
+        for worker in workers:
+            worker.join(WAIT_PROGRESS)
diff --git a/Lib/test/libregrtest/save_env.py b/Lib/test/libregrtest/save_env.py
new file mode 100644
index 0000000000..5bb9e19a91
--- /dev/null
+++ b/Lib/test/libregrtest/save_env.py
@@ -0,0 +1,286 @@
+import builtins
+import locale
+import logging
+import os
+import shutil
+import sys
+import sysconfig
+import warnings
+from test import support
+try:
+    import threading
+except ImportError:
+    threading = None
+try:
+    import _multiprocessing, multiprocessing.process
+except ImportError:
+    multiprocessing = None
+
+
+# Unit tests are supposed to leave the execution environment unchanged
+# once they complete.  But sometimes tests have bugs, especially when
+# tests fail, and the changes to environment go on to mess up other
+# tests.  This can cause issues with buildbot stability, since tests
+# are run in random order and so problems may appear to come and go.
+# There are a few things we can save and restore to mitigate this, and
+# the following context manager handles this task.
+
+class saved_test_environment:
+    """Save bits of the test environment and restore them at block exit.
+
+        with saved_test_environment(testname, verbose, quiet):
+            #stuff
+
+    Unless quiet is True, a warning is printed to stderr if any of
+    the saved items was changed by the test.  The attribute 'changed'
+    is initially False, but is set to True if a change is detected.
+
+    If verbose is more than 1, the before and after state of changed
+    items is also printed.
+    """
+
+    changed = False
+
+    def __init__(self, testname, verbose=0, quiet=False, *, pgo=False):
+        self.testname = testname
+        self.verbose = verbose
+        self.quiet = quiet
+        self.pgo = pgo
+
+    # To add things to save and restore, add a name XXX to the resources list
+    # and add corresponding get_XXX/restore_XXX functions.  get_XXX should
+    # return the value to be saved and compared against a second call to the
+    # get function when test execution completes.  restore_XXX should accept
+    # the saved value and restore the resource using it.  It will be called if
+    # and only if a change in the value is detected.
+    #
+    # Note: XXX will have any '.' replaced with '_' characters when determining
+    # the corresponding method names.
+
+    resources = ('sys.argv', 'cwd', 'sys.stdin', 'sys.stdout', 'sys.stderr',
+                 'os.environ', 'sys.path', 'sys.path_hooks', '__import__',
+                 'warnings.filters', 'asyncore.socket_map',
+                 'logging._handlers', 'logging._handlerList', 'sys.gettrace',
+                 'sys.warnoptions',
+                 # multiprocessing.process._cleanup() may release ref
+                 # to a thread, so check processes first.
+                 'multiprocessing.process._dangling', 'threading._dangling',
+                 'sysconfig._CONFIG_VARS', 'sysconfig._INSTALL_SCHEMES',
+                 'files', 'locale', 'warnings.showwarning',
+                 'shutil_archive_formats', 'shutil_unpack_formats',
+                )
+
+    def get_sys_argv(self):
+        return id(sys.argv), sys.argv, sys.argv[:]
+    def restore_sys_argv(self, saved_argv):
+        sys.argv = saved_argv[1]
+        sys.argv[:] = saved_argv[2]
+
+    def get_cwd(self):
+        return os.getcwd()
+    def restore_cwd(self, saved_cwd):
+        os.chdir(saved_cwd)
+
+    def get_sys_stdout(self):
+        return sys.stdout
+    def restore_sys_stdout(self, saved_stdout):
+        sys.stdout = saved_stdout
+
+    def get_sys_stderr(self):
+        return sys.stderr
+    def restore_sys_stderr(self, saved_stderr):
+        sys.stderr = saved_stderr
+
+    def get_sys_stdin(self):
+        return sys.stdin
+    def restore_sys_stdin(self, saved_stdin):
+        sys.stdin = saved_stdin
+
+    def get_os_environ(self):
+        return id(os.environ), os.environ, dict(os.environ)
+    def restore_os_environ(self, saved_environ):
+        os.environ = saved_environ[1]
+        os.environ.clear()
+        os.environ.update(saved_environ[2])
+
+    def get_sys_path(self):
+        return id(sys.path), sys.path, sys.path[:]
+    def restore_sys_path(self, saved_path):
+        sys.path = saved_path[1]
+        sys.path[:] = saved_path[2]
+
+    def get_sys_path_hooks(self):
+        return id(sys.path_hooks), sys.path_hooks, sys.path_hooks[:]
+    def restore_sys_path_hooks(self, saved_hooks):
+        sys.path_hooks = saved_hooks[1]
+        sys.path_hooks[:] = saved_hooks[2]
+
+    def get_sys_gettrace(self):
+        return sys.gettrace()
+    def restore_sys_gettrace(self, trace_fxn):
+        sys.settrace(trace_fxn)
+
+    def get___import__(self):
+        return builtins.__import__
+    def restore___import__(self, import_):
+        builtins.__import__ = import_
+
+    def get_warnings_filters(self):
+        return id(warnings.filters), warnings.filters, warnings.filters[:]
+    def restore_warnings_filters(self, saved_filters):
+        warnings.filters = saved_filters[1]
+        warnings.filters[:] = saved_filters[2]
+
+    def get_asyncore_socket_map(self):
+        asyncore = sys.modules.get('asyncore')
+        # XXX Making a copy keeps objects alive until __exit__ gets called.
+        return asyncore and asyncore.socket_map.copy() or {}
+    def restore_asyncore_socket_map(self, saved_map):
+        asyncore = sys.modules.get('asyncore')
+        if asyncore is not None:
+            asyncore.close_all(ignore_all=True)
+            asyncore.socket_map.update(saved_map)
+
+    def get_shutil_archive_formats(self):
+        # we could call get_archives_formats() but that only returns the
+        # registry keys; we want to check the values too (the functions that
+        # are registered)
+        return shutil._ARCHIVE_FORMATS, shutil._ARCHIVE_FORMATS.copy()
+    def restore_shutil_archive_formats(self, saved):
+        shutil._ARCHIVE_FORMATS = saved[0]
+        shutil._ARCHIVE_FORMATS.clear()
+        shutil._ARCHIVE_FORMATS.update(saved[1])
+
+    def get_shutil_unpack_formats(self):
+        return shutil._UNPACK_FORMATS, shutil._UNPACK_FORMATS.copy()
+    def restore_shutil_unpack_formats(self, saved):
+        shutil._UNPACK_FORMATS = saved[0]
+        shutil._UNPACK_FORMATS.clear()
+        shutil._UNPACK_FORMATS.update(saved[1])
+
+    def get_logging__handlers(self):
+        # _handlers is a WeakValueDictionary
+        return id(logging._handlers), logging._handlers, logging._handlers.copy()
+    def restore_logging__handlers(self, saved_handlers):
+        # Can't easily revert the logging state
+        pass
+
+    def get_logging__handlerList(self):
+        # _handlerList is a list of weakrefs to handlers
+        return id(logging._handlerList), logging._handlerList, logging._handlerList[:]
+    def restore_logging__handlerList(self, saved_handlerList):
+        # Can't easily revert the logging state
+        pass
+
+    def get_sys_warnoptions(self):
+        return id(sys.warnoptions), sys.warnoptions, sys.warnoptions[:]
+    def restore_sys_warnoptions(self, saved_options):
+        sys.warnoptions = saved_options[1]
+        sys.warnoptions[:] = saved_options[2]
+
+    # Controlling dangling references to Thread objects can make it easier
+    # to track reference leaks.
+    def get_threading__dangling(self):
+        if not threading:
+            return None
+        # This copies the weakrefs without making any strong reference
+        return threading._dangling.copy()
+    def restore_threading__dangling(self, saved):
+        if not threading:
+            return
+        threading._dangling.clear()
+        threading._dangling.update(saved)
+
+    # Same for Process objects
+    def get_multiprocessing_process__dangling(self):
+        if not multiprocessing:
+            return None
+        # Unjoined process objects can survive after process exits
+        multiprocessing.process._cleanup()
+        # This copies the weakrefs without making any strong reference
+        return multiprocessing.process._dangling.copy()
+    def restore_multiprocessing_process__dangling(self, saved):
+        if not multiprocessing:
+            return
+        multiprocessing.process._dangling.clear()
+        multiprocessing.process._dangling.update(saved)
+
+    def get_sysconfig__CONFIG_VARS(self):
+        # make sure the dict is initialized
+        sysconfig.get_config_var('prefix')
+        return (id(sysconfig._CONFIG_VARS), sysconfig._CONFIG_VARS,
+                dict(sysconfig._CONFIG_VARS))
+    def restore_sysconfig__CONFIG_VARS(self, saved):
+        sysconfig._CONFIG_VARS = saved[1]
+        sysconfig._CONFIG_VARS.clear()
+        sysconfig._CONFIG_VARS.update(saved[2])
+
+    def get_sysconfig__INSTALL_SCHEMES(self):
+        return (id(sysconfig._INSTALL_SCHEMES), sysconfig._INSTALL_SCHEMES,
+                sysconfig._INSTALL_SCHEMES.copy())
+    def restore_sysconfig__INSTALL_SCHEMES(self, saved):
+        sysconfig._INSTALL_SCHEMES = saved[1]
+        sysconfig._INSTALL_SCHEMES.clear()
+        sysconfig._INSTALL_SCHEMES.update(saved[2])
+
+    def get_files(self):
+        return sorted(fn + ('/' if os.path.isdir(fn) else '')
+                      for fn in os.listdir())
+    def restore_files(self, saved_value):
+        fn = support.TESTFN
+        if fn not in saved_value and (fn + '/') not in saved_value:
+            if os.path.isfile(fn):
+                support.unlink(fn)
+            elif os.path.isdir(fn):
+                support.rmtree(fn)
+
+    _lc = [getattr(locale, lc) for lc in dir(locale)
+           if lc.startswith('LC_')]
+    def get_locale(self):
+        pairings = []
+        for lc in self._lc:
+            try:
+                pairings.append((lc, locale.setlocale(lc, None)))
+            except (TypeError, ValueError):
+                continue
+        return pairings
+    def restore_locale(self, saved):
+        for lc, setting in saved:
+            locale.setlocale(lc, setting)
+
+    def get_warnings_showwarning(self):
+        return warnings.showwarning
+    def restore_warnings_showwarning(self, fxn):
+        warnings.showwarning = fxn
+
+    def resource_info(self):
+        for name in self.resources:
+            method_suffix = name.replace('.', '_')
+            get_name = 'get_' + method_suffix
+            restore_name = 'restore_' + method_suffix
+            yield name, getattr(self, get_name), getattr(self, restore_name)
+
+    def __enter__(self):
+        self.saved_values = dict((name, get()) for name, get, restore
+                                                   in self.resource_info())
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        saved_values = self.saved_values
+        del self.saved_values
+        for name, get, restore in self.resource_info():
+            current = get()
+            original = saved_values.pop(name)
+            # Check for changes to the resource's value
+            if current != original:
+                self.changed = True
+                restore(original)
+                if not self.quiet and not self.pgo:
+                    print("Warning -- {} was modified by {}".format(
+                                                 name, self.testname),
+                                                 file=sys.stderr)
+                    if self.verbose > 1:
+                        print("  Before: {}\n  After:  {} ".format(
+                                                  original, current),
+                                                  file=sys.stderr)
+        return False
diff --git a/Lib/test/libregrtest/setup.py b/Lib/test/libregrtest/setup.py
new file mode 100644
index 0000000000..1d24531fc2
--- /dev/null
+++ b/Lib/test/libregrtest/setup.py
@@ -0,0 +1,121 @@
+import atexit
+import faulthandler
+import os
+import signal
+import sys
+import unittest
+from test import support
+try:
+    import gc
+except ImportError:
+    gc = None
+
+from test.libregrtest.refleak import warm_caches
+
+
+def setup_tests(ns):
+    # Display the Python traceback on fatal errors (e.g. segfault)
+    faulthandler.enable(all_threads=True)
+
+    # Display the Python traceback on SIGALRM or SIGUSR1 signal
+    signals = []
+    if hasattr(signal, 'SIGALRM'):
+        signals.append(signal.SIGALRM)
+    if hasattr(signal, 'SIGUSR1'):
+        signals.append(signal.SIGUSR1)
+    for signum in signals:
+        faulthandler.register(signum, chain=True)
+
+    replace_stdout()
+    support.record_original_stdout(sys.stdout)
+
+    if ns.testdir:
+        # Prepend test directory to sys.path, so runtest() will be able
+        # to locate tests
+        sys.path.insert(0, os.path.abspath(ns.testdir))
+
+    # Some times __path__ and __file__ are not absolute (e.g. while running from
+    # Lib/) and, if we change the CWD to run the tests in a temporary dir, some
+    # imports might fail.  This affects only the modules imported before os.chdir().
+    # These modules are searched first in sys.path[0] (so '' -- the CWD) and if
+    # they are found in the CWD their __file__ and __path__ will be relative (this
+    # happens before the chdir).  All the modules imported after the chdir, are
+    # not found in the CWD, and since the other paths in sys.path[1:] are absolute
+    # (site.py absolutize them), the __file__ and __path__ will be absolute too.
+    # Therefore it is necessary to absolutize manually the __file__ and __path__ of
+    # the packages to prevent later imports to fail when the CWD is different.
+    for module in sys.modules.values():
+        if hasattr(module, '__path__'):
+            for index, path in enumerate(module.__path__):
+                module.__path__[index] = os.path.abspath(path)
+        if hasattr(module, '__file__'):
+            module.__file__ = os.path.abspath(module.__file__)
+
+    # MacOSX (a.k.a. Darwin) has a default stack size that is too small
+    # for deeply recursive regular expressions.  We see this as crashes in
+    # the Python test suite when running test_re.py and test_sre.py.  The
+    # fix is to set the stack limit to 2048.
+    # This approach may also be useful for other Unixy platforms that
+    # suffer from small default stack limits.
+    if sys.platform == 'darwin':
+        try:
+            import resource
+        except ImportError:
+            pass
+        else:
+            soft, hard = resource.getrlimit(resource.RLIMIT_STACK)
+            newsoft = min(hard, max(soft, 1024*2048))
+            resource.setrlimit(resource.RLIMIT_STACK, (newsoft, hard))
+
+    if ns.huntrleaks:
+        unittest.BaseTestSuite._cleanup = False
+
+        # Avoid false positives due to various caches
+        # filling slowly with random data:
+        warm_caches()
+
+    if ns.memlimit is not None:
+        support.set_memlimit(ns.memlimit)
+
+    if ns.threshold is not None:
+        gc.set_threshold(ns.threshold)
+
+    try:
+        import msvcrt
+    except ImportError:
+        pass
+    else:
+        msvcrt.SetErrorMode(msvcrt.SEM_FAILCRITICALERRORS|
+                            msvcrt.SEM_NOALIGNMENTFAULTEXCEPT|
+                            msvcrt.SEM_NOGPFAULTERRORBOX|
+                            msvcrt.SEM_NOOPENFILEERRORBOX)
+        try:
+            msvcrt.CrtSetReportMode
+        except AttributeError:
+            # release build
+            pass
+        else:
+            for m in [msvcrt.CRT_WARN, msvcrt.CRT_ERROR, msvcrt.CRT_ASSERT]:
+                if ns.verbose and ns.verbose >= 2:
+                    msvcrt.CrtSetReportMode(m, msvcrt.CRTDBG_MODE_FILE)
+                    msvcrt.CrtSetReportFile(m, msvcrt.CRTDBG_FILE_STDERR)
+                else:
+                    msvcrt.CrtSetReportMode(m, 0)
+
+    support.use_resources = ns.use_resources
+
+
+def replace_stdout():
+    """Set stdout encoder error handler to backslashreplace (as stderr error
+    handler) to avoid UnicodeEncodeError when printing a traceback"""
+    stdout = sys.stdout
+    sys.stdout = open(stdout.fileno(), 'w',
+        encoding=stdout.encoding,
+        errors="backslashreplace",
+        closefd=False,
+        newline='\n')
+
+    def restore_stdout():
+        sys.stdout.close()
+        sys.stdout = stdout
+    atexit.register(restore_stdout)
diff --git a/Lib/test/lock_tests.py b/Lib/test/lock_tests.py
index a64aa18cd3..a6cb3b169b 100644
--- a/Lib/test/lock_tests.py
+++ b/Lib/test/lock_tests.py
@@ -7,6 +7,7 @@ import time
 from _thread import start_new_thread, TIMEOUT_MAX
 import threading
 import unittest
+import weakref
 
 from test import support
 
@@ -198,6 +199,17 @@ class BaseLockTests(BaseTestCase):
         self.assertFalse(results[0])
         self.assertTimeout(results[1], 0.5)
 
+    def test_weakref_exists(self):
+        lock = self.locktype()
+        ref = weakref.ref(lock)
+        self.assertIsNotNone(ref())
+
+    def test_weakref_deleted(self):
+        lock = self.locktype()
+        ref = weakref.ref(lock)
+        del lock
+        self.assertIsNone(ref())
+
 
 class LockTests(BaseLockTests):
     """
diff --git a/Lib/test/make_ssl_certs.py b/Lib/test/make_ssl_certs.py
index 81d04f82dc..e4326d7b33 100644
--- a/Lib/test/make_ssl_certs.py
+++ b/Lib/test/make_ssl_certs.py
@@ -3,7 +3,6 @@ and friends."""
 
 import os
 import shutil
-import sys
 import tempfile
 from subprocess import *
 
diff --git a/Lib/test/pickletester.py b/Lib/test/pickletester.py
index f252a0a10f..8deb56fa0f 100644
--- a/Lib/test/pickletester.py
+++ b/Lib/test/pickletester.py
@@ -1000,7 +1000,7 @@ class AbstractUnpickleTests(unittest.TestCase):
             b'0',                       # POP
             b'1',                       # POP_MARK
             b'2',                       # DUP
-            # b'(2',                    # PyUnpickler doesn't raise
+            b'(2',
             b'R',                       # REDUCE
             b')R',
             b'a',                       # APPEND
@@ -1009,7 +1009,7 @@ class AbstractUnpickleTests(unittest.TestCase):
             b'Nb',
             b'd',                       # DICT
             b'e',                       # APPENDS
-            # b'(e',                    # PyUnpickler raises AttributeError
+            b'(e',
             b'ibuiltins\nlist\n',       # INST
             b'l',                       # LIST
             b'o',                       # OBJ
@@ -1022,7 +1022,7 @@ class AbstractUnpickleTests(unittest.TestCase):
             b'NNs',
             b't',                       # TUPLE
             b'u',                       # SETITEMS
-            # b'(u',                    # PyUnpickler doesn't raise
+            b'(u',
             b'}(Nu',
             b'\x81',                    # NEWOBJ
             b')\x81',
@@ -1033,7 +1033,7 @@ class AbstractUnpickleTests(unittest.TestCase):
             b'N\x87',
             b'NN\x87',
             b'\x90',                    # ADDITEMS
-            # b'(\x90',                 # PyUnpickler raises AttributeError
+            b'(\x90',
             b'\x91',                    # FROZENSET
             b'\x92',                    # NEWOBJ_EX
             b')}\x92',
@@ -1046,7 +1046,7 @@ class AbstractUnpickleTests(unittest.TestCase):
 
     def test_bad_mark(self):
         badpickles = [
-            # b'N(.',                     # STOP
+            b'N(.',                     # STOP
             b'N(2',                     # DUP
             b'cbuiltins\nlist\n)(R',    # REDUCE
             b'cbuiltins\nlist\n()R',
@@ -1081,7 +1081,7 @@ class AbstractUnpickleTests(unittest.TestCase):
             b'N(\x94',                  # MEMOIZE
         ]
         for p in badpickles:
-            self.check_unpickling_error(self.bad_mark_errors, p)
+            self.check_unpickling_error(self.bad_stack_errors, p)
 
     def test_truncated_data(self):
         self.check_unpickling_error(EOFError, b'')
@@ -1855,16 +1855,14 @@ class AbstractPickleTests(unittest.TestCase):
         x.abc = 666
         for proto in protocols:
             with self.subTest(proto=proto):
-                if 2 <= proto < 4:
-                    self.assertRaises(ValueError, self.dumps, x, proto)
-                    continue
                 s = self.dumps(x, proto)
                 if proto < 1:
                     self.assertIn(b'\nL64206', s)  # LONG
                 elif proto < 2:
                     self.assertIn(b'M\xce\xfa', s)  # BININT2
+                elif proto < 4:
+                    self.assertIn(b'X\x04\x00\x00\x00FACE', s)  # BINUNICODE
                 else:
-                    assert proto >= 4
                     self.assertIn(b'\x8c\x04FACE', s)  # SHORT_BINUNICODE
                 self.assertFalse(opcode_in_pickle(pickle.NEWOBJ, s))
                 self.assertEqual(opcode_in_pickle(pickle.NEWOBJ_EX, s),
@@ -2583,11 +2581,6 @@ class AbstractPickleModuleTests(unittest.TestCase):
         self.assertRaises(pickle.PicklingError, BadPickler().dump, 0)
         self.assertRaises(pickle.UnpicklingError, BadUnpickler().load)
 
-    def test_bad_input(self):
-        # Test issue4298
-        s = bytes([0x58, 0, 0, 0, 0x54])
-        self.assertRaises(EOFError, pickle.loads, s)
-
 
 class AbstractPersistentPicklerTests(unittest.TestCase):
 
diff --git a/Lib/test/regrtest.py b/Lib/test/regrtest.py
index fecfd0967a..21b0edfd07 100755..100644
--- a/Lib/test/regrtest.py
+++ b/Lib/test/regrtest.py
@@ -6,1604 +6,33 @@ Script to run Python regression tests.
 Run this script with -h or --help for documentation.
 """
 
-USAGE = """\
-python -m test [options] [test_name1 [test_name2 ...]]
-python path/to/Lib/test/regrtest.py [options] [test_name1 [test_name2 ...]]
-"""
-
-DESCRIPTION = """\
-Run Python regression tests.
-
-If no arguments or options are provided, finds all files matching
-the pattern "test_*" in the Lib/test subdirectory and runs
-them in alphabetical order (but see -M and -u, below, for exceptions).
-
-For more rigorous testing, it is useful to use the following
-command line:
-
-python -E -Wd -m test [options] [test_name1 ...]
-"""
-
-EPILOG = """\
-Additional option details:
-
--r randomizes test execution order. You can use --randseed=int to provide an
-int seed value for the randomizer; this is useful for reproducing troublesome
-test orders.
-
--s On the first invocation of regrtest using -s, the first test file found
-or the first test file given on the command line is run, and the name of
-the next test is recorded in a file named pynexttest.  If run from the
-Python build directory, pynexttest is located in the 'build' subdirectory,
-otherwise it is located in tempfile.gettempdir().  On subsequent runs,
-the test in pynexttest is run, and the next test is written to pynexttest.
-When the last test has been run, pynexttest is deleted.  In this way it
-is possible to single step through the test files.  This is useful when
-doing memory analysis on the Python interpreter, which process tends to
-consume too many resources to run the full regression test non-stop.
-
--S is used to continue running tests after an aborted run.  It will
-maintain the order a standard run (ie, this assumes -r is not used).
-This is useful after the tests have prematurely stopped for some external
-reason and you want to start running from where you left off rather
-than starting from the beginning.
-
--f reads the names of tests from the file given as f's argument, one
-or more test names per line.  Whitespace is ignored.  Blank lines and
-lines beginning with '#' are ignored.  This is especially useful for
-whittling down failures involving interactions among tests.
-
--L causes the leaks(1) command to be run just before exit if it exists.
-leaks(1) is available on Mac OS X and presumably on some other
-FreeBSD-derived systems.
-
--R runs each test several times and examines sys.gettotalrefcount() to
-see if the test appears to be leaking references.  The argument should
-be of the form stab:run:fname where 'stab' is the number of times the
-test is run to let gettotalrefcount settle down, 'run' is the number
-of times further it is run and 'fname' is the name of the file the
-reports are written to.  These parameters all have defaults (5, 4 and
-"reflog.txt" respectively), and the minimal invocation is '-R :'.
-
--M runs tests that require an exorbitant amount of memory. These tests
-typically try to ascertain containers keep working when containing more than
-2 billion objects, which only works on 64-bit systems. There are also some
-tests that try to exhaust the address space of the process, which only makes
-sense on 32-bit systems with at least 2Gb of memory. The passed-in memlimit,
-which is a string in the form of '2.5Gb', determines howmuch memory the
-tests will limit themselves to (but they may go slightly over.) The number
-shouldn't be more memory than the machine has (including swap memory). You
-should also keep in mind that swap memory is generally much, much slower
-than RAM, and setting memlimit to all available RAM or higher will heavily
-tax the machine. On the other hand, it is no use running these tests with a
-limit of less than 2.5Gb, and many require more than 20Gb. Tests that expect
-to use more than memlimit memory will be skipped. The big-memory tests
-generally run very, very long.
-
--u is used to specify which special resource intensive tests to run,
-such as those requiring large file support or network connectivity.
-The argument is a comma-separated list of words indicating the
-resources to test.  Currently only the following are defined:
-
-    all -       Enable all special resources.
-
-    none -      Disable all special resources (this is the default).
-
-    audio -     Tests that use the audio device.  (There are known
-                cases of broken audio drivers that can crash Python or
-                even the Linux kernel.)
-
-    curses -    Tests that use curses and will modify the terminal's
-                state and output modes.
-
-    largefile - It is okay to run some test that may create huge
-                files.  These tests can take a long time and may
-                consume >2GB of disk space temporarily.
-
-    network -   It is okay to run tests that use external network
-                resource, e.g. testing SSL support for sockets.
-
-    decimal -   Test the decimal module against a large suite that
-                verifies compliance with standards.
-
-    cpu -       Used for certain CPU-heavy tests.
-
-    subprocess  Run all tests for the subprocess module.
-
-    urlfetch -  It is okay to download files required on testing.
-
-    gui -       Run tests that require a running GUI.
-
-To enable all resources except one, use '-uall,-<resource>'.  For
-example, to run all the tests except for the gui tests, give the
-option '-uall,-gui'.
-"""
-
 # We import importlib *ASAP* in order to test #15386
 import importlib
 
-import argparse
-import builtins
-import faulthandler
-import io
-import json
-import locale
-import logging
 import os
-import platform
-import random
-import re
-import shutil
-import signal
 import sys
-import sysconfig
-import tempfile
-import time
-import traceback
-import unittest
-import warnings
-from inspect import isabstract
-
-try:
-    import threading
-except ImportError:
-    threading = None
-try:
-    import _multiprocessing, multiprocessing.process
-except ImportError:
-    multiprocessing = None
-
-
-# Some times __path__ and __file__ are not absolute (e.g. while running from
-# Lib/) and, if we change the CWD to run the tests in a temporary dir, some
-# imports might fail.  This affects only the modules imported before os.chdir().
-# These modules are searched first in sys.path[0] (so '' -- the CWD) and if
-# they are found in the CWD their __file__ and __path__ will be relative (this
-# happens before the chdir).  All the modules imported after the chdir, are
-# not found in the CWD, and since the other paths in sys.path[1:] are absolute
-# (site.py absolutize them), the __file__ and __path__ will be absolute too.
-# Therefore it is necessary to absolutize manually the __file__ and __path__ of
-# the packages to prevent later imports to fail when the CWD is different.
-for module in sys.modules.values():
-    if hasattr(module, '__path__'):
-        module.__path__ = [os.path.abspath(path) for path in module.__path__]
-    if hasattr(module, '__file__'):
-        module.__file__ = os.path.abspath(module.__file__)
-
-
-# MacOSX (a.k.a. Darwin) has a default stack size that is too small
-# for deeply recursive regular expressions.  We see this as crashes in
-# the Python test suite when running test_re.py and test_sre.py.  The
-# fix is to set the stack limit to 2048.
-# This approach may also be useful for other Unixy platforms that
-# suffer from small default stack limits.
-if sys.platform == 'darwin':
-    try:
-        import resource
-    except ImportError:
-        pass
-    else:
-        soft, hard = resource.getrlimit(resource.RLIMIT_STACK)
-        newsoft = min(hard, max(soft, 1024*2048))
-        resource.setrlimit(resource.RLIMIT_STACK, (newsoft, hard))
-
-# Test result constants.
-PASSED = 1
-FAILED = 0
-ENV_CHANGED = -1
-SKIPPED = -2
-RESOURCE_DENIED = -3
-INTERRUPTED = -4
-CHILD_ERROR = -5   # error in a child process
-
-from test import support
-
-RESOURCE_NAMES = ('audio', 'curses', 'largefile', 'network',
-                  'decimal', 'cpu', 'subprocess', 'urlfetch', 'gui')
-
-# When tests are run from the Python build directory, it is best practice
-# to keep the test files in a subfolder.  This eases the cleanup of leftover
-# files using the "make distclean" command.
-if sysconfig.is_python_build():
-    TEMPDIR = os.path.join(sysconfig.get_config_var('srcdir'), 'build')
-else:
-    TEMPDIR = tempfile.gettempdir()
-TEMPDIR = os.path.abspath(TEMPDIR)
-
-class _ArgParser(argparse.ArgumentParser):
-
-    def error(self, message):
-        super().error(message + "\nPass -h or --help for complete help.")
-
-def _create_parser():
-    # Set prog to prevent the uninformative "__main__.py" from displaying in
-    # error messages when using "python -m test ...".
-    parser = _ArgParser(prog='regrtest.py',
-                        usage=USAGE,
-                        description=DESCRIPTION,
-                        epilog=EPILOG,
-                        add_help=False,
-                        formatter_class=argparse.RawDescriptionHelpFormatter)
-
-    # Arguments with this clause added to its help are described further in
-    # the epilog's "Additional option details" section.
-    more_details = '  See the section at bottom for more details.'
-
-    group = parser.add_argument_group('General options')
-    # We add help explicitly to control what argument group it renders under.
-    group.add_argument('-h', '--help', action='help',
-                       help='show this help message and exit')
-    group.add_argument('--timeout', metavar='TIMEOUT', type=float,
-                        help='dump the traceback and exit if a test takes '
-                             'more than TIMEOUT seconds; disabled if TIMEOUT '
-                             'is negative or equals to zero')
-    group.add_argument('--wait', action='store_true',
-                       help='wait for user input, e.g., allow a debugger '
-                            'to be attached')
-    group.add_argument('--slaveargs', metavar='ARGS')
-    group.add_argument('-S', '--start', metavar='START',
-                       help='the name of the test at which to start.' +
-                            more_details)
-
-    group = parser.add_argument_group('Verbosity')
-    group.add_argument('-v', '--verbose', action='count',
-                       help='run tests in verbose mode with output to stdout')
-    group.add_argument('-w', '--verbose2', action='store_true',
-                       help='re-run failed tests in verbose mode')
-    group.add_argument('-W', '--verbose3', action='store_true',
-                       help='display test output on failure')
-    group.add_argument('-q', '--quiet', action='store_true',
-                       help='no output unless one or more tests fail')
-    group.add_argument('-o', '--slow', action='store_true', dest='print_slow',
-                       help='print the slowest 10 tests')
-    group.add_argument('--header', action='store_true',
-                       help='print header with interpreter info')
-
-    group = parser.add_argument_group('Selecting tests')
-    group.add_argument('-r', '--randomize', action='store_true',
-                       help='randomize test execution order.' + more_details)
-    group.add_argument('--randseed', metavar='SEED',
-                       dest='random_seed', type=int,
-                       help='pass a random seed to reproduce a previous '
-                            'random run')
-    group.add_argument('-f', '--fromfile', metavar='FILE',
-                       help='read names of tests to run from a file.' +
-                            more_details)
-    group.add_argument('-x', '--exclude', action='store_true',
-                       help='arguments are tests to *exclude*')
-    group.add_argument('-s', '--single', action='store_true',
-                       help='single step through a set of tests.' +
-                            more_details)
-    group.add_argument('-m', '--match', metavar='PAT',
-                       dest='match_tests',
-                       help='match test cases and methods with glob pattern PAT')
-    group.add_argument('-G', '--failfast', action='store_true',
-                       help='fail as soon as a test fails (only with -v or -W)')
-    group.add_argument('-u', '--use', metavar='RES1,RES2,...',
-                       action='append', type=resources_list,
-                       help='specify which special resource intensive tests '
-                            'to run.' + more_details)
-    group.add_argument('-M', '--memlimit', metavar='LIMIT',
-                       help='run very large memory-consuming tests.' +
-                            more_details)
-    group.add_argument('--testdir', metavar='DIR',
-                       type=relative_filename,
-                       help='execute test files in the specified directory '
-                            '(instead of the Python stdlib test suite)')
-
-    group = parser.add_argument_group('Special runs')
-    group.add_argument('-l', '--findleaks', action='store_true',
-                       help='if GC is available detect tests that leak memory')
-    group.add_argument('-L', '--runleaks', action='store_true',
-                       help='run the leaks(1) command just before exit.' +
-                            more_details)
-    group.add_argument('-R', '--huntrleaks', metavar='RUNCOUNTS',
-                       type=huntrleaks,
-                       help='search for reference leaks (needs debug build, '
-                            'very slow).' + more_details)
-    group.add_argument('-j', '--multiprocess', metavar='PROCESSES',
-                       dest='use_mp', type=int,
-                       help='run PROCESSES processes at once')
-    group.add_argument('-T', '--coverage', action='store_true',
-                       dest='trace',
-                       help='turn on code coverage tracing using the trace '
-                            'module')
-    group.add_argument('-D', '--coverdir', metavar='DIR',
-                       type=relative_filename,
-                       help='directory where coverage files are put')
-    group.add_argument('-N', '--nocoverdir',
-                       action='store_const', const=None, dest='coverdir',
-                       help='put coverage files alongside modules')
-    group.add_argument('-t', '--threshold', metavar='THRESHOLD',
-                       type=int,
-                       help='call gc.set_threshold(THRESHOLD)')
-    group.add_argument('-n', '--nowindows', action='store_true',
-                       help='suppress error message boxes on Windows')
-    group.add_argument('-F', '--forever', action='store_true',
-                       help='run the specified tests in a loop, until an '
-                            'error happens')
-    group.add_argument('-P', '--pgo', dest='pgo', action='store_true',
-                       help='enable Profile Guided Optimization training')
-
-    parser.add_argument('args', nargs=argparse.REMAINDER,
-                        help=argparse.SUPPRESS)
-
-    return parser
-
-def relative_filename(string):
-    # CWD is replaced with a temporary dir before calling main(), so we
-    # join it with the saved CWD so it ends up where the user expects.
-    return os.path.join(support.SAVEDCWD, string)
-
-def huntrleaks(string):
-    args = string.split(':')
-    if len(args) not in (2, 3):
-        raise argparse.ArgumentTypeError(
-            'needs 2 or 3 colon-separated arguments')
-    nwarmup = int(args[0]) if args[0] else 5
-    ntracked = int(args[1]) if args[1] else 4
-    fname = args[2] if len(args) > 2 and args[2] else 'reflog.txt'
-    return nwarmup, ntracked, fname
-
-def resources_list(string):
-    u = [x.lower() for x in string.split(',')]
-    for r in u:
-        if r == 'all' or r == 'none':
-            continue
-        if r[0] == '-':
-            r = r[1:]
-        if r not in RESOURCE_NAMES:
-            raise argparse.ArgumentTypeError('invalid resource: ' + r)
-    return u
-
-def _parse_args(args, **kwargs):
-    # Defaults
-    ns = argparse.Namespace(testdir=None, verbose=0, quiet=False,
-         exclude=False, single=False, randomize=False, fromfile=None,
-         findleaks=False, use_resources=None, trace=False, coverdir='coverage',
-         runleaks=False, huntrleaks=False, verbose2=False, print_slow=False,
-         random_seed=None, use_mp=None, verbose3=False, forever=False,
-         header=False, failfast=False, match_tests=None, pgo=False)
-    for k, v in kwargs.items():
-        if not hasattr(ns, k):
-            raise TypeError('%r is an invalid keyword argument '
-                            'for this function' % k)
-        setattr(ns, k, v)
-    if ns.use_resources is None:
-        ns.use_resources = []
-
-    parser = _create_parser()
-    parser.parse_args(args=args, namespace=ns)
-
-    if ns.single and ns.fromfile:
-        parser.error("-s and -f don't go together!")
-    if ns.use_mp and ns.trace:
-        parser.error("-T and -j don't go together!")
-    if ns.use_mp and ns.findleaks:
-        parser.error("-l and -j don't go together!")
-    if ns.use_mp and ns.memlimit:
-        parser.error("-M and -j don't go together!")
-    if ns.failfast and not (ns.verbose or ns.verbose3):
-        parser.error("-G/--failfast needs either -v or -W")
-
-    if ns.quiet:
-        ns.verbose = 0
-    if ns.timeout is not None:
-        if hasattr(faulthandler, 'dump_traceback_later'):
-            if ns.timeout <= 0:
-                ns.timeout = None
-        else:
-            print("Warning: The timeout option requires "
-                  "faulthandler.dump_traceback_later")
-            ns.timeout = None
-    if ns.use_mp is not None:
-        if ns.use_mp <= 0:
-            # Use all cores + extras for tests that like to sleep
-            ns.use_mp = 2 + (os.cpu_count() or 1)
-        if ns.use_mp == 1:
-            ns.use_mp = None
-    if ns.use:
-        for a in ns.use:
-            for r in a:
-                if r == 'all':
-                    ns.use_resources[:] = RESOURCE_NAMES
-                    continue
-                if r == 'none':
-                    del ns.use_resources[:]
-                    continue
-                remove = False
-                if r[0] == '-':
-                    remove = True
-                    r = r[1:]
-                if remove:
-                    if r in ns.use_resources:
-                        ns.use_resources.remove(r)
-                elif r not in ns.use_resources:
-                    ns.use_resources.append(r)
-    if ns.random_seed is not None:
-        ns.randomize = True
-
-    return ns
-
-
-def run_test_in_subprocess(testname, ns):
-    """Run the given test in a subprocess with --slaveargs.
-
-    ns is the option Namespace parsed from command-line arguments. regrtest
-    is invoked in a subprocess with the --slaveargs argument; when the
-    subprocess exits, its return code, stdout and stderr are returned as a
-    3-tuple.
-    """
-    from subprocess import Popen, PIPE
-    base_cmd = ([sys.executable] + support.args_from_interpreter_flags() +
-                ['-X', 'faulthandler', '-m', 'test.regrtest'])
-    # required to spawn a new process with PGO flag on/off
-    if ns.pgo:
-        base_cmd = base_cmd + ['--pgo']
-    slaveargs = (
-            (testname, ns.verbose, ns.quiet),
-            dict(huntrleaks=ns.huntrleaks,
-                 use_resources=ns.use_resources,
-                 output_on_failure=ns.verbose3,
-                 timeout=ns.timeout, failfast=ns.failfast,
-                 match_tests=ns.match_tests, pgo=ns.pgo))
-    # Running the child from the same working directory as regrtest's original
-    # invocation ensures that TEMPDIR for the child is the same when
-    # sysconfig.is_python_build() is true. See issue 15300.
-    popen = Popen(base_cmd + ['--slaveargs', json.dumps(slaveargs)],
-                  stdout=PIPE, stderr=PIPE,
-                  universal_newlines=True,
-                  close_fds=(os.name != 'nt'),
-                  cwd=support.SAVEDCWD)
-    stdout, stderr = popen.communicate()
-    retcode = popen.wait()
-    return retcode, stdout, stderr
-
-
-def main(tests=None, **kwargs):
-    """Execute a test suite.
-
-    This also parses command-line options and modifies its behavior
-    accordingly.
-
-    tests -- a list of strings containing test names (optional)
-    testdir -- the directory in which to look for tests (optional)
-
-    Users other than the Python test suite will certainly want to
-    specify testdir; if it's omitted, the directory containing the
-    Python test suite is searched for.
-
-    If the tests argument is omitted, the tests listed on the
-    command-line will be used.  If that's empty, too, then all *.py
-    files beginning with test_ will be used.
-
-    The other default arguments (verbose, quiet, exclude,
-    single, randomize, findleaks, use_resources, trace, coverdir,
-    print_slow, and random_seed) allow programmers calling main()
-    directly to set the values that would normally be set by flags
-    on the command line.
-    """
-    # Display the Python traceback on fatal errors (e.g. segfault)
-    faulthandler.enable(all_threads=True)
-
-    # Display the Python traceback on SIGALRM or SIGUSR1 signal
-    signals = []
-    if hasattr(signal, 'SIGALRM'):
-        signals.append(signal.SIGALRM)
-    if hasattr(signal, 'SIGUSR1'):
-        signals.append(signal.SIGUSR1)
-    for signum in signals:
-        faulthandler.register(signum, chain=True)
-
-    replace_stdout()
-
-    support.record_original_stdout(sys.stdout)
-
-    ns = _parse_args(sys.argv[1:], **kwargs)
-
-    if ns.huntrleaks:
-        # Avoid false positives due to various caches
-        # filling slowly with random data:
-        warm_caches()
-    if ns.memlimit is not None:
-        support.set_memlimit(ns.memlimit)
-    if ns.threshold is not None:
-        import gc
-        gc.set_threshold(ns.threshold)
-    if ns.nowindows:
-        print('The --nowindows (-n) option is deprecated. '
-              'Use -vv to display assertions in stderr.')
-    try:
-        import msvcrt
-    except ImportError:
-        pass
-    else:
-        msvcrt.SetErrorMode(msvcrt.SEM_FAILCRITICALERRORS|
-                            msvcrt.SEM_NOALIGNMENTFAULTEXCEPT|
-                            msvcrt.SEM_NOGPFAULTERRORBOX|
-                            msvcrt.SEM_NOOPENFILEERRORBOX)
-        try:
-            msvcrt.CrtSetReportMode
-        except AttributeError:
-            # release build
-            pass
-        else:
-            for m in [msvcrt.CRT_WARN, msvcrt.CRT_ERROR, msvcrt.CRT_ASSERT]:
-                if ns.verbose and ns.verbose >= 2:
-                    msvcrt.CrtSetReportMode(m, msvcrt.CRTDBG_MODE_FILE)
-                    msvcrt.CrtSetReportFile(m, msvcrt.CRTDBG_FILE_STDERR)
-                else:
-                    msvcrt.CrtSetReportMode(m, 0)
-    if ns.wait:
-        input("Press any key to continue...")
-
-    if ns.slaveargs is not None:
-        args, kwargs = json.loads(ns.slaveargs)
-        if kwargs.get('huntrleaks'):
-            unittest.BaseTestSuite._cleanup = False
-        try:
-            result = runtest(*args, **kwargs)
-        except KeyboardInterrupt:
-            result = INTERRUPTED, ''
-        except BaseException as e:
-            traceback.print_exc()
-            result = CHILD_ERROR, str(e)
-        sys.stdout.flush()
-        print()   # Force a newline (just in case)
-        print(json.dumps(result))
-        sys.exit(0)
-
-    good = []
-    bad = []
-    skipped = []
-    resource_denieds = []
-    environment_changed = []
-    interrupted = False
-
-    if ns.findleaks:
-        try:
-            import gc
-        except ImportError:
-            print('No GC available, disabling findleaks.')
-            ns.findleaks = False
-        else:
-            # Uncomment the line below to report garbage that is not
-            # freeable by reference counting alone.  By default only
-            # garbage that is not collectable by the GC is reported.
-            #gc.set_debug(gc.DEBUG_SAVEALL)
-            found_garbage = []
-
-    if ns.huntrleaks:
-        unittest.BaseTestSuite._cleanup = False
-
-    if ns.single:
-        filename = os.path.join(TEMPDIR, 'pynexttest')
-        try:
-            with open(filename, 'r') as fp:
-                next_test = fp.read().strip()
-                tests = [next_test]
-        except OSError:
-            pass
-
-    if ns.fromfile:
-        tests = []
-        with open(os.path.join(support.SAVEDCWD, ns.fromfile)) as fp:
-            count_pat = re.compile(r'\[\s*\d+/\s*\d+\]')
-            for line in fp:
-                line = count_pat.sub('', line)
-                guts = line.split() # assuming no test has whitespace in its name
-                if guts and not guts[0].startswith('#'):
-                    tests.extend(guts)
-
-    # Strip .py extensions.
-    removepy(ns.args)
-    removepy(tests)
-
-    stdtests = STDTESTS[:]
-    nottests = NOTTESTS.copy()
-    if ns.exclude:
-        for arg in ns.args:
-            if arg in stdtests:
-                stdtests.remove(arg)
-            nottests.add(arg)
-        ns.args = []
-
-    # For a partial run, we do not need to clutter the output.
-    if (ns.verbose or ns.header or
-            not (ns.pgo or ns.quiet or ns.single or tests or ns.args)):
-        # Print basic platform information
-        print("==", platform.python_implementation(), *sys.version.split())
-        print("==  ", platform.platform(aliased=True),
-                        "%s-endian" % sys.byteorder)
-        print("==  ", "hash algorithm:", sys.hash_info.algorithm,
-                "64bit" if sys.maxsize > 2**32 else "32bit")
-        print("==  ", os.getcwd())
-        print("Testing with flags:", sys.flags)
-
-    # if testdir is set, then we are not running the python tests suite, so
-    # don't add default tests to be executed or skipped (pass empty values)
-    if ns.testdir:
-        alltests = findtests(ns.testdir, list(), set())
-    else:
-        alltests = findtests(ns.testdir, stdtests, nottests)
-
-    selected = tests or ns.args or alltests
-    if ns.single:
-        selected = selected[:1]
-        try:
-            next_single_test = alltests[alltests.index(selected[0])+1]
-        except IndexError:
-            next_single_test = None
-    # Remove all the selected tests that precede start if it's set.
-    if ns.start:
-        try:
-            del selected[:selected.index(ns.start)]
-        except ValueError:
-            print("Couldn't find starting test (%s), using all tests" % ns.start)
-    if ns.randomize:
-        if ns.random_seed is None:
-            ns.random_seed = random.randrange(10000000)
-        random.seed(ns.random_seed)
-        print("Using random seed", ns.random_seed)
-        random.shuffle(selected)
-    if ns.trace:
-        import trace, tempfile
-        tracer = trace.Trace(ignoredirs=[sys.base_prefix, sys.base_exec_prefix,
-                                         tempfile.gettempdir()],
-                             trace=False, count=True)
-
-    test_times = []
-    support.verbose = ns.verbose      # Tell tests to be moderately quiet
-    support.use_resources = ns.use_resources
-    save_modules = sys.modules.keys()
-
-    def accumulate_result(test, result):
-        ok, test_time = result
-        if ok not in (CHILD_ERROR, INTERRUPTED):
-            test_times.append((test_time, test))
-        if ok == PASSED:
-            good.append(test)
-        elif ok == FAILED:
-            bad.append(test)
-        elif ok == ENV_CHANGED:
-            environment_changed.append(test)
-        elif ok == SKIPPED:
-            skipped.append(test)
-        elif ok == RESOURCE_DENIED:
-            skipped.append(test)
-            resource_denieds.append(test)
-
-    if ns.forever:
-        def test_forever(tests=list(selected)):
-            while True:
-                for test in tests:
-                    yield test
-                    if bad:
-                        return
-        tests = test_forever()
-        test_count = ''
-        test_count_width = 3
-    else:
-        tests = iter(selected)
-        test_count = '/{}'.format(len(selected))
-        test_count_width = len(test_count) - 1
-
-    if ns.use_mp:
-        try:
-            from threading import Thread
-        except ImportError:
-            print("Multiprocess option requires thread support")
-            sys.exit(2)
-        from queue import Queue
-        debug_output_pat = re.compile(r"\[\d+ refs, \d+ blocks\]$")
-        output = Queue()
-        pending = MultiprocessTests(tests)
-        def work():
-            # A worker thread.
-            try:
-                while True:
-                    try:
-                        test = next(pending)
-                    except StopIteration:
-                        output.put((None, None, None, None))
-                        return
-                    retcode, stdout, stderr = run_test_in_subprocess(test, ns)
-                    # Strip last refcount output line if it exists, since it
-                    # comes from the shutdown of the interpreter in the subcommand.
-                    stderr = debug_output_pat.sub("", stderr)
-                    stdout, _, result = stdout.strip().rpartition("\n")
-                    if retcode != 0:
-                        result = (CHILD_ERROR, "Exit code %s" % retcode)
-                        output.put((test, stdout.rstrip(), stderr.rstrip(), result))
-                        return
-                    if not result:
-                        output.put((None, None, None, None))
-                        return
-                    result = json.loads(result)
-                    output.put((test, stdout.rstrip(), stderr.rstrip(), result))
-            except BaseException:
-                output.put((None, None, None, None))
-                raise
-        workers = [Thread(target=work) for i in range(ns.use_mp)]
-        for worker in workers:
-            worker.start()
-        finished = 0
-        test_index = 1
-        try:
-            while finished < ns.use_mp:
-                test, stdout, stderr, result = output.get()
-                if test is None:
-                    finished += 1
-                    continue
-                accumulate_result(test, result)
-                if not ns.quiet:
-                    if bad and not ns.pgo:
-                        fmt = "[{1:{0}}{2}/{3}] {4}"
-                    else:
-                        fmt = "[{1:{0}}{2}] {4}"
-                    print(fmt.format(
-                        test_count_width, test_index, test_count,
-                        len(bad), test))
-                if stdout:
-                    print(stdout)
-                if stderr and not ns.pgo:
-                    print(stderr, file=sys.stderr)
-                sys.stdout.flush()
-                sys.stderr.flush()
-                if result[0] == INTERRUPTED:
-                    raise KeyboardInterrupt
-                if result[0] == CHILD_ERROR:
-                    raise Exception("Child error on {}: {}".format(test, result[1]))
-                test_index += 1
-        except KeyboardInterrupt:
-            interrupted = True
-            pending.interrupted = True
-        for worker in workers:
-            worker.join()
-    else:
-        for test_index, test in enumerate(tests, 1):
-            if not ns.quiet:
-                if bad and not ns.pgo:
-                    fmt = "[{1:{0}}{2}/{3}] {4}"
-                else:
-                    fmt = "[{1:{0}}{2}] {4}"
-                print(fmt.format(
-                    test_count_width, test_index, test_count, len(bad), test))
-                sys.stdout.flush()
-            if ns.trace:
-                # If we're tracing code coverage, then we don't exit with status
-                # if on a false return value from main.
-                tracer.runctx('runtest(test, ns.verbose, ns.quiet, timeout=ns.timeout)',
-                              globals=globals(), locals=vars())
-            else:
-                try:
-                    result = runtest(test, ns.verbose, ns.quiet,
-                                     ns.huntrleaks,
-                                     output_on_failure=ns.verbose3,
-                                     timeout=ns.timeout, failfast=ns.failfast,
-                                     match_tests=ns.match_tests, pgo=ns.pgo)
-                    accumulate_result(test, result)
-                except KeyboardInterrupt:
-                    interrupted = True
-                    break
-            if ns.findleaks:
-                gc.collect()
-                if gc.garbage:
-                    print("Warning: test created", len(gc.garbage), end=' ')
-                    print("uncollectable object(s).")
-                    # move the uncollectable objects somewhere so we don't see
-                    # them again
-                    found_garbage.extend(gc.garbage)
-                    del gc.garbage[:]
-            # Unload the newly imported modules (best effort finalization)
-            for module in sys.modules.keys():
-                if module not in save_modules and module.startswith("test."):
-                    support.unload(module)
-
-    if interrupted and not ns.pgo:
-        # print a newline after ^C
-        print()
-        print("Test suite interrupted by signal SIGINT.")
-        omitted = set(selected) - set(good) - set(bad) - set(skipped)
-        print(count(len(omitted), "test"), "omitted:")
-        printlist(omitted)
-    if good and not ns.quiet and not ns.pgo:
-        if not bad and not skipped and not interrupted and len(good) > 1:
-            print("All", end=' ')
-        print(count(len(good), "test"), "OK.")
-    if ns.print_slow:
-        test_times.sort(reverse=True)
-        print("10 slowest tests:")
-        for time, test in test_times[:10]:
-            print("%s: %.1fs" % (test, time))
-    if bad and not ns.pgo:
-        print(count(len(bad), "test"), "failed:")
-        printlist(bad)
-    if environment_changed and not ns.pgo:
-        print("{} altered the execution environment:".format(
-                 count(len(environment_changed), "test")))
-        printlist(environment_changed)
-    if skipped and not ns.quiet and not ns.pgo:
-        print(count(len(skipped), "test"), "skipped:")
-        printlist(skipped)
-
-    if ns.verbose2 and bad:
-        print("Re-running failed tests in verbose mode")
-        for test in bad[:]:
-            if not ns.pgo:
-                print("Re-running test %r in verbose mode" % test)
-            sys.stdout.flush()
-            try:
-                ns.verbose = True
-                ok = runtest(test, True, ns.quiet, ns.huntrleaks,
-                             timeout=ns.timeout, pgo=ns.pgo)
-            except KeyboardInterrupt:
-                # print a newline separate from the ^C
-                print()
-                break
-            else:
-                if ok[0] in {PASSED, ENV_CHANGED, SKIPPED, RESOURCE_DENIED}:
-                    bad.remove(test)
-        else:
-            if bad:
-                print(count(len(bad), 'test'), "failed again:")
-                printlist(bad)
-
-    if ns.single:
-        if next_single_test:
-            with open(filename, 'w') as fp:
-                fp.write(next_single_test + '\n')
-        else:
-            os.unlink(filename)
+from test.libregrtest import main
 
-    if ns.trace:
-        r = tracer.results()
-        r.write_results(show_missing=True, summary=True, coverdir=ns.coverdir)
 
-    if ns.runleaks:
-        os.system("leaks %d" % os.getpid())
+# Alias for backward compatibility (just in case)
+main_in_temp_cwd = main
 
-    sys.exit(len(bad) > 0 or interrupted)
 
+def _main():
+    global __file__
 
-# small set of tests to determine if we have a basically functioning interpreter
-# (i.e. if any of these fail, then anything else is likely to follow)
-STDTESTS = [
-    'test_grammar',
-    'test_opcodes',
-    'test_dict',
-    'test_builtin',
-    'test_exceptions',
-    'test_types',
-    'test_unittest',
-    'test_doctest',
-    'test_doctest2',
-    'test_support'
-]
-
-# set of tests that we don't want to be executed when using regrtest
-NOTTESTS = set()
-
-def findtests(testdir=None, stdtests=STDTESTS, nottests=NOTTESTS):
-    """Return a list of all applicable test modules."""
-    testdir = findtestdir(testdir)
-    names = os.listdir(testdir)
-    tests = []
-    others = set(stdtests) | nottests
-    for name in names:
-        mod, ext = os.path.splitext(name)
-        if mod[:5] == "test_" and ext in (".py", "") and mod not in others:
-            tests.append(mod)
-    return stdtests + sorted(tests)
-
-# We do not use a generator so multiple threads can call next().
-class MultiprocessTests(object):
-
-    """A thread-safe iterator over tests for multiprocess mode."""
-
-    def __init__(self, tests):
-        self.interrupted = False
-        self.lock = threading.Lock()
-        self.tests = tests
-
-    def __iter__(self):
-        return self
-
-    def __next__(self):
-        with self.lock:
-            if self.interrupted:
-                raise StopIteration('tests interrupted')
-            return next(self.tests)
-
-def replace_stdout():
-    """Set stdout encoder error handler to backslashreplace (as stderr error
-    handler) to avoid UnicodeEncodeError when printing a traceback"""
-    import atexit
-
-    stdout = sys.stdout
-    sys.stdout = open(stdout.fileno(), 'w',
-        encoding=stdout.encoding,
-        errors="backslashreplace",
-        closefd=False,
-        newline='\n')
-
-    def restore_stdout():
-        sys.stdout.close()
-        sys.stdout = stdout
-    atexit.register(restore_stdout)
-
-def runtest(test, verbose, quiet,
-            huntrleaks=False, use_resources=None,
-            output_on_failure=False, failfast=False, match_tests=None,
-            timeout=None, *, pgo=False):
-    """Run a single test.
-
-    test -- the name of the test
-    verbose -- if true, print more messages
-    quiet -- if true, don't print 'skipped' messages (probably redundant)
-    huntrleaks -- run multiple times to test for leaks; requires a debug
-                  build; a triple corresponding to -R's three arguments
-    use_resources -- list of extra resources to use
-    output_on_failure -- if true, display test output on failure
-    timeout -- dump the traceback and exit if a test takes more than
-               timeout seconds
-    failfast, match_tests -- See regrtest command-line flags for these.
-    pgo -- if true, do not print unnecessary info when running the test
-           for Profile Guided Optimization build
-
-    Returns the tuple result, test_time, where result is one of the constants:
-        INTERRUPTED      KeyboardInterrupt when run under -j
-        RESOURCE_DENIED  test skipped because resource denied
-        SKIPPED          test skipped for some other reason
-        ENV_CHANGED      test failed because it changed the execution environment
-        FAILED           test failed
-        PASSED           test passed
-    """
-    if use_resources is not None:
-        support.use_resources = use_resources
-    use_timeout = (timeout is not None)
-    if use_timeout:
-        faulthandler.dump_traceback_later(timeout, exit=True)
-    try:
-        support.match_tests = match_tests
-        if failfast:
-            support.failfast = True
-        if output_on_failure:
-            support.verbose = True
-
-            # Reuse the same instance to all calls to runtest(). Some
-            # tests keep a reference to sys.stdout or sys.stderr
-            # (eg. test_argparse).
-            if runtest.stringio is None:
-                stream = io.StringIO()
-                runtest.stringio = stream
-            else:
-                stream = runtest.stringio
-                stream.seek(0)
-                stream.truncate()
-
-            orig_stdout = sys.stdout
-            orig_stderr = sys.stderr
-            try:
-                sys.stdout = stream
-                sys.stderr = stream
-                result = runtest_inner(test, verbose, quiet, huntrleaks,
-                                       display_failure=False, pgo=pgo)
-                if result[0] == FAILED and not pgo:
-                    output = stream.getvalue()
-                    orig_stderr.write(output)
-                    orig_stderr.flush()
-            finally:
-                sys.stdout = orig_stdout
-                sys.stderr = orig_stderr
-        else:
-            support.verbose = verbose  # Tell tests to be moderately quiet
-            result = runtest_inner(test, verbose, quiet, huntrleaks,
-                                   display_failure=not verbose, pgo=pgo)
-        return result
-    finally:
-        if use_timeout:
-            faulthandler.cancel_dump_traceback_later()
-        cleanup_test_droppings(test, verbose)
-runtest.stringio = None
-
-# Unit tests are supposed to leave the execution environment unchanged
-# once they complete.  But sometimes tests have bugs, especially when
-# tests fail, and the changes to environment go on to mess up other
-# tests.  This can cause issues with buildbot stability, since tests
-# are run in random order and so problems may appear to come and go.
-# There are a few things we can save and restore to mitigate this, and
-# the following context manager handles this task.
-
-class saved_test_environment:
-    """Save bits of the test environment and restore them at block exit.
-
-        with saved_test_environment(testname, verbose, quiet):
-            #stuff
-
-    Unless quiet is True, a warning is printed to stderr if any of
-    the saved items was changed by the test.  The attribute 'changed'
-    is initially False, but is set to True if a change is detected.
-
-    If verbose is more than 1, the before and after state of changed
-    items is also printed.
-    """
-
-    changed = False
-
-    def __init__(self, testname, verbose=0, quiet=False, *, pgo=False):
-        self.testname = testname
-        self.verbose = verbose
-        self.quiet = quiet
-        self.pgo = pgo
-
-    # To add things to save and restore, add a name XXX to the resources list
-    # and add corresponding get_XXX/restore_XXX functions.  get_XXX should
-    # return the value to be saved and compared against a second call to the
-    # get function when test execution completes.  restore_XXX should accept
-    # the saved value and restore the resource using it.  It will be called if
-    # and only if a change in the value is detected.
-    #
-    # Note: XXX will have any '.' replaced with '_' characters when determining
-    # the corresponding method names.
-
-    resources = ('sys.argv', 'cwd', 'sys.stdin', 'sys.stdout', 'sys.stderr',
-                 'os.environ', 'sys.path', 'sys.path_hooks', '__import__',
-                 'warnings.filters', 'asyncore.socket_map',
-                 'logging._handlers', 'logging._handlerList', 'sys.gettrace',
-                 'sys.warnoptions',
-                 # multiprocessing.process._cleanup() may release ref
-                 # to a thread, so check processes first.
-                 'multiprocessing.process._dangling', 'threading._dangling',
-                 'sysconfig._CONFIG_VARS', 'sysconfig._INSTALL_SCHEMES',
-                 'files', 'locale', 'warnings.showwarning',
-                 'shutil_archive_formats', 'shutil_unpack_formats',
-                )
-
-    def get_sys_argv(self):
-        return id(sys.argv), sys.argv, sys.argv[:]
-    def restore_sys_argv(self, saved_argv):
-        sys.argv = saved_argv[1]
-        sys.argv[:] = saved_argv[2]
-
-    def get_cwd(self):
-        return os.getcwd()
-    def restore_cwd(self, saved_cwd):
-        os.chdir(saved_cwd)
-
-    def get_sys_stdout(self):
-        return sys.stdout
-    def restore_sys_stdout(self, saved_stdout):
-        sys.stdout = saved_stdout
-
-    def get_sys_stderr(self):
-        return sys.stderr
-    def restore_sys_stderr(self, saved_stderr):
-        sys.stderr = saved_stderr
-
-    def get_sys_stdin(self):
-        return sys.stdin
-    def restore_sys_stdin(self, saved_stdin):
-        sys.stdin = saved_stdin
-
-    def get_os_environ(self):
-        return id(os.environ), os.environ, dict(os.environ)
-    def restore_os_environ(self, saved_environ):
-        os.environ = saved_environ[1]
-        os.environ.clear()
-        os.environ.update(saved_environ[2])
-
-    def get_sys_path(self):
-        return id(sys.path), sys.path, sys.path[:]
-    def restore_sys_path(self, saved_path):
-        sys.path = saved_path[1]
-        sys.path[:] = saved_path[2]
-
-    def get_sys_path_hooks(self):
-        return id(sys.path_hooks), sys.path_hooks, sys.path_hooks[:]
-    def restore_sys_path_hooks(self, saved_hooks):
-        sys.path_hooks = saved_hooks[1]
-        sys.path_hooks[:] = saved_hooks[2]
-
-    def get_sys_gettrace(self):
-        return sys.gettrace()
-    def restore_sys_gettrace(self, trace_fxn):
-        sys.settrace(trace_fxn)
-
-    def get___import__(self):
-        return builtins.__import__
-    def restore___import__(self, import_):
-        builtins.__import__ = import_
-
-    def get_warnings_filters(self):
-        return id(warnings.filters), warnings.filters, warnings.filters[:]
-    def restore_warnings_filters(self, saved_filters):
-        warnings.filters = saved_filters[1]
-        warnings.filters[:] = saved_filters[2]
-
-    def get_asyncore_socket_map(self):
-        asyncore = sys.modules.get('asyncore')
-        # XXX Making a copy keeps objects alive until __exit__ gets called.
-        return asyncore and asyncore.socket_map.copy() or {}
-    def restore_asyncore_socket_map(self, saved_map):
-        asyncore = sys.modules.get('asyncore')
-        if asyncore is not None:
-            asyncore.close_all(ignore_all=True)
-            asyncore.socket_map.update(saved_map)
-
-    def get_shutil_archive_formats(self):
-        # we could call get_archives_formats() but that only returns the
-        # registry keys; we want to check the values too (the functions that
-        # are registered)
-        return shutil._ARCHIVE_FORMATS, shutil._ARCHIVE_FORMATS.copy()
-    def restore_shutil_archive_formats(self, saved):
-        shutil._ARCHIVE_FORMATS = saved[0]
-        shutil._ARCHIVE_FORMATS.clear()
-        shutil._ARCHIVE_FORMATS.update(saved[1])
-
-    def get_shutil_unpack_formats(self):
-        return shutil._UNPACK_FORMATS, shutil._UNPACK_FORMATS.copy()
-    def restore_shutil_unpack_formats(self, saved):
-        shutil._UNPACK_FORMATS = saved[0]
-        shutil._UNPACK_FORMATS.clear()
-        shutil._UNPACK_FORMATS.update(saved[1])
-
-    def get_logging__handlers(self):
-        # _handlers is a WeakValueDictionary
-        return id(logging._handlers), logging._handlers, logging._handlers.copy()
-    def restore_logging__handlers(self, saved_handlers):
-        # Can't easily revert the logging state
-        pass
-
-    def get_logging__handlerList(self):
-        # _handlerList is a list of weakrefs to handlers
-        return id(logging._handlerList), logging._handlerList, logging._handlerList[:]
-    def restore_logging__handlerList(self, saved_handlerList):
-        # Can't easily revert the logging state
-        pass
-
-    def get_sys_warnoptions(self):
-        return id(sys.warnoptions), sys.warnoptions, sys.warnoptions[:]
-    def restore_sys_warnoptions(self, saved_options):
-        sys.warnoptions = saved_options[1]
-        sys.warnoptions[:] = saved_options[2]
-
-    # Controlling dangling references to Thread objects can make it easier
-    # to track reference leaks.
-    def get_threading__dangling(self):
-        if not threading:
-            return None
-        # This copies the weakrefs without making any strong reference
-        return threading._dangling.copy()
-    def restore_threading__dangling(self, saved):
-        if not threading:
-            return
-        threading._dangling.clear()
-        threading._dangling.update(saved)
-
-    # Same for Process objects
-    def get_multiprocessing_process__dangling(self):
-        if not multiprocessing:
-            return None
-        # Unjoined process objects can survive after process exits
-        multiprocessing.process._cleanup()
-        # This copies the weakrefs without making any strong reference
-        return multiprocessing.process._dangling.copy()
-    def restore_multiprocessing_process__dangling(self, saved):
-        if not multiprocessing:
-            return
-        multiprocessing.process._dangling.clear()
-        multiprocessing.process._dangling.update(saved)
-
-    def get_sysconfig__CONFIG_VARS(self):
-        # make sure the dict is initialized
-        sysconfig.get_config_var('prefix')
-        return (id(sysconfig._CONFIG_VARS), sysconfig._CONFIG_VARS,
-                dict(sysconfig._CONFIG_VARS))
-    def restore_sysconfig__CONFIG_VARS(self, saved):
-        sysconfig._CONFIG_VARS = saved[1]
-        sysconfig._CONFIG_VARS.clear()
-        sysconfig._CONFIG_VARS.update(saved[2])
-
-    def get_sysconfig__INSTALL_SCHEMES(self):
-        return (id(sysconfig._INSTALL_SCHEMES), sysconfig._INSTALL_SCHEMES,
-                sysconfig._INSTALL_SCHEMES.copy())
-    def restore_sysconfig__INSTALL_SCHEMES(self, saved):
-        sysconfig._INSTALL_SCHEMES = saved[1]
-        sysconfig._INSTALL_SCHEMES.clear()
-        sysconfig._INSTALL_SCHEMES.update(saved[2])
-
-    def get_files(self):
-        return sorted(fn + ('/' if os.path.isdir(fn) else '')
-                      for fn in os.listdir())
-    def restore_files(self, saved_value):
-        fn = support.TESTFN
-        if fn not in saved_value and (fn + '/') not in saved_value:
-            if os.path.isfile(fn):
-                support.unlink(fn)
-            elif os.path.isdir(fn):
-                support.rmtree(fn)
-
-    _lc = [getattr(locale, lc) for lc in dir(locale)
-           if lc.startswith('LC_')]
-    def get_locale(self):
-        pairings = []
-        for lc in self._lc:
-            try:
-                pairings.append((lc, locale.setlocale(lc, None)))
-            except (TypeError, ValueError):
-                continue
-        return pairings
-    def restore_locale(self, saved):
-        for lc, setting in saved:
-            locale.setlocale(lc, setting)
-
-    def get_warnings_showwarning(self):
-        return warnings.showwarning
-    def restore_warnings_showwarning(self, fxn):
-        warnings.showwarning = fxn
-
-    def resource_info(self):
-        for name in self.resources:
-            method_suffix = name.replace('.', '_')
-            get_name = 'get_' + method_suffix
-            restore_name = 'restore_' + method_suffix
-            yield name, getattr(self, get_name), getattr(self, restore_name)
-
-    def __enter__(self):
-        self.saved_values = dict((name, get()) for name, get, restore
-                                                   in self.resource_info())
-        return self
-
-    def __exit__(self, exc_type, exc_val, exc_tb):
-        saved_values = self.saved_values
-        del self.saved_values
-        for name, get, restore in self.resource_info():
-            current = get()
-            original = saved_values.pop(name)
-            # Check for changes to the resource's value
-            if current != original:
-                self.changed = True
-                restore(original)
-                if not self.quiet and not self.pgo:
-                    print("Warning -- {} was modified by {}".format(
-                                                 name, self.testname),
-                                                 file=sys.stderr)
-                    if self.verbose > 1 and not self.pgo:
-                        print("  Before: {}\n  After:  {} ".format(
-                                                  original, current),
-                                                  file=sys.stderr)
-        return False
-
-
-def runtest_inner(test, verbose, quiet,
-                  huntrleaks=False, display_failure=True, pgo=False):
-    support.unload(test)
-
-    test_time = 0.0
-    refleak = False  # True if the test leaked references.
-    try:
-        if test.startswith('test.'):
-            abstest = test
-        else:
-            # Always import it from the test package
-            abstest = 'test.' + test
-        with saved_test_environment(test, verbose, quiet, pgo=pgo) as environment:
-            start_time = time.time()
-            the_module = importlib.import_module(abstest)
-            # If the test has a test_main, that will run the appropriate
-            # tests.  If not, use normal unittest test loading.
-            test_runner = getattr(the_module, "test_main", None)
-            if test_runner is None:
-                def test_runner():
-                    loader = unittest.TestLoader()
-                    tests = loader.loadTestsFromModule(the_module)
-                    for error in loader.errors:
-                        print(error, file=sys.stderr)
-                    if loader.errors:
-                        raise Exception("errors while loading tests")
-                    support.run_unittest(tests)
-            test_runner()
-            if huntrleaks:
-                refleak = dash_R(the_module, test, test_runner, huntrleaks)
-            test_time = time.time() - start_time
-    except support.ResourceDenied as msg:
-        if not quiet and not pgo:
-            print(test, "skipped --", msg)
-            sys.stdout.flush()
-        return RESOURCE_DENIED, test_time
-    except unittest.SkipTest as msg:
-        if not quiet and not pgo:
-            print(test, "skipped --", msg)
-            sys.stdout.flush()
-        return SKIPPED, test_time
-    except KeyboardInterrupt:
-        raise
-    except support.TestFailed as msg:
-        if not pgo:
-            if display_failure:
-                print("test", test, "failed --", msg, file=sys.stderr)
-            else:
-                print("test", test, "failed", file=sys.stderr)
-        sys.stderr.flush()
-        return FAILED, test_time
-    except:
-        msg = traceback.format_exc()
-        if not pgo:
-            print("test", test, "crashed --", msg, file=sys.stderr)
-        sys.stderr.flush()
-        return FAILED, test_time
-    else:
-        if refleak:
-            return FAILED, test_time
-        if environment.changed:
-            return ENV_CHANGED, test_time
-        return PASSED, test_time
-
-def cleanup_test_droppings(testname, verbose):
-    import shutil
-    import stat
-    import gc
-
-    # First kill any dangling references to open files etc.
-    # This can also issue some ResourceWarnings which would otherwise get
-    # triggered during the following test run, and possibly produce failures.
-    gc.collect()
-
-    # Try to clean up junk commonly left behind.  While tests shouldn't leave
-    # any files or directories behind, when a test fails that can be tedious
-    # for it to arrange.  The consequences can be especially nasty on Windows,
-    # since if a test leaves a file open, it cannot be deleted by name (while
-    # there's nothing we can do about that here either, we can display the
-    # name of the offending test, which is a real help).
-    for name in (support.TESTFN,
-                 "db_home",
-                ):
-        if not os.path.exists(name):
-            continue
-
-        if os.path.isdir(name):
-            kind, nuker = "directory", shutil.rmtree
-        elif os.path.isfile(name):
-            kind, nuker = "file", os.unlink
-        else:
-            raise SystemError("os.path says %r exists but is neither "
-                              "directory nor file" % name)
-
-        if verbose:
-            print("%r left behind %s %r" % (testname, kind, name))
-        try:
-            # if we have chmod, fix possible permissions problems
-            # that might prevent cleanup
-            if (hasattr(os, 'chmod')):
-                os.chmod(name, stat.S_IRWXU | stat.S_IRWXG | stat.S_IRWXO)
-            nuker(name)
-        except Exception as msg:
-            print(("%r left behind %s %r and it couldn't be "
-                "removed: %s" % (testname, kind, name, msg)), file=sys.stderr)
-
-def dash_R(the_module, test, indirect_test, huntrleaks):
-    """Run a test multiple times, looking for reference leaks.
-
-    Returns:
-        False if the test didn't leak references; True if we detected refleaks.
-    """
-    # This code is hackish and inelegant, but it seems to do the job.
-    import copyreg
-    import collections.abc
-
-    if not hasattr(sys, 'gettotalrefcount'):
-        raise Exception("Tracking reference leaks requires a debug build "
-                        "of Python")
-
-    # Save current values for dash_R_cleanup() to restore.
-    fs = warnings.filters[:]
-    ps = copyreg.dispatch_table.copy()
-    pic = sys.path_importer_cache.copy()
-    try:
-        import zipimport
-    except ImportError:
-        zdc = None # Run unmodified on platforms without zipimport support
-    else:
-        zdc = zipimport._zip_directory_cache.copy()
-    abcs = {}
-    for abc in [getattr(collections.abc, a) for a in collections.abc.__all__]:
-        if not isabstract(abc):
-            continue
-        for obj in abc.__subclasses__() + [abc]:
-            abcs[obj] = obj._abc_registry.copy()
-
-    nwarmup, ntracked, fname = huntrleaks
-    fname = os.path.join(support.SAVEDCWD, fname)
-    repcount = nwarmup + ntracked
-    rc_deltas = [0] * repcount
-    alloc_deltas = [0] * repcount
-
-    print("beginning", repcount, "repetitions", file=sys.stderr)
-    print(("1234567890"*(repcount//10 + 1))[:repcount], file=sys.stderr)
-    sys.stderr.flush()
-    for i in range(repcount):
-        indirect_test()
-        alloc_after, rc_after = dash_R_cleanup(fs, ps, pic, zdc, abcs)
-        sys.stderr.write('.')
-        sys.stderr.flush()
-        if i >= nwarmup:
-            rc_deltas[i] = rc_after - rc_before
-            alloc_deltas[i] = alloc_after - alloc_before
-        alloc_before, rc_before = alloc_after, rc_after
-    print(file=sys.stderr)
-    # These checkers return False on success, True on failure
-    def check_rc_deltas(deltas):
-        return any(deltas)
-    def check_alloc_deltas(deltas):
-        # At least 1/3rd of 0s
-        if 3 * deltas.count(0) < len(deltas):
-            return True
-        # Nothing else than 1s, 0s and -1s
-        if not set(deltas) <= {1,0,-1}:
-            return True
-        return False
-    failed = False
-    for deltas, item_name, checker in [
-        (rc_deltas, 'references', check_rc_deltas),
-        (alloc_deltas, 'memory blocks', check_alloc_deltas)]:
-        if checker(deltas):
-            msg = '%s leaked %s %s, sum=%s' % (
-                test, deltas[nwarmup:], item_name, sum(deltas))
-            print(msg, file=sys.stderr)
-            sys.stderr.flush()
-            with open(fname, "a") as refrep:
-                print(msg, file=refrep)
-                refrep.flush()
-            failed = True
-    return failed
-
-def dash_R_cleanup(fs, ps, pic, zdc, abcs):
-    import gc, copyreg
-    import _strptime, linecache
-    import urllib.parse, urllib.request, mimetypes, doctest
-    import struct, filecmp, collections.abc
-    from distutils.dir_util import _path_created
-    from weakref import WeakSet
-
-    # Clear the warnings registry, so they can be displayed again
-    for mod in sys.modules.values():
-        if hasattr(mod, '__warningregistry__'):
-            del mod.__warningregistry__
-
-    # Restore some original values.
-    warnings.filters[:] = fs
-    copyreg.dispatch_table.clear()
-    copyreg.dispatch_table.update(ps)
-    sys.path_importer_cache.clear()
-    sys.path_importer_cache.update(pic)
-    try:
-        import zipimport
-    except ImportError:
-        pass # Run unmodified on platforms without zipimport support
-    else:
-        zipimport._zip_directory_cache.clear()
-        zipimport._zip_directory_cache.update(zdc)
-
-    # clear type cache
-    sys._clear_type_cache()
-
-    # Clear ABC registries, restoring previously saved ABC registries.
-    for abc in [getattr(collections.abc, a) for a in collections.abc.__all__]:
-        if not isabstract(abc):
-            continue
-        for obj in abc.__subclasses__() + [abc]:
-            obj._abc_registry = abcs.get(obj, WeakSet()).copy()
-            obj._abc_cache.clear()
-            obj._abc_negative_cache.clear()
-
-    # Flush standard output, so that buffered data is sent to the OS and
-    # associated Python objects are reclaimed.
-    for stream in (sys.stdout, sys.stderr, sys.__stdout__, sys.__stderr__):
-        if stream is not None:
-            stream.flush()
-
-    # Clear assorted module caches.
-    _path_created.clear()
-    re.purge()
-    _strptime._regex_cache.clear()
-    urllib.parse.clear_cache()
-    urllib.request.urlcleanup()
-    linecache.clearcache()
-    mimetypes._default_mime_types()
-    filecmp._cache.clear()
-    struct._clearcache()
-    doctest.master = None
-    try:
-        import ctypes
-    except ImportError:
-        # Don't worry about resetting the cache if ctypes is not supported
-        pass
-    else:
-        ctypes._reset_cache()
-
-    # Collect cyclic trash and read memory statistics immediately after.
-    func1 = sys.getallocatedblocks
-    func2 = sys.gettotalrefcount
-    gc.collect()
-    return func1(), func2()
-
-def warm_caches():
-    # char cache
-    s = bytes(range(256))
-    for i in range(256):
-        s[i:i+1]
-    # unicode cache
-    x = [chr(i) for i in range(256)]
-    # int cache
-    x = list(range(-5, 257))
-
-def findtestdir(path=None):
-    return path or os.path.dirname(__file__) or os.curdir
-
-def removepy(names):
-    if not names:
-        return
-    for idx, name in enumerate(names):
-        basename, ext = os.path.splitext(name)
-        if ext == '.py':
-            names[idx] = basename
-
-def count(n, word):
-    if n == 1:
-        return "%d %s" % (n, word)
-    else:
-        return "%d %ss" % (n, word)
-
-def printlist(x, width=70, indent=4):
-    """Print the elements of iterable x to stdout.
-
-    Optional arg width (default 70) is the maximum line length.
-    Optional arg indent (default 4) is the number of blanks with which to
-    begin each line.
-    """
-
-    from textwrap import fill
-    blanks = ' ' * indent
-    # Print the sorted list: 'x' may be a '--random' list or a set()
-    print(fill(' '.join(str(elt) for elt in sorted(x)), width,
-               initial_indent=blanks, subsequent_indent=blanks))
-
-
-def main_in_temp_cwd():
-    """Run main() in a temporary working directory."""
-    if sysconfig.is_python_build():
-        try:
-            os.mkdir(TEMPDIR)
-        except FileExistsError:
-            pass
-
-    # Define a writable temp dir that will be used as cwd while running
-    # the tests. The name of the dir includes the pid to allow parallel
-    # testing (see the -j option).
-    test_cwd = 'test_python_{}'.format(os.getpid())
-    test_cwd = os.path.join(TEMPDIR, test_cwd)
-
-    # Run the tests in a context manager that temporarily changes the CWD to a
-    # temporary and writable directory.  If it's not possible to create or
-    # change the CWD, the original CWD will be used.  The original CWD is
-    # available from support.SAVEDCWD.
-    with support.temp_cwd(test_cwd, quiet=True):
-        main()
-
-
-if __name__ == '__main__':
     # Remove regrtest.py's own directory from the module search path. Despite
     # the elimination of implicit relative imports, this is still needed to
     # ensure that submodules of the test package do not inappropriately appear
     # as top-level modules even when people (or buildbots!) invoke regrtest.py
     # directly instead of using the -m switch
     mydir = os.path.abspath(os.path.normpath(os.path.dirname(sys.argv[0])))
-    i = len(sys.path)
+    i = len(sys.path) - 1
     while i >= 0:
-        i -= 1
         if os.path.abspath(os.path.normpath(sys.path[i])) == mydir:
             del sys.path[i]
+        else:
+            i -= 1
 
     # findtestdir() gets the dirname out of __file__, so we have to make it
     # absolute before changing the working directory.
@@ -1614,4 +43,8 @@ if __name__ == '__main__':
     # sanity check
     assert __file__ == os.path.abspath(sys.argv[0])
 
-    main_in_temp_cwd()
+    main()
+
+
+if __name__ == '__main__':
+    _main()
diff --git a/Lib/test/seq_tests.py b/Lib/test/seq_tests.py
index 72f4845a97..1e7a6f6522 100644
--- a/Lib/test/seq_tests.py
+++ b/Lib/test/seq_tests.py
@@ -318,7 +318,6 @@ class CommonTest(unittest.TestCase):
             self.assertEqual(id(s), id(s*1))
 
     def test_bigrepeat(self):
-        import sys
         if sys.maxsize <= 2147483647:
             x = self.type2test([0])
             x *= 2**16
diff --git a/Lib/test/signalinterproctester.py b/Lib/test/signalinterproctester.py
new file mode 100644
index 0000000000..d3ae170983
--- /dev/null
+++ b/Lib/test/signalinterproctester.py
@@ -0,0 +1,84 @@
+import os
+import signal
+import subprocess
+import sys
+import time
+import unittest
+
+
+class SIGUSR1Exception(Exception):
+    pass
+
+
+class InterProcessSignalTests(unittest.TestCase):
+    def setUp(self):
+        self.got_signals = {'SIGHUP': 0, 'SIGUSR1': 0, 'SIGALRM': 0}
+
+    def sighup_handler(self, signum, frame):
+        self.got_signals['SIGHUP'] += 1
+
+    def sigusr1_handler(self, signum, frame):
+        self.got_signals['SIGUSR1'] += 1
+        raise SIGUSR1Exception
+
+    def wait_signal(self, child, signame, exc_class=None):
+        try:
+            if child is not None:
+                # This wait should be interrupted by exc_class
+                # (if set)
+                child.wait()
+
+            timeout = 10.0
+            deadline = time.monotonic() + timeout
+
+            while time.monotonic() < deadline:
+                if self.got_signals[signame]:
+                    return
+                signal.pause()
+        except BaseException as exc:
+            if exc_class is not None and isinstance(exc, exc_class):
+                # got the expected exception
+                return
+            raise
+
+        self.fail('signal %s not received after %s seconds'
+                  % (signame, timeout))
+
+    def subprocess_send_signal(self, pid, signame):
+        code = 'import os, signal; os.kill(%s, signal.%s)' % (pid, signame)
+        args = [sys.executable, '-I', '-c', code]
+        return subprocess.Popen(args)
+
+    def test_interprocess_signal(self):
+        # Install handlers. This function runs in a sub-process, so we
+        # don't worry about re-setting the default handlers.
+        signal.signal(signal.SIGHUP, self.sighup_handler)
+        signal.signal(signal.SIGUSR1, self.sigusr1_handler)
+        signal.signal(signal.SIGUSR2, signal.SIG_IGN)
+        signal.signal(signal.SIGALRM, signal.default_int_handler)
+
+        # Let the sub-processes know who to send signals to.
+        pid = str(os.getpid())
+
+        with self.subprocess_send_signal(pid, "SIGHUP") as child:
+            self.wait_signal(child, 'SIGHUP')
+        self.assertEqual(self.got_signals, {'SIGHUP': 1, 'SIGUSR1': 0,
+                                            'SIGALRM': 0})
+
+        with self.subprocess_send_signal(pid, "SIGUSR1") as child:
+            self.wait_signal(child, 'SIGUSR1', SIGUSR1Exception)
+        self.assertEqual(self.got_signals, {'SIGHUP': 1, 'SIGUSR1': 1,
+                                            'SIGALRM': 0})
+
+        with self.subprocess_send_signal(pid, "SIGUSR2") as child:
+            # Nothing should happen: SIGUSR2 is ignored
+            child.wait()
+
+        signal.alarm(1)
+        self.wait_signal(None, 'SIGALRM', KeyboardInterrupt)
+        self.assertEqual(self.got_signals, {'SIGHUP': 1, 'SIGUSR1': 1,
+                                            'SIGALRM': 0})
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py
index e124fab610..04e8629134 100644
--- a/Lib/test/support/__init__.py
+++ b/Lib/test/support/__init__.py
@@ -26,6 +26,7 @@ import sys
 import sysconfig
 import tempfile
 import time
+import types
 import unittest
 import urllib.error
 import warnings
@@ -89,6 +90,7 @@ __all__ = [
     "bigmemtest", "bigaddrspacetest", "cpython_only", "get_attribute",
     "requires_IEEE_754", "skip_unless_xattr", "requires_zlib",
     "anticipate_failure", "load_package_tests", "detect_api_mismatch",
+    "check__all__",
     # sys
     "is_jython", "check_impl_detail",
     # network
@@ -900,7 +902,7 @@ def temp_dir(path=None, quiet=False):
         yield path
     finally:
         if dir_created:
-            shutil.rmtree(path)
+            rmtree(path)
 
 @contextlib.contextmanager
 def change_cwd(path, quiet=False):
@@ -2073,6 +2075,11 @@ def args_from_interpreter_flags():
     settings in sys.flags and sys.warnoptions."""
     return subprocess._args_from_interpreter_flags()
 
+def optim_args_from_interpreter_flags():
+    """Return a list of command-line arguments reproducing the current
+    optimization settings in sys.flags."""
+    return subprocess._optim_args_from_interpreter_flags()
+
 #============================================================
 # Support for assertions about logging.
 #============================================================
@@ -2224,6 +2231,65 @@ def detect_api_mismatch(ref_api, other_api, *, ignore=()):
     return missing_items
 
 
+def check__all__(test_case, module, name_of_module=None, extra=(),
+                 blacklist=()):
+    """Assert that the __all__ variable of 'module' contains all public names.
+
+    The module's public names (its API) are detected automatically based on
+    whether they match the public name convention and were defined in
+    'module'.
+
+    The 'name_of_module' argument can specify (as a string or tuple thereof)
+    what module(s) an API could be defined in in order to be detected as a
+    public API. One case for this is when 'module' imports part of its public
+    API from other modules, possibly a C backend (like 'csv' and its '_csv').
+
+    The 'extra' argument can be a set of names that wouldn't otherwise be
+    automatically detected as "public", like objects without a proper
+    '__module__' attriubute. If provided, it will be added to the
+    automatically detected ones.
+
+    The 'blacklist' argument can be a set of names that must not be treated
+    as part of the public API even though their names indicate otherwise.
+
+    Usage:
+        import bar
+        import foo
+        import unittest
+        from test import support
+
+        class MiscTestCase(unittest.TestCase):
+            def test__all__(self):
+                support.check__all__(self, foo)
+
+        class OtherTestCase(unittest.TestCase):
+            def test__all__(self):
+                extra = {'BAR_CONST', 'FOO_CONST'}
+                blacklist = {'baz'}  # Undocumented name.
+                # bar imports part of its API from _bar.
+                support.check__all__(self, bar, ('bar', '_bar'),
+                                     extra=extra, blacklist=blacklist)
+
+    """
+
+    if name_of_module is None:
+        name_of_module = (module.__name__, )
+    elif isinstance(name_of_module, str):
+        name_of_module = (name_of_module, )
+
+    expected = set(extra)
+
+    for name in dir(module):
+        if name.startswith('_') or name in blacklist:
+            continue
+        obj = getattr(module, name)
+        if (getattr(obj, '__module__', None) in name_of_module or
+                (not hasattr(obj, '__module__') and
+                 not isinstance(obj, types.ModuleType))):
+            expected.add(name)
+    test_case.assertCountEqual(module.__all__, expected)
+
+
 class SuppressCrashReport:
     """Try to prevent a crash report from popping up.
 
diff --git a/Lib/test/test__locale.py b/Lib/test/test__locale.py
index 58f2f04fcd..ab4e247961 100644
--- a/Lib/test/test__locale.py
+++ b/Lib/test/test__locale.py
@@ -4,7 +4,6 @@ try:
 except ImportError:
     nl_langinfo = None
 
-import codecs
 import locale
 import sys
 import unittest
diff --git a/Lib/test/test__osx_support.py b/Lib/test/test__osx_support.py
index ac6325a751..bcba8caa29 100644
--- a/Lib/test/test__osx_support.py
+++ b/Lib/test/test__osx_support.py
@@ -4,7 +4,6 @@ Test suite for _osx_support: shared OS X support functions.
 
 import os
 import platform
-import shutil
 import stat
 import sys
 import unittest
diff --git a/Lib/test/test_aifc.py b/Lib/test/test_aifc.py
index ab5143787b..1bd1f89c8a 100644
--- a/Lib/test/test_aifc.py
+++ b/Lib/test/test_aifc.py
@@ -2,7 +2,6 @@ from test.support import findfile, TESTFN, unlink
 import unittest
 from test import audiotests
 from audioop import byteswap
-import os
 import io
 import sys
 import struct
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index f9ee398899..52c624771c 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -4512,6 +4512,21 @@ class TestStrings(TestCase):
         string = "Namespace(bar='spam', foo=42)"
         self.assertStringEqual(ns, string)
 
+    def test_namespace_starkwargs_notidentifier(self):
+        ns = argparse.Namespace(**{'"': 'quote'})
+        string = """Namespace(**{'"': 'quote'})"""
+        self.assertStringEqual(ns, string)
+
+    def test_namespace_kwargs_and_starkwargs_notidentifier(self):
+        ns = argparse.Namespace(a=1, **{'"': 'quote'})
+        string = """Namespace(a=1, **{'"': 'quote'})"""
+        self.assertStringEqual(ns, string)
+
+    def test_namespace_starkwargs_identifier(self):
+        ns = argparse.Namespace(**{'valid': True})
+        string = "Namespace(valid=True)"
+        self.assertStringEqual(ns, string)
+
     def test_parser(self):
         parser = argparse.ArgumentParser(prog='PROG')
         string = (
diff --git a/Lib/test/test_array.py b/Lib/test/test_array.py
index 482526eec1..8fd54cc1db 100644
--- a/Lib/test/test_array.py
+++ b/Lib/test/test_array.py
@@ -7,8 +7,6 @@ from test import support
 import weakref
 import pickle
 import operator
-import io
-import math
 import struct
 import sys
 import warnings
@@ -318,8 +316,19 @@ class BaseTest:
             d = pickle.dumps((itorig, orig), proto)
             it, a = pickle.loads(d)
             a.fromlist(data2)
-            self.assertEqual(type(it), type(itorig))
-            self.assertEqual(list(it), data2)
+            self.assertEqual(list(it), [])
+
+    def test_exhausted_iterator(self):
+        a = array.array(self.typecode, self.example)
+        self.assertEqual(list(a), list(self.example))
+        exhit = iter(a)
+        empit = iter(a)
+        for x in exhit:  # exhaust the iterator
+            next(empit)  # not exhausted
+        a.append(self.outside)
+        self.assertEqual(list(exhit), [])
+        self.assertEqual(list(empit), [self.outside])
+        self.assertEqual(list(a), list(self.example) + [self.outside])
 
     def test_insert(self):
         a = array.array(self.typecode, self.example)
@@ -1070,6 +1079,12 @@ class BaseTest:
         a = array.array('B', b"")
         self.assertRaises(BufferError, getbuffer_with_null_view, a)
 
+    def test_free_after_iterating(self):
+        support.check_free_after_iterating(self, iter, array.array,
+                                           (self.typecode,))
+        support.check_free_after_iterating(self, reversed, array.array,
+                                           (self.typecode,))
+
 class StringTest(BaseTest):
 
     def test_setitem(self):
diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py
index d3e6d35943..7b43be6dfc 100644
--- a/Lib/test/test_ast.py
+++ b/Lib/test/test_ast.py
@@ -1,7 +1,8 @@
+import ast
+import dis
 import os
 import sys
 import unittest
-import ast
 import weakref
 
 from test import support
@@ -238,7 +239,7 @@ class AST_Tests(unittest.TestCase):
                     ast_tree = compile(i, "?", kind, ast.PyCF_ONLY_AST)
                     self.assertEqual(to_tuple(ast_tree), o)
                     self._assertTrueorder(ast_tree, (0, 0))
-                with self.subTest(action="compiling", input=i):
+                with self.subTest(action="compiling", input=i, kind=kind):
                     compile(ast_tree, "?", kind)
 
     def test_slice(self):
@@ -547,6 +548,17 @@ class ASTHelpers_Test(unittest.TestCase):
             compile(mod, 'test', 'exec')
         self.assertIn("invalid integer value: None", str(cm.exception))
 
+    def test_level_as_none(self):
+        body = [ast.ImportFrom(module='time',
+                               names=[ast.alias(name='sleep')],
+                               level=None,
+                               lineno=0, col_offset=0)]
+        mod = ast.Module(body)
+        code = compile(mod, 'test', 'exec')
+        ns = {}
+        exec(code, ns)
+        self.assertIn('sleep', ns)
+
 
 class ASTValidatorTests(unittest.TestCase):
 
@@ -933,6 +945,125 @@ class ASTValidatorTests(unittest.TestCase):
             compile(mod, fn, "exec")
 
 
+class ConstantTests(unittest.TestCase):
+    """Tests on the ast.Constant node type."""
+
+    def compile_constant(self, value):
+        tree = ast.parse("x = 123")
+
+        node = tree.body[0].value
+        new_node = ast.Constant(value=value)
+        ast.copy_location(new_node, node)
+        tree.body[0].value = new_node
+
+        code = compile(tree, "<string>", "exec")
+
+        ns = {}
+        exec(code, ns)
+        return ns['x']
+
+    def test_validation(self):
+        with self.assertRaises(TypeError) as cm:
+            self.compile_constant([1, 2, 3])
+        self.assertEqual(str(cm.exception),
+                         "got an invalid type in Constant: list")
+
+    def test_singletons(self):
+        for const in (None, False, True, Ellipsis, b'', frozenset()):
+            with self.subTest(const=const):
+                value = self.compile_constant(const)
+                self.assertIs(value, const)
+
+    def test_values(self):
+        nested_tuple = (1,)
+        nested_frozenset = frozenset({1})
+        for level in range(3):
+            nested_tuple = (nested_tuple, 2)
+            nested_frozenset = frozenset({nested_frozenset, 2})
+        values = (123, 123.0, 123j,
+                  "unicode", b'bytes',
+                  tuple("tuple"), frozenset("frozenset"),
+                  nested_tuple, nested_frozenset)
+        for value in values:
+            with self.subTest(value=value):
+                result = self.compile_constant(value)
+                self.assertEqual(result, value)
+
+    def test_assign_to_constant(self):
+        tree = ast.parse("x = 1")
+
+        target = tree.body[0].targets[0]
+        new_target = ast.Constant(value=1)
+        ast.copy_location(new_target, target)
+        tree.body[0].targets[0] = new_target
+
+        with self.assertRaises(ValueError) as cm:
+            compile(tree, "string", "exec")
+        self.assertEqual(str(cm.exception),
+                         "expression which can't be assigned "
+                         "to in Store context")
+
+    def test_get_docstring(self):
+        tree = ast.parse("'docstring'\nx = 1")
+        self.assertEqual(ast.get_docstring(tree), 'docstring')
+
+        tree.body[0].value = ast.Constant(value='constant docstring')
+        self.assertEqual(ast.get_docstring(tree), 'constant docstring')
+
+    def get_load_const(self, tree):
+        # Compile to bytecode, disassemble and get parameter of LOAD_CONST
+        # instructions
+        co = compile(tree, '<string>', 'exec')
+        consts = []
+        for instr in dis.get_instructions(co):
+            if instr.opname == 'LOAD_CONST':
+                consts.append(instr.argval)
+        return consts
+
+    @support.cpython_only
+    def test_load_const(self):
+        consts = [None,
+                  True, False,
+                  124,
+                  2.0,
+                  3j,
+                  "unicode",
+                  b'bytes',
+                  (1, 2, 3)]
+
+        code = '\n'.join(['x={!r}'.format(const) for const in consts])
+        code += '\nx = ...'
+        consts.extend((Ellipsis, None))
+
+        tree = ast.parse(code)
+        self.assertEqual(self.get_load_const(tree),
+                         consts)
+
+        # Replace expression nodes with constants
+        for assign, const in zip(tree.body, consts):
+            assert isinstance(assign, ast.Assign), ast.dump(assign)
+            new_node = ast.Constant(value=const)
+            ast.copy_location(new_node, assign.value)
+            assign.value = new_node
+
+        self.assertEqual(self.get_load_const(tree),
+                         consts)
+
+    def test_literal_eval(self):
+        tree = ast.parse("1 + 2")
+        binop = tree.body[0].value
+
+        new_left = ast.Constant(value=10)
+        ast.copy_location(new_left, binop.left)
+        binop.left = new_left
+
+        new_right = ast.Constant(value=20)
+        ast.copy_location(new_right, binop.right)
+        binop.right = new_right
+
+        self.assertEqual(ast.literal_eval(binop), 30)
+
+
 def main():
     if __name__ != '__main__':
         return
@@ -940,8 +1071,9 @@ def main():
         for statements, kind in ((exec_tests, "exec"), (single_tests, "single"),
                                  (eval_tests, "eval")):
             print(kind+"_results = [")
-            for s in statements:
-                print(repr(to_tuple(compile(s, "?", kind, 0x400)))+",")
+            for statement in statements:
+                tree = ast.parse(statement, "?", kind)
+                print("%r," % (to_tuple(tree),))
             print("]")
         print("main()")
         raise SystemExit
diff --git a/Lib/test/test_asynchat.py b/Lib/test/test_asynchat.py
index 3a33fc8b2d..0eba76db47 100644
--- a/Lib/test/test_asynchat.py
+++ b/Lib/test/test_asynchat.py
@@ -12,7 +12,6 @@ import socket
 import sys
 import time
 import unittest
-import warnings
 import unittest.mock
 try:
     import threading
@@ -297,37 +296,6 @@ class TestHelperFunctions(unittest.TestCase):
         self.assertEqual(asynchat.find_prefix_at_end("qwertydkjf", "\r\n"), 0)
 
 
-class TestFifo(unittest.TestCase):
-    def test_basic(self):
-        with self.assertWarns(DeprecationWarning) as cm:
-            f = asynchat.fifo()
-        self.assertEqual(str(cm.warning),
-                         "fifo class will be removed in Python 3.6")
-        f.push(7)
-        f.push(b'a')
-        self.assertEqual(len(f), 2)
-        self.assertEqual(f.first(), 7)
-        self.assertEqual(f.pop(), (1, 7))
-        self.assertEqual(len(f), 1)
-        self.assertEqual(f.first(), b'a')
-        self.assertEqual(f.is_empty(), False)
-        self.assertEqual(f.pop(), (1, b'a'))
-        self.assertEqual(len(f), 0)
-        self.assertEqual(f.is_empty(), True)
-        self.assertEqual(f.pop(), (0, None))
-
-    def test_given_list(self):
-        with self.assertWarns(DeprecationWarning) as cm:
-            f = asynchat.fifo([b'x', 17, 3])
-        self.assertEqual(str(cm.warning),
-                         "fifo class will be removed in Python 3.6")
-        self.assertEqual(len(f), 3)
-        self.assertEqual(f.pop(), (1, b'x'))
-        self.assertEqual(f.pop(), (1, 17))
-        self.assertEqual(f.pop(), (1, 3))
-        self.assertEqual(f.pop(), (0, None))
-
-
 class TestNotConnected(unittest.TestCase):
     def test_disallow_negative_terminator(self):
         # Issue #11259
diff --git a/Lib/test/test_bigmem.py b/Lib/test/test_bigmem.py
index 40ac9bff2f..6133bbcac5 100644
--- a/Lib/test/test_bigmem.py
+++ b/Lib/test/test_bigmem.py
@@ -14,7 +14,6 @@ from test.support import bigmemtest, _1G, _2G, _4G
 import unittest
 import operator
 import sys
-import functools
 
 # These tests all use one of the bigmemtest decorators to indicate how much
 # memory they use and how much memory they need to be even meaningful.  The
diff --git a/Lib/test/test_binascii.py b/Lib/test/test_binascii.py
index 8367afe083..fbc933e4e6 100644
--- a/Lib/test/test_binascii.py
+++ b/Lib/test/test_binascii.py
@@ -159,11 +159,25 @@ class BinASCIITest(unittest.TestCase):
         # Then calculate the hexbin4 binary-to-ASCII translation
         rle = binascii.rlecode_hqx(self.data)
         a = binascii.b2a_hqx(self.type2test(rle))
+
         b, _ = binascii.a2b_hqx(self.type2test(a))
         res = binascii.rledecode_hqx(b)
-
         self.assertEqual(res, self.rawdata)
 
+    def test_rle(self):
+        # test repetition with a repetition longer than the limit of 255
+        data = (b'a' * 100 + b'b' + b'c' * 300)
+
+        encoded = binascii.rlecode_hqx(data)
+        self.assertEqual(encoded,
+                         (b'a\x90d'      # 'a' * 100
+                          b'b'           # 'b'
+                          b'c\x90\xff'   # 'c' * 255
+                          b'c\x90-'))    # 'c' * 45
+
+        decoded = binascii.rledecode_hqx(encoded)
+        self.assertEqual(decoded, data)
+
     def test_hex(self):
         # test hexlification
         s = b'{s\005\000\000\000worldi\002\000\000\000s\005\000\000\000helloi\001\000\000\0000'
@@ -262,6 +276,16 @@ class BinASCIITest(unittest.TestCase):
             # non-ASCII string
             self.assertRaises(ValueError, a2b, "\x80")
 
+    def test_b2a_base64_newline(self):
+        # Issue #25357: test newline parameter
+        b = self.type2test(b'hello')
+        self.assertEqual(binascii.b2a_base64(b),
+                         b'aGVsbG8=\n')
+        self.assertEqual(binascii.b2a_base64(b, newline=True),
+                         b'aGVsbG8=\n')
+        self.assertEqual(binascii.b2a_base64(b, newline=False),
+                         b'aGVsbG8=')
+
 
 class ArrayBinASCIITest(BinASCIITest):
     def type2test(self, s):
diff --git a/Lib/test/test_binhex.py b/Lib/test/test_binhex.py
index 9d4c85afaa..21f446325a 100644
--- a/Lib/test/test_binhex.py
+++ b/Lib/test/test_binhex.py
@@ -4,7 +4,6 @@
    Based on an original test by Roger E. Masse.
 """
 import binhex
-import os
 import unittest
 from test import support
 
diff --git a/Lib/test/test_binop.py b/Lib/test/test_binop.py
index e9dbddcd93..fc8d30fac1 100644
--- a/Lib/test/test_binop.py
+++ b/Lib/test/test_binop.py
@@ -2,7 +2,7 @@
 
 import unittest
 from test import support
-from operator import eq, ne, lt, gt, le, ge
+from operator import eq, le
 from abc import ABCMeta
 
 def gcd(a, b):
diff --git a/Lib/test/test_buffer.py b/Lib/test/test_buffer.py
index 2eef9fc685..b83f2f107c 100644
--- a/Lib/test/test_buffer.py
+++ b/Lib/test/test_buffer.py
@@ -16,7 +16,6 @@ import unittest
 from test import support
 from itertools import permutations, product
 from random import randrange, sample, choice
-from sysconfig import get_config_var
 import warnings
 import sys, array, io
 from decimal import Decimal
diff --git a/Lib/test/test_bytes.py b/Lib/test/test_bytes.py
index 65c00d7a5f..1cedd3a855 100644
--- a/Lib/test/test_bytes.py
+++ b/Lib/test/test_bytes.py
@@ -300,6 +300,20 @@ class BaseBytesTest:
         self.assertRaises(ValueError, self.type2test.fromhex, '\x00')
         self.assertRaises(ValueError, self.type2test.fromhex, '12   \x00   34')
 
+        for data, pos in (
+            # invalid first hexadecimal character
+            ('12 x4 56', 3),
+            # invalid second hexadecimal character
+            ('12 3x 56', 4),
+            # two invalid hexadecimal characters
+            ('12 xy 56', 3),
+            # test non-ASCII string
+            ('12 3\xff 56', 4),
+        ):
+            with self.assertRaises(ValueError) as cm:
+                self.type2test.fromhex(data)
+            self.assertIn('at position %s' % pos, str(cm.exception))
+
     def test_hex(self):
         self.assertRaises(TypeError, self.type2test.hex)
         self.assertRaises(TypeError, self.type2test.hex, 1)
@@ -722,26 +736,107 @@ class BytesTest(BaseBytesTest, unittest.TestCase):
 
     # Test PyBytes_FromFormat()
     def test_from_format(self):
-        test.support.import_module('ctypes')
-        from ctypes import pythonapi, py_object, c_int, c_char_p
+        ctypes = test.support.import_module('ctypes')
+        _testcapi = test.support.import_module('_testcapi')
+        from ctypes import pythonapi, py_object
+        from ctypes import (
+            c_int, c_uint,
+            c_long, c_ulong,
+            c_size_t, c_ssize_t,
+            c_char_p)
+
         PyBytes_FromFormat = pythonapi.PyBytes_FromFormat
         PyBytes_FromFormat.restype = py_object
 
+        # basic tests
         self.assertEqual(PyBytes_FromFormat(b'format'),
                          b'format')
-
+        self.assertEqual(PyBytes_FromFormat(b'Hello %s !', b'world'),
+                         b'Hello world !')
+
+        # test formatters
+        self.assertEqual(PyBytes_FromFormat(b'c=%c', c_int(0)),
+                         b'c=\0')
+        self.assertEqual(PyBytes_FromFormat(b'c=%c', c_int(ord('@'))),
+                         b'c=@')
+        self.assertEqual(PyBytes_FromFormat(b'c=%c', c_int(255)),
+                         b'c=\xff')
+        self.assertEqual(PyBytes_FromFormat(b'd=%d ld=%ld zd=%zd',
+                                            c_int(1), c_long(2),
+                                            c_size_t(3)),
+                         b'd=1 ld=2 zd=3')
+        self.assertEqual(PyBytes_FromFormat(b'd=%d ld=%ld zd=%zd',
+                                            c_int(-1), c_long(-2),
+                                            c_size_t(-3)),
+                         b'd=-1 ld=-2 zd=-3')
+        self.assertEqual(PyBytes_FromFormat(b'u=%u lu=%lu zu=%zu',
+                                            c_uint(123), c_ulong(456),
+                                            c_size_t(789)),
+                         b'u=123 lu=456 zu=789')
+        self.assertEqual(PyBytes_FromFormat(b'i=%i', c_int(123)),
+                         b'i=123')
+        self.assertEqual(PyBytes_FromFormat(b'i=%i', c_int(-123)),
+                         b'i=-123')
+        self.assertEqual(PyBytes_FromFormat(b'x=%x', c_int(0xabc)),
+                         b'x=abc')
+
+        sizeof_ptr = ctypes.sizeof(c_char_p)
+
+        if os.name == 'nt':
+            # Windows (MSCRT)
+            ptr_format = '0x%0{}X'.format(2 * sizeof_ptr)
+            def ptr_formatter(ptr):
+                return (ptr_format % ptr)
+        else:
+            # UNIX (glibc)
+            def ptr_formatter(ptr):
+                return '%#x' % ptr
+
+        ptr = 0xabcdef
+        self.assertEqual(PyBytes_FromFormat(b'ptr=%p', c_char_p(ptr)),
+                         ('ptr=' + ptr_formatter(ptr)).encode('ascii'))
+        self.assertEqual(PyBytes_FromFormat(b's=%s', c_char_p(b'cstr')),
+                         b's=cstr')
+
+        # test minimum and maximum integer values
+        size_max = c_size_t(-1).value
+        for formatstr, ctypes_type, value, py_formatter in (
+            (b'%d', c_int, _testcapi.INT_MIN, str),
+            (b'%d', c_int, _testcapi.INT_MAX, str),
+            (b'%ld', c_long, _testcapi.LONG_MIN, str),
+            (b'%ld', c_long, _testcapi.LONG_MAX, str),
+            (b'%lu', c_ulong, _testcapi.ULONG_MAX, str),
+            (b'%zd', c_ssize_t, _testcapi.PY_SSIZE_T_MIN, str),
+            (b'%zd', c_ssize_t, _testcapi.PY_SSIZE_T_MAX, str),
+            (b'%zu', c_size_t, size_max, str),
+            (b'%p', c_char_p, size_max, ptr_formatter),
+        ):
+            self.assertEqual(PyBytes_FromFormat(formatstr, ctypes_type(value)),
+                             py_formatter(value).encode('ascii')),
+
+        # width and precision (width is currently ignored)
+        self.assertEqual(PyBytes_FromFormat(b'%5s', b'a'),
+                         b'a')
+        self.assertEqual(PyBytes_FromFormat(b'%.3s', b'abcdef'),
+                         b'abc')
+
+        # '%%' formatter
+        self.assertEqual(PyBytes_FromFormat(b'%%'),
+                         b'%')
+        self.assertEqual(PyBytes_FromFormat(b'[%%]'),
+                         b'[%]')
+        self.assertEqual(PyBytes_FromFormat(b'%%%c', c_int(ord('_'))),
+                         b'%_')
+        self.assertEqual(PyBytes_FromFormat(b'%%s'),
+                         b'%s')
+
+        # Invalid formats and partial formatting
         self.assertEqual(PyBytes_FromFormat(b'%'), b'%')
-        self.assertEqual(PyBytes_FromFormat(b'%%'), b'%')
-        self.assertEqual(PyBytes_FromFormat(b'%%s'), b'%s')
-        self.assertEqual(PyBytes_FromFormat(b'[%%]'), b'[%]')
-        self.assertEqual(PyBytes_FromFormat(b'%%%c', c_int(ord('_'))), b'%_')
-
-        self.assertEqual(PyBytes_FromFormat(b'c:%c', c_int(255)),
-                         b'c:\xff')
-        self.assertEqual(PyBytes_FromFormat(b's:%s', c_char_p(b'cstr')),
-                         b's:cstr')
+        self.assertEqual(PyBytes_FromFormat(b'x=%i y=%', c_int(2), c_int(3)),
+                         b'x=2 y=%')
 
-        # Issue #19969
+        # Issue #19969: %c must raise OverflowError for values
+        # not in the range [0; 255]
         self.assertRaises(OverflowError,
                           PyBytes_FromFormat, b'%c', c_int(-1))
         self.assertRaises(OverflowError,
diff --git a/Lib/test/test_calendar.py b/Lib/test/test_calendar.py
index 80ed632588..6dad058e77 100644
--- a/Lib/test/test_calendar.py
+++ b/Lib/test/test_calendar.py
@@ -702,19 +702,19 @@ class CommandLineTestCase(unittest.TestCase):
 
     def assertFailure(self, *args):
         rc, stdout, stderr = assert_python_failure('-m', 'calendar', *args)
-        self.assertIn(b'Usage:', stderr)
+        self.assertIn(b'usage:', stderr)
         self.assertEqual(rc, 2)
 
     def test_help(self):
         stdout = self.run_ok('-h')
-        self.assertIn(b'Usage:', stdout)
+        self.assertIn(b'usage:', stdout)
         self.assertIn(b'calendar.py', stdout)
         self.assertIn(b'--help', stdout)
 
     def test_illegal_arguments(self):
         self.assertFailure('-z')
-        #self.assertFailure('spam')
-        #self.assertFailure('2004', 'spam')
+        self.assertFailure('spam')
+        self.assertFailure('2004', 'spam')
         self.assertFailure('-t', 'html', '2004', '1')
 
     def test_output_current_year(self):
@@ -815,5 +815,14 @@ class CommandLineTestCase(unittest.TestCase):
                       b'href="custom.css" />', stdout)
 
 
+class MiscTestCase(unittest.TestCase):
+    def test__all__(self):
+        blacklist = {'mdays', 'January', 'February', 'EPOCH',
+                     'MONDAY', 'TUESDAY', 'WEDNESDAY', 'THURSDAY', 'FRIDAY',
+                     'SATURDAY', 'SUNDAY', 'different_locale', 'c',
+                     'prweek', 'week', 'format', 'formatstring', 'main'}
+        support.check__all__(self, calendar, blacklist=blacklist)
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_capi.py b/Lib/test/test_capi.py
index 1eadd2249e..a0746f097a 100644
--- a/Lib/test/test_capi.py
+++ b/Lib/test/test_capi.py
@@ -4,8 +4,10 @@
 import os
 import pickle
 import random
+import re
 import subprocess
 import sys
+import sysconfig
 import textwrap
 import time
 import unittest
@@ -442,6 +444,7 @@ class EmbeddingTests(unittest.TestCase):
         self.maxDiff = None
         self.assertEqual(out.strip(), expected_output)
 
+
 class SkipitemTest(unittest.TestCase):
 
     def test_skipitem(self):
@@ -491,10 +494,10 @@ class SkipitemTest(unittest.TestCase):
                 _testcapi.parse_tuple_and_keywords(tuple_1, dict_b,
                     format.encode("ascii"), keywords)
                 when_not_skipped = False
-            except TypeError as e:
+            except SystemError as e:
                 s = "argument 1 (impossible<bad format char>)"
                 when_not_skipped = (str(e) == s)
-            except RuntimeError as e:
+            except TypeError:
                 when_not_skipped = False
 
             # test the format unit when skipped
@@ -503,7 +506,7 @@ class SkipitemTest(unittest.TestCase):
                 _testcapi.parse_tuple_and_keywords(empty_tuple, dict_b,
                     optional_format.encode("ascii"), keywords)
                 when_skipped = False
-            except RuntimeError as e:
+            except SystemError as e:
                 s = "impossible<bad format char>: '{}'".format(format)
                 when_skipped = (str(e) == s)
 
@@ -524,6 +527,7 @@ class SkipitemTest(unittest.TestCase):
         self.assertRaises(ValueError, _testcapi.parse_tuple_and_keywords,
                           (), {}, b'', [42])
 
+
 @unittest.skipUnless(threading, 'Threading required for this test.')
 class TestThreadState(unittest.TestCase):
 
@@ -548,6 +552,7 @@ class TestThreadState(unittest.TestCase):
         t.start()
         t.join()
 
+
 class Test_testcapi(unittest.TestCase):
     def test__testcapi(self):
         for name in dir(_testcapi):
@@ -556,5 +561,84 @@ class Test_testcapi(unittest.TestCase):
                     test = getattr(_testcapi, name)
                     test()
 
+
+class PyMemDebugTests(unittest.TestCase):
+    PYTHONMALLOC = 'debug'
+    # '0x04c06e0' or '04C06E0'
+    PTR_REGEX = r'(?:0x)?[0-9a-fA-F]+'
+
+    def check(self, code):
+        with support.SuppressCrashReport():
+            out = assert_python_failure('-c', code,
+                                        PYTHONMALLOC=self.PYTHONMALLOC)
+        stderr = out.err
+        return stderr.decode('ascii', 'replace')
+
+    def test_buffer_overflow(self):
+        out = self.check('import _testcapi; _testcapi.pymem_buffer_overflow()')
+        regex = (r"Debug memory block at address p={ptr}: API 'm'\n"
+                 r"    16 bytes originally requested\n"
+                 r"    The [0-9] pad bytes at p-[0-9] are FORBIDDENBYTE, as expected.\n"
+                 r"    The [0-9] pad bytes at tail={ptr} are not all FORBIDDENBYTE \(0x[0-9a-f]{{2}}\):\n"
+                 r"        at tail\+0: 0x78 \*\*\* OUCH\n"
+                 r"        at tail\+1: 0xfb\n"
+                 r"        at tail\+2: 0xfb\n"
+                 r"        .*\n"
+                 r"    The block was made by call #[0-9]+ to debug malloc/realloc.\n"
+                 r"    Data at p: cb cb cb .*\n"
+                 r"\n"
+                 r"Fatal Python error: bad trailing pad byte")
+        regex = regex.format(ptr=self.PTR_REGEX)
+        regex = re.compile(regex, flags=re.DOTALL)
+        self.assertRegex(out, regex)
+
+    def test_api_misuse(self):
+        out = self.check('import _testcapi; _testcapi.pymem_api_misuse()')
+        regex = (r"Debug memory block at address p={ptr}: API 'm'\n"
+                 r"    16 bytes originally requested\n"
+                 r"    The [0-9] pad bytes at p-[0-9] are FORBIDDENBYTE, as expected.\n"
+                 r"    The [0-9] pad bytes at tail={ptr} are FORBIDDENBYTE, as expected.\n"
+                 r"    The block was made by call #[0-9]+ to debug malloc/realloc.\n"
+                 r"    Data at p: cb cb cb .*\n"
+                 r"\n"
+                 r"Fatal Python error: bad ID: Allocated using API 'm', verified using API 'r'\n")
+        regex = regex.format(ptr=self.PTR_REGEX)
+        self.assertRegex(out, regex)
+
+    def check_malloc_without_gil(self, code):
+        out = self.check(code)
+        expected = ('Fatal Python error: Python memory allocator called '
+                    'without holding the GIL')
+        self.assertIn(expected, out)
+
+    def test_pymem_malloc_without_gil(self):
+        # Debug hooks must raise an error if PyMem_Malloc() is called
+        # without holding the GIL
+        code = 'import _testcapi; _testcapi.pymem_malloc_without_gil()'
+        self.check_malloc_without_gil(code)
+
+    def test_pyobject_malloc_without_gil(self):
+        # Debug hooks must raise an error if PyObject_Malloc() is called
+        # without holding the GIL
+        code = 'import _testcapi; _testcapi.pyobject_malloc_without_gil()'
+        self.check_malloc_without_gil(code)
+
+
+class PyMemMallocDebugTests(PyMemDebugTests):
+    PYTHONMALLOC = 'malloc_debug'
+
+
+@unittest.skipUnless(sysconfig.get_config_var('WITH_PYMALLOC') == 1,
+                     'need pymalloc')
+class PyMemPymallocDebugTests(PyMemDebugTests):
+    PYTHONMALLOC = 'pymalloc_debug'
+
+
+@unittest.skipUnless(Py_DEBUG, 'need Py_DEBUG')
+class PyMemDefaultTests(PyMemDebugTests):
+    # test default allocator of Python compiled in debug mode
+    PYTHONMALLOC = ''
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_cgi.py b/Lib/test/test_cgi.py
index ab9f6ab6a5..164784923a 100644
--- a/Lib/test/test_cgi.py
+++ b/Lib/test/test_cgi.py
@@ -7,6 +7,7 @@ import unittest
 import warnings
 from collections import namedtuple
 from io import StringIO, BytesIO
+from test import support
 
 class HackedSysModule:
     # The regression test will have real values in sys.argv, which
@@ -473,6 +474,11 @@ this is the content of the fake file
             cgi.parse_header('form-data; name="files"; filename="fo\\"o;bar"'),
             ("form-data", {"name": "files", "filename": 'fo"o;bar'}))
 
+    def test_all(self):
+        blacklist = {"logfile", "logfp", "initlog", "dolog", "nolog",
+                     "closelog", "log", "maxlen", "valid_boundary"}
+        support.check__all__(self, cgi, blacklist=blacklist)
+
 
 BOUNDARY = "---------------------------721837373350705526688164684"
 
diff --git a/Lib/test/test_charmapcodec.py b/Lib/test/test_charmapcodec.py
index 4064aef935..0d4594d8c0 100644
--- a/Lib/test/test_charmapcodec.py
+++ b/Lib/test/test_charmapcodec.py
@@ -9,7 +9,7 @@ Written by Marc-Andre Lemburg (mal@lemburg.com).
 
 """#"
 
-import test.support, unittest
+import unittest
 
 import codecs
 
diff --git a/Lib/test/test_class.py b/Lib/test/test_class.py
index 4d554a397b..e02a3cbb97 100644
--- a/Lib/test/test_class.py
+++ b/Lib/test/test_class.py
@@ -568,5 +568,15 @@ class ClassTests(unittest.TestCase):
         a = A(hash(A.f)^(-1))
         hash(a.f)
 
+    def test_class_repr(self):
+        # We should get the address of the object
+        class A:
+            pass
+
+        result = repr(A)
+        self.assertRegex(result,
+            "<class 'test.test_class.ClassTests.test_class_repr.<locals>.A'"
+            " at 0x.+>")
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/Lib/test/test_cmd_line.py b/Lib/test/test_cmd_line.py
index dce418b65c..8faa8e1986 100644
--- a/Lib/test/test_cmd_line.py
+++ b/Lib/test/test_cmd_line.py
@@ -348,8 +348,9 @@ class CmdLineTest(unittest.TestCase):
             test.support.SuppressCrashReport().__enter__()
             sys.stdout.write('x')
             os.close(sys.stdout.fileno())"""
-        rc, out, err = assert_python_ok('-c', code)
+        rc, out, err = assert_python_failure('-c', code)
         self.assertEqual(b'', out)
+        self.assertEqual(120, rc)
         self.assertRegex(err.decode('ascii', 'ignore'),
                          'Exception ignored in.*\nOSError: .*')
 
diff --git a/Lib/test/test_cmd_line_script.py b/Lib/test/test_cmd_line_script.py
index b2be9b1b70..e7c6351317 100644
--- a/Lib/test/test_cmd_line_script.py
+++ b/Lib/test/test_cmd_line_script.py
@@ -127,7 +127,10 @@ class CmdLineTest(unittest.TestCase):
             print(printed_package)
             print(printed_argv0)
             print(printed_cwd)
-        self.assertIn(printed_loader.encode('utf-8'), data)
+        expected = printed_loader.encode('utf-8')
+        idx = expected.find(b"at 0x")
+        expected = expected[:idx]
+        self.assertIn(expected, data)
         self.assertIn(printed_file.encode('utf-8'), data)
         self.assertIn(printed_package.encode('utf-8'), data)
         self.assertIn(printed_argv0.encode('utf-8'), data)
@@ -138,9 +141,8 @@ class CmdLineTest(unittest.TestCase):
                             expected_argv0, expected_path0,
                             expected_package, expected_loader,
                             *cmd_line_switches):
-        if not __debug__:
-            cmd_line_switches += ('-' + 'O' * sys.flags.optimize,)
-        run_args = cmd_line_switches + (script_name,) + tuple(example_args)
+        run_args = [*support.optim_args_from_interpreter_flags(),
+                    *cmd_line_switches, script_name, *example_args]
         rc, out, err = assert_python_ok(*run_args, __isolated=False)
         self._check_output(script_name, rc, out + err, expected_file,
                            expected_argv0, expected_path0,
@@ -159,6 +161,8 @@ class CmdLineTest(unittest.TestCase):
     def test_dash_c_loader(self):
         rc, out, err = assert_python_ok("-c", "print(__loader__)")
         expected = repr(importlib.machinery.BuiltinImporter).encode("utf-8")
+        idx = expected.find(b"at 0x")
+        expected = expected[:idx]
         self.assertIn(expected, out)
 
     def test_stdin_loader(self):
@@ -172,6 +176,8 @@ class CmdLineTest(unittest.TestCase):
         finally:
             out = kill_python(p)
         expected = repr(importlib.machinery.BuiltinImporter).encode("utf-8")
+        idx = expected.find(b"at 0x")
+        expected = expected[:idx]
         self.assertIn(expected, out)
 
     @contextlib.contextmanager
diff --git a/Lib/test/test_codeccallbacks.py b/Lib/test/test_codeccallbacks.py
index ee1e28a763..c8cdacf718 100644
--- a/Lib/test/test_codeccallbacks.py
+++ b/Lib/test/test_codeccallbacks.py
@@ -4,7 +4,6 @@ import sys
 import test.support
 import unicodedata
 import unittest
-import warnings
 
 class PosReturn:
     # this can be used for configurable callbacks
diff --git a/Lib/test/test_codecencodings_cn.py b/Lib/test/test_codecencodings_cn.py
index d0e3a15d16..3bdf7d0e14 100644
--- a/Lib/test/test_codecencodings_cn.py
+++ b/Lib/test/test_codecencodings_cn.py
@@ -3,7 +3,6 @@
 #   Codec encoding tests for PRC encodings.
 #
 
-from test import support
 from test import multibytecodec_support
 import unittest
 
diff --git a/Lib/test/test_codecencodings_hk.py b/Lib/test/test_codecencodings_hk.py
index bb9be11184..c5e2f999ef 100644
--- a/Lib/test/test_codecencodings_hk.py
+++ b/Lib/test/test_codecencodings_hk.py
@@ -3,7 +3,6 @@
 #   Codec encoding tests for HongKong encodings.
 #
 
-from test import support
 from test import multibytecodec_support
 import unittest
 
diff --git a/Lib/test/test_codecencodings_iso2022.py b/Lib/test/test_codecencodings_iso2022.py
index 8a3ca70de6..00ea1c39dd 100644
--- a/Lib/test/test_codecencodings_iso2022.py
+++ b/Lib/test/test_codecencodings_iso2022.py
@@ -1,6 +1,5 @@
 # Codec encoding tests for ISO 2022 encodings.
 
-from test import support
 from test import multibytecodec_support
 import unittest
 
diff --git a/Lib/test/test_codecencodings_jp.py b/Lib/test/test_codecencodings_jp.py
index 44b63a00c8..94378d124f 100644
--- a/Lib/test/test_codecencodings_jp.py
+++ b/Lib/test/test_codecencodings_jp.py
@@ -3,7 +3,6 @@
 #   Codec encoding tests for Japanese encodings.
 #
 
-from test import support
 from test import multibytecodec_support
 import unittest
 
diff --git a/Lib/test/test_codecencodings_kr.py b/Lib/test/test_codecencodings_kr.py
index b6a74fbd5b..863d16b8fd 100644
--- a/Lib/test/test_codecencodings_kr.py
+++ b/Lib/test/test_codecencodings_kr.py
@@ -3,7 +3,6 @@
 #   Codec encoding tests for ROK encodings.
 #
 
-from test import support
 from test import multibytecodec_support
 import unittest
 
diff --git a/Lib/test/test_codecencodings_tw.py b/Lib/test/test_codecencodings_tw.py
index 9174296726..bb1d133cad 100644
--- a/Lib/test/test_codecencodings_tw.py
+++ b/Lib/test/test_codecencodings_tw.py
@@ -3,7 +3,6 @@
 #   Codec encoding tests for ROC encodings.
 #
 
-from test import support
 from test import multibytecodec_support
 import unittest
 
diff --git a/Lib/test/test_codecmaps_cn.py b/Lib/test/test_codecmaps_cn.py
index f1bd3840c9..89e51c6e2a 100644
--- a/Lib/test/test_codecmaps_cn.py
+++ b/Lib/test/test_codecmaps_cn.py
@@ -3,7 +3,6 @@
 #   Codec mapping tests for PRC encodings
 #
 
-from test import support
 from test import multibytecodec_support
 import unittest
 
diff --git a/Lib/test/test_codecmaps_hk.py b/Lib/test/test_codecmaps_hk.py
index 4c0c4156da..7a48d24fdd 100644
--- a/Lib/test/test_codecmaps_hk.py
+++ b/Lib/test/test_codecmaps_hk.py
@@ -3,7 +3,6 @@
 #   Codec mapping tests for HongKong encodings
 #
 
-from test import support
 from test import multibytecodec_support
 import unittest
 
diff --git a/Lib/test/test_codecmaps_jp.py b/Lib/test/test_codecmaps_jp.py
index 577382329a..fdfec8085b 100644
--- a/Lib/test/test_codecmaps_jp.py
+++ b/Lib/test/test_codecmaps_jp.py
@@ -3,7 +3,6 @@
 #   Codec mapping tests for Japanese encodings
 #
 
-from test import support
 from test import multibytecodec_support
 import unittest
 
diff --git a/Lib/test/test_codecmaps_kr.py b/Lib/test/test_codecmaps_kr.py
index 6cb41c8b29..471cd749b8 100644
--- a/Lib/test/test_codecmaps_kr.py
+++ b/Lib/test/test_codecmaps_kr.py
@@ -3,7 +3,6 @@
 #   Codec mapping tests for ROK encodings
 #
 
-from test import support
 from test import multibytecodec_support
 import unittest
 
diff --git a/Lib/test/test_codecmaps_tw.py b/Lib/test/test_codecmaps_tw.py
index 2ea44b56f1..145a97d511 100644
--- a/Lib/test/test_codecmaps_tw.py
+++ b/Lib/test/test_codecmaps_tw.py
@@ -3,7 +3,6 @@
 #   Codec mapping tests for ROC encodings
 #
 
-from test import support
 from test import multibytecodec_support
 import unittest
 
diff --git a/Lib/test/test_codecs.py b/Lib/test/test_codecs.py
index 0479542745..d8753402ef 100644
--- a/Lib/test/test_codecs.py
+++ b/Lib/test/test_codecs.py
@@ -4,7 +4,6 @@ import io
 import locale
 import sys
 import unittest
-import warnings
 import encodings
 
 from test import support
@@ -27,6 +26,7 @@ def coding_checker(self, coder):
         self.assertEqual(coder(input), (expect, len(input)))
     return check
 
+
 class Queue(object):
     """
     queue: write bytes at one end, read bytes from the other end
@@ -47,6 +47,7 @@ class Queue(object):
             self._buffer = self._buffer[size:]
             return s
 
+
 class MixInCheckStateHandling:
     def check_state_handling_decode(self, encoding, u, s):
         for i in range(len(s)+1):
@@ -80,6 +81,7 @@ class MixInCheckStateHandling:
             part2 = d.encode(u[i:], True)
             self.assertEqual(s, part1+part2)
 
+
 class ReadTest(MixInCheckStateHandling):
     def check_partial(self, input, partialresults):
         # get a StreamReader for the encoding and feed the bytestring version
@@ -358,6 +360,12 @@ class ReadTest(MixInCheckStateHandling):
         self.assertEqual("[\uDC80]".encode(self.encoding, "replace"),
                          "[?]".encode(self.encoding))
 
+        # sequential surrogate characters
+        self.assertEqual("[\uD800\uDC80]".encode(self.encoding, "ignore"),
+                         "[]".encode(self.encoding))
+        self.assertEqual("[\uD800\uDC80]".encode(self.encoding, "replace"),
+                         "[??]".encode(self.encoding))
+
         bom = "".encode(self.encoding)
         for before, after in [("\U00010fff", "A"), ("[", "]"),
                               ("A", "\U00010fff")]:
@@ -383,6 +391,7 @@ class ReadTest(MixInCheckStateHandling):
             self.assertEqual(test_sequence.decode(self.encoding, "backslashreplace"),
                              before + backslashreplace + after)
 
+
 class UTF32Test(ReadTest, unittest.TestCase):
     encoding = "utf-32"
     if sys.byteorder == 'little':
@@ -478,6 +487,7 @@ class UTF32Test(ReadTest, unittest.TestCase):
         self.assertEqual('\U00010000' * 1024,
                          codecs.utf_32_decode(encoded_be)[0])
 
+
 class UTF32LETest(ReadTest, unittest.TestCase):
     encoding = "utf-32-le"
     ill_formed_sequence = b"\x80\xdc\x00\x00"
@@ -523,6 +533,7 @@ class UTF32LETest(ReadTest, unittest.TestCase):
         self.assertEqual('\U00010000' * 1024,
                          codecs.utf_32_le_decode(encoded)[0])
 
+
 class UTF32BETest(ReadTest, unittest.TestCase):
     encoding = "utf-32-be"
     ill_formed_sequence = b"\x00\x00\xdc\x80"
@@ -747,6 +758,7 @@ class UTF8Test(ReadTest, unittest.TestCase):
     encoding = "utf-8"
     ill_formed_sequence = b"\xed\xb2\x80"
     ill_formed_sequence_replace = "\ufffd" * 3
+    BOM = b''
 
     def test_partial(self):
         self.check_partial(
@@ -775,27 +787,49 @@ class UTF8Test(ReadTest, unittest.TestCase):
         self.check_state_handling_decode(self.encoding,
                                          u, u.encode(self.encoding))
 
+    def test_decode_error(self):
+        for data, error_handler, expected in (
+            (b'[\x80\xff]', 'ignore', '[]'),
+            (b'[\x80\xff]', 'replace', '[\ufffd\ufffd]'),
+            (b'[\x80\xff]', 'surrogateescape', '[\udc80\udcff]'),
+            (b'[\x80\xff]', 'backslashreplace', '[\\x80\\xff]'),
+        ):
+            with self.subTest(data=data, error_handler=error_handler,
+                              expected=expected):
+                self.assertEqual(data.decode(self.encoding, error_handler),
+                                 expected)
+
     def test_lone_surrogates(self):
         super().test_lone_surrogates()
         # not sure if this is making sense for
         # UTF-16 and UTF-32
-        self.assertEqual("[\uDC80]".encode('utf-8', "surrogateescape"),
-                         b'[\x80]')
+        self.assertEqual("[\uDC80]".encode(self.encoding, "surrogateescape"),
+                         self.BOM + b'[\x80]')
+
+        with self.assertRaises(UnicodeEncodeError) as cm:
+            "[\uDC80\uD800\uDFFF]".encode(self.encoding, "surrogateescape")
+        exc = cm.exception
+        self.assertEqual(exc.object[exc.start:exc.end], '\uD800\uDFFF')
 
     def test_surrogatepass_handler(self):
-        self.assertEqual("abc\ud800def".encode("utf-8", "surrogatepass"),
-                         b"abc\xed\xa0\x80def")
-        self.assertEqual(b"abc\xed\xa0\x80def".decode("utf-8", "surrogatepass"),
+        self.assertEqual("abc\ud800def".encode(self.encoding, "surrogatepass"),
+                         self.BOM + b"abc\xed\xa0\x80def")
+        self.assertEqual("\U00010fff\uD800".encode(self.encoding, "surrogatepass"),
+                         self.BOM + b"\xf0\x90\xbf\xbf\xed\xa0\x80")
+        self.assertEqual("[\uD800\uDC80]".encode(self.encoding, "surrogatepass"),
+                         self.BOM + b'[\xed\xa0\x80\xed\xb2\x80]')
+
+        self.assertEqual(b"abc\xed\xa0\x80def".decode(self.encoding, "surrogatepass"),
                          "abc\ud800def")
-        self.assertEqual("\U00010fff\uD800".encode("utf-8", "surrogatepass"),
-                         b"\xf0\x90\xbf\xbf\xed\xa0\x80")
-        self.assertEqual(b"\xf0\x90\xbf\xbf\xed\xa0\x80".decode("utf-8", "surrogatepass"),
+        self.assertEqual(b"\xf0\x90\xbf\xbf\xed\xa0\x80".decode(self.encoding, "surrogatepass"),
                          "\U00010fff\uD800")
+
         self.assertTrue(codecs.lookup_error("surrogatepass"))
         with self.assertRaises(UnicodeDecodeError):
-            b"abc\xed\xa0".decode("utf-8", "surrogatepass")
+            b"abc\xed\xa0".decode(self.encoding, "surrogatepass")
         with self.assertRaises(UnicodeDecodeError):
-            b"abc\xed\xa0z".decode("utf-8", "surrogatepass")
+            b"abc\xed\xa0z".decode(self.encoding, "surrogatepass")
+
 
 @unittest.skipUnless(sys.platform == 'win32',
                      'cp65001 is a Windows-only codec')
@@ -1059,6 +1093,7 @@ class ReadBufferTest(unittest.TestCase):
 
 class UTF8SigTest(UTF8Test, unittest.TestCase):
     encoding = "utf-8-sig"
+    BOM = codecs.BOM_UTF8
 
     def test_partial(self):
         self.check_partial(
@@ -1194,6 +1229,7 @@ class EscapeDecodeTest(unittest.TestCase):
         self.assertEqual(decode(br"[\x0]\x0", "ignore"), (b"[]", 8))
         self.assertEqual(decode(br"[\x0]\x0", "replace"), (b"[?]?", 8))
 
+
 class RecodingTest(unittest.TestCase):
     def test_recoding(self):
         f = io.BytesIO()
@@ -1313,6 +1349,7 @@ for i in punycode_testcases:
     if len(i)!=2:
         print(repr(i))
 
+
 class PunycodeTest(unittest.TestCase):
     def test_encode(self):
         for uni, puny in punycode_testcases:
@@ -1332,6 +1369,7 @@ class PunycodeTest(unittest.TestCase):
             puny = puny.decode("ascii").encode("ascii")
             self.assertEqual(uni, puny.decode("punycode"))
 
+
 class UnicodeInternalTest(unittest.TestCase):
     @unittest.skipUnless(SIZEOF_WCHAR_T == 4, 'specific to 32-bit wchar_t')
     def test_bug1251300(self):
@@ -1586,6 +1624,7 @@ class NameprepTest(unittest.TestCase):
                 except Exception as e:
                     raise support.TestFailed("Test 3.%d: %s" % (pos+1, str(e)))
 
+
 class IDNACodecTest(unittest.TestCase):
     def test_builtin_decode(self):
         self.assertEqual(str(b"python.org", "idna"), "python.org")
@@ -1672,6 +1711,7 @@ class IDNACodecTest(unittest.TestCase):
             self.assertRaises(Exception,
                 b"python.org".decode, "idna", errors)
 
+
 class CodecsModuleTest(unittest.TestCase):
 
     def test_decode(self):
@@ -1780,6 +1820,7 @@ class CodecsModuleTest(unittest.TestCase):
             self.assertRaises(UnicodeError,
                 codecs.decode, b'abc', 'undefined', errors)
 
+
 class StreamReaderTest(unittest.TestCase):
 
     def setUp(self):
@@ -1790,6 +1831,7 @@ class StreamReaderTest(unittest.TestCase):
         f = self.reader(self.stream)
         self.assertEqual(f.readlines(), ['\ud55c\n', '\uae00'])
 
+
 class EncodedFileTest(unittest.TestCase):
 
     def test_basic(self):
@@ -1920,6 +1962,7 @@ broken_unicode_with_stateful = [
     "unicode_internal"
 ]
 
+
 class BasicUnicodeTest(unittest.TestCase, MixInCheckStateHandling):
     def test_basics(self):
         s = "abc123"  # all codecs should be able to encode these
@@ -2082,6 +2125,7 @@ class BasicUnicodeTest(unittest.TestCase, MixInCheckStateHandling):
                 self.check_state_handling_decode(encoding, u, u.encode(encoding))
                 self.check_state_handling_encode(encoding, u, u.encode(encoding))
 
+
 class CharmapTest(unittest.TestCase):
     def test_decode_with_string_map(self):
         self.assertEqual(
@@ -2332,6 +2376,7 @@ class WithStmtTest(unittest.TestCase):
                                        info.streamwriter, 'strict') as srw:
             self.assertEqual(srw.read(), "\xfc")
 
+
 class TypesTest(unittest.TestCase):
     def test_decode_unicode(self):
         # Most decoders don't accept unicode input
@@ -2622,6 +2667,7 @@ else:
     bytes_transform_encodings.append("bz2_codec")
     transform_aliases["bz2_codec"] = ["bz2"]
 
+
 class TransformCodecTest(unittest.TestCase):
 
     def test_basics(self):
@@ -3099,5 +3145,81 @@ class CodePageTest(unittest.TestCase):
         self.assertEqual(decoded, ('abc', 3))
 
 
+class ASCIITest(unittest.TestCase):
+    def test_encode(self):
+        self.assertEqual('abc123'.encode('ascii'), b'abc123')
+
+    def test_encode_error(self):
+        for data, error_handler, expected in (
+            ('[\x80\xff\u20ac]', 'ignore', b'[]'),
+            ('[\x80\xff\u20ac]', 'replace', b'[???]'),
+            ('[\x80\xff\u20ac]', 'xmlcharrefreplace', b'[&#128;&#255;&#8364;]'),
+            ('[\x80\xff\u20ac\U000abcde]', 'backslashreplace',
+             b'[\\x80\\xff\\u20ac\\U000abcde]'),
+            ('[\udc80\udcff]', 'surrogateescape', b'[\x80\xff]'),
+        ):
+            with self.subTest(data=data, error_handler=error_handler,
+                              expected=expected):
+                self.assertEqual(data.encode('ascii', error_handler),
+                                 expected)
+
+    def test_encode_surrogateescape_error(self):
+        with self.assertRaises(UnicodeEncodeError):
+            # the first character can be decoded, but not the second
+            '\udc80\xff'.encode('ascii', 'surrogateescape')
+
+    def test_decode(self):
+        self.assertEqual(b'abc'.decode('ascii'), 'abc')
+
+    def test_decode_error(self):
+        for data, error_handler, expected in (
+            (b'[\x80\xff]', 'ignore', '[]'),
+            (b'[\x80\xff]', 'replace', '[\ufffd\ufffd]'),
+            (b'[\x80\xff]', 'surrogateescape', '[\udc80\udcff]'),
+            (b'[\x80\xff]', 'backslashreplace', '[\\x80\\xff]'),
+        ):
+            with self.subTest(data=data, error_handler=error_handler,
+                              expected=expected):
+                self.assertEqual(data.decode('ascii', error_handler),
+                                 expected)
+
+
+class Latin1Test(unittest.TestCase):
+    def test_encode(self):
+        for data, expected in (
+            ('abc', b'abc'),
+            ('\x80\xe9\xff', b'\x80\xe9\xff'),
+        ):
+            with self.subTest(data=data, expected=expected):
+                self.assertEqual(data.encode('latin1'), expected)
+
+    def test_encode_errors(self):
+        for data, error_handler, expected in (
+            ('[\u20ac\udc80]', 'ignore', b'[]'),
+            ('[\u20ac\udc80]', 'replace', b'[??]'),
+            ('[\u20ac\U000abcde]', 'backslashreplace',
+             b'[\\u20ac\\U000abcde]'),
+            ('[\u20ac\udc80]', 'xmlcharrefreplace', b'[&#8364;&#56448;]'),
+            ('[\udc80\udcff]', 'surrogateescape', b'[\x80\xff]'),
+        ):
+            with self.subTest(data=data, error_handler=error_handler,
+                              expected=expected):
+                self.assertEqual(data.encode('latin1', error_handler),
+                                 expected)
+
+    def test_encode_surrogateescape_error(self):
+        with self.assertRaises(UnicodeEncodeError):
+            # the first character can be decoded, but not the second
+            '\udc80\u20ac'.encode('latin1', 'surrogateescape')
+
+    def test_decode(self):
+        for data, expected in (
+            (b'abc', 'abc'),
+            (b'[\x80\xff]', '[\x80\xff]'),
+        ):
+            with self.subTest(data=data, expected=expected):
+                self.assertEqual(data.decode('latin1'), expected)
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_codeop.py b/Lib/test/test_codeop.py
index 509bf5dfd2..98da26fa5d 100644
--- a/Lib/test/test_codeop.py
+++ b/Lib/test/test_codeop.py
@@ -282,7 +282,6 @@ class CodeopTests(unittest.TestCase):
         ai("if (a == 1 and b = 2): pass")
 
         ai("del 1")
-        ai("del ()")
         ai("del (1,)")
         ai("del [1]")
         ai("del '1'")
diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py
index 4c32e094f9..3824a87365 100644
--- a/Lib/test/test_collections.py
+++ b/Lib/test/test_collections.py
@@ -20,10 +20,10 @@ from collections import UserDict, UserString, UserList
 from collections import ChainMap
 from collections import deque
 from collections.abc import Awaitable, Coroutine, AsyncIterator, AsyncIterable
-from collections.abc import Hashable, Iterable, Iterator, Generator
+from collections.abc import Hashable, Iterable, Iterator, Generator, Reversible
 from collections.abc import Sized, Container, Callable
 from collections.abc import Set, MutableSet
-from collections.abc import Mapping, MutableMapping, KeysView, ItemsView
+from collections.abc import Mapping, MutableMapping, KeysView, ItemsView, ValuesView
 from collections.abc import Sequence, MutableSequence
 from collections.abc import ByteString
 
@@ -689,6 +689,31 @@ class TestOneTrickPonyABCs(ABCTestCase):
         self.validate_abstract_methods(Iterable, '__iter__')
         self.validate_isinstance(Iterable, '__iter__')
 
+    def test_Reversible(self):
+        # Check some non-reversibles
+        non_samples = [None, 42, 3.14, 1j, dict(), set(), frozenset()]
+        for x in non_samples:
+            self.assertNotIsInstance(x, Reversible)
+            self.assertFalse(issubclass(type(x), Reversible), repr(type(x)))
+        # Check some reversibles
+        samples = [tuple(), list()]
+        for x in samples:
+            self.assertIsInstance(x, Reversible)
+            self.assertTrue(issubclass(type(x), Reversible), repr(type(x)))
+        # Check also Mapping, MutableMapping, and Sequence
+        self.assertTrue(issubclass(Sequence, Reversible), repr(Sequence))
+        self.assertFalse(issubclass(Mapping, Reversible), repr(Mapping))
+        self.assertFalse(issubclass(MutableMapping, Reversible), repr(MutableMapping))
+        # Check direct subclassing
+        class R(Reversible):
+            def __iter__(self):
+                return iter(list())
+            def __reversed__(self):
+                return iter(list())
+        self.assertEqual(list(reversed(R())), [])
+        self.assertFalse(issubclass(float, R))
+        self.validate_abstract_methods(Reversible, '__reversed__', '__iter__')
+
     def test_Iterator(self):
         non_samples = [None, 42, 3.14, 1j, b"", "", (), [], {}, set()]
         for x in non_samples:
@@ -842,14 +867,14 @@ class TestOneTrickPonyABCs(ABCTestCase):
         self.validate_isinstance(Callable, '__call__')
 
     def test_direct_subclassing(self):
-        for B in Hashable, Iterable, Iterator, Sized, Container, Callable:
+        for B in Hashable, Iterable, Iterator, Reversible, Sized, Container, Callable:
             class C(B):
                 pass
             self.assertTrue(issubclass(C, B))
             self.assertFalse(issubclass(int, C))
 
     def test_registration(self):
-        for B in Hashable, Iterable, Iterator, Sized, Container, Callable:
+        for B in Hashable, Iterable, Iterator, Reversible, Sized, Container, Callable:
             class C:
                 __hash__ = None  # Make sure it isn't hashable by default
             self.assertFalse(issubclass(C, B), B.__name__)
@@ -1049,6 +1074,26 @@ class TestCollectionABCs(ABCTestCase):
         self.assertFalse(ncs > cs)
         self.assertTrue(ncs >= cs)
 
+    def test_issue26915(self):
+        # Container membership test should check identity first
+        class CustomEqualObject:
+            def __eq__(self, other):
+                return False
+        class CustomSequence(list):
+            def __contains__(self, value):
+                return Sequence.__contains__(self, value)
+
+        nan = float('nan')
+        obj = CustomEqualObject()
+        containers = [
+            CustomSequence([nan, obj]),
+            ItemsView({1: nan, 2: obj}),
+            ValuesView({1: nan, 2: obj})
+        ]
+        for container in containers:
+            for elem in container:
+                self.assertIn(elem, container)
+
     def assertSameSet(self, s1, s2):
         # coerce both to a real set then check equality
         self.assertSetEqual(set(s1), set(s2))
diff --git a/Lib/test/test_compileall.py b/Lib/test/test_compileall.py
index 2ce8a61e39..9b424a7250 100644
--- a/Lib/test/test_compileall.py
+++ b/Lib/test/test_compileall.py
@@ -1,6 +1,7 @@
 import sys
 import compileall
 import importlib.util
+import test.test_importlib.util
 import os
 import pathlib
 import py_compile
@@ -40,6 +41,11 @@ class CompileallTests(unittest.TestCase):
     def tearDown(self):
         shutil.rmtree(self.directory)
 
+    def add_bad_source_file(self):
+        self.bad_source_path = os.path.join(self.directory, '_test_bad.py')
+        with open(self.bad_source_path, 'w') as file:
+            file.write('x (\n')
+
     def data(self):
         with open(self.bc_path, 'rb') as file:
             data = file.read(8)
@@ -78,15 +84,43 @@ class CompileallTests(unittest.TestCase):
                 os.unlink(fn)
             except:
                 pass
-        compileall.compile_file(self.source_path, force=False, quiet=True)
+        self.assertTrue(compileall.compile_file(self.source_path,
+                                                force=False, quiet=True))
         self.assertTrue(os.path.isfile(self.bc_path) and
                         not os.path.isfile(self.bc_path2))
         os.unlink(self.bc_path)
-        compileall.compile_dir(self.directory, force=False, quiet=True)
+        self.assertTrue(compileall.compile_dir(self.directory, force=False,
+                                               quiet=True))
         self.assertTrue(os.path.isfile(self.bc_path) and
                         os.path.isfile(self.bc_path2))
         os.unlink(self.bc_path)
         os.unlink(self.bc_path2)
+        # Test against bad files
+        self.add_bad_source_file()
+        self.assertFalse(compileall.compile_file(self.bad_source_path,
+                                                 force=False, quiet=2))
+        self.assertFalse(compileall.compile_dir(self.directory,
+                                                force=False, quiet=2))
+
+    def test_compile_path(self):
+        # Exclude Lib/test/ which contains invalid Python files like
+        # Lib/test/badsyntax_pep3120.py
+        testdir = os.path.realpath(os.path.dirname(__file__))
+        if testdir in sys.path:
+            self.addCleanup(setattr, sys, 'path', sys.path)
+
+            sys.path = list(sys.path)
+            try:
+                sys.path.remove(testdir)
+            except ValueError:
+                pass
+
+        self.assertTrue(compileall.compile_path(quiet=2))
+
+        with test.test_importlib.util.import_state(path=[self.directory]):
+            self.add_bad_source_file()
+            self.assertFalse(compileall.compile_path(skip_curdir=False,
+                                                     force=True, quiet=2))
 
     def test_no_pycache_in_non_package(self):
         # Bug 8563 reported that __pycache__ directories got created by
@@ -197,10 +231,9 @@ class CommandLineTests(unittest.TestCase):
             raise unittest.SkipTest('not all entries on sys.path are writable')
 
     def _get_run_args(self, args):
-        interp_args = ['-S']
-        if sys.flags.optimize:
-            interp_args.append({1 : '-O', 2 : '-OO'}[sys.flags.optimize])
-        return interp_args + ['-m', 'compileall'] + list(args)
+        return [*support.optim_args_from_interpreter_flags(),
+                '-S', '-m', 'compileall',
+                *args]
 
     def assertRunOK(self, *args, **env_vars):
         rc, out, err = script_helper.assert_python_ok(
diff --git a/Lib/test/test_contextlib.py b/Lib/test/test_contextlib.py
index 30a6377bed..5c8bc981fe 100644
--- a/Lib/test/test_contextlib.py
+++ b/Lib/test/test_contextlib.py
@@ -12,6 +12,39 @@ except ImportError:
     threading = None
 
 
+class TestAbstractContextManager(unittest.TestCase):
+
+    def test_enter(self):
+        class DefaultEnter(AbstractContextManager):
+            def __exit__(self, *args):
+                super().__exit__(*args)
+
+        manager = DefaultEnter()
+        self.assertIs(manager.__enter__(), manager)
+
+    def test_exit_is_abstract(self):
+        class MissingExit(AbstractContextManager):
+            pass
+
+        with self.assertRaises(TypeError):
+            MissingExit()
+
+    def test_structural_subclassing(self):
+        class ManagerFromScratch:
+            def __enter__(self):
+                return self
+            def __exit__(self, exc_type, exc_value, traceback):
+                return None
+
+        self.assertTrue(issubclass(ManagerFromScratch, AbstractContextManager))
+
+        class DefaultEnter(AbstractContextManager):
+            def __exit__(self, *args):
+                super().__exit__(*args)
+
+        self.assertTrue(issubclass(DefaultEnter, AbstractContextManager))
+
+
 class ContextManagerTestCase(unittest.TestCase):
 
     def test_contextmanager_plain(self):
@@ -89,7 +122,7 @@ class ContextManagerTestCase(unittest.TestCase):
         def woohoo():
             yield
         try:
-            with self.assertWarnsRegex(PendingDeprecationWarning,
+            with self.assertWarnsRegex(DeprecationWarning,
                                        "StopIteration"):
                 with woohoo():
                     raise stop_exc
diff --git a/Lib/test/test_copy.py b/Lib/test/test_copy.py
index 0e1f670bf0..45a692022f 100644
--- a/Lib/test/test_copy.py
+++ b/Lib/test/test_copy.py
@@ -98,7 +98,7 @@ class TestCopy(unittest.TestCase):
         tests = [None, ..., NotImplemented,
                  42, 2**100, 3.14, True, False, 1j,
                  "hello", "hello\u1234", f.__code__,
-                 b"world", bytes(range(256)), range(10),
+                 b"world", bytes(range(256)), range(10), slice(1, 10, 2),
                  NewStyle, Classic, max, WithMetaclass]
         for x in tests:
             self.assertIs(copy.copy(x), x)
diff --git a/Lib/test/test_cprofile.py b/Lib/test/test_cprofile.py
index f18983fbb2..53f8917330 100644
--- a/Lib/test/test_cprofile.py
+++ b/Lib/test/test_cprofile.py
@@ -6,7 +6,7 @@ from test.support import run_unittest, TESTFN, unlink
 # rip off all interesting stuff from test_profile
 import cProfile
 from test.test_profile import ProfileTest, regenerate_expected_output
-from test.profilee import testfunc
+
 
 class CProfileTest(ProfileTest):
     profilerclass = cProfile.Profile
diff --git a/Lib/test/test_csv.py b/Lib/test/test_csv.py
index 77c315edb1..e97c9f366e 100644
--- a/Lib/test/test_csv.py
+++ b/Lib/test/test_csv.py
@@ -2,9 +2,7 @@
 # csv package unit tests
 
 import copy
-import io
 import sys
-import os
 import unittest
 from io import StringIO
 from tempfile import TemporaryFile
@@ -426,17 +424,16 @@ class TestDialectRegistry(unittest.TestCase):
         self.assertRaises(TypeError, csv.reader, [], quoting = -1)
         self.assertRaises(TypeError, csv.reader, [], quoting = 100)
 
-    # See issue #22995
-    ## def test_copy(self):
-    ##     for name in csv.list_dialects():
-    ##         dialect = csv.get_dialect(name)
-    ##         self.assertRaises(TypeError, copy.copy, dialect)
+    def test_copy(self):
+        for name in csv.list_dialects():
+            dialect = csv.get_dialect(name)
+            self.assertRaises(TypeError, copy.copy, dialect)
 
-    ## def test_pickle(self):
-    ##     for name in csv.list_dialects():
-    ##         dialect = csv.get_dialect(name)
-    ##         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
-    ##             self.assertRaises(TypeError, pickle.dumps, dialect, proto)
+    def test_pickle(self):
+        for name in csv.list_dialects():
+            dialect = csv.get_dialect(name)
+            for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+                self.assertRaises(TypeError, pickle.dumps, dialect, proto)
 
 class TestCsvBase(unittest.TestCase):
     def readerAssertEqual(self, input, expected_result):
@@ -1080,7 +1077,6 @@ class TestUnicode(unittest.TestCase):
              "François Pinard"]
 
     def test_unicode_read(self):
-        import io
         with TemporaryFile("w+", newline='', encoding="utf-8") as fileobj:
             fileobj.write(",".join(self.names) + "\r\n")
             fileobj.seek(0)
@@ -1089,7 +1085,6 @@ class TestUnicode(unittest.TestCase):
 
 
     def test_unicode_write(self):
-        import io
         with TemporaryFile("w+", newline='', encoding="utf-8") as fileobj:
             writer = csv.writer(fileobj)
             writer.writerow(self.names)
@@ -1098,5 +1093,11 @@ class TestUnicode(unittest.TestCase):
             self.assertEqual(fileobj.read(), expected)
 
 
+class MiscTestCase(unittest.TestCase):
+    def test__all__(self):
+        extra = {'__doc__', '__version__'}
+        support.check__all__(self, csv, ('csv', '_csv'), extra=extra)
+
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/Lib/test/test_dbm.py b/Lib/test/test_dbm.py
index 623d9929d5..f0a428deaf 100644
--- a/Lib/test/test_dbm.py
+++ b/Lib/test/test_dbm.py
@@ -1,6 +1,5 @@
 """Test script for the dbm.open function based on testdumbdbm.py"""
 
-import os
 import unittest
 import glob
 import test.support
diff --git a/Lib/test/test_dbm_gnu.py b/Lib/test/test_dbm_gnu.py
index a7808f51c7..304b332869 100644
--- a/Lib/test/test_dbm_gnu.py
+++ b/Lib/test/test_dbm_gnu.py
@@ -2,7 +2,7 @@ from test import support
 gdbm = support.import_module("dbm.gnu") #skip if not supported
 import unittest
 import os
-from test.support import verbose, TESTFN, unlink
+from test.support import TESTFN, unlink
 
 
 filename = TESTFN
diff --git a/Lib/test/test_dbm_ndbm.py b/Lib/test/test_dbm_ndbm.py
index 2291561def..49f4426e4c 100644
--- a/Lib/test/test_dbm_ndbm.py
+++ b/Lib/test/test_dbm_ndbm.py
@@ -1,8 +1,6 @@
 from test import support
 support.import_module("dbm.ndbm") #skip if not supported
 import unittest
-import os
-import random
 import dbm.ndbm
 from dbm.ndbm import error
 
diff --git a/Lib/test/test_decimal.py b/Lib/test/test_decimal.py
index c0d21b1c80..f56f9add58 100644
--- a/Lib/test/test_decimal.py
+++ b/Lib/test/test_decimal.py
@@ -2047,6 +2047,39 @@ class UsabilityTest(unittest.TestCase):
         d = Decimal( (1, (0, 2, 7, 1), 'F') )
         self.assertEqual(d.as_tuple(), (1, (0,), 'F'))
 
+    def test_as_integer_ratio(self):
+        Decimal = self.decimal.Decimal
+
+        # exceptional cases
+        self.assertRaises(OverflowError,
+                          Decimal.as_integer_ratio, Decimal('inf'))
+        self.assertRaises(OverflowError,
+                          Decimal.as_integer_ratio, Decimal('-inf'))
+        self.assertRaises(ValueError,
+                          Decimal.as_integer_ratio, Decimal('-nan'))
+        self.assertRaises(ValueError,
+                          Decimal.as_integer_ratio, Decimal('snan123'))
+
+        for exp in range(-4, 2):
+            for coeff in range(1000):
+                for sign in '+', '-':
+                    d = Decimal('%s%dE%d' % (sign, coeff, exp))
+                    pq = d.as_integer_ratio()
+                    p, q = pq
+
+                    # check return type
+                    self.assertIsInstance(pq, tuple)
+                    self.assertIsInstance(p, int)
+                    self.assertIsInstance(q, int)
+
+                    # check normalization:  q should be positive;
+                    # p should be relatively prime to q.
+                    self.assertGreater(q, 0)
+                    self.assertEqual(math.gcd(p, q), 1)
+
+                    # check that p/q actually gives the correct value
+                    self.assertEqual(Decimal(p) / Decimal(q), d)
+
     def test_subclassing(self):
         # Different behaviours when subclassing Decimal
         Decimal = self.decimal.Decimal
diff --git a/Lib/test/test_defaultdict.py b/Lib/test/test_defaultdict.py
index a90bc2b488..5bb4e12278 100644
--- a/Lib/test/test_defaultdict.py
+++ b/Lib/test/test_defaultdict.py
@@ -65,7 +65,7 @@ class TestDefaultDict(unittest.TestCase):
         d2 = defaultdict(int)
         self.assertEqual(d2.default_factory, int)
         d2[12] = 42
-        self.assertEqual(repr(d2), "defaultdict(<class 'int'>, {12: 42})")
+        self.assertRegex(repr(d2), r"defaultdict\(<class 'int' at 0x.+>, {12: 42}\)")
         def foo(): return 43
         d3 = defaultdict(foo)
         self.assertTrue(d3.default_factory is foo)
diff --git a/Lib/test/test_deque.py b/Lib/test/test_deque.py
index f525429a17..4fd0cc7de5 100644
--- a/Lib/test/test_deque.py
+++ b/Lib/test/test_deque.py
@@ -289,7 +289,7 @@ class TestBasic(unittest.TestCase):
                     else:
                         self.assertEqual(d.index(element, start, stop), target)
 
-    def test_insert_bug_24913(self):
+    def test_index_bug_24913(self):
         d = deque('A' * 3)
         with self.assertRaises(ValueError):
             i = d.index("Hello world", 0, 4)
@@ -622,20 +622,22 @@ class TestBasic(unittest.TestCase):
         self.assertEqual(list(d), list(e))
 
     def test_pickle(self):
-        d = deque(range(200))
-        for i in range(pickle.HIGHEST_PROTOCOL + 1):
-            s = pickle.dumps(d, i)
-            e = pickle.loads(s)
-            self.assertNotEqual(id(d), id(e))
-            self.assertEqual(list(d), list(e))
-
-##    def test_pickle_recursive(self):
-##        d = deque('abc')
-##        d.append(d)
-##        for i in range(pickle.HIGHEST_PROTOCOL + 1):
-##            e = pickle.loads(pickle.dumps(d, i))
-##            self.assertNotEqual(id(d), id(e))
-##            self.assertEqual(id(e), id(e[-1]))
+        for d in deque(range(200)), deque(range(200), 100):
+            for i in range(pickle.HIGHEST_PROTOCOL + 1):
+                s = pickle.dumps(d, i)
+                e = pickle.loads(s)
+                self.assertNotEqual(id(e), id(d))
+                self.assertEqual(list(e), list(d))
+                self.assertEqual(e.maxlen, d.maxlen)
+
+    def test_pickle_recursive(self):
+        for d in deque('abc'), deque('abc', 3):
+            d.append(d)
+            for i in range(pickle.HIGHEST_PROTOCOL + 1):
+                e = pickle.loads(pickle.dumps(d, i))
+                self.assertNotEqual(id(e), id(d))
+                self.assertEqual(id(e[-1]), id(e))
+                self.assertEqual(e.maxlen, d.maxlen)
 
     def test_iterator_pickle(self):
         orig = deque(range(200))
@@ -696,6 +698,15 @@ class TestBasic(unittest.TestCase):
         self.assertNotEqual(id(d), id(e))
         self.assertEqual(list(d), list(e))
 
+        for i in range(5):
+            for maxlen in range(-1, 6):
+                s = [random.random() for j in range(i)]
+                d = deque(s) if maxlen == -1 else deque(s, maxlen)
+                e = d.copy()
+                self.assertEqual(d, e)
+                self.assertEqual(d.maxlen, e.maxlen)
+                self.assertTrue(all(x is y for x, y in zip(d, e)))
+
     def test_copy_method(self):
         mut = [10]
         d = deque([mut])
@@ -845,24 +856,26 @@ class TestSubclass(unittest.TestCase):
             self.assertEqual(type(d), type(e))
             self.assertEqual(list(d), list(e))
 
-##    def test_pickle(self):
-##        d = Deque('abc')
-##        d.append(d)
-##
-##        e = pickle.loads(pickle.dumps(d))
-##        self.assertNotEqual(id(d), id(e))
-##        self.assertEqual(type(d), type(e))
-##        dd = d.pop()
-##        ee = e.pop()
-##        self.assertEqual(id(e), id(ee))
-##        self.assertEqual(d, e)
-##
-##        d.x = d
-##        e = pickle.loads(pickle.dumps(d))
-##        self.assertEqual(id(e), id(e.x))
-##
-##        d = DequeWithBadIter('abc')
-##        self.assertRaises(TypeError, pickle.dumps, d)
+    def test_pickle_recursive(self):
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            for d in Deque('abc'), Deque('abc', 3):
+                d.append(d)
+
+                e = pickle.loads(pickle.dumps(d, proto))
+                self.assertNotEqual(id(e), id(d))
+                self.assertEqual(type(e), type(d))
+                self.assertEqual(e.maxlen, d.maxlen)
+                dd = d.pop()
+                ee = e.pop()
+                self.assertEqual(id(ee), id(e))
+                self.assertEqual(e, d)
+
+                d.x = d
+                e = pickle.loads(pickle.dumps(d, proto))
+                self.assertEqual(id(e.x), id(e))
+
+            for d in DequeWithBadIter('abc'), DequeWithBadIter('abc', 2):
+                self.assertRaises(TypeError, pickle.dumps, d, proto)
 
     def test_weakref(self):
         d = deque('gallahad')
diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index a130cecb89..954ef2d3b3 100644
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -4544,9 +4544,9 @@ order (MRO) for bases """
                 pass
         foo = Foo()
         self.assertRegex(repr(foo.method), # access via instance
-            r"<bound method .*Foo\.method of <class '.*Foo'>>")
+            r"<bound method .*Foo\.method of <class '.*Foo' at 0x.+>>")
         self.assertRegex(repr(Foo.method), # access via the class
-            r"<bound method .*Foo\.method of <class '.*Foo'>>")
+            r"<bound method .*Foo\.method of <class '.*Foo' at 0x.+>>")
 
 
         class MyCallable:
@@ -4738,11 +4738,8 @@ class PicklingTests(unittest.TestCase):
                 return (args, kwargs)
         obj = C3()
         for proto in protocols:
-            if proto >= 4:
+            if proto >= 2:
                 self._check_reduce(proto, obj, args, kwargs)
-            elif proto >= 2:
-                with self.assertRaises(ValueError):
-                    obj.__reduce_ex__(proto)
 
         class C4:
             def __getnewargs_ex__(self):
@@ -5061,10 +5058,6 @@ class PicklingTests(unittest.TestCase):
                 kwargs = getattr(cls, 'KWARGS', {})
                 obj = cls(*cls.ARGS, **kwargs)
                 proto = pickle_copier.proto
-                if 2 <= proto < 4 and hasattr(cls, '__getnewargs_ex__'):
-                    with self.assertRaises(ValueError):
-                        pickle_copier.dumps(obj, proto)
-                    continue
                 objcopy = pickle_copier.copy(obj)
                 self._assert_is_copy(obj, objcopy)
                 # For test classes that supports this, make sure we didn't go
diff --git a/Lib/test/test_descrtut.py b/Lib/test/test_descrtut.py
index 506d1abeb6..80cfa41ecb 100644
--- a/Lib/test/test_descrtut.py
+++ b/Lib/test/test_descrtut.py
@@ -37,16 +37,16 @@ test_1 = """
 Here's the new type at work:
 
     >>> print(defaultdict)              # show our type
-    <class 'test.test_descrtut.defaultdict'>
+    <class 'test.test_descrtut.defaultdict' ...>
     >>> print(type(defaultdict))        # its metatype
-    <class 'type'>
+    <class 'type' ...>
     >>> a = defaultdict(default=0.0)    # create an instance
     >>> print(a)                        # show the instance
     {}
     >>> print(type(a))                  # show its type
-    <class 'test.test_descrtut.defaultdict'>
+    <class 'test.test_descrtut.defaultdict' ...>
     >>> print(a.__class__)              # show its class
-    <class 'test.test_descrtut.defaultdict'>
+    <class 'test.test_descrtut.defaultdict' ...>
     >>> print(type(a) is a.__class__)   # its type is its class
     True
     >>> a[1] = 3.25                     # modify the instance
@@ -149,11 +149,11 @@ Introspecting instances of built-in types
 For instance of built-in types, x.__class__ is now the same as type(x):
 
     >>> type([])
-    <class 'list'>
+    <class 'list' ...>
     >>> [].__class__
-    <class 'list'>
+    <class 'list' ...>
     >>> list
-    <class 'list'>
+    <class 'list' ...>
     >>> isinstance([], list)
     True
     >>> isinstance([], dict)
@@ -258,19 +258,19 @@ implicit first argument that is the *class* for which they are invoked.
     ...         print("classmethod", cls, y)
 
     >>> C.foo(1)
-    classmethod <class 'test.test_descrtut.C'> 1
+    classmethod <class 'test.test_descrtut.C' ...> 1
     >>> c = C()
     >>> c.foo(1)
-    classmethod <class 'test.test_descrtut.C'> 1
+    classmethod <class 'test.test_descrtut.C' ...> 1
 
     >>> class D(C):
     ...     pass
 
     >>> D.foo(1)
-    classmethod <class 'test.test_descrtut.D'> 1
+    classmethod <class 'test.test_descrtut.D' ...> 1
     >>> d = D()
     >>> d.foo(1)
-    classmethod <class 'test.test_descrtut.D'> 1
+    classmethod <class 'test.test_descrtut.D' ...> 1
 
 This prints "classmethod __main__.D 1" both times; in other words, the
 class passed as the first argument of foo() is the class involved in the
@@ -286,11 +286,11 @@ But notice this:
 
     >>> E.foo(1)
     E.foo() called
-    classmethod <class 'test.test_descrtut.C'> 1
+    classmethod <class 'test.test_descrtut.C' ...> 1
     >>> e = E()
     >>> e.foo(1)
     E.foo() called
-    classmethod <class 'test.test_descrtut.C'> 1
+    classmethod <class 'test.test_descrtut.C' ...> 1
 
 In this example, the call to C.foo() from E.foo() will see class C as its
 first argument, not class E. This is to be expected, since the call
@@ -350,7 +350,7 @@ Hmm -- property is builtin now, so let's try it that way too.
 
     >>> del property  # unmask the builtin
     >>> property
-    <class 'property'>
+    <class 'property' ...>
 
     >>> class C(object):
     ...     def __init__(self):
@@ -478,7 +478,8 @@ def test_main(verbose=None):
     # business is used the name can change depending on how the test is
     # invoked.
     from test import support, test_descrtut
-    support.run_doctest(test_descrtut, verbose)
+    import doctest
+    support.run_doctest(test_descrtut, verbose, optionflags=doctest.ELLIPSIS)
 
 # This part isn't needed for regrtest, but for running the test directly.
 if __name__ == "__main__":
diff --git a/Lib/test/test_devpoll.py b/Lib/test/test_devpoll.py
index 955618ae15..c133c811b1 100644
--- a/Lib/test/test_devpoll.py
+++ b/Lib/test/test_devpoll.py
@@ -5,9 +5,8 @@
 import os
 import random
 import select
-import sys
 import unittest
-from test.support import TESTFN, run_unittest, cpython_only
+from test.support import run_unittest, cpython_only
 
 if not hasattr(select, 'devpoll') :
     raise unittest.SkipTest('test works only on Solaris OS family')
diff --git a/Lib/test/test_dict.py b/Lib/test/test_dict.py
index 6d68e761c6..6c4706636e 100644
--- a/Lib/test/test_dict.py
+++ b/Lib/test/test_dict.py
@@ -1,10 +1,12 @@
-import unittest
-from test import support
-
-import collections, random, string
+import collections
 import collections.abc
-import gc, weakref
+import gc
 import pickle
+import random
+import string
+import unittest
+import weakref
+from test import support
 
 
 class DictTest(unittest.TestCase):
@@ -969,5 +971,6 @@ class Dict(dict):
 class SubclassMappingTests(mapping_tests.BasicTestMappingProtocol):
     type2test = Dict
 
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_dictcomps.py b/Lib/test/test_dictcomps.py
index 3c8b95cf32..0873071883 100644
--- a/Lib/test/test_dictcomps.py
+++ b/Lib/test/test_dictcomps.py
@@ -1,7 +1,5 @@
 import unittest
 
-from test import support
-
 # For scope testing.
 g = "Global variable"
 
diff --git a/Lib/test/test_dictviews.py b/Lib/test/test_dictviews.py
index ab23ca1cf7..4c290ffaa1 100644
--- a/Lib/test/test_dictviews.py
+++ b/Lib/test/test_dictviews.py
@@ -1,3 +1,4 @@
+import collections
 import copy
 import pickle
 import unittest
@@ -219,6 +220,27 @@ class DictSetTest(unittest.TestCase):
             self.assertRaises((TypeError, pickle.PicklingError),
                 pickle.dumps, d.items(), proto)
 
+    def test_abc_registry(self):
+        d = dict(a=1)
+
+        self.assertIsInstance(d.keys(), collections.KeysView)
+        self.assertIsInstance(d.keys(), collections.MappingView)
+        self.assertIsInstance(d.keys(), collections.Set)
+        self.assertIsInstance(d.keys(), collections.Sized)
+        self.assertIsInstance(d.keys(), collections.Iterable)
+        self.assertIsInstance(d.keys(), collections.Container)
+
+        self.assertIsInstance(d.values(), collections.ValuesView)
+        self.assertIsInstance(d.values(), collections.MappingView)
+        self.assertIsInstance(d.values(), collections.Sized)
+
+        self.assertIsInstance(d.items(), collections.ItemsView)
+        self.assertIsInstance(d.items(), collections.MappingView)
+        self.assertIsInstance(d.items(), collections.Set)
+        self.assertIsInstance(d.items(), collections.Sized)
+        self.assertIsInstance(d.items(), collections.Iterable)
+        self.assertIsInstance(d.items(), collections.Container)
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_dis.py b/Lib/test/test_dis.py
index 0fd1348027..7e125ef59b 100644
--- a/Lib/test/test_dis.py
+++ b/Lib/test/test_dis.py
@@ -40,41 +40,41 @@ class _C:
 
 dis_c_instance_method = """\
 %3d           0 LOAD_FAST                1 (x)
-              3 LOAD_CONST               1 (1)
-              6 COMPARE_OP               2 (==)
-              9 LOAD_FAST                0 (self)
-             12 STORE_ATTR               0 (x)
-             15 LOAD_CONST               0 (None)
-             18 RETURN_VALUE
+              2 LOAD_CONST               1 (1)
+              4 COMPARE_OP               2 (==)
+              6 LOAD_FAST                0 (self)
+              8 STORE_ATTR               0 (x)
+             10 LOAD_CONST               0 (None)
+             12 RETURN_VALUE
 """ % (_C.__init__.__code__.co_firstlineno + 1,)
 
 dis_c_instance_method_bytes = """\
           0 LOAD_FAST                1 (1)
-          3 LOAD_CONST               1 (1)
-          6 COMPARE_OP               2 (==)
-          9 LOAD_FAST                0 (0)
-         12 STORE_ATTR               0 (0)
-         15 LOAD_CONST               0 (0)
-         18 RETURN_VALUE
+          2 LOAD_CONST               1 (1)
+          4 COMPARE_OP               2 (==)
+          6 LOAD_FAST                0 (0)
+          8 STORE_ATTR               0 (0)
+         10 LOAD_CONST               0 (0)
+         12 RETURN_VALUE
 """
 
 dis_c_class_method = """\
 %3d           0 LOAD_FAST                1 (x)
-              3 LOAD_CONST               1 (1)
-              6 COMPARE_OP               2 (==)
-              9 LOAD_FAST                0 (cls)
-             12 STORE_ATTR               0 (x)
-             15 LOAD_CONST               0 (None)
-             18 RETURN_VALUE
+              2 LOAD_CONST               1 (1)
+              4 COMPARE_OP               2 (==)
+              6 LOAD_FAST                0 (cls)
+              8 STORE_ATTR               0 (x)
+             10 LOAD_CONST               0 (None)
+             12 RETURN_VALUE
 """ % (_C.cm.__code__.co_firstlineno + 2,)
 
 dis_c_static_method = """\
 %3d           0 LOAD_FAST                0 (x)
-              3 LOAD_CONST               1 (1)
-              6 COMPARE_OP               2 (==)
-              9 STORE_FAST               0 (x)
-             12 LOAD_CONST               0 (None)
-             15 RETURN_VALUE
+              2 LOAD_CONST               1 (1)
+              4 COMPARE_OP               2 (==)
+              6 STORE_FAST               0 (x)
+              8 LOAD_CONST               0 (None)
+             10 RETURN_VALUE
 """ % (_C.sm.__code__.co_firstlineno + 2,)
 
 # Class disassembling info has an extra newline at end.
@@ -95,23 +95,23 @@ def _f(a):
 
 dis_f = """\
 %3d           0 LOAD_GLOBAL              0 (print)
-              3 LOAD_FAST                0 (a)
-              6 CALL_FUNCTION            1 (1 positional, 0 keyword pair)
-              9 POP_TOP
+              2 LOAD_FAST                0 (a)
+              4 CALL_FUNCTION            1 (1 positional, 0 keyword pair)
+              6 POP_TOP
 
-%3d          10 LOAD_CONST               1 (1)
-             13 RETURN_VALUE
+%3d           8 LOAD_CONST               1 (1)
+             10 RETURN_VALUE
 """ % (_f.__code__.co_firstlineno + 1,
        _f.__code__.co_firstlineno + 2)
 
 
 dis_f_co_code = """\
           0 LOAD_GLOBAL              0 (0)
-          3 LOAD_FAST                0 (0)
-          6 CALL_FUNCTION            1 (1 positional, 0 keyword pair)
-          9 POP_TOP
-         10 LOAD_CONST               1 (1)
-         13 RETURN_VALUE
+          2 LOAD_FAST                0 (0)
+          4 CALL_FUNCTION            1 (1 positional, 0 keyword pair)
+          6 POP_TOP
+          8 LOAD_CONST               1 (1)
+         10 RETURN_VALUE
 """
 
 
@@ -121,20 +121,20 @@ def bug708901():
         pass
 
 dis_bug708901 = """\
-%3d           0 SETUP_LOOP              23 (to 26)
-              3 LOAD_GLOBAL              0 (range)
-              6 LOAD_CONST               1 (1)
-
-%3d           9 LOAD_CONST               2 (10)
-             12 CALL_FUNCTION            2 (2 positional, 0 keyword pair)
-             15 GET_ITER
-        >>   16 FOR_ITER                 6 (to 25)
-             19 STORE_FAST               0 (res)
-
-%3d          22 JUMP_ABSOLUTE           16
-        >>   25 POP_BLOCK
-        >>   26 LOAD_CONST               0 (None)
-             29 RETURN_VALUE
+%3d           0 SETUP_LOOP              18 (to 20)
+              2 LOAD_GLOBAL              0 (range)
+              4 LOAD_CONST               1 (1)
+
+%3d           6 LOAD_CONST               2 (10)
+              8 CALL_FUNCTION            2 (2 positional, 0 keyword pair)
+             10 GET_ITER
+        >>   12 FOR_ITER                 4 (to 18)
+             14 STORE_FAST               0 (res)
+
+%3d          16 JUMP_ABSOLUTE           12
+        >>   18 POP_BLOCK
+        >>   20 LOAD_CONST               0 (None)
+             22 RETURN_VALUE
 """ % (bug708901.__code__.co_firstlineno + 1,
        bug708901.__code__.co_firstlineno + 2,
        bug708901.__code__.co_firstlineno + 3)
@@ -147,22 +147,22 @@ def bug1333982(x=[]):
 
 dis_bug1333982 = """\
 %3d           0 LOAD_CONST               1 (0)
-              3 POP_JUMP_IF_TRUE        35
-              6 LOAD_GLOBAL              0 (AssertionError)
-              9 LOAD_CONST               2 (<code object <listcomp> at 0x..., file "%s", line %d>)
-             12 LOAD_CONST               3 ('bug1333982.<locals>.<listcomp>')
-             15 MAKE_FUNCTION            0
-             18 LOAD_FAST                0 (x)
-             21 GET_ITER
+              2 POP_JUMP_IF_TRUE        26
+              4 LOAD_GLOBAL              0 (AssertionError)
+              6 LOAD_CONST               2 (<code object <listcomp> at 0x..., file "%s", line %d>)
+              8 LOAD_CONST               3 ('bug1333982.<locals>.<listcomp>')
+             10 MAKE_FUNCTION            0
+             12 LOAD_FAST                0 (x)
+             14 GET_ITER
+             16 CALL_FUNCTION            1 (1 positional, 0 keyword pair)
+
+%3d          18 LOAD_CONST               4 (1)
+             20 BINARY_ADD
              22 CALL_FUNCTION            1 (1 positional, 0 keyword pair)
+             24 RAISE_VARARGS            1
 
-%3d          25 LOAD_CONST               4 (1)
-             28 BINARY_ADD
-             29 CALL_FUNCTION            1 (1 positional, 0 keyword pair)
-             32 RAISE_VARARGS            1
-
-%3d     >>   35 LOAD_CONST               0 (None)
-             38 RETURN_VALUE
+%3d     >>   26 LOAD_CONST               0 (None)
+             28 RETURN_VALUE
 """ % (bug1333982.__code__.co_firstlineno + 1,
        __file__,
        bug1333982.__code__.co_firstlineno + 1,
@@ -171,19 +171,19 @@ dis_bug1333982 = """\
 
 _BIG_LINENO_FORMAT = """\
 %3d           0 LOAD_GLOBAL              0 (spam)
-              3 POP_TOP
+              2 POP_TOP
               4 LOAD_CONST               0 (None)
-              7 RETURN_VALUE
+              6 RETURN_VALUE
 """
 
 dis_module_expected_results = """\
 Disassembly of f:
   4           0 LOAD_CONST               0 (None)
-              3 RETURN_VALUE
+              2 RETURN_VALUE
 
 Disassembly of g:
   5           0 LOAD_CONST               0 (None)
-              3 RETURN_VALUE
+              2 RETURN_VALUE
 
 """
 
@@ -191,20 +191,20 @@ expr_str = "x + 1"
 
 dis_expr_str = """\
   1           0 LOAD_NAME                0 (x)
-              3 LOAD_CONST               0 (1)
-              6 BINARY_ADD
-              7 RETURN_VALUE
+              2 LOAD_CONST               0 (1)
+              4 BINARY_ADD
+              6 RETURN_VALUE
 """
 
 simple_stmt_str = "x = x + 1"
 
 dis_simple_stmt_str = """\
   1           0 LOAD_NAME                0 (x)
-              3 LOAD_CONST               0 (1)
-              6 BINARY_ADD
-              7 STORE_NAME               0 (x)
-             10 LOAD_CONST               1 (None)
-             13 RETURN_VALUE
+              2 LOAD_CONST               0 (1)
+              4 BINARY_ADD
+              6 STORE_NAME               0 (x)
+              8 LOAD_CONST               1 (None)
+             10 RETURN_VALUE
 """
 
 compound_stmt_str = """\
@@ -215,54 +215,54 @@ while 1:
 
 dis_compound_stmt_str = """\
   1           0 LOAD_CONST               0 (0)
-              3 STORE_NAME               0 (x)
-
-  2           6 SETUP_LOOP              14 (to 23)
-
-  3     >>    9 LOAD_NAME                0 (x)
-             12 LOAD_CONST               1 (1)
-             15 INPLACE_ADD
-             16 STORE_NAME               0 (x)
-             19 JUMP_ABSOLUTE            9
-             22 POP_BLOCK
-        >>   23 LOAD_CONST               2 (None)
-             26 RETURN_VALUE
+              2 STORE_NAME               0 (x)
+
+  2           4 SETUP_LOOP              12 (to 18)
+
+  3     >>    6 LOAD_NAME                0 (x)
+              8 LOAD_CONST               1 (1)
+             10 INPLACE_ADD
+             12 STORE_NAME               0 (x)
+             14 JUMP_ABSOLUTE            6
+             16 POP_BLOCK
+        >>   18 LOAD_CONST               2 (None)
+             20 RETURN_VALUE
 """
 
 dis_traceback = """\
-%3d           0 SETUP_EXCEPT            12 (to 15)
+%3d           0 SETUP_EXCEPT            12 (to 14)
 
-%3d           3 LOAD_CONST               1 (1)
-              6 LOAD_CONST               2 (0)
-    -->       9 BINARY_TRUE_DIVIDE
-             10 POP_TOP
-             11 POP_BLOCK
-             12 JUMP_FORWARD            46 (to 61)
+%3d           2 LOAD_CONST               1 (1)
+              4 LOAD_CONST               2 (0)
+    -->       6 BINARY_TRUE_DIVIDE
+              8 POP_TOP
+             10 POP_BLOCK
+             12 JUMP_FORWARD            40 (to 54)
 
-%3d     >>   15 DUP_TOP
+%3d     >>   14 DUP_TOP
              16 LOAD_GLOBAL              0 (Exception)
-             19 COMPARE_OP              10 (exception match)
-             22 POP_JUMP_IF_FALSE       60
-             25 POP_TOP
-             26 STORE_FAST               0 (e)
-             29 POP_TOP
-             30 SETUP_FINALLY           14 (to 47)
-
-%3d          33 LOAD_FAST                0 (e)
-             36 LOAD_ATTR                1 (__traceback__)
-             39 STORE_FAST               1 (tb)
-             42 POP_BLOCK
-             43 POP_EXCEPT
-             44 LOAD_CONST               0 (None)
-        >>   47 LOAD_CONST               0 (None)
-             50 STORE_FAST               0 (e)
-             53 DELETE_FAST              0 (e)
-             56 END_FINALLY
-             57 JUMP_FORWARD             1 (to 61)
-        >>   60 END_FINALLY
-
-%3d     >>   61 LOAD_FAST                1 (tb)
-             64 RETURN_VALUE
+             18 COMPARE_OP              10 (exception match)
+             20 POP_JUMP_IF_FALSE       52
+             22 POP_TOP
+             24 STORE_FAST               0 (e)
+             26 POP_TOP
+             28 SETUP_FINALLY           12 (to 42)
+
+%3d          30 LOAD_FAST                0 (e)
+             32 LOAD_ATTR                1 (__traceback__)
+             34 STORE_FAST               1 (tb)
+             36 POP_BLOCK
+             38 POP_EXCEPT
+             40 LOAD_CONST               0 (None)
+        >>   42 LOAD_CONST               0 (None)
+             44 STORE_FAST               0 (e)
+             46 DELETE_FAST              0 (e)
+             48 END_FINALLY
+             50 JUMP_FORWARD             2 (to 54)
+        >>   52 END_FINALLY
+
+%3d     >>   54 LOAD_FAST                1 (tb)
+             56 RETURN_VALUE
 """ % (TRACEBACK_CODE.co_firstlineno + 1,
        TRACEBACK_CODE.co_firstlineno + 2,
        TRACEBACK_CODE.co_firstlineno + 3,
@@ -650,170 +650,170 @@ expected_jumpy_line = 1
 Instruction = dis.Instruction
 expected_opinfo_outer = [
   Instruction(opname='LOAD_CONST', opcode=100, arg=1, argval=3, argrepr='3', offset=0, starts_line=2, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=2, argval=4, argrepr='4', offset=3, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CLOSURE', opcode=135, arg=0, argval='a', argrepr='a', offset=6, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CLOSURE', opcode=135, arg=1, argval='b', argrepr='b', offset=9, starts_line=None, is_jump_target=False),
-  Instruction(opname='BUILD_TUPLE', opcode=102, arg=2, argval=2, argrepr='', offset=12, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=3, argval=code_object_f, argrepr=repr(code_object_f), offset=15, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=4, argval='outer.<locals>.f', argrepr="'outer.<locals>.f'", offset=18, starts_line=None, is_jump_target=False),
-  Instruction(opname='MAKE_CLOSURE', opcode=134, arg=2, argval=2, argrepr='', offset=21, starts_line=None, is_jump_target=False),
-  Instruction(opname='STORE_FAST', opcode=125, arg=2, argval='f', argrepr='f', offset=24, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=0, argval='print', argrepr='print', offset=27, starts_line=7, is_jump_target=False),
-  Instruction(opname='LOAD_DEREF', opcode=136, arg=0, argval='a', argrepr='a', offset=30, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_DEREF', opcode=136, arg=1, argval='b', argrepr='b', offset=33, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval='', argrepr="''", offset=36, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=6, argval=1, argrepr='1', offset=39, starts_line=None, is_jump_target=False),
-  Instruction(opname='BUILD_LIST', opcode=103, arg=0, argval=0, argrepr='', offset=42, starts_line=None, is_jump_target=False),
-  Instruction(opname='BUILD_MAP', opcode=105, arg=0, argval=0, argrepr='', offset=45, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=7, argval='Hello world!', argrepr="'Hello world!'", offset=48, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=7, argval=7, argrepr='7 positional, 0 keyword pair', offset=51, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=54, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=2, argval='f', argrepr='f', offset=55, starts_line=8, is_jump_target=False),
-  Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=58, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=2, argval=4, argrepr='4', offset=2, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CLOSURE', opcode=135, arg=0, argval='a', argrepr='a', offset=4, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CLOSURE', opcode=135, arg=1, argval='b', argrepr='b', offset=6, starts_line=None, is_jump_target=False),
+  Instruction(opname='BUILD_TUPLE', opcode=102, arg=2, argval=2, argrepr='', offset=8, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=3, argval=code_object_f, argrepr=repr(code_object_f), offset=10, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=4, argval='outer.<locals>.f', argrepr="'outer.<locals>.f'", offset=12, starts_line=None, is_jump_target=False),
+  Instruction(opname='MAKE_CLOSURE', opcode=134, arg=2, argval=2, argrepr='', offset=14, starts_line=None, is_jump_target=False),
+  Instruction(opname='STORE_FAST', opcode=125, arg=2, argval='f', argrepr='f', offset=16, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=0, argval='print', argrepr='print', offset=18, starts_line=7, is_jump_target=False),
+  Instruction(opname='LOAD_DEREF', opcode=136, arg=0, argval='a', argrepr='a', offset=20, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_DEREF', opcode=136, arg=1, argval='b', argrepr='b', offset=22, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval='', argrepr="''", offset=24, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=6, argval=1, argrepr='1', offset=26, starts_line=None, is_jump_target=False),
+  Instruction(opname='BUILD_LIST', opcode=103, arg=0, argval=0, argrepr='', offset=28, starts_line=None, is_jump_target=False),
+  Instruction(opname='BUILD_MAP', opcode=105, arg=0, argval=0, argrepr='', offset=30, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=7, argval='Hello world!', argrepr="'Hello world!'", offset=32, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=7, argval=7, argrepr='7 positional, 0 keyword pair', offset=34, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=36, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=2, argval='f', argrepr='f', offset=38, starts_line=8, is_jump_target=False),
+  Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=40, starts_line=None, is_jump_target=False),
 ]
 
 expected_opinfo_f = [
   Instruction(opname='LOAD_CONST', opcode=100, arg=1, argval=5, argrepr='5', offset=0, starts_line=3, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=2, argval=6, argrepr='6', offset=3, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CLOSURE', opcode=135, arg=2, argval='a', argrepr='a', offset=6, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CLOSURE', opcode=135, arg=3, argval='b', argrepr='b', offset=9, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CLOSURE', opcode=135, arg=0, argval='c', argrepr='c', offset=12, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CLOSURE', opcode=135, arg=1, argval='d', argrepr='d', offset=15, starts_line=None, is_jump_target=False),
-  Instruction(opname='BUILD_TUPLE', opcode=102, arg=4, argval=4, argrepr='', offset=18, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=3, argval=code_object_inner, argrepr=repr(code_object_inner), offset=21, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=4, argval='outer.<locals>.f.<locals>.inner', argrepr="'outer.<locals>.f.<locals>.inner'", offset=24, starts_line=None, is_jump_target=False),
-  Instruction(opname='MAKE_CLOSURE', opcode=134, arg=2, argval=2, argrepr='', offset=27, starts_line=None, is_jump_target=False),
-  Instruction(opname='STORE_FAST', opcode=125, arg=2, argval='inner', argrepr='inner', offset=30, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=0, argval='print', argrepr='print', offset=33, starts_line=5, is_jump_target=False),
-  Instruction(opname='LOAD_DEREF', opcode=136, arg=2, argval='a', argrepr='a', offset=36, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_DEREF', opcode=136, arg=3, argval='b', argrepr='b', offset=39, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_DEREF', opcode=136, arg=0, argval='c', argrepr='c', offset=42, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_DEREF', opcode=136, arg=1, argval='d', argrepr='d', offset=45, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=4, argval=4, argrepr='4 positional, 0 keyword pair', offset=48, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=51, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=2, argval='inner', argrepr='inner', offset=52, starts_line=6, is_jump_target=False),
-  Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=55, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=2, argval=6, argrepr='6', offset=2, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CLOSURE', opcode=135, arg=2, argval='a', argrepr='a', offset=4, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CLOSURE', opcode=135, arg=3, argval='b', argrepr='b', offset=6, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CLOSURE', opcode=135, arg=0, argval='c', argrepr='c', offset=8, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CLOSURE', opcode=135, arg=1, argval='d', argrepr='d', offset=10, starts_line=None, is_jump_target=False),
+  Instruction(opname='BUILD_TUPLE', opcode=102, arg=4, argval=4, argrepr='', offset=12, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=3, argval=code_object_inner, argrepr=repr(code_object_inner), offset=14, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=4, argval='outer.<locals>.f.<locals>.inner', argrepr="'outer.<locals>.f.<locals>.inner'", offset=16, starts_line=None, is_jump_target=False),
+  Instruction(opname='MAKE_CLOSURE', opcode=134, arg=2, argval=2, argrepr='', offset=18, starts_line=None, is_jump_target=False),
+  Instruction(opname='STORE_FAST', opcode=125, arg=2, argval='inner', argrepr='inner', offset=20, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=0, argval='print', argrepr='print', offset=22, starts_line=5, is_jump_target=False),
+  Instruction(opname='LOAD_DEREF', opcode=136, arg=2, argval='a', argrepr='a', offset=24, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_DEREF', opcode=136, arg=3, argval='b', argrepr='b', offset=26, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_DEREF', opcode=136, arg=0, argval='c', argrepr='c', offset=28, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_DEREF', opcode=136, arg=1, argval='d', argrepr='d', offset=30, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=4, argval=4, argrepr='4 positional, 0 keyword pair', offset=32, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=34, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=2, argval='inner', argrepr='inner', offset=36, starts_line=6, is_jump_target=False),
+  Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=38, starts_line=None, is_jump_target=False),
 ]
 
 expected_opinfo_inner = [
   Instruction(opname='LOAD_GLOBAL', opcode=116, arg=0, argval='print', argrepr='print', offset=0, starts_line=4, is_jump_target=False),
-  Instruction(opname='LOAD_DEREF', opcode=136, arg=0, argval='a', argrepr='a', offset=3, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_DEREF', opcode=136, arg=1, argval='b', argrepr='b', offset=6, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_DEREF', opcode=136, arg=2, argval='c', argrepr='c', offset=9, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_DEREF', opcode=136, arg=3, argval='d', argrepr='d', offset=12, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='e', argrepr='e', offset=15, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=1, argval='f', argrepr='f', offset=18, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=6, argval=6, argrepr='6 positional, 0 keyword pair', offset=21, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=24, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=25, starts_line=None, is_jump_target=False),
-  Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=28, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_DEREF', opcode=136, arg=0, argval='a', argrepr='a', offset=2, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_DEREF', opcode=136, arg=1, argval='b', argrepr='b', offset=4, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_DEREF', opcode=136, arg=2, argval='c', argrepr='c', offset=6, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_DEREF', opcode=136, arg=3, argval='d', argrepr='d', offset=8, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='e', argrepr='e', offset=10, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=1, argval='f', argrepr='f', offset=12, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=6, argval=6, argrepr='6 positional, 0 keyword pair', offset=14, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=16, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=18, starts_line=None, is_jump_target=False),
+  Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=20, starts_line=None, is_jump_target=False),
 ]
 
 expected_opinfo_jumpy = [
-  Instruction(opname='SETUP_LOOP', opcode=120, arg=68, argval=71, argrepr='to 71', offset=0, starts_line=3, is_jump_target=False),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=0, argval='range', argrepr='range', offset=3, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=1, argval=10, argrepr='10', offset=6, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=9, starts_line=None, is_jump_target=False),
-  Instruction(opname='GET_ITER', opcode=68, arg=None, argval=None, argrepr='', offset=12, starts_line=None, is_jump_target=False),
-  Instruction(opname='FOR_ITER', opcode=93, arg=44, argval=60, argrepr='to 60', offset=13, starts_line=None, is_jump_target=True),
-  Instruction(opname='STORE_FAST', opcode=125, arg=0, argval='i', argrepr='i', offset=16, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=19, starts_line=4, is_jump_target=False),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=22, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=25, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=28, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=29, starts_line=5, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=2, argval=4, argrepr='4', offset=32, starts_line=None, is_jump_target=False),
-  Instruction(opname='COMPARE_OP', opcode=107, arg=0, argval='<', argrepr='<', offset=35, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=44, argval=44, argrepr='', offset=38, starts_line=None, is_jump_target=False),
-  Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=13, argval=13, argrepr='', offset=41, starts_line=6, is_jump_target=False),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=44, starts_line=7, is_jump_target=True),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=3, argval=6, argrepr='6', offset=47, starts_line=None, is_jump_target=False),
-  Instruction(opname='COMPARE_OP', opcode=107, arg=4, argval='>', argrepr='>', offset=50, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=13, argval=13, argrepr='', offset=53, starts_line=None, is_jump_target=False),
-  Instruction(opname='BREAK_LOOP', opcode=80, arg=None, argval=None, argrepr='', offset=56, starts_line=8, is_jump_target=False),
-  Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=13, argval=13, argrepr='', offset=57, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=60, starts_line=None, is_jump_target=True),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=61, starts_line=10, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=4, argval='I can haz else clause?', argrepr="'I can haz else clause?'", offset=64, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=67, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=70, starts_line=None, is_jump_target=False),
-  Instruction(opname='SETUP_LOOP', opcode=120, arg=68, argval=142, argrepr='to 142', offset=71, starts_line=11, is_jump_target=True),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=74, starts_line=None, is_jump_target=True),
-  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=131, argval=131, argrepr='', offset=77, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=80, starts_line=12, is_jump_target=False),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=83, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=86, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=89, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=90, starts_line=13, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval=1, argrepr='1', offset=93, starts_line=None, is_jump_target=False),
-  Instruction(opname='INPLACE_SUBTRACT', opcode=56, arg=None, argval=None, argrepr='', offset=96, starts_line=None, is_jump_target=False),
-  Instruction(opname='STORE_FAST', opcode=125, arg=0, argval='i', argrepr='i', offset=97, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=100, starts_line=14, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=3, argval=6, argrepr='6', offset=103, starts_line=None, is_jump_target=False),
-  Instruction(opname='COMPARE_OP', opcode=107, arg=4, argval='>', argrepr='>', offset=106, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=115, argval=115, argrepr='', offset=109, starts_line=None, is_jump_target=False),
-  Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=74, argval=74, argrepr='', offset=112, starts_line=15, is_jump_target=False),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=115, starts_line=16, is_jump_target=True),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=2, argval=4, argrepr='4', offset=118, starts_line=None, is_jump_target=False),
-  Instruction(opname='COMPARE_OP', opcode=107, arg=0, argval='<', argrepr='<', offset=121, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=74, argval=74, argrepr='', offset=124, starts_line=None, is_jump_target=False),
-  Instruction(opname='BREAK_LOOP', opcode=80, arg=None, argval=None, argrepr='', offset=127, starts_line=17, is_jump_target=False),
-  Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=74, argval=74, argrepr='', offset=128, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=131, starts_line=None, is_jump_target=True),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=132, starts_line=19, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=6, argval='Who let lolcatz into this test suite?', argrepr="'Who let lolcatz into this test suite?'", offset=135, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=138, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=141, starts_line=None, is_jump_target=False),
-  Instruction(opname='SETUP_FINALLY', opcode=122, arg=73, argval=218, argrepr='to 218', offset=142, starts_line=20, is_jump_target=True),
-  Instruction(opname='SETUP_EXCEPT', opcode=121, arg=12, argval=160, argrepr='to 160', offset=145, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval=1, argrepr='1', offset=148, starts_line=21, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=7, argval=0, argrepr='0', offset=151, starts_line=None, is_jump_target=False),
-  Instruction(opname='BINARY_TRUE_DIVIDE', opcode=27, arg=None, argval=None, argrepr='', offset=154, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=155, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=156, starts_line=None, is_jump_target=False),
-  Instruction(opname='JUMP_FORWARD', opcode=110, arg=28, argval=188, argrepr='to 188', offset=157, starts_line=None, is_jump_target=False),
-  Instruction(opname='DUP_TOP', opcode=4, arg=None, argval=None, argrepr='', offset=160, starts_line=22, is_jump_target=True),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=2, argval='ZeroDivisionError', argrepr='ZeroDivisionError', offset=161, starts_line=None, is_jump_target=False),
-  Instruction(opname='COMPARE_OP', opcode=107, arg=10, argval='exception match', argrepr='exception match', offset=164, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=187, argval=187, argrepr='', offset=167, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=170, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=171, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=172, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=173, starts_line=23, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=8, argval='Here we go, here we go, here we go...', argrepr="'Here we go, here we go, here we go...'", offset=176, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=179, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=182, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_EXCEPT', opcode=89, arg=None, argval=None, argrepr='', offset=183, starts_line=None, is_jump_target=False),
-  Instruction(opname='JUMP_FORWARD', opcode=110, arg=27, argval=214, argrepr='to 214', offset=184, starts_line=None, is_jump_target=False),
-  Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=187, starts_line=None, is_jump_target=True),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=188, starts_line=25, is_jump_target=True),
-  Instruction(opname='SETUP_WITH', opcode=143, arg=17, argval=211, argrepr='to 211', offset=191, starts_line=None, is_jump_target=False),
-  Instruction(opname='STORE_FAST', opcode=125, arg=1, argval='dodgy', argrepr='dodgy', offset=194, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=197, starts_line=26, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=9, argval='Never reach this', argrepr="'Never reach this'", offset=200, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=203, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=206, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=207, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=208, starts_line=None, is_jump_target=False),
-  Instruction(opname='WITH_CLEANUP_START', opcode=81, arg=None, argval=None, argrepr='', offset=211, starts_line=None, is_jump_target=True),
-  Instruction(opname='WITH_CLEANUP_FINISH', opcode=82, arg=None, argval=None, argrepr='', offset=212, starts_line=None, is_jump_target=False),
-  Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=213, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=214, starts_line=None, is_jump_target=True),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=215, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=218, starts_line=28, is_jump_target=True),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=10, argval="OK, now we're done", argrepr='"OK, now we\'re done"', offset=221, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=224, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=227, starts_line=None, is_jump_target=False),
-  Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=228, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=229, starts_line=None, is_jump_target=False),
-  Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=232, starts_line=None, is_jump_target=False),
+  Instruction(opname='SETUP_LOOP', opcode=120, arg=52, argval=54, argrepr='to 54', offset=0, starts_line=3, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=0, argval='range', argrepr='range', offset=2, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=1, argval=10, argrepr='10', offset=4, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=6, starts_line=None, is_jump_target=False),
+  Instruction(opname='GET_ITER', opcode=68, arg=None, argval=None, argrepr='', offset=8, starts_line=None, is_jump_target=False),
+  Instruction(opname='FOR_ITER', opcode=93, arg=32, argval=44, argrepr='to 44', offset=10, starts_line=None, is_jump_target=True),
+  Instruction(opname='STORE_FAST', opcode=125, arg=0, argval='i', argrepr='i', offset=12, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=14, starts_line=4, is_jump_target=False),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=16, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=18, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=20, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=22, starts_line=5, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=2, argval=4, argrepr='4', offset=24, starts_line=None, is_jump_target=False),
+  Instruction(opname='COMPARE_OP', opcode=107, arg=0, argval='<', argrepr='<', offset=26, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=32, argval=32, argrepr='', offset=28, starts_line=None, is_jump_target=False),
+  Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=10, argval=10, argrepr='', offset=30, starts_line=6, is_jump_target=False),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=32, starts_line=7, is_jump_target=True),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=3, argval=6, argrepr='6', offset=34, starts_line=None, is_jump_target=False),
+  Instruction(opname='COMPARE_OP', opcode=107, arg=4, argval='>', argrepr='>', offset=36, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=10, argval=10, argrepr='', offset=38, starts_line=None, is_jump_target=False),
+  Instruction(opname='BREAK_LOOP', opcode=80, arg=None, argval=None, argrepr='', offset=40, starts_line=8, is_jump_target=False),
+  Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=10, argval=10, argrepr='', offset=42, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=44, starts_line=None, is_jump_target=True),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=46, starts_line=10, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=4, argval='I can haz else clause?', argrepr="'I can haz else clause?'", offset=48, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=50, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=52, starts_line=None, is_jump_target=False),
+  Instruction(opname='SETUP_LOOP', opcode=120, arg=52, argval=108, argrepr='to 108', offset=54, starts_line=11, is_jump_target=True),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=56, starts_line=None, is_jump_target=True),
+  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=98, argval=98, argrepr='', offset=58, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=60, starts_line=12, is_jump_target=False),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=62, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=64, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=66, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=68, starts_line=13, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval=1, argrepr='1', offset=70, starts_line=None, is_jump_target=False),
+  Instruction(opname='INPLACE_SUBTRACT', opcode=56, arg=None, argval=None, argrepr='', offset=72, starts_line=None, is_jump_target=False),
+  Instruction(opname='STORE_FAST', opcode=125, arg=0, argval='i', argrepr='i', offset=74, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=76, starts_line=14, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=3, argval=6, argrepr='6', offset=78, starts_line=None, is_jump_target=False),
+  Instruction(opname='COMPARE_OP', opcode=107, arg=4, argval='>', argrepr='>', offset=80, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=86, argval=86, argrepr='', offset=82, starts_line=None, is_jump_target=False),
+  Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=56, argval=56, argrepr='', offset=84, starts_line=15, is_jump_target=False),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=86, starts_line=16, is_jump_target=True),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=2, argval=4, argrepr='4', offset=88, starts_line=None, is_jump_target=False),
+  Instruction(opname='COMPARE_OP', opcode=107, arg=0, argval='<', argrepr='<', offset=90, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=56, argval=56, argrepr='', offset=92, starts_line=None, is_jump_target=False),
+  Instruction(opname='BREAK_LOOP', opcode=80, arg=None, argval=None, argrepr='', offset=94, starts_line=17, is_jump_target=False),
+  Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=56, argval=56, argrepr='', offset=96, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=98, starts_line=None, is_jump_target=True),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=100, starts_line=19, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=6, argval='Who let lolcatz into this test suite?', argrepr="'Who let lolcatz into this test suite?'", offset=102, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=104, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=106, starts_line=None, is_jump_target=False),
+  Instruction(opname='SETUP_FINALLY', opcode=122, arg=70, argval=180, argrepr='to 180', offset=108, starts_line=20, is_jump_target=True),
+  Instruction(opname='SETUP_EXCEPT', opcode=121, arg=12, argval=124, argrepr='to 124', offset=110, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval=1, argrepr='1', offset=112, starts_line=21, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=7, argval=0, argrepr='0', offset=114, starts_line=None, is_jump_target=False),
+  Instruction(opname='BINARY_TRUE_DIVIDE', opcode=27, arg=None, argval=None, argrepr='', offset=116, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=118, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=120, starts_line=None, is_jump_target=False),
+  Instruction(opname='JUMP_FORWARD', opcode=110, arg=28, argval=152, argrepr='to 152', offset=122, starts_line=None, is_jump_target=False),
+  Instruction(opname='DUP_TOP', opcode=4, arg=None, argval=None, argrepr='', offset=124, starts_line=22, is_jump_target=True),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=2, argval='ZeroDivisionError', argrepr='ZeroDivisionError', offset=126, starts_line=None, is_jump_target=False),
+  Instruction(opname='COMPARE_OP', opcode=107, arg=10, argval='exception match', argrepr='exception match', offset=128, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=150, argval=150, argrepr='', offset=130, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=132, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=134, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=136, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=138, starts_line=23, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=8, argval='Here we go, here we go, here we go...', argrepr="'Here we go, here we go, here we go...'", offset=140, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=142, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=144, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_EXCEPT', opcode=89, arg=None, argval=None, argrepr='', offset=146, starts_line=None, is_jump_target=False),
+  Instruction(opname='JUMP_FORWARD', opcode=110, arg=26, argval=176, argrepr='to 176', offset=148, starts_line=None, is_jump_target=False),
+  Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=150, starts_line=None, is_jump_target=True),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=152, starts_line=25, is_jump_target=True),
+  Instruction(opname='SETUP_WITH', opcode=143, arg=14, argval=170, argrepr='to 170', offset=154, starts_line=None, is_jump_target=False),
+  Instruction(opname='STORE_FAST', opcode=125, arg=1, argval='dodgy', argrepr='dodgy', offset=156, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=158, starts_line=26, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=9, argval='Never reach this', argrepr="'Never reach this'", offset=160, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=162, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=164, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=166, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=168, starts_line=None, is_jump_target=False),
+  Instruction(opname='WITH_CLEANUP_START', opcode=81, arg=None, argval=None, argrepr='', offset=170, starts_line=None, is_jump_target=True),
+  Instruction(opname='WITH_CLEANUP_FINISH', opcode=82, arg=None, argval=None, argrepr='', offset=172, starts_line=None, is_jump_target=False),
+  Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=174, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=176, starts_line=None, is_jump_target=True),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=178, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=180, starts_line=28, is_jump_target=True),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=10, argval="OK, now we're done", argrepr='"OK, now we\'re done"', offset=182, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=184, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=186, starts_line=None, is_jump_target=False),
+  Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=188, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=190, starts_line=None, is_jump_target=False),
+  Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=192, starts_line=None, is_jump_target=False),
 ]
 
 # One last piece of inspect fodder to check the default line number handling
 def simple(): pass
 expected_opinfo_simple = [
   Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=0, starts_line=simple.__code__.co_firstlineno, is_jump_target=False),
-  Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=3, starts_line=None, is_jump_target=False)
+  Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=2, starts_line=None, is_jump_target=False)
 ]
 
 
diff --git a/Lib/test/test_doctest.py b/Lib/test/test_doctest.py
index 29426a3185..ec12fe7372 100644
--- a/Lib/test/test_doctest.py
+++ b/Lib/test/test_doctest.py
@@ -1876,7 +1876,6 @@ if not hasattr(sys, 'gettrace') or not sys.gettrace():
         To demonstrate this, we'll create a fake standard input that
         captures our debugger input:
 
-          >>> import tempfile
           >>> real_stdin = sys.stdin
           >>> sys.stdin = _FakeInput([
           ...    'print(x)',  # print data defined by the example
@@ -1917,7 +1916,7 @@ if not hasattr(sys, 'gettrace') or not sys.gettrace():
           ... finally:
           ...     sys.stdin = real_stdin
           --Return--
-          > <doctest test.test_doctest.test_pdb_set_trace[8]>(3)calls_set_trace()->None
+          > <doctest test.test_doctest.test_pdb_set_trace[7]>(3)calls_set_trace()->None
           -> import pdb; pdb.set_trace()
           (Pdb) print(y)
           2
@@ -2339,7 +2338,7 @@ def test_DocFileSuite():
        `__file__` global, which is set to the name of the file
        containing the tests:
 
-         >>> suite = doctest.DocFileSuite('test_doctest3.txt')
+         >>> suite = doctest.DocFileSuite('test_doctest3.txt', optionflags=doctest.ELLIPSIS)
          >>> suite.run(unittest.TestResult())
          <unittest.result.TestResult run=1 errors=0 failures=0>
 
@@ -2804,7 +2803,6 @@ text files).
     ...         _ = f.write("       'abc def'\n")
     ...         _ = f.write("\n")
     ...         _ = f.write('   \"\"\"\n')
-    ...     import shutil
     ...     rc1, out1, err1 = script_helper.assert_python_failure(
     ...             '-m', 'doctest', fn, fn2, TERM='')
     ...     rc2, out2, err2 = script_helper.assert_python_ok(
@@ -2948,12 +2946,11 @@ Invalid doctest option:
 def test_main():
     # Check the doctest cases in doctest itself:
     ret = support.run_doctest(doctest, verbosity=True)
+
     # Check the doctest cases defined here:
     from test import test_doctest
     support.run_doctest(test_doctest, verbosity=True)
 
-import sys, re, io
-
 def test_coverage(coverdir):
     trace = support.import_module('trace')
     tracer = trace.Trace(ignoredirs=[sys.base_prefix, sys.base_exec_prefix,],
diff --git a/Lib/test/test_doctest3.txt b/Lib/test/test_doctest3.txt
index dd8557e57a..380ea76e4c 100644
--- a/Lib/test/test_doctest3.txt
+++ b/Lib/test/test_doctest3.txt
@@ -2,4 +2,4 @@
 Here we check that `__file__` is provided:
 
   >>> type(__file__)
-  <class 'str'>
+  <class 'str' ...>
diff --git a/Lib/test/test_dynamic.py b/Lib/test/test_dynamic.py
index 5080ec9f79..3ae090fd66 100644
--- a/Lib/test/test_dynamic.py
+++ b/Lib/test/test_dynamic.py
@@ -1,7 +1,6 @@
 # Test the most dynamic corner cases of Python's runtime semantics.
 
 import builtins
-import contextlib
 import unittest
 
 from test.support import swap_item, swap_attr
diff --git a/Lib/test/test_eintr.py b/Lib/test/test_eintr.py
index aabad835a0..25f86d31de 100644
--- a/Lib/test/test_eintr.py
+++ b/Lib/test/test_eintr.py
@@ -1,7 +1,5 @@
 import os
 import signal
-import subprocess
-import sys
 import unittest
 
 from test import support
@@ -16,14 +14,8 @@ class EINTRTests(unittest.TestCase):
         # Run the tester in a sub-process, to make sure there is only one
         # thread (for reliable signal delivery).
         tester = support.findfile("eintr_tester.py", subdir="eintrdata")
-
-        if support.verbose:
-            args = [sys.executable, tester]
-            with subprocess.Popen(args) as proc:
-                exitcode = proc.wait()
-            self.assertEqual(exitcode, 0)
-        else:
-            script_helper.assert_python_ok(tester)
+        # use -u to try to get the full output if the test hangs or crash
+        script_helper.assert_python_ok("-u", tester)
 
 
 if __name__ == "__main__":
diff --git a/Lib/test/test_email/__init__.py b/Lib/test/test_email/__init__.py
index d2f7d31934..16001596e4 100644
--- a/Lib/test/test_email/__init__.py
+++ b/Lib/test/test_email/__init__.py
@@ -1,5 +1,4 @@
 import os
-import sys
 import unittest
 import collections
 import email
diff --git a/Lib/test/test_email/test_asian_codecs.py b/Lib/test/test_email/test_asian_codecs.py
index f9cd7d9b4e..1e0caeeaed 100644
--- a/Lib/test/test_email/test_asian_codecs.py
+++ b/Lib/test/test_email/test_asian_codecs.py
@@ -3,7 +3,6 @@
 # email package unit tests for (optional) Asian codecs
 
 import unittest
-from test.support import run_unittest
 
 from test.test_email import TestEmailBase
 from email.charset import Charset
diff --git a/Lib/test/test_email/test_email.py b/Lib/test/test_email/test_email.py
index 894b8003cd..af3fb85c56 100644
--- a/Lib/test/test_email/test_email.py
+++ b/Lib/test/test_email/test_email.py
@@ -3421,7 +3421,6 @@ Do you like this message?
 class TestFeedParsers(TestEmailBase):
 
     def parse(self, chunks):
-        from email.feedparser import FeedParser
         feedparser = FeedParser()
         for chunk in chunks:
             feedparser.feed(chunk)
diff --git a/Lib/test/test_email/test_headerregistry.py b/Lib/test/test_email/test_headerregistry.py
index 55ecdea9aa..af836dc972 100644
--- a/Lib/test/test_email/test_headerregistry.py
+++ b/Lib/test/test_email/test_headerregistry.py
@@ -1,7 +1,6 @@
 import datetime
 import textwrap
 import unittest
-import types
 from email import errors
 from email import policy
 from email.message import Message
diff --git a/Lib/test/test_enum.py b/Lib/test/test_enum.py
index e970a264d7..b1a5855790 100644
--- a/Lib/test/test_enum.py
+++ b/Lib/test/test_enum.py
@@ -6,6 +6,7 @@ from collections import OrderedDict
 from enum import Enum, IntEnum, EnumMeta, unique
 from io import StringIO
 from pickle import dumps, loads, PicklingError, HIGHEST_PROTOCOL
+from test import support
 
 # for pickle tests
 try:
@@ -283,6 +284,28 @@ class TestEnum(unittest.TestCase):
             class Wrong(Enum):
                 _any_name_ = 9
 
+    def test_bool(self):
+        # plain Enum members are always True
+        class Logic(Enum):
+            true = True
+            false = False
+        self.assertTrue(Logic.true)
+        self.assertTrue(Logic.false)
+        # unless overridden
+        class RealLogic(Enum):
+            true = True
+            false = False
+            def __bool__(self):
+                return bool(self._value_)
+        self.assertTrue(RealLogic.true)
+        self.assertFalse(RealLogic.false)
+        # mixed Enums depend on mixed-in type
+        class IntLogic(int, Enum):
+            true = 1
+            false = 0
+        self.assertTrue(IntLogic.true)
+        self.assertFalse(IntLogic.false)
+
     def test_contains(self):
         Season = self.Season
         self.assertIn(Season.AUTUMN, Season)
@@ -1739,5 +1762,47 @@ class TestStdLib(unittest.TestCase):
         if failed:
             self.fail("result does not equal expected, see print above")
 
+
+class MiscTestCase(unittest.TestCase):
+    def test__all__(self):
+        support.check__all__(self, enum)
+
+
+# These are unordered here on purpose to ensure that declaration order
+# makes no difference.
+CONVERT_TEST_NAME_D = 5
+CONVERT_TEST_NAME_C = 5
+CONVERT_TEST_NAME_B = 5
+CONVERT_TEST_NAME_A = 5  # This one should sort first.
+CONVERT_TEST_NAME_E = 5
+CONVERT_TEST_NAME_F = 5
+
+class TestIntEnumConvert(unittest.TestCase):
+    def test_convert_value_lookup_priority(self):
+        test_type = enum.IntEnum._convert(
+                'UnittestConvert', 'test.test_enum',
+                filter=lambda x: x.startswith('CONVERT_TEST_'))
+        # We don't want the reverse lookup value to vary when there are
+        # multiple possible names for a given value.  It should always
+        # report the first lexigraphical name in that case.
+        self.assertEqual(test_type(5).name, 'CONVERT_TEST_NAME_A')
+
+    def test_convert(self):
+        test_type = enum.IntEnum._convert(
+                'UnittestConvert', 'test.test_enum',
+                filter=lambda x: x.startswith('CONVERT_TEST_'))
+        # Ensure that test_type has all of the desired names and values.
+        self.assertEqual(test_type.CONVERT_TEST_NAME_F,
+                         test_type.CONVERT_TEST_NAME_A)
+        self.assertEqual(test_type.CONVERT_TEST_NAME_B, 5)
+        self.assertEqual(test_type.CONVERT_TEST_NAME_C, 5)
+        self.assertEqual(test_type.CONVERT_TEST_NAME_D, 5)
+        self.assertEqual(test_type.CONVERT_TEST_NAME_E, 5)
+        # Ensure that test_type only picked up names matching the filter.
+        self.assertEqual([name for name in dir(test_type)
+                          if name[0:2] not in ('CO', '__')],
+                         [], msg='Names other than CONVERT_TEST_* found.')
+
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/Lib/test/test_epoll.py b/Lib/test/test_epoll.py
index a7359e9c29..a7aff8a59e 100644
--- a/Lib/test/test_epoll.py
+++ b/Lib/test/test_epoll.py
@@ -28,7 +28,6 @@ import socket
 import time
 import unittest
 
-from test import support
 if not hasattr(select, "epoll"):
     raise unittest.SkipTest("test works only on Linux 2.6")
 
diff --git a/Lib/test/test_faulthandler.py b/Lib/test/test_faulthandler.py
index 1562eecbd6..fc2d6d7bae 100644
--- a/Lib/test/test_faulthandler.py
+++ b/Lib/test/test_faulthandler.py
@@ -23,6 +23,7 @@ except ImportError:
     _testcapi = None
 
 TIMEOUT = 0.5
+MS_WINDOWS = (os.name == 'nt')
 
 def expected_traceback(lineno1, lineno2, header, min_count=1):
     regex = header
@@ -58,8 +59,9 @@ class FaultHandlerTests(unittest.TestCase):
             pass_fds.append(fd)
         with support.SuppressCrashReport():
             process = script_helper.spawn_python('-c', code, pass_fds=pass_fds)
-        stdout, stderr = process.communicate()
-        exitcode = process.wait()
+            with process:
+                stdout, stderr = process.communicate()
+                exitcode = process.wait()
         output = support.strip_python_stderr(stdout)
         output = output.decode('ascii', 'backslashreplace')
         if filename:
@@ -73,14 +75,11 @@ class FaultHandlerTests(unittest.TestCase):
             with open(fd, "rb", closefd=False) as fp:
                 output = fp.read()
             output = output.decode('ascii', 'backslashreplace')
-        output = re.sub('Current thread 0x[0-9a-f]+',
-                        'Current thread XXX',
-                        output)
         return output.splitlines(), exitcode
 
-    def check_fatal_error(self, code, line_number, name_regex,
-                          filename=None, all_threads=True, other_regex=None,
-                          fd=None):
+    def check_error(self, code, line_number, fatal_error, *,
+                    filename=None, all_threads=True, other_regex=None,
+                    fd=None, know_current_thread=True):
         """
         Check that the fault handler for fatal errors is enabled and check the
         traceback from the child process output.
@@ -88,19 +87,22 @@ class FaultHandlerTests(unittest.TestCase):
         Raise an error if the output doesn't match the expected format.
         """
         if all_threads:
-            header = 'Current thread XXX (most recent call first)'
+            if know_current_thread:
+                header = 'Current thread 0x[0-9a-f]+'
+            else:
+                header = 'Thread 0x[0-9a-f]+'
         else:
-            header = 'Stack (most recent call first)'
+            header = 'Stack'
         regex = """
-            ^Fatal Python error: {name}
+            ^{fatal_error}
 
-            {header}:
+            {header} \(most recent call first\):
               File "<string>", line {lineno} in <module>
             """
         regex = dedent(regex.format(
             lineno=line_number,
-            name=name_regex,
-            header=re.escape(header))).strip()
+            fatal_error=fatal_error,
+            header=header)).strip()
         if other_regex:
             regex += '|' + other_regex
         output, exitcode = self.get_output(code, filename=filename, fd=fd)
@@ -108,26 +110,56 @@ class FaultHandlerTests(unittest.TestCase):
         self.assertRegex(output, regex)
         self.assertNotEqual(exitcode, 0)
 
+    def check_fatal_error(self, code, line_number, name_regex, **kw):
+        fatal_error = 'Fatal Python error: %s' % name_regex
+        self.check_error(code, line_number, fatal_error, **kw)
+
+    def check_windows_exception(self, code, line_number, name_regex, **kw):
+        fatal_error = 'Windows fatal exception: %s' % name_regex
+        self.check_error(code, line_number, fatal_error, **kw)
+
     @unittest.skipIf(sys.platform.startswith('aix'),
                      "the first page of memory is a mapped read-only on AIX")
     def test_read_null(self):
+        if not MS_WINDOWS:
+            self.check_fatal_error("""
+                import faulthandler
+                faulthandler.enable()
+                faulthandler._read_null()
+                """,
+                3,
+                # Issue #12700: Read NULL raises SIGILL on Mac OS X Lion
+                '(?:Segmentation fault'
+                    '|Bus error'
+                    '|Illegal instruction)')
+        else:
+            self.check_windows_exception("""
+                import faulthandler
+                faulthandler.enable()
+                faulthandler._read_null()
+                """,
+                3,
+                'access violation')
+
+    def test_sigsegv(self):
         self.check_fatal_error("""
             import faulthandler
             faulthandler.enable()
-            faulthandler._read_null()
+            faulthandler._sigsegv()
             """,
             3,
-            # Issue #12700: Read NULL raises SIGILL on Mac OS X Lion
-            '(?:Segmentation fault|Bus error|Illegal instruction)')
+            'Segmentation fault')
 
-    def test_sigsegv(self):
+    @unittest.skipIf(not HAVE_THREADS, 'need threads')
+    def test_fatal_error_c_thread(self):
         self.check_fatal_error("""
             import faulthandler
             faulthandler.enable()
-            faulthandler._sigsegv()
+            faulthandler._fatal_error_c_thread()
             """,
             3,
-            'Segmentation fault')
+            'in new thread',
+            know_current_thread=False)
 
     def test_sigabrt(self):
         self.check_fatal_error("""
@@ -465,7 +497,7 @@ class FaultHandlerTests(unittest.TestCase):
               File ".*threading.py", line [0-9]+ in _bootstrap_inner
               File ".*threading.py", line [0-9]+ in _bootstrap
 
-            Current thread XXX \(most recent call first\):
+            Current thread 0x[0-9a-f]+ \(most recent call first\):
               File "<string>", line {lineno} in dump
               File "<string>", line 28 in <module>$
             """
@@ -637,7 +669,7 @@ class FaultHandlerTests(unittest.TestCase):
         trace = '\n'.join(trace)
         if not unregister:
             if all_threads:
-                regex = 'Current thread XXX \(most recent call first\):\n'
+                regex = 'Current thread 0x[0-9a-f]+ \(most recent call first\):\n'
             else:
                 regex = 'Stack \(most recent call first\):\n'
             regex = expected_traceback(14, 32, regex)
@@ -696,6 +728,22 @@ class FaultHandlerTests(unittest.TestCase):
             with self.check_stderr_none():
                 faulthandler.register(signal.SIGUSR1)
 
+    @unittest.skipUnless(MS_WINDOWS, 'specific to Windows')
+    def test_raise_exception(self):
+        for exc, name in (
+            ('EXCEPTION_ACCESS_VIOLATION', 'access violation'),
+            ('EXCEPTION_INT_DIVIDE_BY_ZERO', 'int divide by zero'),
+            ('EXCEPTION_STACK_OVERFLOW', 'stack overflow'),
+        ):
+            self.check_windows_exception(f"""
+                import faulthandler
+                faulthandler.enable()
+                faulthandler._raise_exception(faulthandler._{exc})
+                """,
+                3,
+                name)
+
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_file.py b/Lib/test/test_file.py
index 4e392b770c..65be30f0b2 100644
--- a/Lib/test/test_file.py
+++ b/Lib/test/test_file.py
@@ -7,7 +7,7 @@ from weakref import proxy
 import io
 import _pyio as pyio
 
-from test.support import TESTFN, run_unittest
+from test.support import TESTFN
 from collections import UserList
 
 class AutoFileTests:
@@ -139,7 +139,7 @@ class OtherFileTests:
 
     def testModeStrings(self):
         # check invalid mode strings
-        for mode in ("", "aU", "wU+"):
+        for mode in ("", "aU", "wU+", "U+", "+U", "rU+"):
             try:
                 f = self.open(TESTFN, mode)
             except ValueError:
diff --git a/Lib/test/test_fileinput.py b/Lib/test/test_fileinput.py
index 784bc92d23..565633fccc 100644
--- a/Lib/test/test_fileinput.py
+++ b/Lib/test/test_fileinput.py
@@ -22,8 +22,9 @@ except ImportError:
 from io import BytesIO, StringIO
 from fileinput import FileInput, hook_encoded
 
-from test.support import verbose, TESTFN, run_unittest, check_warnings
+from test.support import verbose, TESTFN, check_warnings
 from test.support import unlink as safe_unlink
+from test import support
 from unittest import mock
 
 
@@ -92,7 +93,11 @@ class BufferSizesTests(unittest.TestCase):
                 t2 = writeTmp(2, ["Line %s of file 2\n" % (i+1) for i in range(10)])
                 t3 = writeTmp(3, ["Line %s of file 3\n" % (i+1) for i in range(5)])
                 t4 = writeTmp(4, ["Line %s of file 4\n" % (i+1) for i in range(1)])
-                self.buffer_size_test(t1, t2, t3, t4, bs, round)
+                if bs:
+                    with self.assertWarns(DeprecationWarning):
+                        self.buffer_size_test(t1, t2, t3, t4, bs, round)
+                else:
+                    self.buffer_size_test(t1, t2, t3, t4, bs, round)
             finally:
                 remove_tempfiles(t1, t2, t3, t4)
 
@@ -940,7 +945,8 @@ class Test_hook_encoded(unittest.TestCase):
 
     def test(self):
         encoding = object()
-        result = fileinput.hook_encoded(encoding)
+        errors = object()
+        result = fileinput.hook_encoded(encoding, errors=errors)
 
         fake_open = InvocationRecorder()
         original_open = builtins.open
@@ -958,8 +964,26 @@ class Test_hook_encoded(unittest.TestCase):
         self.assertIs(args[0], filename)
         self.assertIs(args[1], mode)
         self.assertIs(kwargs.pop('encoding'), encoding)
+        self.assertIs(kwargs.pop('errors'), errors)
         self.assertFalse(kwargs)
 
+    def test_errors(self):
+        with open(TESTFN, 'wb') as f:
+            f.write(b'\x80abc')
+        self.addCleanup(safe_unlink, TESTFN)
+
+        def check(errors, expected_lines):
+            with FileInput(files=TESTFN, mode='r',
+                           openhook=hook_encoded('utf-8', errors=errors)) as fi:
+                lines = list(fi)
+            self.assertEqual(lines, expected_lines)
+
+        check('ignore', ['abc'])
+        with self.assertRaises(UnicodeDecodeError):
+            check('strict', ['abc'])
+        check('replace', ['\ufffdabc'])
+        check('backslashreplace', ['\\x80abc'])
+
     def test_modes(self):
         with open(TESTFN, 'wb') as f:
             # UTF-7 is a convenient, seldom used encoding
@@ -981,5 +1005,11 @@ class Test_hook_encoded(unittest.TestCase):
             check('rb', ['A\n', 'B\r\n', 'C\r', 'D\u20ac'])
 
 
+class MiscTest(unittest.TestCase):
+
+    def test_all(self):
+        support.check__all__(self, fileinput)
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_float.py b/Lib/test/test_float.py
index cb1f6db8fc..68b212e195 100644
--- a/Lib/test/test_float.py
+++ b/Lib/test/test_float.py
@@ -1,6 +1,5 @@
 
 import fractions
-import math
 import operator
 import os
 import random
@@ -162,11 +161,12 @@ class GeneralFloatCases(unittest.TestCase):
             def __float__(self):
                 return float(str(self)) + 1
 
-        self.assertAlmostEqual(float(Foo1()), 42.)
-        self.assertAlmostEqual(float(Foo2()), 42.)
-        self.assertAlmostEqual(float(Foo3(21)), 42.)
+        self.assertEqual(float(Foo1()), 42.)
+        self.assertEqual(float(Foo2()), 42.)
+        with self.assertWarns(DeprecationWarning):
+            self.assertEqual(float(Foo3(21)), 42.)
         self.assertRaises(TypeError, float, Foo4(42))
-        self.assertAlmostEqual(float(FooStr('8')), 9.)
+        self.assertEqual(float(FooStr('8')), 9.)
 
         class Foo5:
             def __float__(self):
@@ -177,10 +177,14 @@ class GeneralFloatCases(unittest.TestCase):
         class F:
             def __float__(self):
                 return OtherFloatSubclass(42.)
-        self.assertAlmostEqual(float(F()), 42.)
-        self.assertIs(type(float(F())), OtherFloatSubclass)
-        self.assertAlmostEqual(FloatSubclass(F()), 42.)
-        self.assertIs(type(FloatSubclass(F())), FloatSubclass)
+        with self.assertWarns(DeprecationWarning):
+            self.assertEqual(float(F()), 42.)
+        with self.assertWarns(DeprecationWarning):
+            self.assertIs(type(float(F())), float)
+        with self.assertWarns(DeprecationWarning):
+            self.assertEqual(FloatSubclass(F()), 42.)
+        with self.assertWarns(DeprecationWarning):
+            self.assertIs(type(FloatSubclass(F())), FloatSubclass)
 
     def test_is_integer(self):
         self.assertFalse((1.1).is_integer())
diff --git a/Lib/test/test_format.py b/Lib/test/test_format.py
index 9b13632591..8afd5b8f1f 100644
--- a/Lib/test/test_format.py
+++ b/Lib/test/test_format.py
@@ -274,7 +274,7 @@ class FormatTest(unittest.TestCase):
         test_exc('%d', '1', TypeError, "%d format: a number is required, not str")
         test_exc('%x', '1', TypeError, "%x format: an integer is required, not str")
         test_exc('%x', 3.14, TypeError, "%x format: an integer is required, not float")
-        test_exc('%g', '1', TypeError, "a float is required")
+        test_exc('%g', '1', TypeError, "must be real number, not str")
         test_exc('no format', '1', TypeError,
                  "not all arguments converted during string formatting")
         test_exc('%c', -1, OverflowError, "%c arg not in range(0x110000)")
@@ -300,6 +300,8 @@ class FormatTest(unittest.TestCase):
         testcommon(b"%c", 7, b"\x07")
         testcommon(b"%c", b"Z", b"Z")
         testcommon(b"%c", bytearray(b"Z"), b"Z")
+        testcommon(b"%5c", 65, b"    A")
+        testcommon(b"%-5c", 65, b"A    ")
         # %b will insert a series of bytes, either from a type that supports
         # the Py_buffer protocol, or something that has a __bytes__ method
         class FakeBytes(object):
diff --git a/Lib/test/test_fractions.py b/Lib/test/test_fractions.py
index 1699852216..73d2dd3031 100644
--- a/Lib/test/test_fractions.py
+++ b/Lib/test/test_fractions.py
@@ -263,13 +263,13 @@ class FractionTest(unittest.TestCase):
         nan = inf - inf
         # bug 16469: error types should be consistent with float -> int
         self.assertRaisesMessage(
-            OverflowError, "Cannot convert inf to Fraction.",
+            OverflowError, "cannot convert Infinity to integer ratio",
             F.from_float, inf)
         self.assertRaisesMessage(
-            OverflowError, "Cannot convert -inf to Fraction.",
+            OverflowError, "cannot convert Infinity to integer ratio",
             F.from_float, -inf)
         self.assertRaisesMessage(
-            ValueError, "Cannot convert nan to Fraction.",
+            ValueError, "cannot convert NaN to integer ratio",
             F.from_float, nan)
 
     def testFromDecimal(self):
@@ -284,16 +284,16 @@ class FractionTest(unittest.TestCase):
 
         # bug 16469: error types should be consistent with decimal -> int
         self.assertRaisesMessage(
-            OverflowError, "Cannot convert Infinity to Fraction.",
+            OverflowError, "cannot convert Infinity to integer ratio",
             F.from_decimal, Decimal("inf"))
         self.assertRaisesMessage(
-            OverflowError, "Cannot convert -Infinity to Fraction.",
+            OverflowError, "cannot convert Infinity to integer ratio",
             F.from_decimal, Decimal("-inf"))
         self.assertRaisesMessage(
-            ValueError, "Cannot convert NaN to Fraction.",
+            ValueError, "cannot convert NaN to integer ratio",
             F.from_decimal, Decimal("nan"))
         self.assertRaisesMessage(
-            ValueError, "Cannot convert sNaN to Fraction.",
+            ValueError, "cannot convert NaN to integer ratio",
             F.from_decimal, Decimal("snan"))
 
     def testLimitDenominator(self):
diff --git a/Lib/test/test_fstring.py b/Lib/test/test_fstring.py
new file mode 100644
index 0000000000..a82dedffe4
--- /dev/null
+++ b/Lib/test/test_fstring.py
@@ -0,0 +1,745 @@
+import ast
+import types
+import decimal
+import unittest
+
+a_global = 'global variable'
+
+# You could argue that I'm too strict in looking for specific error
+#  values with assertRaisesRegex, but without it it's way too easy to
+#  make a syntax error in the test strings. Especially with all of the
+#  triple quotes, raw strings, backslashes, etc. I think it's a
+#  worthwhile tradeoff. When I switched to this method, I found many
+#  examples where I wasn't testing what I thought I was.
+
+class TestCase(unittest.TestCase):
+    def assertAllRaise(self, exception_type, regex, error_strings):
+        for str in error_strings:
+            with self.subTest(str=str):
+                with self.assertRaisesRegex(exception_type, regex):
+                    eval(str)
+
+    def test__format__lookup(self):
+        # Make sure __format__ is looked up on the type, not the instance.
+        class X:
+            def __format__(self, spec):
+                return 'class'
+
+        x = X()
+
+        # Add a bound __format__ method to the 'y' instance, but not
+        #  the 'x' instance.
+        y = X()
+        y.__format__ = types.MethodType(lambda self, spec: 'instance', y)
+
+        self.assertEqual(f'{y}', format(y))
+        self.assertEqual(f'{y}', 'class')
+        self.assertEqual(format(x), format(y))
+
+        # __format__ is not called this way, but still make sure it
+        #  returns what we expect (so we can make sure we're bypassing
+        #  it).
+        self.assertEqual(x.__format__(''), 'class')
+        self.assertEqual(y.__format__(''), 'instance')
+
+        # This is how __format__ is actually called.
+        self.assertEqual(type(x).__format__(x, ''), 'class')
+        self.assertEqual(type(y).__format__(y, ''), 'class')
+
+    def test_ast(self):
+        # Inspired by http://bugs.python.org/issue24975
+        class X:
+            def __init__(self):
+                self.called = False
+            def __call__(self):
+                self.called = True
+                return 4
+        x = X()
+        expr = """
+a = 10
+f'{a * x()}'"""
+        t = ast.parse(expr)
+        c = compile(t, '', 'exec')
+
+        # Make sure x was not called.
+        self.assertFalse(x.called)
+
+        # Actually run the code.
+        exec(c)
+
+        # Make sure x was called.
+        self.assertTrue(x.called)
+
+    def test_literal_eval(self):
+        # With no expressions, an f-string is okay.
+        self.assertEqual(ast.literal_eval("f'x'"), 'x')
+        self.assertEqual(ast.literal_eval("f'x' 'y'"), 'xy')
+
+        # But this should raise an error.
+        with self.assertRaisesRegex(ValueError, 'malformed node or string'):
+            ast.literal_eval("f'x{3}'")
+
+        # As should this, which uses a different ast node
+        with self.assertRaisesRegex(ValueError, 'malformed node or string'):
+            ast.literal_eval("f'{3}'")
+
+    def test_ast_compile_time_concat(self):
+        x = ['']
+
+        expr = """x[0] = 'foo' f'{3}'"""
+        t = ast.parse(expr)
+        c = compile(t, '', 'exec')
+        exec(c)
+        self.assertEqual(x[0], 'foo3')
+
+    def test_literal(self):
+        self.assertEqual(f'', '')
+        self.assertEqual(f'a', 'a')
+        self.assertEqual(f' ', ' ')
+        self.assertEqual(f'\N{GREEK CAPITAL LETTER DELTA}',
+                         '\N{GREEK CAPITAL LETTER DELTA}')
+        self.assertEqual(f'\N{GREEK CAPITAL LETTER DELTA}',
+                         '\u0394')
+        self.assertEqual(f'\N{True}', '\u22a8')
+        self.assertEqual(rf'\N{True}', r'\NTrue')
+
+    def test_escape_order(self):
+        # note that hex(ord('{')) == 0x7b, so this
+        #  string becomes f'a{4*10}b'
+        self.assertEqual(f'a\u007b4*10}b', 'a40b')
+        self.assertEqual(f'a\x7b4*10}b', 'a40b')
+        self.assertEqual(f'a\x7b4*10\N{RIGHT CURLY BRACKET}b', 'a40b')
+        self.assertEqual(f'{"a"!\N{LATIN SMALL LETTER R}}', "'a'")
+        self.assertEqual(f'{10\x3a02X}', '0A')
+        self.assertEqual(f'{10:02\N{LATIN CAPITAL LETTER X}}', '0A')
+
+        self.assertAllRaise(SyntaxError, "f-string: single '}' is not allowed",
+                            [r"""f'a{\u007b4*10}b'""",    # mis-matched brackets
+                             ])
+        self.assertAllRaise(SyntaxError, 'unexpected character after line continuation character',
+                            [r"""f'{"a"\!r}'""",
+                             r"""f'{a\!r}'""",
+                             ])
+
+    def test_unterminated_string(self):
+        self.assertAllRaise(SyntaxError, 'f-string: unterminated string',
+                            [r"""f'{"x'""",
+                             r"""f'{"x}'""",
+                             r"""f'{("x'""",
+                             r"""f'{("x}'""",
+                             ])
+
+    def test_mismatched_parens(self):
+        self.assertAllRaise(SyntaxError, 'f-string: mismatched',
+                            ["f'{((}'",
+                             ])
+
+    def test_double_braces(self):
+        self.assertEqual(f'{{', '{')
+        self.assertEqual(f'a{{', 'a{')
+        self.assertEqual(f'{{b', '{b')
+        self.assertEqual(f'a{{b', 'a{b')
+        self.assertEqual(f'}}', '}')
+        self.assertEqual(f'a}}', 'a}')
+        self.assertEqual(f'}}b', '}b')
+        self.assertEqual(f'a}}b', 'a}b')
+
+        self.assertEqual(f'{{{10}', '{10')
+        self.assertEqual(f'}}{10}', '}10')
+        self.assertEqual(f'}}{{{10}', '}{10')
+        self.assertEqual(f'}}a{{{10}', '}a{10')
+
+        self.assertEqual(f'{10}{{', '10{')
+        self.assertEqual(f'{10}}}', '10}')
+        self.assertEqual(f'{10}}}{{', '10}{')
+        self.assertEqual(f'{10}}}a{{' '}', '10}a{}')
+
+        # Inside of strings, don't interpret doubled brackets.
+        self.assertEqual(f'{"{{}}"}', '{{}}')
+
+        self.assertAllRaise(TypeError, 'unhashable type',
+                            ["f'{ {{}} }'", # dict in a set
+                             ])
+
+    def test_compile_time_concat(self):
+        x = 'def'
+        self.assertEqual('abc' f'## {x}ghi', 'abc## defghi')
+        self.assertEqual('abc' f'{x}' 'ghi', 'abcdefghi')
+        self.assertEqual('abc' f'{x}' 'gh' f'i{x:4}', 'abcdefghidef ')
+        self.assertEqual('{x}' f'{x}', '{x}def')
+        self.assertEqual('{x' f'{x}', '{xdef')
+        self.assertEqual('{x}' f'{x}', '{x}def')
+        self.assertEqual('{{x}}' f'{x}', '{{x}}def')
+        self.assertEqual('{{x' f'{x}', '{{xdef')
+        self.assertEqual('x}}' f'{x}', 'x}}def')
+        self.assertEqual(f'{x}' 'x}}', 'defx}}')
+        self.assertEqual(f'{x}' '', 'def')
+        self.assertEqual('' f'{x}' '', 'def')
+        self.assertEqual('' f'{x}', 'def')
+        self.assertEqual(f'{x}' '2', 'def2')
+        self.assertEqual('1' f'{x}' '2', '1def2')
+        self.assertEqual('1' f'{x}', '1def')
+        self.assertEqual(f'{x}' f'-{x}', 'def-def')
+        self.assertEqual('' f'', '')
+        self.assertEqual('' f'' '', '')
+        self.assertEqual('' f'' '' f'', '')
+        self.assertEqual(f'', '')
+        self.assertEqual(f'' '', '')
+        self.assertEqual(f'' '' f'', '')
+        self.assertEqual(f'' '' f'' '', '')
+
+        self.assertAllRaise(SyntaxError, "f-string: expecting '}'",
+                            ["f'{3' f'}'",  # can't concat to get a valid f-string
+                             ])
+
+    def test_comments(self):
+        # These aren't comments, since they're in strings.
+        d = {'#': 'hash'}
+        self.assertEqual(f'{"#"}', '#')
+        self.assertEqual(f'{d["#"]}', 'hash')
+
+        self.assertAllRaise(SyntaxError, "f-string cannot include '#'",
+                            ["f'{1#}'",   # error because the expression becomes "(1#)"
+                             "f'{3(#)}'",
+                             ])
+
+    def test_many_expressions(self):
+        # Create a string with many expressions in it. Note that
+        #  because we have a space in here as a literal, we're actually
+        #  going to use twice as many ast nodes: one for each literal
+        #  plus one for each expression.
+        def build_fstr(n, extra=''):
+            return "f'" + ('{x} ' * n) + extra + "'"
+
+        x = 'X'
+        width = 1
+
+        # Test around 256.
+        for i in range(250, 260):
+            self.assertEqual(eval(build_fstr(i)), (x+' ')*i)
+
+        # Test concatenating 2 largs fstrings.
+        self.assertEqual(eval(build_fstr(255)*256), (x+' ')*(255*256))
+
+        s = build_fstr(253, '{x:{width}} ')
+        self.assertEqual(eval(s), (x+' ')*254)
+
+        # Test lots of expressions and constants, concatenated.
+        s = "f'{1}' 'x' 'y'" * 1024
+        self.assertEqual(eval(s), '1xy' * 1024)
+
+    def test_format_specifier_expressions(self):
+        width = 10
+        precision = 4
+        value = decimal.Decimal('12.34567')
+        self.assertEqual(f'result: {value:{width}.{precision}}', 'result:      12.35')
+        self.assertEqual(f'result: {value:{width!r}.{precision}}', 'result:      12.35')
+        self.assertEqual(f'result: {value:{width:0}.{precision:1}}', 'result:      12.35')
+        self.assertEqual(f'result: {value:{1}{0:0}.{precision:1}}', 'result:      12.35')
+        self.assertEqual(f'result: {value:{ 1}{ 0:0}.{ precision:1}}', 'result:      12.35')
+        self.assertEqual(f'{10:#{1}0x}', '       0xa')
+        self.assertEqual(f'{10:{"#"}1{0}{"x"}}', '       0xa')
+        self.assertEqual(f'{-10:-{"#"}1{0}x}', '      -0xa')
+        self.assertEqual(f'{-10:{"-"}#{1}0{"x"}}', '      -0xa')
+        self.assertEqual(f'{10:#{3 != {4:5} and width}x}', '       0xa')
+
+        self.assertAllRaise(SyntaxError, "f-string: expecting '}'",
+                            ["""f'{"s"!r{":10"}}'""",
+
+                             # This looks like a nested format spec.
+                             ])
+
+        self.assertAllRaise(SyntaxError, "invalid syntax",
+                            [# Invalid sytax inside a nested spec.
+                             "f'{4:{/5}}'",
+                             ])
+
+        self.assertAllRaise(SyntaxError, "f-string: expressions nested too deeply",
+                            [# Can't nest format specifiers.
+                             "f'result: {value:{width:{0}}.{precision:1}}'",
+                             ])
+
+        self.assertAllRaise(SyntaxError, 'f-string: invalid conversion character',
+                            [# No expansion inside conversion or for
+                             #  the : or ! itself.
+                             """f'{"s"!{"r"}}'""",
+                             ])
+
+    def test_side_effect_order(self):
+        class X:
+            def __init__(self):
+                self.i = 0
+            def __format__(self, spec):
+                self.i += 1
+                return str(self.i)
+
+        x = X()
+        self.assertEqual(f'{x} {x}', '1 2')
+
+    def test_missing_expression(self):
+        self.assertAllRaise(SyntaxError, 'f-string: empty expression not allowed',
+                            ["f'{}'",
+                             "f'{ }'"
+                             "f' {} '",
+                             "f'{!r}'",
+                             "f'{ !r}'",
+                             "f'{10:{ }}'",
+                             "f' { } '",
+                             r"f'{\n}'",
+                             r"f'{\n \n}'",
+
+                             # Catch the empty expression before the
+                             #  invalid conversion.
+                             "f'{!x}'",
+                             "f'{ !xr}'",
+                             "f'{!x:}'",
+                             "f'{!x:a}'",
+                             "f'{ !xr:}'",
+                             "f'{ !xr:a}'",
+
+                             "f'{!}'",
+                             "f'{:}'",
+
+                             # We find the empty expression before the
+                             #  missing closing brace.
+                             "f'{!'",
+                             "f'{!s:'",
+                             "f'{:'",
+                             "f'{:x'",
+                             ])
+
+    def test_parens_in_expressions(self):
+        self.assertEqual(f'{3,}', '(3,)')
+
+        # Add these because when an expression is evaluated, parens
+        #  are added around it. But we shouldn't go from an invalid
+        #  expression to a valid one. The added parens are just
+        #  supposed to allow whitespace (including newlines).
+        self.assertAllRaise(SyntaxError, 'invalid syntax',
+                            ["f'{,}'",
+                             "f'{,}'",  # this is (,), which is an error
+                             ])
+
+        self.assertAllRaise(SyntaxError, "f-string: expecting '}'",
+                            ["f'{3)+(4}'",
+                             ])
+
+        self.assertAllRaise(SyntaxError, 'EOL while scanning string literal',
+                            ["f'{\n}'",
+                             ])
+
+    def test_newlines_in_expressions(self):
+        self.assertEqual(f'{0}', '0')
+        self.assertEqual(f'{0\n}', '0')
+        self.assertEqual(f'{0\r}', '0')
+        self.assertEqual(f'{\n0\n}', '0')
+        self.assertEqual(f'{\r0\r}', '0')
+        self.assertEqual(f'{\n0\r}', '0')
+        self.assertEqual(f'{\n0}', '0')
+        self.assertEqual(f'{3+\n4}', '7')
+        self.assertEqual(f'{3+\\\n4}', '7')
+        self.assertEqual(rf'''{3+
+4}''', '7')
+        self.assertEqual(f'''{3+\
+4}''', '7')
+
+        self.assertAllRaise(SyntaxError, 'f-string: empty expression not allowed',
+                            [r"f'{\n}'",
+                             ])
+
+    def test_lambda(self):
+        x = 5
+        self.assertEqual(f'{(lambda y:x*y)("8")!r}', "'88888'")
+        self.assertEqual(f'{(lambda y:x*y)("8")!r:10}', "'88888'   ")
+        self.assertEqual(f'{(lambda y:x*y)("8"):10}', "88888     ")
+
+        # lambda doesn't work without parens, because the colon
+        #  makes the parser think it's a format_spec
+        self.assertAllRaise(SyntaxError, 'unexpected EOF while parsing',
+                            ["f'{lambda x:x}'",
+                             ])
+
+    def test_yield(self):
+        # Not terribly useful, but make sure the yield turns
+        #  a function into a generator
+        def fn(y):
+            f'y:{yield y*2}'
+
+        g = fn(4)
+        self.assertEqual(next(g), 8)
+
+    def test_yield_send(self):
+        def fn(x):
+            yield f'x:{yield (lambda i: x * i)}'
+
+        g = fn(10)
+        the_lambda = next(g)
+        self.assertEqual(the_lambda(4), 40)
+        self.assertEqual(g.send('string'), 'x:string')
+
+    def test_expressions_with_triple_quoted_strings(self):
+        self.assertEqual(f"{'''x'''}", 'x')
+        self.assertEqual(f"{'''eric's'''}", "eric's")
+        self.assertEqual(f'{"""eric\'s"""}', "eric's")
+        self.assertEqual(f"{'''eric\"s'''}", 'eric"s')
+        self.assertEqual(f'{"""eric"s"""}', 'eric"s')
+
+        # Test concatenation within an expression
+        self.assertEqual(f'{"x" """eric"s""" "y"}', 'xeric"sy')
+        self.assertEqual(f'{"x" """eric"s"""}', 'xeric"s')
+        self.assertEqual(f'{"""eric"s""" "y"}', 'eric"sy')
+        self.assertEqual(f'{"""x""" """eric"s""" "y"}', 'xeric"sy')
+        self.assertEqual(f'{"""x""" """eric"s""" """y"""}', 'xeric"sy')
+        self.assertEqual(f'{r"""x""" """eric"s""" """y"""}', 'xeric"sy')
+
+    def test_multiple_vars(self):
+        x = 98
+        y = 'abc'
+        self.assertEqual(f'{x}{y}', '98abc')
+
+        self.assertEqual(f'X{x}{y}', 'X98abc')
+        self.assertEqual(f'{x}X{y}', '98Xabc')
+        self.assertEqual(f'{x}{y}X', '98abcX')
+
+        self.assertEqual(f'X{x}Y{y}', 'X98Yabc')
+        self.assertEqual(f'X{x}{y}Y', 'X98abcY')
+        self.assertEqual(f'{x}X{y}Y', '98XabcY')
+
+        self.assertEqual(f'X{x}Y{y}Z', 'X98YabcZ')
+
+    def test_closure(self):
+        def outer(x):
+            def inner():
+                return f'x:{x}'
+            return inner
+
+        self.assertEqual(outer('987')(), 'x:987')
+        self.assertEqual(outer(7)(), 'x:7')
+
+    def test_arguments(self):
+        y = 2
+        def f(x, width):
+            return f'x={x*y:{width}}'
+
+        self.assertEqual(f('foo', 10), 'x=foofoo    ')
+        x = 'bar'
+        self.assertEqual(f(10, 10), 'x=        20')
+
+    def test_locals(self):
+        value = 123
+        self.assertEqual(f'v:{value}', 'v:123')
+
+    def test_missing_variable(self):
+        with self.assertRaises(NameError):
+            f'v:{value}'
+
+    def test_missing_format_spec(self):
+        class O:
+            def __format__(self, spec):
+                if not spec:
+                    return '*'
+                return spec
+
+        self.assertEqual(f'{O():x}', 'x')
+        self.assertEqual(f'{O()}', '*')
+        self.assertEqual(f'{O():}', '*')
+
+        self.assertEqual(f'{3:}', '3')
+        self.assertEqual(f'{3!s:}', '3')
+
+    def test_global(self):
+        self.assertEqual(f'g:{a_global}', 'g:global variable')
+        self.assertEqual(f'g:{a_global!r}', "g:'global variable'")
+
+        a_local = 'local variable'
+        self.assertEqual(f'g:{a_global} l:{a_local}',
+                         'g:global variable l:local variable')
+        self.assertEqual(f'g:{a_global!r}',
+                         "g:'global variable'")
+        self.assertEqual(f'g:{a_global} l:{a_local!r}',
+                         "g:global variable l:'local variable'")
+
+        self.assertIn("module 'unittest' from", f'{unittest}')
+
+    def test_shadowed_global(self):
+        a_global = 'really a local'
+        self.assertEqual(f'g:{a_global}', 'g:really a local')
+        self.assertEqual(f'g:{a_global!r}', "g:'really a local'")
+
+        a_local = 'local variable'
+        self.assertEqual(f'g:{a_global} l:{a_local}',
+                         'g:really a local l:local variable')
+        self.assertEqual(f'g:{a_global!r}',
+                         "g:'really a local'")
+        self.assertEqual(f'g:{a_global} l:{a_local!r}',
+                         "g:really a local l:'local variable'")
+
+    def test_call(self):
+        def foo(x):
+            return 'x=' + str(x)
+
+        self.assertEqual(f'{foo(10)}', 'x=10')
+
+    def test_nested_fstrings(self):
+        y = 5
+        self.assertEqual(f'{f"{0}"*3}', '000')
+        self.assertEqual(f'{f"{y}"*3}', '555')
+        self.assertEqual(f'{f"{\'x\'}"*3}', 'xxx')
+
+        self.assertEqual(f"{r'x' f'{\"s\"}'}", 'xs')
+        self.assertEqual(f"{r'x'rf'{\"s\"}'}", 'xs')
+
+    def test_invalid_string_prefixes(self):
+        self.assertAllRaise(SyntaxError, 'unexpected EOF while parsing',
+                            ["fu''",
+                             "uf''",
+                             "Fu''",
+                             "fU''",
+                             "Uf''",
+                             "uF''",
+                             "ufr''",
+                             "urf''",
+                             "fur''",
+                             "fru''",
+                             "rfu''",
+                             "ruf''",
+                             "FUR''",
+                             "Fur''",
+                             ])
+
+    def test_leading_trailing_spaces(self):
+        self.assertEqual(f'{ 3}', '3')
+        self.assertEqual(f'{  3}', '3')
+        self.assertEqual(f'{\t3}', '3')
+        self.assertEqual(f'{\t\t3}', '3')
+        self.assertEqual(f'{3 }', '3')
+        self.assertEqual(f'{3  }', '3')
+        self.assertEqual(f'{3\t}', '3')
+        self.assertEqual(f'{3\t\t}', '3')
+
+        self.assertEqual(f'expr={ {x: y for x, y in [(1, 2), ]}}',
+                         'expr={1: 2}')
+        self.assertEqual(f'expr={ {x: y for x, y in [(1, 2), ]} }',
+                         'expr={1: 2}')
+
+    def test_character_name(self):
+        self.assertEqual(f'{4}\N{GREEK CAPITAL LETTER DELTA}{3}',
+                         '4\N{GREEK CAPITAL LETTER DELTA}3')
+        self.assertEqual(f'{{}}\N{GREEK CAPITAL LETTER DELTA}{3}',
+                         '{}\N{GREEK CAPITAL LETTER DELTA}3')
+
+    def test_not_equal(self):
+        # There's a special test for this because there's a special
+        #  case in the f-string parser to look for != as not ending an
+        #  expression. Normally it would, while looking for !s or !r.
+
+        self.assertEqual(f'{3!=4}', 'True')
+        self.assertEqual(f'{3!=4:}', 'True')
+        self.assertEqual(f'{3!=4!s}', 'True')
+        self.assertEqual(f'{3!=4!s:.3}', 'Tru')
+
+    def test_conversions(self):
+        self.assertEqual(f'{3.14:10.10}', '      3.14')
+        self.assertEqual(f'{3.14!s:10.10}', '3.14      ')
+        self.assertEqual(f'{3.14!r:10.10}', '3.14      ')
+        self.assertEqual(f'{3.14!a:10.10}', '3.14      ')
+
+        self.assertEqual(f'{"a"}', 'a')
+        self.assertEqual(f'{"a"!r}', "'a'")
+        self.assertEqual(f'{"a"!a}', "'a'")
+
+        # Not a conversion.
+        self.assertEqual(f'{"a!r"}', "a!r")
+
+        # Not a conversion, but show that ! is allowed in a format spec.
+        self.assertEqual(f'{3.14:!<10.10}', '3.14!!!!!!')
+
+        self.assertEqual(f'{"\N{GREEK CAPITAL LETTER DELTA}"}', '\u0394')
+        self.assertEqual(f'{"\N{GREEK CAPITAL LETTER DELTA}"!r}', "'\u0394'")
+        self.assertEqual(f'{"\N{GREEK CAPITAL LETTER DELTA}"!a}', "'\\u0394'")
+
+        self.assertAllRaise(SyntaxError, 'f-string: invalid conversion character',
+                            ["f'{3!g}'",
+                             "f'{3!A}'",
+                             "f'{3!A}'",
+                             "f'{3!A}'",
+                             "f'{3!!}'",
+                             "f'{3!:}'",
+                             "f'{3!\N{GREEK CAPITAL LETTER DELTA}}'",
+                             "f'{3! s}'",  # no space before conversion char
+                             "f'{x!\\x00:.<10}'",
+                             ])
+
+        self.assertAllRaise(SyntaxError, "f-string: expecting '}'",
+                            ["f'{x!s{y}}'",
+                             "f'{3!ss}'",
+                             "f'{3!ss:}'",
+                             "f'{3!ss:s}'",
+                             ])
+
+    def test_assignment(self):
+        self.assertAllRaise(SyntaxError, 'invalid syntax',
+                            ["f'' = 3",
+                             "f'{0}' = x",
+                             "f'{x}' = x",
+                             ])
+
+    def test_del(self):
+        self.assertAllRaise(SyntaxError, 'invalid syntax',
+                            ["del f''",
+                             "del '' f''",
+                             ])
+
+    def test_mismatched_braces(self):
+        self.assertAllRaise(SyntaxError, "f-string: single '}' is not allowed",
+                            ["f'{{}'",
+                             "f'{{}}}'",
+                             "f'}'",
+                             "f'x}'",
+                             "f'x}x'",
+
+                             # Can't have { or } in a format spec.
+                             "f'{3:}>10}'",
+                             r"f'{3:\\}>10}'",
+                             "f'{3:}}>10}'",
+                             ])
+
+        self.assertAllRaise(SyntaxError, "f-string: expecting '}'",
+                            ["f'{3:{{>10}'",
+                             "f'{3'",
+                             "f'{3!'",
+                             "f'{3:'",
+                             "f'{3!s'",
+                             "f'{3!s:'",
+                             "f'{3!s:3'",
+                             "f'x{'",
+                             "f'x{x'",
+                             "f'{3:s'",
+                             "f'{{{'",
+                             "f'{{}}{'",
+                             "f'{'",
+                             ])
+
+        self.assertAllRaise(SyntaxError, 'invalid syntax',
+                            [r"f'{3:\\{>10}'",
+                             ])
+
+        # But these are just normal strings.
+        self.assertEqual(f'{"{"}', '{')
+        self.assertEqual(f'{"}"}', '}')
+        self.assertEqual(f'{3:{"}"}>10}', '}}}}}}}}}3')
+        self.assertEqual(f'{2:{"{"}>10}', '{{{{{{{{{2')
+
+    def test_if_conditional(self):
+        # There's special logic in compile.c to test if the
+        #  conditional for an if (and while) are constants. Exercise
+        #  that code.
+
+        def test_fstring(x, expected):
+            flag = 0
+            if f'{x}':
+                flag = 1
+            else:
+                flag = 2
+            self.assertEqual(flag, expected)
+
+        def test_concat_empty(x, expected):
+            flag = 0
+            if '' f'{x}':
+                flag = 1
+            else:
+                flag = 2
+            self.assertEqual(flag, expected)
+
+        def test_concat_non_empty(x, expected):
+            flag = 0
+            if ' ' f'{x}':
+                flag = 1
+            else:
+                flag = 2
+            self.assertEqual(flag, expected)
+
+        test_fstring('', 2)
+        test_fstring(' ', 1)
+
+        test_concat_empty('', 2)
+        test_concat_empty(' ', 1)
+
+        test_concat_non_empty('', 1)
+        test_concat_non_empty(' ', 1)
+
+    def test_empty_format_specifier(self):
+        x = 'test'
+        self.assertEqual(f'{x}', 'test')
+        self.assertEqual(f'{x:}', 'test')
+        self.assertEqual(f'{x!s:}', 'test')
+        self.assertEqual(f'{x!r:}', "'test'")
+
+    def test_str_format_differences(self):
+        d = {'a': 'string',
+             0: 'integer',
+             }
+        a = 0
+        self.assertEqual(f'{d[0]}', 'integer')
+        self.assertEqual(f'{d["a"]}', 'string')
+        self.assertEqual(f'{d[a]}', 'integer')
+        self.assertEqual('{d[a]}'.format(d=d), 'string')
+        self.assertEqual('{d[0]}'.format(d=d), 'integer')
+
+    def test_invalid_expressions(self):
+        self.assertAllRaise(SyntaxError, 'invalid syntax',
+                            [r"f'{a[4)}'",
+                             r"f'{a(4]}'",
+                            ])
+
+    def test_errors(self):
+        # see issue 26287
+        self.assertAllRaise(TypeError, 'non-empty',
+                            [r"f'{(lambda: 0):x}'",
+                             r"f'{(0,):x}'",
+                             ])
+        self.assertAllRaise(ValueError, 'Unknown format code',
+                            [r"f'{1000:j}'",
+                             r"f'{1000:j}'",
+                            ])
+
+    def test_loop(self):
+        for i in range(1000):
+            self.assertEqual(f'i:{i}', 'i:' + str(i))
+
+    def test_dict(self):
+        d = {'"': 'dquote',
+             "'": 'squote',
+             'foo': 'bar',
+             }
+        self.assertEqual(f'{d["\'"]}', 'squote')
+        self.assertEqual(f"{d['\"']}", 'dquote')
+
+        self.assertEqual(f'''{d["'"]}''', 'squote')
+        self.assertEqual(f"""{d['"']}""", 'dquote')
+
+        self.assertEqual(f'{d["foo"]}', 'bar')
+        self.assertEqual(f"{d['foo']}", 'bar')
+        self.assertEqual(f'{d[\'foo\']}', 'bar')
+        self.assertEqual(f"{d[\"foo\"]}", 'bar')
+
+    def test_escaped_quotes(self):
+        d = {'"': 'a',
+             "'": 'b'}
+
+        self.assertEqual(fr"{d['\"']}", 'a')
+        self.assertEqual(fr'{d["\'"]}', 'b')
+        self.assertEqual(fr"{'\"'}", '"')
+        self.assertEqual(fr'{"\'"}', "'")
+        self.assertEqual(f'{"\\"3"}', '"3')
+
+        self.assertAllRaise(SyntaxError, 'f-string: unterminated string',
+                            [r'''f'{"""\\}' ''',  # Backslash at end of expression
+                             ])
+        self.assertAllRaise(SyntaxError, 'unexpected character after line continuation',
+                            [r"rf'{3\}'",
+                             ])
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/Lib/test/test_ftplib.py b/Lib/test/test_ftplib.py
index aef66da98a..9d8de211df 100644
--- a/Lib/test/test_ftplib.py
+++ b/Lib/test/test_ftplib.py
@@ -1049,10 +1049,19 @@ class TestTimeouts(TestCase):
         ftp.close()
 
 
+class MiscTestCase(TestCase):
+    def test__all__(self):
+        blacklist = {'MSG_OOB', 'FTP_PORT', 'MAXLINE', 'CRLF', 'B_CRLF',
+                     'Error', 'parse150', 'parse227', 'parse229', 'parse257',
+                     'print_line', 'ftpcp', 'test'}
+        support.check__all__(self, ftplib, blacklist=blacklist)
+
+
 def test_main():
     tests = [TestFTPClass, TestTimeouts,
              TestIPv6Environment,
-             TestTLS_FTPClassMixin, TestTLS_FTPClass]
+             TestTLS_FTPClassMixin, TestTLS_FTPClass,
+             MiscTestCase]
 
     thread_info = support.threading_setup()
     try:
diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
index 9abe984330..852173cc0a 100644
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@ -1516,7 +1516,7 @@ class TestSingleDispatch(unittest.TestCase):
             m = mro(D, bases)
             self.assertEqual(m, [D, c.MutableSequence, c.Sequence,
                                  c.defaultdict, dict, c.MutableMapping,
-                                 c.Mapping, c.Sized, c.Iterable, c.Container,
+                                 c.Mapping, c.Sized, c.Reversible, c.Iterable, c.Container,
                                  object])
 
         # Container and Callable are registered on different base classes and
@@ -1697,13 +1697,10 @@ class TestSingleDispatch(unittest.TestCase):
         c.Container.register(P)
         with self.assertRaises(RuntimeError) as re_one:
             g(p)
-        self.assertIn(
-            str(re_one.exception),
-            (("Ambiguous dispatch: <class 'collections.abc.Container'> "
-              "or <class 'collections.abc.Iterable'>"),
-             ("Ambiguous dispatch: <class 'collections.abc.Iterable'> "
-              "or <class 'collections.abc.Container'>")),
-        )
+        self.assertIn("Ambiguous dispatch:", str(re_one.exception))
+        self.assertIn("<class 'collections.abc.Container'", str(re_one.exception))
+        self.assertIn("<class 'collections.abc.Iterable'", str(re_one.exception))
+
         class Q(c.Sized):
             def __len__(self):
                 return 0
@@ -1729,13 +1726,10 @@ class TestSingleDispatch(unittest.TestCase):
         # perspective.
         with self.assertRaises(RuntimeError) as re_two:
             h(c.defaultdict(lambda: 0))
-        self.assertIn(
-            str(re_two.exception),
-            (("Ambiguous dispatch: <class 'collections.abc.Container'> "
-              "or <class 'collections.abc.Sized'>"),
-             ("Ambiguous dispatch: <class 'collections.abc.Sized'> "
-              "or <class 'collections.abc.Container'>")),
-        )
+        self.assertIn("Ambiguous dispatch:", str(re_two.exception))
+        self.assertIn("<class 'collections.abc.Container'", str(re_two.exception))
+        self.assertIn("<class 'collections.abc.Sized'", str(re_two.exception))
+
         class R(c.defaultdict):
             pass
         c.MutableSequence.register(R)
@@ -1769,13 +1763,10 @@ class TestSingleDispatch(unittest.TestCase):
         # There is no preference for registered versus inferred ABCs.
         with self.assertRaises(RuntimeError) as re_three:
             h(u)
-        self.assertIn(
-            str(re_three.exception),
-            (("Ambiguous dispatch: <class 'collections.abc.Container'> "
-              "or <class 'collections.abc.Sized'>"),
-             ("Ambiguous dispatch: <class 'collections.abc.Sized'> "
-              "or <class 'collections.abc.Container'>")),
-        )
+        self.assertIn("Ambiguous dispatch:", str(re_three.exception))
+        self.assertIn("<class 'collections.abc.Container'", str(re_three.exception))
+        self.assertIn("<class 'collections.abc.Sized'", str(re_three.exception))
+
         class V(c.Sized, S):
             def __len__(self):
                 return 0
diff --git a/Lib/test/test_gc.py b/Lib/test/test_gc.py
index 1f0867d379..872ca62b5e 100644
--- a/Lib/test/test_gc.py
+++ b/Lib/test/test_gc.py
@@ -682,7 +682,6 @@ class GCTests(unittest.TestCase):
         # Create a reference cycle through the __main__ module and check
         # it gets collected at interpreter shutdown.
         code = """if 1:
-            import weakref
             class C:
                 def __del__(self):
                     print('__del__ called')
@@ -696,7 +695,6 @@ class GCTests(unittest.TestCase):
         # Same as above, but with a non-__main__ module.
         with temp_dir() as script_dir:
             module = """if 1:
-                import weakref
                 class C:
                     def __del__(self):
                         print('__del__ called')
diff --git a/Lib/test/test_gdb.py b/Lib/test/test_gdb.py
index cd7d2925f4..730b628b58 100644
--- a/Lib/test/test_gdb.py
+++ b/Lib/test/test_gdb.py
@@ -5,7 +5,6 @@
 
 import os
 import re
-import pprint
 import subprocess
 import sys
 import sysconfig
@@ -176,6 +175,7 @@ class DebuggerTests(unittest.TestCase):
         args = ['--eval-command=%s' % cmd for cmd in commands]
         args += ["--args",
                  sys.executable]
+        args.extend(subprocess._args_from_interpreter_flags())
 
         if not import_site:
             # -S suppresses the default 'import site'
@@ -291,7 +291,9 @@ class PrettyPrintTests(DebuggerTests):
         'Verify the pretty-printing of dictionaries'
         self.assertGdbRepr({})
         self.assertGdbRepr({'foo': 'bar'}, "{'foo': 'bar'}")
-        self.assertGdbRepr({'foo': 'bar', 'douglas': 42}, "{'douglas': 42, 'foo': 'bar'}")
+        # PYTHONHASHSEED is need to get the exact item order
+        if not sys.flags.ignore_environment:
+            self.assertGdbRepr({'foo': 'bar', 'douglas': 42}, "{'douglas': 42, 'foo': 'bar'}")
 
     def test_lists(self):
         'Verify the pretty-printing of lists'
@@ -354,9 +356,12 @@ class PrettyPrintTests(DebuggerTests):
         'Verify the pretty-printing of sets'
         if (gdb_major_version, gdb_minor_version) < (7, 3):
             self.skipTest("pretty-printing of sets needs gdb 7.3 or later")
-        self.assertGdbRepr(set(), 'set()')
-        self.assertGdbRepr(set(['a', 'b']), "{'a', 'b'}")
-        self.assertGdbRepr(set([4, 5, 6]), "{4, 5, 6}")
+        self.assertGdbRepr(set(), "set()")
+        self.assertGdbRepr(set(['a']), "{'a'}")
+        # PYTHONHASHSEED is need to get the exact frozenset item order
+        if not sys.flags.ignore_environment:
+            self.assertGdbRepr(set(['a', 'b']), "{'a', 'b'}")
+            self.assertGdbRepr(set([4, 5, 6]), "{4, 5, 6}")
 
         # Ensure that we handle sets containing the "dummy" key value,
         # which happens on deletion:
@@ -369,9 +374,12 @@ id(s)''')
         'Verify the pretty-printing of frozensets'
         if (gdb_major_version, gdb_minor_version) < (7, 3):
             self.skipTest("pretty-printing of frozensets needs gdb 7.3 or later")
-        self.assertGdbRepr(frozenset(), 'frozenset()')
-        self.assertGdbRepr(frozenset(['a', 'b']), "frozenset({'a', 'b'})")
-        self.assertGdbRepr(frozenset([4, 5, 6]), "frozenset({4, 5, 6})")
+        self.assertGdbRepr(frozenset(), "frozenset()")
+        self.assertGdbRepr(frozenset(['a']), "frozenset({'a'})")
+        # PYTHONHASHSEED is need to get the exact frozenset item order
+        if not sys.flags.ignore_environment:
+            self.assertGdbRepr(frozenset(['a', 'b']), "frozenset({'a', 'b'})")
+            self.assertGdbRepr(frozenset([4, 5, 6]), "frozenset({4, 5, 6})")
 
     def test_exceptions(self):
         # Test a RuntimeError
@@ -500,6 +508,10 @@ id(foo)''')
 
     def test_builtins_help(self):
         'Ensure that the new-style class _Helper in site.py can be handled'
+
+        if sys.flags.no_site:
+            self.skipTest("need site module, but -S option was used")
+
         # (this was the issue causing tracebacks in
         #  http://bugs.python.org/issue8032#msg100537 )
         gdb_repr, gdb_output = self.get_gdb_repr('id(__builtins__.help)', import_site=True)
diff --git a/Lib/test/test_generators.py b/Lib/test/test_generators.py
index 3f82462478..c193301b27 100644
--- a/Lib/test/test_generators.py
+++ b/Lib/test/test_generators.py
@@ -245,11 +245,11 @@ class ExceptionTest(unittest.TestCase):
             yield
 
         with self.assertRaises(StopIteration), \
-             self.assertWarnsRegex(PendingDeprecationWarning, "StopIteration"):
+             self.assertWarnsRegex(DeprecationWarning, "StopIteration"):
 
             next(gen())
 
-        with self.assertRaisesRegex(PendingDeprecationWarning,
+        with self.assertRaisesRegex(DeprecationWarning,
                                     "generator .* raised StopIteration"), \
              warnings.catch_warnings():
 
@@ -268,7 +268,7 @@ class ExceptionTest(unittest.TestCase):
         g = f()
         self.assertEqual(next(g), 1)
 
-        with self.assertWarnsRegex(PendingDeprecationWarning, "StopIteration"):
+        with self.assertWarnsRegex(DeprecationWarning, "StopIteration"):
             with self.assertRaises(StopIteration):
                 next(g)
 
@@ -671,10 +671,10 @@ From the Iterators list, about the types of these things.
 ...     yield 1
 ...
 >>> type(g)
-<class 'function'>
+<class 'function' ...>
 >>> i = g()
 >>> type(i)
-<class 'generator'>
+<class 'generator' ...>
 >>> [s for s in dir(i) if not s.startswith('_')]
 ['close', 'gi_code', 'gi_frame', 'gi_running', 'gi_yieldfrom', 'send', 'throw']
 >>> from test.support import HAVE_DOCSTRINGS
@@ -691,7 +691,7 @@ And more, added later.
 >>> i.gi_running
 0
 >>> type(i.gi_frame)
-<class 'frame'>
+<class 'frame' ...>
 >>> i.gi_running = 42
 Traceback (most recent call last):
   ...
@@ -1066,27 +1066,27 @@ These are fine:
 >>> def f():
 ...    yield
 >>> type(f())
-<class 'generator'>
+<class 'generator' ...>
 
 
 >>> def f():
 ...    if 0:
 ...        yield
 >>> type(f())
-<class 'generator'>
+<class 'generator' ...>
 
 
 >>> def f():
 ...     if 0:
 ...         yield 1
 >>> type(f())
-<class 'generator'>
+<class 'generator' ...>
 
 >>> def f():
 ...    if "":
 ...        yield None
 >>> type(f())
-<class 'generator'>
+<class 'generator' ...>
 
 >>> def f():
 ...     return
@@ -1110,7 +1110,7 @@ These are fine:
 ...         x = 1
 ...     return
 >>> type(f())
-<class 'generator'>
+<class 'generator' ...>
 
 >>> def f():
 ...     if 0:
@@ -1118,7 +1118,7 @@ These are fine:
 ...             yield 1
 ...
 >>> type(f())
-<class 'NoneType'>
+<class 'NoneType' ...>
 
 >>> def f():
 ...     if 0:
@@ -1128,7 +1128,7 @@ These are fine:
 ...             def f(self):
 ...                 yield 2
 >>> type(f())
-<class 'NoneType'>
+<class 'NoneType' ...>
 
 >>> def f():
 ...     if 0:
@@ -1136,7 +1136,7 @@ These are fine:
 ...     if 0:
 ...         yield 2
 >>> type(f())
-<class 'generator'>
+<class 'generator' ...>
 
 This one caused a crash (see SF bug 567538):
 
@@ -1791,7 +1791,7 @@ And a more sane, but still weird usage:
 
 >>> def f(): list(i for i in [(yield 26)])
 >>> type(f())
-<class 'generator'>
+<class 'generator' ...>
 
 
 A yield expression with augmented assignment.
@@ -2047,25 +2047,25 @@ enclosing function a generator:
 
 >>> def f(): x += yield
 >>> type(f())
-<class 'generator'>
+<class 'generator' ...>
 
 >>> def f(): x = yield
 >>> type(f())
-<class 'generator'>
+<class 'generator' ...>
 
 >>> def f(): lambda x=(yield): 1
 >>> type(f())
-<class 'generator'>
+<class 'generator' ...>
 
 >>> def f(): x=(i for i in (yield) if (yield))
 >>> type(f())
-<class 'generator'>
+<class 'generator' ...>
 
 >>> def f(d): d[(yield "a")] = d[(yield "b")] = 27
 >>> data = [1,2]
 >>> g = f(data)
 >>> type(g)
-<class 'generator'>
+<class 'generator' ...>
 >>> g.send(None)
 'a'
 >>> data
@@ -2174,8 +2174,9 @@ __test__ = {"tut":      tutorial_tests,
 # so this works as expected in both ways of running regrtest.
 def test_main(verbose=None):
     from test import support, test_generators
+    import doctest
     support.run_unittest(__name__)
-    support.run_doctest(test_generators, verbose)
+    support.run_doctest(test_generators, verbose, optionflags=doctest.ELLIPSIS)
 
 # This part isn't needed for regrtest, but for running the test directly.
 if __name__ == "__main__":
diff --git a/Lib/test/test_genericpath.py b/Lib/test/test_genericpath.py
index 86fc2de753..9c28a6872b 100644
--- a/Lib/test/test_genericpath.py
+++ b/Lib/test/test_genericpath.py
@@ -10,11 +10,9 @@ import warnings
 from test import support
 
 
-def safe_rmdir(dirname):
-    try:
-        os.rmdir(dirname)
-    except OSError:
-        pass
+def create_file(filename, data=b'foo'):
+    with open(filename, 'xb', 0) as fp:
+        fp.write(data)
 
 
 class GenericTest:
@@ -97,52 +95,47 @@ class GenericTest:
                     self.assertNotEqual(s1[n:n+1], s2[n:n+1])
 
     def test_getsize(self):
-        f = open(support.TESTFN, "wb")
-        try:
-            f.write(b"foo")
-            f.close()
-            self.assertEqual(self.pathmodule.getsize(support.TESTFN), 3)
-        finally:
-            if not f.closed:
-                f.close()
-            support.unlink(support.TESTFN)
+        filename = support.TESTFN
+        self.addCleanup(support.unlink, filename)
 
-    def test_time(self):
-        f = open(support.TESTFN, "wb")
-        try:
-            f.write(b"foo")
-            f.close()
-            f = open(support.TESTFN, "ab")
+        create_file(filename, b'Hello')
+        self.assertEqual(self.pathmodule.getsize(filename), 5)
+        os.remove(filename)
+
+        create_file(filename, b'Hello World!')
+        self.assertEqual(self.pathmodule.getsize(filename), 12)
+
+    def test_filetime(self):
+        filename = support.TESTFN
+        self.addCleanup(support.unlink, filename)
+
+        create_file(filename, b'foo')
+
+        with open(filename, "ab", 0) as f:
             f.write(b"bar")
-            f.close()
-            f = open(support.TESTFN, "rb")
-            d = f.read()
-            f.close()
-            self.assertEqual(d, b"foobar")
-
-            self.assertLessEqual(
-                self.pathmodule.getctime(support.TESTFN),
-                self.pathmodule.getmtime(support.TESTFN)
-            )
-        finally:
-            if not f.closed:
-                f.close()
-            support.unlink(support.TESTFN)
+
+        with open(filename, "rb", 0) as f:
+            data = f.read()
+        self.assertEqual(data, b"foobar")
+
+        self.assertLessEqual(
+            self.pathmodule.getctime(filename),
+            self.pathmodule.getmtime(filename)
+        )
 
     def test_exists(self):
-        self.assertIs(self.pathmodule.exists(support.TESTFN), False)
-        f = open(support.TESTFN, "wb")
-        try:
+        filename = support.TESTFN
+        self.addCleanup(support.unlink, filename)
+
+        self.assertIs(self.pathmodule.exists(filename), False)
+
+        with open(filename, "xb") as f:
             f.write(b"foo")
-            f.close()
-            self.assertIs(self.pathmodule.exists(support.TESTFN), True)
-            if not self.pathmodule == genericpath:
-                self.assertIs(self.pathmodule.lexists(support.TESTFN),
-                              True)
-        finally:
-            if not f.close():
-                f.close()
-            support.unlink(support.TESTFN)
+
+        self.assertIs(self.pathmodule.exists(filename), True)
+
+        if not self.pathmodule == genericpath:
+            self.assertIs(self.pathmodule.lexists(filename), True)
 
     @unittest.skipUnless(hasattr(os, "pipe"), "requires os.pipe()")
     def test_exists_fd(self):
@@ -154,53 +147,66 @@ class GenericTest:
             os.close(w)
         self.assertFalse(self.pathmodule.exists(r))
 
-    def test_isdir(self):
-        self.assertIs(self.pathmodule.isdir(support.TESTFN), False)
-        f = open(support.TESTFN, "wb")
-        try:
-            f.write(b"foo")
-            f.close()
-            self.assertIs(self.pathmodule.isdir(support.TESTFN), False)
-            os.remove(support.TESTFN)
-            os.mkdir(support.TESTFN)
-            self.assertIs(self.pathmodule.isdir(support.TESTFN), True)
-            os.rmdir(support.TESTFN)
-        finally:
-            if not f.close():
-                f.close()
-            support.unlink(support.TESTFN)
-            safe_rmdir(support.TESTFN)
-
-    def test_isfile(self):
-        self.assertIs(self.pathmodule.isfile(support.TESTFN), False)
-        f = open(support.TESTFN, "wb")
-        try:
-            f.write(b"foo")
-            f.close()
-            self.assertIs(self.pathmodule.isfile(support.TESTFN), True)
-            os.remove(support.TESTFN)
-            os.mkdir(support.TESTFN)
-            self.assertIs(self.pathmodule.isfile(support.TESTFN), False)
-            os.rmdir(support.TESTFN)
-        finally:
-            if not f.close():
-                f.close()
-            support.unlink(support.TESTFN)
-            safe_rmdir(support.TESTFN)
+    def test_isdir_file(self):
+        filename = support.TESTFN
+        self.addCleanup(support.unlink, filename)
+        self.assertIs(self.pathmodule.isdir(filename), False)
+
+        create_file(filename)
+        self.assertIs(self.pathmodule.isdir(filename), False)
+
+    def test_isdir_dir(self):
+        filename = support.TESTFN
+        self.addCleanup(support.rmdir, filename)
+        self.assertIs(self.pathmodule.isdir(filename), False)
+
+        os.mkdir(filename)
+        self.assertIs(self.pathmodule.isdir(filename), True)
+
+    def test_isfile_file(self):
+        filename = support.TESTFN
+        self.addCleanup(support.unlink, filename)
+        self.assertIs(self.pathmodule.isfile(filename), False)
 
-    @staticmethod
-    def _create_file(filename):
-        with open(filename, 'wb') as f:
-            f.write(b'foo')
+        create_file(filename)
+        self.assertIs(self.pathmodule.isfile(filename), True)
+
+    def test_isfile_dir(self):
+        filename = support.TESTFN
+        self.addCleanup(support.rmdir, filename)
+        self.assertIs(self.pathmodule.isfile(filename), False)
+
+        os.mkdir(filename)
+        self.assertIs(self.pathmodule.isfile(filename), False)
 
     def test_samefile(self):
-        try:
-            test_fn = support.TESTFN + "1"
-            self._create_file(test_fn)
-            self.assertTrue(self.pathmodule.samefile(test_fn, test_fn))
-            self.assertRaises(TypeError, self.pathmodule.samefile)
-        finally:
-            os.remove(test_fn)
+        file1 = support.TESTFN
+        file2 = support.TESTFN + "2"
+        self.addCleanup(support.unlink, file1)
+        self.addCleanup(support.unlink, file2)
+
+        create_file(file1)
+        self.assertTrue(self.pathmodule.samefile(file1, file1))
+
+        create_file(file2)
+        self.assertFalse(self.pathmodule.samefile(file1, file2))
+
+        self.assertRaises(TypeError, self.pathmodule.samefile)
+
+    def _test_samefile_on_link_func(self, func):
+        test_fn1 = support.TESTFN
+        test_fn2 = support.TESTFN + "2"
+        self.addCleanup(support.unlink, test_fn1)
+        self.addCleanup(support.unlink, test_fn2)
+
+        create_file(test_fn1)
+
+        func(test_fn1, test_fn2)
+        self.assertTrue(self.pathmodule.samefile(test_fn1, test_fn2))
+        os.remove(test_fn2)
+
+        create_file(test_fn2)
+        self.assertFalse(self.pathmodule.samefile(test_fn1, test_fn2))
 
     @support.skip_unless_symlink
     def test_samefile_on_symlink(self):
@@ -209,31 +215,37 @@ class GenericTest:
     def test_samefile_on_link(self):
         self._test_samefile_on_link_func(os.link)
 
-    def _test_samefile_on_link_func(self, func):
-        try:
-            test_fn1 = support.TESTFN + "1"
-            test_fn2 = support.TESTFN + "2"
-            self._create_file(test_fn1)
+    def test_samestat(self):
+        test_fn1 = support.TESTFN
+        test_fn2 = support.TESTFN + "2"
+        self.addCleanup(support.unlink, test_fn1)
+        self.addCleanup(support.unlink, test_fn2)
 
-            func(test_fn1, test_fn2)
-            self.assertTrue(self.pathmodule.samefile(test_fn1, test_fn2))
-            os.remove(test_fn2)
+        create_file(test_fn1)
+        stat1 = os.stat(test_fn1)
+        self.assertTrue(self.pathmodule.samestat(stat1, os.stat(test_fn1)))
 
-            self._create_file(test_fn2)
-            self.assertFalse(self.pathmodule.samefile(test_fn1, test_fn2))
-        finally:
-            os.remove(test_fn1)
-            os.remove(test_fn2)
+        create_file(test_fn2)
+        stat2 = os.stat(test_fn2)
+        self.assertFalse(self.pathmodule.samestat(stat1, stat2))
 
-    def test_samestat(self):
-        try:
-            test_fn = support.TESTFN + "1"
-            self._create_file(test_fn)
-            test_fns = [test_fn]*2
-            stats = map(os.stat, test_fns)
-            self.assertTrue(self.pathmodule.samestat(*stats))
-        finally:
-            os.remove(test_fn)
+        self.assertRaises(TypeError, self.pathmodule.samestat)
+
+    def _test_samestat_on_link_func(self, func):
+        test_fn1 = support.TESTFN + "1"
+        test_fn2 = support.TESTFN + "2"
+        self.addCleanup(support.unlink, test_fn1)
+        self.addCleanup(support.unlink, test_fn2)
+
+        create_file(test_fn1)
+        func(test_fn1, test_fn2)
+        self.assertTrue(self.pathmodule.samestat(os.stat(test_fn1),
+                                                 os.stat(test_fn2)))
+        os.remove(test_fn2)
+
+        create_file(test_fn2)
+        self.assertFalse(self.pathmodule.samestat(os.stat(test_fn1),
+                                                  os.stat(test_fn2)))
 
     @support.skip_unless_symlink
     def test_samestat_on_symlink(self):
@@ -242,31 +254,17 @@ class GenericTest:
     def test_samestat_on_link(self):
         self._test_samestat_on_link_func(os.link)
 
-    def _test_samestat_on_link_func(self, func):
-        try:
-            test_fn1 = support.TESTFN + "1"
-            test_fn2 = support.TESTFN + "2"
-            self._create_file(test_fn1)
-            test_fns = (test_fn1, test_fn2)
-            func(*test_fns)
-            stats = map(os.stat, test_fns)
-            self.assertTrue(self.pathmodule.samestat(*stats))
-            os.remove(test_fn2)
-
-            self._create_file(test_fn2)
-            stats = map(os.stat, test_fns)
-            self.assertFalse(self.pathmodule.samestat(*stats))
-
-            self.assertRaises(TypeError, self.pathmodule.samestat)
-        finally:
-            os.remove(test_fn1)
-            os.remove(test_fn2)
-
     def test_sameopenfile(self):
-        fname = support.TESTFN + "1"
-        with open(fname, "wb") as a, open(fname, "wb") as b:
-            self.assertTrue(self.pathmodule.sameopenfile(
-                                a.fileno(), b.fileno()))
+        filename = support.TESTFN
+        self.addCleanup(support.unlink, filename)
+        create_file(filename)
+
+        with open(filename, "rb", 0) as fp1:
+            fd1 = fp1.fileno()
+            with open(filename, "rb", 0) as fp2:
+                fd2 = fp2.fileno()
+                self.assertTrue(self.pathmodule.sameopenfile(fd1, fd2))
+
 
 class TestGenericTest(GenericTest, unittest.TestCase):
     # Issue 16852: GenericTest can't inherit from unittest.TestCase
diff --git a/Lib/test/test_genexps.py b/Lib/test/test_genexps.py
index fb531d6d47..c5e10dda8c 100644
--- a/Lib/test/test_genexps.py
+++ b/Lib/test/test_genexps.py
@@ -27,7 +27,7 @@ Test first class
 
     >>> g = (i*i for i in range(4))
     >>> type(g)
-    <class 'generator'>
+    <class 'generator' ...>
     >>> list(g)
     [0, 1, 4, 9]
 
@@ -269,7 +269,8 @@ else:
 def test_main(verbose=None):
     from test import support
     from test import test_genexps
-    support.run_doctest(test_genexps, verbose)
+    import doctest
+    support.run_doctest(test_genexps, verbose, optionflags=doctest.ELLIPSIS)
 
     # verify reference counting
     if verbose and hasattr(sys, "gettotalrefcount"):
diff --git a/Lib/test/test_getargs2.py b/Lib/test/test_getargs2.py
index 984aac7d91..ecc19088ff 100644
--- a/Lib/test/test_getargs2.py
+++ b/Lib/test/test_getargs2.py
@@ -365,7 +365,8 @@ class Float_TestCase(unittest.TestCase):
         self.assertEqual(getargs_f(FloatSubclass(7.5)), 7.5)
         self.assertEqual(getargs_f(FloatSubclass2(7.5)), 7.5)
         self.assertRaises(TypeError, getargs_f, BadFloat())
-        self.assertEqual(getargs_f(BadFloat2()), 4.25)
+        with self.assertWarns(DeprecationWarning):
+            self.assertEqual(getargs_f(BadFloat2()), 4.25)
         self.assertEqual(getargs_f(BadFloat3(7.5)), 7.5)
 
         for x in (FLT_MIN, -FLT_MIN, FLT_MAX, -FLT_MAX, INF, -INF):
@@ -390,7 +391,8 @@ class Float_TestCase(unittest.TestCase):
         self.assertEqual(getargs_d(FloatSubclass(7.5)), 7.5)
         self.assertEqual(getargs_d(FloatSubclass2(7.5)), 7.5)
         self.assertRaises(TypeError, getargs_d, BadFloat())
-        self.assertEqual(getargs_d(BadFloat2()), 4.25)
+        with self.assertWarns(DeprecationWarning):
+            self.assertEqual(getargs_d(BadFloat2()), 4.25)
         self.assertEqual(getargs_d(BadFloat3(7.5)), 7.5)
 
         for x in (DBL_MIN, -DBL_MIN, DBL_MAX, -DBL_MAX, INF, -INF):
@@ -474,7 +476,7 @@ class Tuple_TestCase(unittest.TestCase):
 
         ret = get_args(*TupleSubclass([1, 2]))
         self.assertEqual(ret, (1, 2))
-        self.assertIsInstance(ret, tuple)
+        self.assertIs(type(ret), tuple)
 
         ret = get_args()
         self.assertIn(ret, ((), None))
@@ -512,7 +514,7 @@ class Keywords_TestCase(unittest.TestCase):
 
         ret = get_kwargs(**DictSubclass({'a': 1, 'b': 2}))
         self.assertEqual(ret, {'a': 1, 'b': 2})
-        self.assertIsInstance(ret, dict)
+        self.assertIs(type(ret), dict)
 
         ret = get_kwargs()
         self.assertIn(ret, ({}, None))
@@ -822,10 +824,10 @@ class String_TestCase(unittest.TestCase):
         self.assertEqual(getargs_es_hash('abc\xe9', 'latin1', buf), b'abc\xe9')
         self.assertEqual(buf, bytearray(b'abc\xe9\x00'))
         buf = bytearray(b'x'*4)
-        self.assertRaises(TypeError, getargs_es_hash, 'abc\xe9', 'latin1', buf)
+        self.assertRaises(ValueError, getargs_es_hash, 'abc\xe9', 'latin1', buf)
         self.assertEqual(buf, bytearray(b'x'*4))
         buf = bytearray()
-        self.assertRaises(TypeError, getargs_es_hash, 'abc\xe9', 'latin1', buf)
+        self.assertRaises(ValueError, getargs_es_hash, 'abc\xe9', 'latin1', buf)
 
     def test_et_hash(self):
         from _testcapi import getargs_et_hash
@@ -848,10 +850,10 @@ class String_TestCase(unittest.TestCase):
         self.assertEqual(getargs_et_hash('abc\xe9', 'latin1', buf), b'abc\xe9')
         self.assertEqual(buf, bytearray(b'abc\xe9\x00'))
         buf = bytearray(b'x'*4)
-        self.assertRaises(TypeError, getargs_et_hash, 'abc\xe9', 'latin1', buf)
+        self.assertRaises(ValueError, getargs_et_hash, 'abc\xe9', 'latin1', buf)
         self.assertEqual(buf, bytearray(b'x'*4))
         buf = bytearray()
-        self.assertRaises(TypeError, getargs_et_hash, 'abc\xe9', 'latin1', buf)
+        self.assertRaises(ValueError, getargs_et_hash, 'abc\xe9', 'latin1', buf)
 
     def test_u(self):
         from _testcapi import getargs_u
diff --git a/Lib/test/test_gettext.py b/Lib/test/test_gettext.py
index de610c752a..d345baa26b 100644
--- a/Lib/test/test_gettext.py
+++ b/Lib/test/test_gettext.py
@@ -1,6 +1,5 @@
 import os
 import base64
-import shutil
 import gettext
 import unittest
 
@@ -440,6 +439,12 @@ class GettextCacheTestCase(GettextBaseTest):
         self.assertEqual(t.__class__, DummyGNUTranslations)
 
 
+class MiscTestCase(unittest.TestCase):
+    def test__all__(self):
+        blacklist = {'c2py', 'ENOENT'}
+        support.check__all__(self, gettext, blacklist=blacklist)
+
+
 def test_main():
     support.run_unittest(__name__)
 
diff --git a/Lib/test/test_grammar.py b/Lib/test/test_grammar.py
index d68cc7da7c..331f48c54d 100644
--- a/Lib/test/test_grammar.py
+++ b/Lib/test/test_grammar.py
@@ -295,6 +295,10 @@ class GrammarTests(unittest.TestCase):
         pos2key2dict(1,2,k2=100,tokwarg1=100,tokwarg2=200)
         pos2key2dict(1,2,tokwarg1=100,tokwarg2=200, k2=100)
 
+        self.assertRaises(SyntaxError, eval, "def f(*): pass")
+        self.assertRaises(SyntaxError, eval, "def f(*,): pass")
+        self.assertRaises(SyntaxError, eval, "def f(*, **kwds): pass")
+
         # keyword arguments after *arglist
         def f(*args, **kwargs):
             return args, kwargs
@@ -352,6 +356,23 @@ class GrammarTests(unittest.TestCase):
         check_syntax_error(self, "f(*g(1=2))")
         check_syntax_error(self, "f(**g(1=2))")
 
+        # Check trailing commas are permitted in funcdef argument list
+        def f(a,): pass
+        def f(*args,): pass
+        def f(**kwds,): pass
+        def f(a, *args,): pass
+        def f(a, **kwds,): pass
+        def f(*args, b,): pass
+        def f(*, b,): pass
+        def f(*args, **kwds,): pass
+        def f(a, *args, b,): pass
+        def f(a, *, b,): pass
+        def f(a, *args, **kwds,): pass
+        def f(*args, b, **kwds,): pass
+        def f(*, b, **kwds,): pass
+        def f(a, *args, b, **kwds,): pass
+        def f(a, *, b, **kwds,): pass
+
     def test_lambdef(self):
         ### lambdef: 'lambda' [varargslist] ':' test
         l1 = lambda : 0
@@ -370,6 +391,23 @@ class GrammarTests(unittest.TestCase):
         self.assertEqual(l6(1,2), 1+2+20)
         self.assertEqual(l6(1,2,k=10), 1+2+10)
 
+        # check that trailing commas are permitted
+        l10 = lambda a,: 0
+        l11 = lambda *args,: 0
+        l12 = lambda **kwds,: 0
+        l13 = lambda a, *args,: 0
+        l14 = lambda a, **kwds,: 0
+        l15 = lambda *args, b,: 0
+        l16 = lambda *, b,: 0
+        l17 = lambda *args, **kwds,: 0
+        l18 = lambda a, *args, b,: 0
+        l19 = lambda a, *, b,: 0
+        l20 = lambda a, *args, **kwds,: 0
+        l21 = lambda *args, b, **kwds,: 0
+        l22 = lambda *, b, **kwds,: 0
+        l23 = lambda a, *args, b, **kwds,: 0
+        l24 = lambda a, *, b, **kwds,: 0
+
 
     ### stmt: simple_stmt | compound_stmt
     # Tested below
diff --git a/Lib/test/test_grp.py b/Lib/test/test_grp.py
index 272b08615d..69095a3fb9 100644
--- a/Lib/test/test_grp.py
+++ b/Lib/test/test_grp.py
@@ -92,5 +92,15 @@ class GroupDatabaseTestCase(unittest.TestCase):
 
         self.assertRaises(KeyError, grp.getgrgid, fakegid)
 
+    def test_noninteger_gid(self):
+        entries = grp.getgrall()
+        if not entries:
+            self.skipTest('no groups')
+        # Choose an existent gid.
+        gid = entries[0][2]
+        self.assertWarns(DeprecationWarning, grp.getgrgid, float(gid))
+        self.assertWarns(DeprecationWarning, grp.getgrgid, str(gid))
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_heapq.py b/Lib/test/test_heapq.py
index b7e8259f8d..2f8c648d84 100644
--- a/Lib/test/test_heapq.py
+++ b/Lib/test/test_heapq.py
@@ -1,6 +1,5 @@
 """Unittests for heapq."""
 
-import sys
 import random
 import unittest
 
diff --git a/Lib/test/test_hmac.py b/Lib/test/test_hmac.py
index 98826b5a60..067e13f107 100644
--- a/Lib/test/test_hmac.py
+++ b/Lib/test/test_hmac.py
@@ -3,7 +3,6 @@ import hmac
 import hashlib
 import unittest
 import warnings
-from test import support
 
 
 def ignore_warning(func):
diff --git a/Lib/test/test_htmlparser.py b/Lib/test/test_htmlparser.py
index 11420b2c84..a7f53d382e 100644
--- a/Lib/test/test_htmlparser.py
+++ b/Lib/test/test_htmlparser.py
@@ -3,7 +3,6 @@
 import html.parser
 import pprint
 import unittest
-from test import support
 
 
 class EventCollector(html.parser.HTMLParser):
diff --git a/Lib/test/test_httpservers.py b/Lib/test/test_httpservers.py
index 72e6e08880..7f4b0f90d0 100644
--- a/Lib/test/test_httpservers.py
+++ b/Lib/test/test_httpservers.py
@@ -18,6 +18,7 @@ import urllib.parse
 import html
 import http.client
 import tempfile
+import time
 from io import BytesIO
 
 import unittest
@@ -388,7 +389,7 @@ class SimpleHTTPServerTestCase(BaseTestCase):
         quotedname = urllib.parse.quote(filename, errors='surrogatepass')
         self.assertIn(('href="%s"' % quotedname)
                       .encode(enc, 'surrogateescape'), body)
-        self.assertIn(('>%s<' % html.escape(filename))
+        self.assertIn(('>%s<' % html.escape(filename, quote=False))
                       .encode(enc, 'surrogateescape'), body)
         response = self.request(self.base_url + '/' + quotedname)
         self.check_status_and_reason(response, HTTPStatus.OK,
@@ -466,6 +467,27 @@ class SimpleHTTPServerTestCase(BaseTestCase):
         self.assertEqual(response.getheader("Location"),
                          self.tempdir_name + "/?hi=1")
 
+    def test_html_escape_filename(self):
+        filename = '<test&>.txt'
+        fullpath = os.path.join(self.tempdir, filename)
+
+        try:
+            open(fullpath, 'w').close()
+        except OSError:
+            raise unittest.SkipTest('Can not create file %s on current file '
+                                    'system' % filename)
+
+        try:
+            response = self.request(self.base_url + '/')
+            body = self.check_status_and_reason(response, HTTPStatus.OK)
+            enc = response.headers.get_content_charset()
+        finally:
+            os.unlink(fullpath)  # avoid affecting test_undecodable_filename
+
+        self.assertIsNotNone(enc)
+        html_text = '>%s<' % html.escape(filename, quote=False)
+        self.assertIn(html_text.encode(enc), body)
+
 
 cgi_file1 = """\
 #!%s
@@ -916,7 +938,7 @@ class BaseHTTPRequestHandlerTestCase(unittest.TestCase):
         # Issue #6791: same for headers
         result = self.send_typical_request(
             b'GET / HTTP/1.1\r\nX-Foo: bar' + b'r' * 65537 + b'\r\n\r\n')
-        self.assertEqual(result[0], b'HTTP/1.1 400 Line too long\r\n')
+        self.assertEqual(result[0], b'HTTP/1.1 431 Line too long\r\n')
         self.assertFalse(self.handler.get_called)
         self.assertEqual(self.handler.requestline, 'GET / HTTP/1.1')
 
@@ -927,6 +949,13 @@ class BaseHTTPRequestHandlerTestCase(unittest.TestCase):
         self.assertFalse(self.handler.get_called)
         self.assertEqual(self.handler.requestline, 'GET / HTTP/1.1')
 
+    def test_html_escape_on_error(self):
+        result = self.send_typical_request(
+            b'<script>alert("hello")</script> / HTTP/1.1')
+        result = b''.join(result)
+        text = '<script>alert("hello")</script>'
+        self.assertIn(html.escape(text, quote=False).encode('ascii'), result)
+
     def test_close_connection(self):
         # handle_one_request() should be repeatedly called until
         # it sets close_connection
@@ -942,6 +971,19 @@ class BaseHTTPRequestHandlerTestCase(unittest.TestCase):
         self.handler.handle()
         self.assertRaises(StopIteration, next, close_values)
 
+    def test_date_time_string(self):
+        now = time.time()
+        # this is the old code that formats the timestamp
+        year, month, day, hh, mm, ss, wd, y, z = time.gmtime(now)
+        expected = "%s, %02d %3s %4d %02d:%02d:%02d GMT" % (
+            self.handler.weekdayname[wd],
+            day,
+            self.handler.monthname[month],
+            year, hh, mm, ss
+        )
+        self.assertEqual(self.handler.date_time_string(timestamp=now), expected)
+
+
 class SimpleHTTPRequestHandlerTestCase(unittest.TestCase):
     """ Test url parsing """
     def setUp(self):
diff --git a/Lib/test/test_idle.py b/Lib/test/test_idle.py
index 141e89e493..0b34e97ccc 100644
--- a/Lib/test/test_idle.py
+++ b/Lib/test/test_idle.py
@@ -1,5 +1,4 @@
 import unittest
-from test import support
 from test.support import import_module
 
 # Skip test if _thread or _tkinter wasn't built or idlelib was deleted.
diff --git a/Lib/test/test_imaplib.py b/Lib/test/test_imaplib.py
index 07157f52d6..8e4990b3cf 100644
--- a/Lib/test/test_imaplib.py
+++ b/Lib/test/test_imaplib.py
@@ -243,6 +243,55 @@ class ThreadedNetworkedTests(unittest.TestCase):
             client.shutdown()
 
     @reap_threads
+    def test_bracket_flags(self):
+
+        # This violates RFC 3501, which disallows ']' characters in tag names,
+        # but imaplib has allowed producing such tags forever, other programs
+        # also produce them (eg: OtherInbox's Organizer app as of 20140716),
+        # and Gmail, for example, accepts them and produces them.  So we
+        # support them.  See issue #21815.
+
+        class BracketFlagHandler(SimpleIMAPHandler):
+
+            def handle(self):
+                self.flags = ['Answered', 'Flagged', 'Deleted', 'Seen', 'Draft']
+                super().handle()
+
+            def cmd_AUTHENTICATE(self, tag, args):
+                self._send_textline('+')
+                self.server.response = yield
+                self._send_tagged(tag, 'OK', 'FAKEAUTH successful')
+
+            def cmd_SELECT(self, tag, args):
+                flag_msg = ' \\'.join(self.flags)
+                self._send_line(('* FLAGS (%s)' % flag_msg).encode('ascii'))
+                self._send_line(b'* 2 EXISTS')
+                self._send_line(b'* 0 RECENT')
+                msg = ('* OK [PERMANENTFLAGS %s \\*)] Flags permitted.'
+                        % flag_msg)
+                self._send_line(msg.encode('ascii'))
+                self._send_tagged(tag, 'OK', '[READ-WRITE] SELECT completed.')
+
+            def cmd_STORE(self, tag, args):
+                new_flags = args[2].strip('(').strip(')').split()
+                self.flags.extend(new_flags)
+                flags_msg = '(FLAGS (%s))' % ' \\'.join(self.flags)
+                msg = '* %s FETCH %s' % (args[0], flags_msg)
+                self._send_line(msg.encode('ascii'))
+                self._send_tagged(tag, 'OK', 'STORE completed.')
+
+        with self.reaped_pair(BracketFlagHandler) as (server, client):
+            code, data = client.authenticate('MYAUTH', lambda x: b'fake')
+            self.assertEqual(code, 'OK')
+            self.assertEqual(server.response, b'ZmFrZQ==\r\n')
+            client.select('test')
+            typ, [data] = client.store(b'1', "+FLAGS", "[test]")
+            self.assertIn(b'[test]', data)
+            client.select('test')
+            typ, [data] = client.response('PERMANENTFLAGS')
+            self.assertIn(b'[test]', data)
+
+    @reap_threads
     def test_issue5949(self):
 
         class EOFHandler(socketserver.StreamRequestHandler):
diff --git a/Lib/test/test_imp.py b/Lib/test/test_imp.py
index ee9ee1ad8c..4ece365410 100644
--- a/Lib/test/test_imp.py
+++ b/Lib/test/test_imp.py
@@ -6,13 +6,12 @@ import importlib
 import importlib.util
 import os
 import os.path
-import shutil
 import sys
 from test import support
 import unittest
 import warnings
 with warnings.catch_warnings():
-    warnings.simplefilter('ignore', PendingDeprecationWarning)
+    warnings.simplefilter('ignore', DeprecationWarning)
     import imp
 
 
diff --git a/Lib/test/test_importlib/extension/test_case_sensitivity.py b/Lib/test/test_importlib/extension/test_case_sensitivity.py
index 706c3e4b87..b74e900391 100644
--- a/Lib/test/test_importlib/extension/test_case_sensitivity.py
+++ b/Lib/test/test_importlib/extension/test_case_sensitivity.py
@@ -1,5 +1,4 @@
 from importlib import _bootstrap_external
-import sys
 from test import support
 import unittest
 
@@ -8,8 +7,6 @@ from .. import util
 machinery = util.import_importlib('importlib.machinery')
 
 
-# XXX find_spec tests
-
 @unittest.skipIf(util.EXTENSIONS.filename is None, '_testcapi not available')
 @util.case_insensitive_tests
 class ExtensionModuleCaseSensitivityTest:
diff --git a/Lib/test/test_importlib/extension/test_finder.py b/Lib/test/test_importlib/extension/test_finder.py
index 71bf67febd..c9b4a3772c 100644
--- a/Lib/test/test_importlib/extension/test_finder.py
+++ b/Lib/test/test_importlib/extension/test_finder.py
@@ -6,7 +6,6 @@ machinery = util.import_importlib('importlib.machinery')
 import unittest
 import warnings
 
-# XXX find_spec tests
 
 class FinderTests(abc.FinderTests):
 
diff --git a/Lib/test/test_importlib/extension/test_path_hook.py b/Lib/test/test_importlib/extension/test_path_hook.py
index 8f4b8bb161..a4b5a64aae 100644
--- a/Lib/test/test_importlib/extension/test_path_hook.py
+++ b/Lib/test/test_importlib/extension/test_path_hook.py
@@ -2,8 +2,6 @@ from .. import util
 
 machinery = util.import_importlib('importlib.machinery')
 
-import collections
-import sys
 import unittest
 
 
diff --git a/Lib/test/test_importlib/frozen/test_loader.py b/Lib/test/test_importlib/frozen/test_loader.py
index 603c7d7b19..29ecff1774 100644
--- a/Lib/test/test_importlib/frozen/test_loader.py
+++ b/Lib/test/test_importlib/frozen/test_loader.py
@@ -3,8 +3,6 @@ from .. import util
 
 machinery = util.import_importlib('importlib.machinery')
 
-
-import sys
 from test.support import captured_stdout
 import types
 import unittest
diff --git a/Lib/test/test_importlib/import_/test___package__.py b/Lib/test/test_importlib/import_/test___package__.py
index c7d3a2a204..7f64548748 100644
--- a/Lib/test/test_importlib/import_/test___package__.py
+++ b/Lib/test/test_importlib/import_/test___package__.py
@@ -5,6 +5,7 @@ of using the typical __path__/__name__ test).
 
 """
 import unittest
+import warnings
 from .. import util
 
 
@@ -33,31 +34,50 @@ class Using__package__:
 
     """
 
-    def test_using___package__(self):
-        # [__package__]
+    def import_module(self, globals_):
         with self.mock_modules('pkg.__init__', 'pkg.fake') as importer:
             with util.import_state(meta_path=[importer]):
                 self.__import__('pkg.fake')
                 module = self.__import__('',
-                                            globals={'__package__': 'pkg.fake'},
-                                            fromlist=['attr'], level=2)
+                                         globals=globals_,
+                                         fromlist=['attr'], level=2)
+        return module
+
+    def test_using___package__(self):
+        # [__package__]
+        module = self.import_module({'__package__': 'pkg.fake'})
         self.assertEqual(module.__name__, 'pkg')
 
-    def test_using___name__(self, package_as_None=False):
+    def test_using___name__(self):
         # [__name__]
-        globals_ = {'__name__': 'pkg.fake', '__path__': []}
-        if package_as_None:
-            globals_['__package__'] = None
-        with self.mock_modules('pkg.__init__', 'pkg.fake') as importer:
-            with util.import_state(meta_path=[importer]):
-                self.__import__('pkg.fake')
-                module = self.__import__('', globals= globals_,
-                                                fromlist=['attr'], level=2)
-            self.assertEqual(module.__name__, 'pkg')
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore")
+            module = self.import_module({'__name__': 'pkg.fake',
+                                         '__path__': []})
+        self.assertEqual(module.__name__, 'pkg')
+
+    def test_warn_when_using___name__(self):
+        with self.assertWarns(ImportWarning):
+            self.import_module({'__name__': 'pkg.fake', '__path__': []})
 
     def test_None_as___package__(self):
         # [None]
-        self.test_using___name__(package_as_None=True)
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore")
+            module = self.import_module({
+                '__name__': 'pkg.fake', '__path__': [], '__package__': None })
+        self.assertEqual(module.__name__, 'pkg')
+
+    def test_spec_fallback(self):
+        # If __package__ isn't defined, fall back on __spec__.parent.
+        module = self.import_module({'__spec__': FakeSpec('pkg.fake')})
+        self.assertEqual(module.__name__, 'pkg')
+
+    def test_warn_when_package_and_spec_disagree(self):
+        # Raise an ImportWarning if __package__ != __spec__.parent.
+        with self.assertWarns(ImportWarning):
+            self.import_module({'__package__': 'pkg.fake',
+                                '__spec__': FakeSpec('pkg.fakefake')})
 
     def test_bad__package__(self):
         globals = {'__package__': '<not real>'}
@@ -70,6 +90,11 @@ class Using__package__:
             self.__import__('', globals, {}, ['relimport'], 1)
 
 
+class FakeSpec:
+    def __init__(self, parent):
+        self.parent = parent
+
+
 class Using__package__PEP302(Using__package__):
     mock_modules = util.mock_modules
 
diff --git a/Lib/test/test_importlib/import_/test_packages.py b/Lib/test/test_importlib/import_/test_packages.py
index 3755b84a1a..24396044a5 100644
--- a/Lib/test/test_importlib/import_/test_packages.py
+++ b/Lib/test/test_importlib/import_/test_packages.py
@@ -1,7 +1,6 @@
 from .. import util
 import sys
 import unittest
-import importlib
 from test import support
 
 
diff --git a/Lib/test/test_importlib/import_/test_path.py b/Lib/test/test_importlib/import_/test_path.py
index b32a876f89..7aa26b0eee 100644
--- a/Lib/test/test_importlib/import_/test_path.py
+++ b/Lib/test/test_importlib/import_/test_path.py
@@ -16,11 +16,14 @@ class FinderTests:
 
     """Tests for PathFinder."""
 
+    find = None
+    check_found = None
+
     def test_failure(self):
         # Test None returned upon not finding a suitable loader.
         module = '<test module>'
         with util.import_state():
-            self.assertIsNone(self.machinery.PathFinder.find_module(module))
+            self.assertIsNone(self.find(module))
 
     def test_sys_path(self):
         # Test that sys.path is used when 'path' is None.
@@ -30,8 +33,8 @@ class FinderTests:
         importer = util.mock_spec(module)
         with util.import_state(path_importer_cache={path: importer},
                                path=[path]):
-            loader = self.machinery.PathFinder.find_module(module)
-            self.assertIs(loader, importer)
+            found = self.find(module)
+            self.check_found(found, importer)
 
     def test_path(self):
         # Test that 'path' is used when set.
@@ -40,8 +43,8 @@ class FinderTests:
         path = '<test path>'
         importer = util.mock_spec(module)
         with util.import_state(path_importer_cache={path: importer}):
-            loader = self.machinery.PathFinder.find_module(module, [path])
-            self.assertIs(loader, importer)
+            found = self.find(module, [path])
+            self.check_found(found, importer)
 
     def test_empty_list(self):
         # An empty list should not count as asking for sys.path.
@@ -50,7 +53,7 @@ class FinderTests:
         importer = util.mock_spec(module)
         with util.import_state(path_importer_cache={path: importer},
                                path=[path]):
-            self.assertIsNone(self.machinery.PathFinder.find_module('module', []))
+            self.assertIsNone(self.find('module', []))
 
     def test_path_hooks(self):
         # Test that sys.path_hooks is used.
@@ -60,8 +63,8 @@ class FinderTests:
         importer = util.mock_spec(module)
         hook = util.mock_path_hook(path, importer=importer)
         with util.import_state(path_hooks=[hook]):
-            loader = self.machinery.PathFinder.find_module(module, [path])
-            self.assertIs(loader, importer)
+            found = self.find(module, [path])
+            self.check_found(found, importer)
             self.assertIn(path, sys.path_importer_cache)
             self.assertIs(sys.path_importer_cache[path], importer)
 
@@ -73,7 +76,7 @@ class FinderTests:
                                path=[path_entry]):
             with warnings.catch_warnings(record=True) as w:
                 warnings.simplefilter('always')
-                self.assertIsNone(self.machinery.PathFinder.find_module('os'))
+                self.assertIsNone(self.find('os'))
                 self.assertIsNone(sys.path_importer_cache[path_entry])
                 self.assertEqual(len(w), 1)
                 self.assertTrue(issubclass(w[-1].category, ImportWarning))
@@ -85,8 +88,8 @@ class FinderTests:
         importer = util.mock_spec(module)
         hook = util.mock_path_hook(os.getcwd(), importer=importer)
         with util.import_state(path=[path], path_hooks=[hook]):
-            loader = self.machinery.PathFinder.find_module(module)
-            self.assertIs(loader, importer)
+            found = self.find(module)
+            self.check_found(found, importer)
             self.assertIn(os.getcwd(), sys.path_importer_cache)
 
     def test_None_on_sys_path(self):
@@ -182,16 +185,33 @@ class FinderTests:
             self.assertIsNone(self.machinery.PathFinder.find_spec('whatever'))
 
 
+class FindModuleTests(FinderTests):
+    def find(self, *args, **kwargs):
+        return self.machinery.PathFinder.find_module(*args, **kwargs)
+    def check_found(self, found, importer):
+        self.assertIs(found, importer)
+
+
+(Frozen_FindModuleTests,
+ Source_FindModuleTests
+) = util.test_both(FindModuleTests, importlib=importlib, machinery=machinery)
 
 
-(Frozen_FinderTests,
- Source_FinderTests
- ) = util.test_both(FinderTests, importlib=importlib, machinery=machinery)
+class FindSpecTests(FinderTests):
+    def find(self, *args, **kwargs):
+        return self.machinery.PathFinder.find_spec(*args, **kwargs)
+    def check_found(self, found, importer):
+        self.assertIs(found.loader, importer)
+
+
+(Frozen_FindSpecTests,
+ Source_FindSpecTests
+ ) = util.test_both(FindSpecTests, importlib=importlib, machinery=machinery)
 
 
 class PathEntryFinderTests:
 
-    def test_finder_with_failing_find_module(self):
+    def test_finder_with_failing_find_spec(self):
         # PathEntryFinder with find_module() defined should work.
         # Issue #20763.
         class Finder:
@@ -209,6 +229,24 @@ class PathEntryFinderTests:
                                path_hooks=[Finder]):
             self.machinery.PathFinder.find_spec('importlib')
 
+    def test_finder_with_failing_find_module(self):
+        # PathEntryFinder with find_module() defined should work.
+        # Issue #20763.
+        class Finder:
+            path_location = 'test_finder_with_find_module'
+            def __init__(self, path):
+                if path != self.path_location:
+                    raise ImportError
+
+            @staticmethod
+            def find_module(fullname):
+                return None
+
+
+        with util.import_state(path=[Finder.path_location]+sys.path[:],
+                               path_hooks=[Finder]):
+            self.machinery.PathFinder.find_module('importlib')
+
 
 (Frozen_PEFTests,
  Source_PEFTests
diff --git a/Lib/test/test_importlib/import_/test_relative_imports.py b/Lib/test/test_importlib/import_/test_relative_imports.py
index 3bb819f906..8a95a32109 100644
--- a/Lib/test/test_importlib/import_/test_relative_imports.py
+++ b/Lib/test/test_importlib/import_/test_relative_imports.py
@@ -1,7 +1,8 @@
 """Test relative imports (PEP 328)."""
 from .. import util
-import sys
 import unittest
+import warnings
+
 
 class RelativeImports:
 
@@ -65,9 +66,11 @@ class RelativeImports:
                 uncache_names.append(name[:-len('.__init__')])
         with util.mock_spec(*create) as importer:
             with util.import_state(meta_path=[importer]):
-                for global_ in globals_:
-                    with util.uncache(*uncache_names):
-                        callback(global_)
+                with warnings.catch_warnings():
+                    warnings.simplefilter("ignore")
+                    for global_ in globals_:
+                        with util.uncache(*uncache_names):
+                            callback(global_)
 
 
     def test_module_from_module(self):
@@ -204,11 +207,18 @@ class RelativeImports:
 
     def test_relative_import_no_globals(self):
         # No globals for a relative import is an error.
-        with self.assertRaises(KeyError):
-            self.__import__('sys', level=1)
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore")
+            with self.assertRaises(KeyError):
+                self.__import__('sys', level=1)
+
+    def test_relative_import_no_package(self):
+        with self.assertRaises(ImportError):
+            self.__import__('a', {'__package__': '', '__spec__': None},
+                            level=1)
 
     def test_relative_import_no_package_exists_absolute(self):
-        with self.assertRaises(SystemError):
+        with self.assertRaises(ImportError):
             self.__import__('sys', {'__package__': '', '__spec__': None},
                             level=1)
 
diff --git a/Lib/test/test_importlib/regrtest.py b/Lib/test/test_importlib/regrtest.py
deleted file mode 100644
index a5be11fd4e..0000000000
--- a/Lib/test/test_importlib/regrtest.py
+++ /dev/null
@@ -1,17 +0,0 @@
-"""Run Python's standard test suite using importlib.__import__.
-
-Tests known to fail because of assumptions that importlib (properly)
-invalidates are automatically skipped if the entire test suite is run.
-Otherwise all command-line options valid for test.regrtest are also valid for
-this script.
-
-"""
-import importlib
-import sys
-from test import regrtest
-
-if __name__ == '__main__':
-    __builtins__.__import__ = importlib.__import__
-    sys.path_importer_cache.clear()
-
-    regrtest.main(quiet=True, verbose2=True)
diff --git a/Lib/test/test_importlib/source/test_case_sensitivity.py b/Lib/test/test_importlib/source/test_case_sensitivity.py
index c274b3823f..0d6c388a57 100644
--- a/Lib/test/test_importlib/source/test_case_sensitivity.py
+++ b/Lib/test/test_importlib/source/test_case_sensitivity.py
@@ -5,7 +5,6 @@ importlib = util.import_importlib('importlib')
 machinery = util.import_importlib('importlib.machinery')
 
 import os
-import sys
 from test import support as test_support
 import unittest
 
diff --git a/Lib/test/test_importlib/source/test_file_loader.py b/Lib/test/test_importlib/source/test_file_loader.py
index 73f4c62070..a151149f31 100644
--- a/Lib/test/test_importlib/source/test_file_loader.py
+++ b/Lib/test/test_importlib/source/test_file_loader.py
@@ -217,7 +217,7 @@ class SimpleTest(abc.LoaderTests):
             # PEP 302
             with warnings.catch_warnings():
                 warnings.simplefilter('ignore', DeprecationWarning)
-                mod = loader.load_module('_temp') # XXX
+                mod = loader.load_module('_temp')
             # Sanity checks.
             self.assertEqual(mod.__cached__, compiled)
             self.assertEqual(mod.x, 5)
@@ -245,12 +245,7 @@ class SimpleTest(abc.LoaderTests):
 class BadBytecodeTest:
 
     def import_(self, file, module_name):
-        loader = self.loader(module_name, file)
-        with warnings.catch_warnings():
-            warnings.simplefilter('ignore', DeprecationWarning)
-            # XXX Change to use exec_module().
-            module = loader.load_module(module_name)
-        self.assertIn(module_name, sys.modules)
+        raise NotImplementedError
 
     def manipulate_bytecode(self, name, mapping, manipulator, *,
                             del_source=False):
diff --git a/Lib/test/test_importlib/source/test_path_hook.py b/Lib/test/test_importlib/source/test_path_hook.py
index e6a2415bda..795d436c3b 100644
--- a/Lib/test/test_importlib/source/test_path_hook.py
+++ b/Lib/test/test_importlib/source/test_path_hook.py
@@ -16,10 +16,19 @@ class PathHookTest:
     def test_success(self):
         with util.create_modules('dummy') as mapping:
             self.assertTrue(hasattr(self.path_hook()(mapping['.root']),
-                                 'find_module'))
+                                    'find_spec'))
+
+    def test_success_legacy(self):
+        with util.create_modules('dummy') as mapping:
+            self.assertTrue(hasattr(self.path_hook()(mapping['.root']),
+                                    'find_module'))
 
     def test_empty_string(self):
         # The empty string represents the cwd.
+        self.assertTrue(hasattr(self.path_hook()(''), 'find_spec'))
+
+    def test_empty_string_legacy(self):
+        # The empty string represents the cwd.
         self.assertTrue(hasattr(self.path_hook()(''), 'find_module'))
 
 
diff --git a/Lib/test/test_importlib/source/test_source_encoding.py b/Lib/test/test_importlib/source/test_source_encoding.py
index 1e0771b19d..980855fe1a 100644
--- a/Lib/test/test_importlib/source/test_source_encoding.py
+++ b/Lib/test/test_importlib/source/test_source_encoding.py
@@ -5,7 +5,6 @@ machinery = util.import_importlib('importlib.machinery')
 import codecs
 import importlib.util
 import re
-import sys
 import types
 # Because sys.path gets essentially blanked, need to have unicodedata already
 # imported for the parser to use.
diff --git a/Lib/test/test_importlib/test_abc.py b/Lib/test/test_importlib/test_abc.py
index d4bf9153e9..c86248047f 100644
--- a/Lib/test/test_importlib/test_abc.py
+++ b/Lib/test/test_importlib/test_abc.py
@@ -207,6 +207,10 @@ class LoaderDefaultsTests(ABCTestHarness):
 
     SPLIT = make_abc_subclasses(Loader)
 
+    def test_create_module(self):
+        spec = 'a spec'
+        self.assertIsNone(self.ins.create_module(spec))
+
     def test_load_module(self):
         with self.assertRaises(ImportError):
             self.ins.load_module('something')
@@ -519,6 +523,12 @@ class InspectLoaderLoadModuleTests:
         support.unload(self.module_name)
         self.addCleanup(support.unload, self.module_name)
 
+    def load(self, loader):
+        spec = self.util.spec_from_loader(self.module_name, loader)
+        with warnings.catch_warnings():
+            warnings.simplefilter('ignore', DeprecationWarning)
+            return self.init._bootstrap._load_unlocked(spec)
+
     def mock_get_code(self):
         return mock.patch.object(self.InspectLoaderSubclass, 'get_code')
 
@@ -528,9 +538,7 @@ class InspectLoaderLoadModuleTests:
             mocked_get_code.side_effect = ImportError
             with self.assertRaises(ImportError):
                 loader = self.InspectLoaderSubclass()
-                with warnings.catch_warnings():
-                    warnings.simplefilter('ignore', DeprecationWarning)
-                    loader.load_module(self.module_name)
+                self.load(loader)
 
     def test_get_code_None(self):
         # If get_code() returns None, raise ImportError.
@@ -538,7 +546,7 @@ class InspectLoaderLoadModuleTests:
             mocked_get_code.return_value = None
             with self.assertRaises(ImportError):
                 loader = self.InspectLoaderSubclass()
-                loader.load_module(self.module_name)
+                self.load(loader)
 
     def test_module_returned(self):
         # The loaded module should be returned.
@@ -546,14 +554,16 @@ class InspectLoaderLoadModuleTests:
         with self.mock_get_code() as mocked_get_code:
             mocked_get_code.return_value = code
             loader = self.InspectLoaderSubclass()
-            module = loader.load_module(self.module_name)
+            module = self.load(loader)
             self.assertEqual(module, sys.modules[self.module_name])
 
 
 (Frozen_ILLoadModuleTests,
  Source_ILLoadModuleTests
  ) = test_util.test_both(InspectLoaderLoadModuleTests,
-                         InspectLoaderSubclass=SPLIT_IL)
+                         InspectLoaderSubclass=SPLIT_IL,
+                         init=init,
+                         util=util)
 
 
 ##### ExecutionLoader concrete methods #########################################
diff --git a/Lib/test/test_importlib/test_api.py b/Lib/test/test_importlib/test_api.py
index 6bc3c564a5..b0a94aaff5 100644
--- a/Lib/test/test_importlib/test_api.py
+++ b/Lib/test/test_importlib/test_api.py
@@ -99,9 +99,7 @@ class ImportModuleTests:
 
 class FindLoaderTests:
 
-    class FakeMetaFinder:
-        @staticmethod
-        def find_module(name, path=None): return name, path
+    FakeMetaFinder = None
 
     def test_sys_modules(self):
         # If a module with __loader__ is in sys.modules, then return it.
@@ -171,9 +169,30 @@ class FindLoaderTests:
             self.assertIsNone(self.init.find_loader('nevergoingtofindthismodule'))
 
 
-(Frozen_FindLoaderTests,
- Source_FindLoaderTests
- ) = test_util.test_both(FindLoaderTests, init=init)
+class FindLoaderPEP451Tests(FindLoaderTests):
+
+    class FakeMetaFinder:
+        @staticmethod
+        def find_spec(name, path=None, target=None):
+            return machinery['Source'].ModuleSpec(name, (name, path))
+
+
+(Frozen_FindLoaderPEP451Tests,
+ Source_FindLoaderPEP451Tests
+ ) = test_util.test_both(FindLoaderPEP451Tests, init=init)
+
+
+class FindLoaderPEP302Tests(FindLoaderTests):
+
+    class FakeMetaFinder:
+        @staticmethod
+        def find_module(name, path=None):
+            return name, path
+
+
+(Frozen_FindLoaderPEP302Tests,
+ Source_FindLoaderPEP302Tests
+ ) = test_util.test_both(FindLoaderPEP302Tests, init=init)
 
 
 class ReloadTests:
diff --git a/Lib/test/test_importlib/test_locks.py b/Lib/test/test_importlib/test_locks.py
index df0af12d38..b2aadff289 100644
--- a/Lib/test/test_importlib/test_locks.py
+++ b/Lib/test/test_importlib/test_locks.py
@@ -3,7 +3,6 @@ from . import util as test_util
 init = test_util.import_importlib('importlib')
 
 import sys
-import time
 import unittest
 import weakref
 
diff --git a/Lib/test/test_importlib/test_namespace_pkgs.py b/Lib/test/test_importlib/test_namespace_pkgs.py
index 6639612631..e37d8a18f4 100644
--- a/Lib/test/test_importlib/test_namespace_pkgs.py
+++ b/Lib/test/test_importlib/test_namespace_pkgs.py
@@ -1,13 +1,10 @@
 import contextlib
-import importlib.abc
-import importlib.machinery
+import importlib
 import os
 import sys
-import types
 import unittest
 
 from test.test_importlib import util
-from test.support import run_unittest
 
 # needed tests:
 #
@@ -71,6 +68,7 @@ class NamespacePackageTest(unittest.TestCase):
         # TODO: will we ever want to pass exc_info to __exit__?
         self.ctx.__exit__(None, None, None)
 
+
 class SingleNamespacePackage(NamespacePackageTest):
     paths = ['portion1']
 
@@ -87,7 +85,7 @@ class SingleNamespacePackage(NamespacePackageTest):
         self.assertEqual(repr(foo), "<module 'foo' (namespace)>")
 
 
-class DynamicPatheNamespacePackage(NamespacePackageTest):
+class DynamicPathNamespacePackage(NamespacePackageTest):
     paths = ['portion1']
 
     def test_dynamic_path(self):
@@ -289,5 +287,35 @@ class ModuleAndNamespacePackageInSameDir(NamespacePackageTest):
         self.assertEqual(a_test.attr, 'in module')
 
 
+class ReloadTests(NamespacePackageTest):
+    paths = ['portion1']
+
+    def test_simple_package(self):
+        import foo.one
+        foo = importlib.reload(foo)
+        self.assertEqual(foo.one.attr, 'portion1 foo one')
+
+    def test_cant_import_other(self):
+        import foo
+        with self.assertRaises(ImportError):
+            import foo.two
+        foo = importlib.reload(foo)
+        with self.assertRaises(ImportError):
+            import foo.two
+
+    def test_dynamic_path(self):
+        import foo.one
+        with self.assertRaises(ImportError):
+            import foo.two
+
+        # Now modify sys.path and reload.
+        sys.path.append(os.path.join(self.root, 'portion2'))
+        foo = importlib.reload(foo)
+
+        # And make sure foo.two is now importable
+        import foo.two
+        self.assertEqual(foo.two.attr, 'portion2 foo two')
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_importlib/test_windows.py b/Lib/test/test_importlib/test_windows.py
index c893bcf565..005b685cc0 100644
--- a/Lib/test/test_importlib/test_windows.py
+++ b/Lib/test/test_importlib/test_windows.py
@@ -40,7 +40,7 @@ def setup_module(machinery, name, path=None):
     else:
         root = machinery.WindowsRegistryFinder.REGISTRY_KEY
     key = root.format(fullname=name,
-                      sys_version=sys.version[:3])
+                      sys_version='%d.%d' % sys.version_info[:2])
     try:
         with temp_module(name, "a = 1") as location:
             subkey = CreateKey(HKEY_CURRENT_USER, key)
diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py
index 671e05a7b5..47244aeaa4 100644
--- a/Lib/test/test_inspect.py
+++ b/Lib/test/test_inspect.py
@@ -30,6 +30,7 @@ from test.support import MISSING_C_DOCSTRINGS, cpython_only
 from test.support.script_helper import assert_python_ok, assert_python_failure
 from test import inspect_fodder as mod
 from test import inspect_fodder2 as mod2
+from test import support
 
 from test.test_import import _ready_to_import
 
@@ -38,7 +39,7 @@ from test.test_import import _ready_to_import
 # ismodule, isclass, ismethod, isfunction, istraceback, isframe, iscode,
 # isbuiltin, isroutine, isgenerator, isgeneratorfunction, getmembers,
 # getdoc, getfile, getmodule, getsourcefile, getcomments, getsource,
-# getclasstree, getargspec, getargvalues, formatargspec, formatargvalues,
+# getclasstree, getargvalues, formatargspec, formatargvalues,
 # currentframe, stack, trace, isdatadescriptor
 
 # NOTE: There are some additional tests relating to interaction with
@@ -400,7 +401,7 @@ class TestRetrievingSourceCode(GetSourceBase):
         self.assertEqual(normcase(inspect.getsourcefile(mod.spam)), modfile)
         self.assertEqual(normcase(inspect.getsourcefile(git.abuse)), modfile)
         fn = "_non_existing_filename_used_for_sourcefile_test.py"
-        co = compile("None", fn, "exec")
+        co = compile("x=1", fn, "exec")
         self.assertEqual(inspect.getsourcefile(co), None)
         linecache.cache[co.co_filename] = (1, None, "None", co.co_filename)
         try:
@@ -2902,6 +2903,10 @@ class TestParameterObject(unittest.TestCase):
                                     'is not a valid parameter name'):
             inspect.Parameter('$', kind=inspect.Parameter.VAR_KEYWORD)
 
+        with self.assertRaisesRegex(ValueError,
+                                    'is not a valid parameter name'):
+            inspect.Parameter('.a', kind=inspect.Parameter.VAR_KEYWORD)
+
         with self.assertRaisesRegex(ValueError, 'cannot have default values'):
             inspect.Parameter('a', default=42,
                               kind=inspect.Parameter.VAR_KEYWORD)
@@ -2985,6 +2990,17 @@ class TestParameterObject(unittest.TestCase):
         with self.assertRaisesRegex(TypeError, 'name must be a str'):
             inspect.Parameter(None, kind=inspect.Parameter.POSITIONAL_ONLY)
 
+    @cpython_only
+    def test_signature_parameter_implicit(self):
+        with self.assertRaisesRegex(ValueError,
+                                    'implicit arguments must be passed in as'):
+            inspect.Parameter('.0', kind=inspect.Parameter.POSITIONAL_ONLY)
+
+        param = inspect.Parameter(
+            '.0', kind=inspect.Parameter.POSITIONAL_OR_KEYWORD)
+        self.assertEqual(param.kind, inspect.Parameter.POSITIONAL_ONLY)
+        self.assertEqual(param.name, 'implicit0')
+
     def test_signature_parameter_immutability(self):
         p = inspect.Parameter('spam', kind=inspect.Parameter.KEYWORD_ONLY)
 
@@ -3233,6 +3249,17 @@ class TestSignatureBind(unittest.TestCase):
         ba = sig.bind(args=1)
         self.assertEqual(ba.arguments, {'kwargs': {'args': 1}})
 
+    @cpython_only
+    def test_signature_bind_implicit_arg(self):
+        # Issue #19611: getcallargs should work with set comprehensions
+        def make_set():
+            return {z * z for z in range(5)}
+        setcomp_code = make_set.__code__.co_consts[1]
+        setcomp_func = types.FunctionType(setcomp_code, {})
+
+        iterator = iter(range(5))
+        self.assertEqual(self.call(setcomp_func, iterator), {0, 1, 4, 9, 16})
+
 
 class TestBoundArguments(unittest.TestCase):
     def test_signature_bound_arguments_unhashable(self):
@@ -3543,14 +3570,14 @@ class TestMain(unittest.TestCase):
 
     def test_details(self):
         module = importlib.import_module('unittest')
-        rc, out, err = assert_python_ok('-m', 'inspect',
+        args = support.optim_args_from_interpreter_flags()
+        rc, out, err = assert_python_ok(*args, '-m', 'inspect',
                                         'unittest', '--details')
         output = out.decode()
         # Just a quick sanity check on the output
         self.assertIn(module.__name__, output)
         self.assertIn(module.__file__, output)
-        if not sys.flags.optimize:
-            self.assertIn(module.__cached__, output)
+        self.assertIn(module.__cached__, output)
         self.assertEqual(err, b'')
 
 
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index 000b525003..8581865145 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -496,7 +496,11 @@ class IOTest(unittest.TestCase):
     def test_open_handles_NUL_chars(self):
         fn_with_NUL = 'foo\0bar'
         self.assertRaises(ValueError, self.open, fn_with_NUL, 'w')
-        self.assertRaises(ValueError, self.open, bytes(fn_with_NUL, 'ascii'), 'w')
+
+        bytes_fn = bytes(fn_with_NUL, 'ascii')
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", DeprecationWarning)
+            self.assertRaises(ValueError, self.open, bytes_fn, 'w')
 
     def test_raw_file_io(self):
         with self.open(support.TESTFN, "wb", buffering=0) as f:
@@ -856,6 +860,32 @@ class IOTest(unittest.TestCase):
                 self.assertEqual(getattr(stream, method)(buffer), 5)
                 self.assertEqual(bytes(buffer), b"12345")
 
+    def test_fspath_support(self):
+        class PathLike:
+            def __init__(self, path):
+                self.path = path
+
+            def __fspath__(self):
+                return self.path
+
+        def check_path_succeeds(path):
+            with self.open(path, "w") as f:
+                f.write("egg\n")
+
+            with self.open(path, "r") as f:
+                self.assertEqual(f.read(), "egg\n")
+
+        check_path_succeeds(PathLike(support.TESTFN))
+        check_path_succeeds(PathLike(support.TESTFN.encode('utf-8')))
+
+        bad_path = PathLike(TypeError)
+        with self.assertRaisesRegex(TypeError, 'invalid file'):
+            self.open(bad_path, 'w')
+
+        # ensure that refcounting is correct with some error conditions
+        with self.assertRaisesRegex(ValueError, 'read/write/append mode'):
+            self.open(PathLike(support.TESTFN), 'rwxa')
+
 
 class CIOTest(IOTest):
 
@@ -3244,8 +3274,7 @@ class CTextIOWrapperTest(TextIOWrapperTest):
 
 class PyTextIOWrapperTest(TextIOWrapperTest):
     io = pyio
-    #shutdown_error = "LookupError: unknown encoding: ascii"
-    shutdown_error = "TypeError: 'NoneType' object is not iterable"
+    shutdown_error = "LookupError: unknown encoding: ascii"
 
 
 class IncrementalNewlineDecoderTest(unittest.TestCase):
diff --git a/Lib/test/test_iterlen.py b/Lib/test/test_iterlen.py
index 152f5fc0cb..41c9752e55 100644
--- a/Lib/test/test_iterlen.py
+++ b/Lib/test/test_iterlen.py
@@ -42,7 +42,6 @@ enumerate(iter('abc')).
 """
 
 import unittest
-from test import support
 from itertools import repeat
 from collections import deque
 from operator import length_hint
diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py
index f940852ce1..945c58d5d0 100644
--- a/Lib/test/test_itertools.py
+++ b/Lib/test/test_itertools.py
@@ -4,7 +4,6 @@ from itertools import *
 import weakref
 from decimal import Decimal
 from fractions import Fraction
-import sys
 import operator
 import random
 import copy
@@ -613,6 +612,56 @@ class TestBasicOps(unittest.TestCase):
         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
             self.pickletest(proto, cycle('abc'))
 
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            # test with partial consumed input iterable
+            it = iter('abcde')
+            c = cycle(it)
+            _ = [next(c) for i in range(2)]      # consume 2 of 5 inputs
+            p = pickle.dumps(c, proto)
+            d = pickle.loads(p)                  # rebuild the cycle object
+            self.assertEqual(take(20, d), list('cdeabcdeabcdeabcdeab'))
+
+            # test with completely consumed input iterable
+            it = iter('abcde')
+            c = cycle(it)
+            _ = [next(c) for i in range(7)]      # consume 7 of 5 inputs
+            p = pickle.dumps(c, proto)
+            d = pickle.loads(p)                  # rebuild the cycle object
+            self.assertEqual(take(20, d), list('cdeabcdeabcdeabcdeab'))
+
+    def test_cycle_setstate(self):
+        # Verify both modes for restoring state
+
+        # Mode 0 is efficient.  It uses an incompletely consumed input
+        # iterator to build a cycle object and then passes in state with
+        # a list of previously consumed values.  There is no data
+        # overlap between the two.
+        c = cycle('defg')
+        c.__setstate__((list('abc'), 0))
+        self.assertEqual(take(20, c), list('defgabcdefgabcdefgab'))
+
+        # Mode 1 is inefficient.  It starts with a cycle object built
+        # from an iterator over the remaining elements in a partial
+        # cycle and then passes in state with all of the previously
+        # seen values (this overlaps values included in the iterator).
+        c = cycle('defg')
+        c.__setstate__((list('abcdefg'), 1))
+        self.assertEqual(take(20, c), list('defgabcdefgabcdefgab'))
+
+        # The first argument to setstate needs to be a tuple
+        with self.assertRaises(SystemError):
+            cycle('defg').__setstate__([list('abcdefg'), 0])
+
+        # The first argument in the setstate tuple must be a list
+        with self.assertRaises(TypeError):
+            c = cycle('defg')
+            c.__setstate__((dict.fromkeys('defg'), 0))
+            take(20, c)
+
+        # The first argument in the setstate tuple must be a list
+        with self.assertRaises(TypeError):
+            cycle('defg').__setstate__((list('abcdefg'), 'x'))
+
     def test_groupby(self):
         # Check whether it accepts arguments correctly
         self.assertEqual([], list(groupby([])))
diff --git a/Lib/test/test_json/__init__.py b/Lib/test/test_json/__init__.py
index 0807e6fb4f..bac370dadf 100644
--- a/Lib/test/test_json/__init__.py
+++ b/Lib/test/test_json/__init__.py
@@ -1,5 +1,4 @@
 import os
-import sys
 import json
 import doctest
 import unittest
diff --git a/Lib/test/test_json/test_fail.py b/Lib/test/test_json/test_fail.py
index 95ff5b8d1e..7910521021 100644
--- a/Lib/test/test_json/test_fail.py
+++ b/Lib/test/test_json/test_fail.py
@@ -1,5 +1,4 @@
 from test.test_json import PyTest, CTest
-import re
 
 # 2007-10-05
 JSONDOCS = [
diff --git a/Lib/test/test_kqueue.py b/Lib/test/test_kqueue.py
index f822024aa0..9f49886878 100644
--- a/Lib/test/test_kqueue.py
+++ b/Lib/test/test_kqueue.py
@@ -5,7 +5,6 @@ import errno
 import os
 import select
 import socket
-import sys
 import time
 import unittest
 
diff --git a/Lib/test/test_linecache.py b/Lib/test/test_linecache.py
index 47e2eddfb1..375d9c4213 100644
--- a/Lib/test/test_linecache.py
+++ b/Lib/test/test_linecache.py
@@ -3,6 +3,8 @@
 import linecache
 import unittest
 import os.path
+import tempfile
+import tokenize
 from test import support
 
 
@@ -10,8 +12,6 @@ FILENAME = linecache.__file__
 NONEXISTENT_FILENAME = FILENAME + '.missing'
 INVALID_NAME = '!@$)(!@#_1'
 EMPTY = ''
-TESTS = 'inspect_fodder inspect_fodder2 mapping_tests'
-TESTS = TESTS.split()
 TEST_PATH = os.path.dirname(__file__)
 MODULES = "linecache abc".split()
 MODULE_PATH = os.path.dirname(FILENAME)
@@ -37,6 +37,65 @@ def f():
     return 3''' # No ending newline
 
 
+class TempFile:
+
+    def setUp(self):
+        super().setUp()
+        with tempfile.NamedTemporaryFile(delete=False) as fp:
+            self.file_name = fp.name
+            fp.write(self.file_byte_string)
+        self.addCleanup(support.unlink, self.file_name)
+
+
+class GetLineTestsGoodData(TempFile):
+    # file_list   = ['list\n', 'of\n', 'good\n', 'strings\n']
+
+    def setUp(self):
+        self.file_byte_string = ''.join(self.file_list).encode('utf-8')
+        super().setUp()
+
+    def test_getline(self):
+        with tokenize.open(self.file_name) as fp:
+            for index, line in enumerate(fp):
+                if not line.endswith('\n'):
+                    line += '\n'
+
+                cached_line = linecache.getline(self.file_name, index + 1)
+                self.assertEqual(line, cached_line)
+
+    def test_getlines(self):
+        lines = linecache.getlines(self.file_name)
+        self.assertEqual(lines, self.file_list)
+
+
+class GetLineTestsBadData(TempFile):
+    # file_byte_string = b'Bad data goes here'
+
+    def test_getline(self):
+        self.assertRaises((SyntaxError, UnicodeDecodeError),
+                          linecache.getline, self.file_name, 1)
+
+    def test_getlines(self):
+        self.assertRaises((SyntaxError, UnicodeDecodeError),
+                          linecache.getlines, self.file_name)
+
+
+class EmptyFile(GetLineTestsGoodData, unittest.TestCase):
+    file_list = []
+
+
+class SingleEmptyLine(GetLineTestsGoodData, unittest.TestCase):
+    file_list = ['\n']
+
+
+class GoodUnicode(GetLineTestsGoodData, unittest.TestCase):
+    file_list = ['á\n', 'b\n', 'abcdef\n', 'ááááá\n']
+
+
+class BadUnicode(GetLineTestsBadData, unittest.TestCase):
+    file_byte_string = b'\x80abc'
+
+
 class LineCacheTests(unittest.TestCase):
 
     def test_getline(self):
@@ -53,13 +112,6 @@ class LineCacheTests(unittest.TestCase):
         self.assertEqual(getline(EMPTY, 1), EMPTY)
         self.assertEqual(getline(INVALID_NAME, 1), EMPTY)
 
-        # Check whether lines correspond to those from file iteration
-        for entry in TESTS:
-            filename = os.path.join(TEST_PATH, entry) + '.py'
-            with open(filename) as file:
-                for index, line in enumerate(file):
-                    self.assertEqual(line, getline(filename, index + 1))
-
         # Check module loading
         for entry in MODULES:
             filename = os.path.join(MODULE_PATH, entry) + '.py'
@@ -80,12 +132,13 @@ class LineCacheTests(unittest.TestCase):
 
     def test_clearcache(self):
         cached = []
-        for entry in TESTS:
-            filename = os.path.join(TEST_PATH, entry) + '.py'
+        for entry in MODULES:
+            filename = os.path.join(MODULE_PATH, entry) + '.py'
             cached.append(filename)
             linecache.getline(filename, 1)
 
         # Are all files cached?
+        self.assertNotEqual(cached, [])
         cached_empty = [fn for fn in cached if fn not in linecache.cache]
         self.assertEqual(cached_empty, [])
 
diff --git a/Lib/test/test_list.py b/Lib/test/test_list.py
index 8f82ab5297..aee62dca1c 100644
--- a/Lib/test/test_list.py
+++ b/Lib/test/test_list.py
@@ -1,5 +1,5 @@
 import sys
-from test import support, list_tests
+from test import list_tests
 import pickle
 import unittest
 
diff --git a/Lib/test/test_logging.py b/Lib/test/test_logging.py
index 84fd8b57c7..9e391dc222 100644
--- a/Lib/test/test_logging.py
+++ b/Lib/test/test_logging.py
@@ -4160,6 +4160,17 @@ class NTEventLogHandlerTest(BaseTest):
         msg = 'Record not found in event log, went back %d records' % GO_BACK
         self.assertTrue(found, msg=msg)
 
+
+class MiscTestCase(unittest.TestCase):
+    def test__all__(self):
+        blacklist = {'logThreads', 'logMultiprocessing',
+                     'logProcesses', 'currentframe',
+                     'PercentStyle', 'StrFormatStyle', 'StringTemplateStyle',
+                     'Filterer', 'PlaceHolder', 'Manager', 'RootLogger',
+                     'root'}
+        support.check__all__(self, logging, blacklist=blacklist)
+
+
 # Set the locale to the platform-dependent default.  I have no idea
 # why the test does this, but in any case we save the current locale
 # first and restore it at the end.
@@ -4176,7 +4187,8 @@ def test_main():
         RotatingFileHandlerTest,  LastResortTest, LogRecordTest,
         ExceptionTest, SysLogHandlerTest, HTTPHandlerTest,
         NTEventLogHandlerTest, TimedRotatingFileHandlerTest,
-        UnixSocketHandlerTest, UnixDatagramHandlerTest, UnixSysLogHandlerTest)
+        UnixSocketHandlerTest, UnixDatagramHandlerTest, UnixSysLogHandlerTest,
+        MiscTestCase)
 
 if __name__ == "__main__":
     test_main()
diff --git a/Lib/test/test_long.py b/Lib/test/test_long.py
index b2d008b101..f0dd0749f7 100644
--- a/Lib/test/test_long.py
+++ b/Lib/test/test_long.py
@@ -689,6 +689,20 @@ class LongTest(unittest.TestCase):
         self.assertRaises(OverflowError, int, float('-inf'))
         self.assertRaises(ValueError, int, float('nan'))
 
+    def test_mod_division(self):
+        with self.assertRaises(ZeroDivisionError):
+            _ = 1 % 0
+
+        self.assertEqual(13 % 10, 3)
+        self.assertEqual(-13 % 10, 7)
+        self.assertEqual(13 % -10, -7)
+        self.assertEqual(-13 % -10, -3)
+
+        self.assertEqual(12 % 4, 0)
+        self.assertEqual(-12 % 4, 0)
+        self.assertEqual(12 % -4, 0)
+        self.assertEqual(-12 % -4, 0)
+
     def test_true_division(self):
         huge = 1 << 40000
         mhuge = -huge
@@ -723,6 +737,25 @@ class LongTest(unittest.TestCase):
         for zero in ["huge / 0", "mhuge / 0"]:
             self.assertRaises(ZeroDivisionError, eval, zero, namespace)
 
+    def test_floordiv(self):
+        with self.assertRaises(ZeroDivisionError):
+            _ = 1 // 0
+
+        self.assertEqual(2 // 3, 0)
+        self.assertEqual(2 // -3, -1)
+        self.assertEqual(-2 // 3, -1)
+        self.assertEqual(-2 // -3, 0)
+
+        self.assertEqual(-11 // -3, 3)
+        self.assertEqual(-11 // 3, -4)
+        self.assertEqual(11 // -3, -4)
+        self.assertEqual(11 // 3, 3)
+
+        self.assertEqual(-12 // -3, 4)
+        self.assertEqual(-12 // 3, -4)
+        self.assertEqual(12 // -3, -4)
+        self.assertEqual(12 // 3, 4)
+
     def check_truediv(self, a, b, skip_small=True):
         """Verify that the result of a/b is correctly rounded, by
         comparing it with a pure Python implementation of correctly
diff --git a/Lib/test/test_macpath.py b/Lib/test/test_macpath.py
index 80bec7a799..0698ff5f6b 100644
--- a/Lib/test/test_macpath.py
+++ b/Lib/test/test_macpath.py
@@ -1,5 +1,5 @@
 import macpath
-from test import support, test_genericpath
+from test import test_genericpath
 import unittest
 
 
diff --git a/Lib/test/test_mailbox.py b/Lib/test/test_mailbox.py
index 0991f74f84..aeabdbb2b5 100644
--- a/Lib/test/test_mailbox.py
+++ b/Lib/test/test_mailbox.py
@@ -7,17 +7,12 @@ import email
 import email.message
 import re
 import io
-import shutil
 import tempfile
 from test import support
 import unittest
 import textwrap
 import mailbox
 import glob
-try:
-    import fcntl
-except ImportError:
-    pass
 
 
 class TestBase:
@@ -2273,12 +2268,18 @@ Gregory K. Johnson
 """)
 
 
+class MiscTestCase(unittest.TestCase):
+    def test__all__(self):
+        blacklist = {"linesep", "fcntl"}
+        support.check__all__(self, mailbox, blacklist=blacklist)
+
+
 def test_main():
     tests = (TestMailboxSuperclass, TestMaildir, TestMbox, TestMMDF, TestMH,
              TestBabyl, TestMessage, TestMaildirMessage, TestMboxMessage,
              TestMHMessage, TestBabylMessage, TestMMDFMessage,
              TestMessageConversion, TestProxyFile, TestPartialFile,
-             MaildirTestCase, TestFakeMailBox)
+             MaildirTestCase, TestFakeMailBox, MiscTestCase)
     support.run_unittest(*tests)
     support.reap_children()
 
diff --git a/Lib/test/test_mailcap.py b/Lib/test/test_mailcap.py
index 22b2fcc4a7..623fadb8ed 100644
--- a/Lib/test/test_mailcap.py
+++ b/Lib/test/test_mailcap.py
@@ -1,6 +1,5 @@
 import mailcap
 import os
-import shutil
 import test.support
 import unittest
 
diff --git a/Lib/test/test_marshal.py b/Lib/test/test_marshal.py
index c7def9a599..b378ffea00 100644
--- a/Lib/test/test_marshal.py
+++ b/Lib/test/test_marshal.py
@@ -135,6 +135,13 @@ class ContainerTestCase(unittest.TestCase, HelperMixin):
         for constructor in (set, frozenset):
             self.helper(constructor(self.d.keys()))
 
+    @support.cpython_only
+    def test_empty_frozenset_singleton(self):
+        # marshal.loads() must reuse the empty frozenset singleton
+        obj = frozenset()
+        obj2 = marshal.loads(marshal.dumps(obj))
+        self.assertIs(obj2, obj)
+
 
 class BufferTestCase(unittest.TestCase, HelperMixin):
 
diff --git a/Lib/test/test_math.py b/Lib/test/test_math.py
index 6c7b99d2d2..d0bc79065f 100644
--- a/Lib/test/test_math.py
+++ b/Lib/test/test_math.py
@@ -6,7 +6,6 @@ from test import support
 import unittest
 import math
 import os
-import platform
 import sys
 import struct
 import sysconfig
diff --git a/Lib/test/test_metaclass.py b/Lib/test/test_metaclass.py
index e6fe20a107..be683dd1a1 100644
--- a/Lib/test/test_metaclass.py
+++ b/Lib/test/test_metaclass.py
@@ -78,7 +78,7 @@ Also pass another keyword.
     >>> class C(object, metaclass=M, other="haha"):
     ...     pass
     ...
-    Prepare called: ('C', (<class 'object'>,)) {'other': 'haha'}
+    Prepare called: ('C', (<class 'object' ...>,)) {'other': 'haha'}
     New called: {'other': 'haha'}
     >>> C.__class__ is M
     True
@@ -104,7 +104,7 @@ Use various combinations of explicit keywords and **kwds.
     >>> kwds = {'metaclass': M, 'other': 'haha'}
     >>> class C(*bases, **kwds): pass
     ...
-    Prepare called: ('C', (<class 'object'>,)) {'other': 'haha'}
+    Prepare called: ('C', (<class 'object' ...>,)) {'other': 'haha'}
     New called: {'other': 'haha'}
     >>> C.__class__ is M
     True
@@ -114,7 +114,7 @@ Use various combinations of explicit keywords and **kwds.
     >>> kwds = {'other': 'haha'}
     >>> class C(B, metaclass=M, *bases, **kwds): pass
     ...
-    Prepare called: ('C', (<class 'test.test_metaclass.B'>, <class 'object'>)) {'other': 'haha'}
+    Prepare called: ('C', (<class 'test.test_metaclass.B' ...>, <class 'object' ...>)) {'other': 'haha'}
     New called: {'other': 'haha'}
     >>> C.__class__ is M
     True
@@ -259,7 +259,8 @@ else:
 def test_main(verbose=False):
     from test import support
     from test import test_metaclass
-    support.run_doctest(test_metaclass, verbose)
+    import doctest
+    support.run_doctest(test_metaclass, verbose, optionflags=doctest.ELLIPSIS)
 
 if __name__ == "__main__":
     test_main(verbose=True)
diff --git a/Lib/test/test_mimetypes.py b/Lib/test/test_mimetypes.py
index 68565930a4..4e2c9089b5 100644
--- a/Lib/test/test_mimetypes.py
+++ b/Lib/test/test_mimetypes.py
@@ -101,5 +101,11 @@ class Win32MimeTypesTestCase(unittest.TestCase):
         eq(self.db.guess_type("image.jpg"), ("image/jpeg", None))
         eq(self.db.guess_type("image.png"), ("image/png", None))
 
+
+class MiscTestCase(unittest.TestCase):
+    def test__all__(self):
+        support.check__all__(self, mimetypes)
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_mmap.py b/Lib/test/test_mmap.py
index b365d84865..bbb4070148 100644
--- a/Lib/test/test_mmap.py
+++ b/Lib/test/test_mmap.py
@@ -713,6 +713,14 @@ class MmapTests(unittest.TestCase):
         gc_collect()
         self.assertIs(wr(), None)
 
+    def test_write_returning_the_number_of_bytes_written(self):
+        mm = mmap.mmap(-1, 16)
+        self.assertEqual(mm.write(b""), 0)
+        self.assertEqual(mm.write(b"x"), 1)
+        self.assertEqual(mm.write(b"yz"), 2)
+        self.assertEqual(mm.write(b"python"), 6)
+
+
 class LargeMmapTests(unittest.TestCase):
 
     def setUp(self):
diff --git a/Lib/test/test_msilib.py b/Lib/test/test_msilib.py
index 8ef334fdb3..f656f7234e 100644
--- a/Lib/test/test_msilib.py
+++ b/Lib/test/test_msilib.py
@@ -1,6 +1,5 @@
 """ Test suite for the code in msilib """
 import unittest
-import os
 from test.support import import_module
 msilib = import_module('msilib')
 
diff --git a/Lib/test/test_multibytecodec.py b/Lib/test/test_multibytecodec.py
index 8d7a213c16..01a1cd3c69 100644
--- a/Lib/test/test_multibytecodec.py
+++ b/Lib/test/test_multibytecodec.py
@@ -5,7 +5,7 @@
 
 from test import support
 from test.support import TESTFN
-import unittest, io, codecs, sys, os
+import unittest, io, codecs, sys
 import _multibytecodec
 
 ALL_CJKENCODINGS = [
diff --git a/Lib/test/test_multiprocessing_main_handling.py b/Lib/test/test_multiprocessing_main_handling.py
index 52273ea22d..2e15cd8a6b 100644
--- a/Lib/test/test_multiprocessing_main_handling.py
+++ b/Lib/test/test_multiprocessing_main_handling.py
@@ -6,7 +6,6 @@ support.import_module('_multiprocessing')
 
 import importlib
 import importlib.machinery
-import zipimport
 import unittest
 import sys
 import os
@@ -15,7 +14,7 @@ import py_compile
 
 from test.support.script_helper import (
     make_pkg, make_script, make_zip_pkg, make_zip_script,
-    assert_python_ok, assert_python_failure, spawn_python, kill_python)
+    assert_python_ok)
 
 # Look up which start methods are available to test
 import multiprocessing
diff --git a/Lib/test/test_nis.py b/Lib/test/test_nis.py
index 387a4e7856..21074c6810 100644
--- a/Lib/test/test_nis.py
+++ b/Lib/test/test_nis.py
@@ -1,6 +1,5 @@
 from test import support
 import unittest
-import sys
 
 # Skip test if nis module does not exist.
 nis = support.import_module('nis')
diff --git a/Lib/test/test_normalization.py b/Lib/test/test_normalization.py
index 30fa612645..5b590e1af3 100644
--- a/Lib/test/test_normalization.py
+++ b/Lib/test/test_normalization.py
@@ -3,7 +3,6 @@ import unittest
 
 from http.client import HTTPException
 import sys
-import os
 from unicodedata import normalize, unidata_version
 
 TESTDATAFILE = "NormalizationTest.txt"
diff --git a/Lib/test/test_operator.py b/Lib/test/test_operator.py
index b5ba97625f..6254091e78 100644
--- a/Lib/test/test_operator.py
+++ b/Lib/test/test_operator.py
@@ -120,63 +120,63 @@ class OperatorTestCase:
         operator = self.module
         self.assertRaises(TypeError, operator.add)
         self.assertRaises(TypeError, operator.add, None, None)
-        self.assertTrue(operator.add(3, 4) == 7)
+        self.assertEqual(operator.add(3, 4), 7)
 
     def test_bitwise_and(self):
         operator = self.module
         self.assertRaises(TypeError, operator.and_)
         self.assertRaises(TypeError, operator.and_, None, None)
-        self.assertTrue(operator.and_(0xf, 0xa) == 0xa)
+        self.assertEqual(operator.and_(0xf, 0xa), 0xa)
 
     def test_concat(self):
         operator = self.module
         self.assertRaises(TypeError, operator.concat)
         self.assertRaises(TypeError, operator.concat, None, None)
-        self.assertTrue(operator.concat('py', 'thon') == 'python')
-        self.assertTrue(operator.concat([1, 2], [3, 4]) == [1, 2, 3, 4])
-        self.assertTrue(operator.concat(Seq1([5, 6]), Seq1([7])) == [5, 6, 7])
-        self.assertTrue(operator.concat(Seq2([5, 6]), Seq2([7])) == [5, 6, 7])
+        self.assertEqual(operator.concat('py', 'thon'), 'python')
+        self.assertEqual(operator.concat([1, 2], [3, 4]), [1, 2, 3, 4])
+        self.assertEqual(operator.concat(Seq1([5, 6]), Seq1([7])), [5, 6, 7])
+        self.assertEqual(operator.concat(Seq2([5, 6]), Seq2([7])), [5, 6, 7])
         self.assertRaises(TypeError, operator.concat, 13, 29)
 
     def test_countOf(self):
         operator = self.module
         self.assertRaises(TypeError, operator.countOf)
         self.assertRaises(TypeError, operator.countOf, None, None)
-        self.assertTrue(operator.countOf([1, 2, 1, 3, 1, 4], 3) == 1)
-        self.assertTrue(operator.countOf([1, 2, 1, 3, 1, 4], 5) == 0)
+        self.assertEqual(operator.countOf([1, 2, 1, 3, 1, 4], 3), 1)
+        self.assertEqual(operator.countOf([1, 2, 1, 3, 1, 4], 5), 0)
 
     def test_delitem(self):
         operator = self.module
         a = [4, 3, 2, 1]
         self.assertRaises(TypeError, operator.delitem, a)
         self.assertRaises(TypeError, operator.delitem, a, None)
-        self.assertTrue(operator.delitem(a, 1) is None)
-        self.assertTrue(a == [4, 2, 1])
+        self.assertIsNone(operator.delitem(a, 1))
+        self.assertEqual(a, [4, 2, 1])
 
     def test_floordiv(self):
         operator = self.module
         self.assertRaises(TypeError, operator.floordiv, 5)
         self.assertRaises(TypeError, operator.floordiv, None, None)
-        self.assertTrue(operator.floordiv(5, 2) == 2)
+        self.assertEqual(operator.floordiv(5, 2), 2)
 
     def test_truediv(self):
         operator = self.module
         self.assertRaises(TypeError, operator.truediv, 5)
         self.assertRaises(TypeError, operator.truediv, None, None)
-        self.assertTrue(operator.truediv(5, 2) == 2.5)
+        self.assertEqual(operator.truediv(5, 2), 2.5)
 
     def test_getitem(self):
         operator = self.module
         a = range(10)
         self.assertRaises(TypeError, operator.getitem)
         self.assertRaises(TypeError, operator.getitem, a, None)
-        self.assertTrue(operator.getitem(a, 2) == 2)
+        self.assertEqual(operator.getitem(a, 2), 2)
 
     def test_indexOf(self):
         operator = self.module
         self.assertRaises(TypeError, operator.indexOf)
         self.assertRaises(TypeError, operator.indexOf, None, None)
-        self.assertTrue(operator.indexOf([4, 3, 2, 1], 3) == 1)
+        self.assertEqual(operator.indexOf([4, 3, 2, 1], 3), 1)
         self.assertRaises(ValueError, operator.indexOf, [4, 3, 2, 1], 0)
 
     def test_invert(self):
@@ -189,21 +189,21 @@ class OperatorTestCase:
         operator = self.module
         self.assertRaises(TypeError, operator.lshift)
         self.assertRaises(TypeError, operator.lshift, None, 42)
-        self.assertTrue(operator.lshift(5, 1) == 10)
-        self.assertTrue(operator.lshift(5, 0) == 5)
+        self.assertEqual(operator.lshift(5, 1), 10)
+        self.assertEqual(operator.lshift(5, 0), 5)
         self.assertRaises(ValueError, operator.lshift, 2, -1)
 
     def test_mod(self):
         operator = self.module
         self.assertRaises(TypeError, operator.mod)
         self.assertRaises(TypeError, operator.mod, None, 42)
-        self.assertTrue(operator.mod(5, 2) == 1)
+        self.assertEqual(operator.mod(5, 2), 1)
 
     def test_mul(self):
         operator = self.module
         self.assertRaises(TypeError, operator.mul)
         self.assertRaises(TypeError, operator.mul, None, None)
-        self.assertTrue(operator.mul(5, 2) == 10)
+        self.assertEqual(operator.mul(5, 2), 10)
 
     def test_matmul(self):
         operator = self.module
@@ -227,7 +227,7 @@ class OperatorTestCase:
         operator = self.module
         self.assertRaises(TypeError, operator.or_)
         self.assertRaises(TypeError, operator.or_, None, None)
-        self.assertTrue(operator.or_(0xa, 0x5) == 0xf)
+        self.assertEqual(operator.or_(0xa, 0x5), 0xf)
 
     def test_pos(self):
         operator = self.module
@@ -250,8 +250,8 @@ class OperatorTestCase:
         operator = self.module
         self.assertRaises(TypeError, operator.rshift)
         self.assertRaises(TypeError, operator.rshift, None, 42)
-        self.assertTrue(operator.rshift(5, 1) == 2)
-        self.assertTrue(operator.rshift(5, 0) == 5)
+        self.assertEqual(operator.rshift(5, 1), 2)
+        self.assertEqual(operator.rshift(5, 0), 5)
         self.assertRaises(ValueError, operator.rshift, 2, -1)
 
     def test_contains(self):
@@ -266,15 +266,15 @@ class OperatorTestCase:
         a = list(range(3))
         self.assertRaises(TypeError, operator.setitem, a)
         self.assertRaises(TypeError, operator.setitem, a, None, None)
-        self.assertTrue(operator.setitem(a, 0, 2) is None)
-        self.assertTrue(a == [2, 1, 2])
+        self.assertIsNone(operator.setitem(a, 0, 2))
+        self.assertEqual(a, [2, 1, 2])
         self.assertRaises(IndexError, operator.setitem, a, 4, 2)
 
     def test_sub(self):
         operator = self.module
         self.assertRaises(TypeError, operator.sub)
         self.assertRaises(TypeError, operator.sub, None, None)
-        self.assertTrue(operator.sub(5, 2) == 3)
+        self.assertEqual(operator.sub(5, 2), 3)
 
     def test_truth(self):
         operator = self.module
@@ -292,7 +292,7 @@ class OperatorTestCase:
         operator = self.module
         self.assertRaises(TypeError, operator.xor)
         self.assertRaises(TypeError, operator.xor, None, None)
-        self.assertTrue(operator.xor(0xb, 0xc) == 0x7)
+        self.assertEqual(operator.xor(0xb, 0xc), 0x7)
 
     def test_is(self):
         operator = self.module
diff --git a/Lib/test/test_optparse.py b/Lib/test/test_optparse.py
index 7621c24305..91a0319a73 100644
--- a/Lib/test/test_optparse.py
+++ b/Lib/test/test_optparse.py
@@ -16,6 +16,7 @@ from io import StringIO
 from test import support
 
 
+import optparse
 from optparse import make_option, Option, \
      TitledHelpFormatter, OptionParser, OptionGroup, \
      SUPPRESS_USAGE, OptionError, OptionConflictError, \
@@ -1650,6 +1651,12 @@ class TestParseNumber(BaseTest):
                              "option -l: invalid integer value: '0x12x'")
 
 
+class MiscTestCase(unittest.TestCase):
+    def test__all__(self):
+        blacklist = {'check_builtin', 'AmbiguousOptionError', 'NO_DEFAULT'}
+        support.check__all__(self, optparse, blacklist=blacklist)
+
+
 def test_main():
     support.run_unittest(__name__)
 
diff --git a/Lib/test/test_ordered_dict.py b/Lib/test/test_ordered_dict.py
index 901d4b2ad2..6fbc1b4132 100644
--- a/Lib/test/test_ordered_dict.py
+++ b/Lib/test/test_ordered_dict.py
@@ -298,9 +298,11 @@ class OrderedDictTests:
         # do not save instance dictionary if not needed
         pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
         od = OrderedDict(pairs)
+        self.assertIsInstance(od.__dict__, dict)
         self.assertIsNone(od.__reduce__()[2])
         od.x = 10
-        self.assertIsNotNone(od.__reduce__()[2])
+        self.assertEqual(od.__dict__['x'], 10)
+        self.assertEqual(od.__reduce__()[2], {'x': 10})
 
     def test_pickle_recursive(self):
         OrderedDict = self.OrderedDict
@@ -403,6 +405,14 @@ class OrderedDictTests:
         od = OrderedDict(**d)
         self.assertGreater(sys.getsizeof(od), sys.getsizeof(d))
 
+    def test_views(self):
+        OrderedDict = self.OrderedDict
+        # See http://bugs.python.org/issue24286
+        s = 'the quick brown fox jumped over a lazy dog yesterday before dawn'.split()
+        od = OrderedDict.fromkeys(s)
+        self.assertEqual(od.keys(), dict(od).keys())
+        self.assertEqual(od.items(), dict(od).items())
+
     def test_override_update(self):
         OrderedDict = self.OrderedDict
         # Verify that subclasses can override update() without breaking __init__()
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index 874f9e4c90..6853ebbd7f 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -15,7 +15,6 @@ import locale
 import mmap
 import os
 import pickle
-import platform
 import re
 import shutil
 import signal
@@ -66,6 +65,7 @@ except ImportError:
 
 from test.support.script_helper import assert_python_ok
 
+
 root_in_posix = False
 if hasattr(os, 'geteuid'):
     root_in_posix = (os.geteuid() == 0)
@@ -82,6 +82,28 @@ else:
 # Issue #14110: Some tests fail on FreeBSD if the user is in the wheel group.
 HAVE_WHEEL_GROUP = sys.platform.startswith('freebsd') and os.getgid() == 0
 
+
+@contextlib.contextmanager
+def ignore_deprecation_warnings(msg_regex, quiet=False):
+    with support.check_warnings((msg_regex, DeprecationWarning), quiet=quiet):
+        yield
+
+
+@contextlib.contextmanager
+def bytes_filename_warn(expected):
+    msg = 'The Windows bytes API has been deprecated'
+    if os.name == 'nt':
+        with ignore_deprecation_warnings(msg, quiet=not expected):
+            yield
+    else:
+        yield
+
+
+def create_file(filename, content=b'content'):
+    with open(filename, "xb", 0) as fp:
+        fp.write(content)
+
+
 # Tests creating TESTFN
 class FileTests(unittest.TestCase):
     def setUp(self):
@@ -140,9 +162,8 @@ class FileTests(unittest.TestCase):
                          "needs INT_MAX < PY_SSIZE_T_MAX")
     @support.bigmemtest(size=INT_MAX + 10, memuse=1, dry_run=False)
     def test_large_read(self, size):
-        with open(support.TESTFN, "wb") as fp:
-            fp.write(b'test')
         self.addCleanup(support.unlink, support.TESTFN)
+        create_file(support.TESTFN, b'test')
 
         # Issue #21932: Make sure that os.read() does not raise an
         # OverflowError for size larger than INT_MAX
@@ -199,11 +220,12 @@ class FileTests(unittest.TestCase):
 
     def test_replace(self):
         TESTFN2 = support.TESTFN + ".2"
-        with open(support.TESTFN, 'w') as f:
-            f.write("1")
-        with open(TESTFN2, 'w') as f:
-            f.write("2")
-        self.addCleanup(os.unlink, TESTFN2)
+        self.addCleanup(support.unlink, support.TESTFN)
+        self.addCleanup(support.unlink, TESTFN2)
+
+        create_file(support.TESTFN, b"1")
+        create_file(TESTFN2, b"2")
+
         os.replace(support.TESTFN, TESTFN2)
         self.assertRaises(FileNotFoundError, os.stat, support.TESTFN)
         with open(TESTFN2, 'r') as f:
@@ -226,15 +248,9 @@ class FileTests(unittest.TestCase):
 # Test attributes on return values from os.*stat* family.
 class StatAttributeTests(unittest.TestCase):
     def setUp(self):
-        os.mkdir(support.TESTFN)
-        self.fname = os.path.join(support.TESTFN, "f1")
-        f = open(self.fname, 'wb')
-        f.write(b"ABC")
-        f.close()
-
-    def tearDown(self):
-        os.unlink(self.fname)
-        os.rmdir(support.TESTFN)
+        self.fname = support.TESTFN
+        self.addCleanup(support.unlink, self.fname)
+        create_file(self.fname, b"ABC")
 
     @unittest.skipUnless(hasattr(os, 'stat'), 'test needs os.stat()')
     def check_stat_attributes(self, fname):
@@ -310,8 +326,7 @@ class StatAttributeTests(unittest.TestCase):
             fname = self.fname.encode(sys.getfilesystemencoding())
         except UnicodeEncodeError:
             self.skipTest("cannot encode %a for the filesystem" % self.fname)
-        with warnings.catch_warnings():
-            warnings.simplefilter("ignore", DeprecationWarning)
+        with bytes_filename_warn(True):
             self.check_stat_attributes(fname)
 
     def test_stat_result_pickle(self):
@@ -426,7 +441,11 @@ class StatAttributeTests(unittest.TestCase):
             0)
 
         # test directory st_file_attributes (FILE_ATTRIBUTE_DIRECTORY set)
-        result = os.stat(support.TESTFN)
+        dirname = support.TESTFN + "dir"
+        os.mkdir(dirname)
+        self.addCleanup(os.rmdir, dirname)
+
+        result = os.stat(dirname)
         self.check_file_attributes(result)
         self.assertEqual(
             result.st_file_attributes & stat.FILE_ATTRIBUTE_DIRECTORY,
@@ -440,19 +459,14 @@ class UtimeTests(unittest.TestCase):
 
         self.addCleanup(support.rmtree, self.dirname)
         os.mkdir(self.dirname)
-        with open(self.fname, 'wb') as fp:
-            fp.write(b"ABC")
+        create_file(self.fname)
 
         def restore_float_times(state):
-            with warnings.catch_warnings():
-                warnings.simplefilter("ignore", DeprecationWarning)
-
+            with ignore_deprecation_warnings('stat_float_times'):
                 os.stat_float_times(state)
 
         # ensure that st_atime and st_mtime are float
-        with warnings.catch_warnings():
-            warnings.simplefilter("ignore", DeprecationWarning)
-
+        with ignore_deprecation_warnings('stat_float_times'):
             old_float_times = os.stat_float_times(-1)
             self.addCleanup(restore_float_times, old_float_times)
 
@@ -544,7 +558,7 @@ class UtimeTests(unittest.TestCase):
                          "fd support for utime required for this test.")
     def test_utime_fd(self):
         def set_time(filename, ns):
-            with open(filename, 'wb') as fp:
+            with open(filename, 'wb', 0) as fp:
                 # use a file descriptor to test futimens(timespec)
                 # or futimes(timeval)
                 os.utime(fp.fileno(), ns=ns)
@@ -798,6 +812,7 @@ class WalkTests(unittest.TestCase):
 
     def setUp(self):
         join = os.path.join
+        self.addCleanup(support.rmtree, support.TESTFN)
 
         # Build:
         #     TESTFN/
@@ -830,9 +845,8 @@ class WalkTests(unittest.TestCase):
         os.makedirs(t2_path)
 
         for path in tmp1_path, tmp2_path, tmp3_path, tmp4_path:
-            f = open(path, "w")
-            f.write("I'm " + path + " and proud of it.  Blame test_os.\n")
-            f.close()
+            with open(path, "x") as f:
+                f.write("I'm " + path + " and proud of it.  Blame test_os.\n")
 
         if support.can_symlink():
             os.symlink(os.path.abspath(t2_path), self.link_path)
@@ -878,7 +892,7 @@ class WalkTests(unittest.TestCase):
         # Walk bottom-up.
         all = list(self.walk(self.walk_path, topdown=False))
 
-        self.assertEqual(len(all), 4)
+        self.assertEqual(len(all), 4, all)
         # We can't know which order SUB1 and SUB2 will appear in.
         # Not flipped:  SUB11, SUB1, SUB2, TESTFN
         #     flipped:  SUB2, SUB11, SUB1, TESTFN
@@ -908,22 +922,6 @@ class WalkTests(unittest.TestCase):
         else:
             self.fail("Didn't follow symlink with followlinks=True")
 
-    def tearDown(self):
-        # Tear everything down.  This is a decent use for bottom-up on
-        # Windows, which doesn't have a recursive delete command.  The
-        # (not so) subtlety is that rmdir will fail unless the dir's
-        # kids are removed first, so bottom up is essential.
-        for root, dirs, files in os.walk(support.TESTFN, topdown=False):
-            for name in files:
-                os.remove(os.path.join(root, name))
-            for name in dirs:
-                dirname = os.path.join(root, name)
-                if not os.path.islink(dirname):
-                    os.rmdir(dirname)
-                else:
-                    os.remove(dirname)
-        os.rmdir(support.TESTFN)
-
     def test_walk_bad_dir(self):
         # Walk top-down.
         errors = []
@@ -1006,27 +1004,13 @@ class FwalkTests(WalkTests):
         self.addCleanup(os.close, newfd)
         self.assertEqual(newfd, minfd)
 
-    def tearDown(self):
-        # cleanup
-        for root, dirs, files, rootfd in os.fwalk(support.TESTFN, topdown=False):
-            for name in files:
-                os.unlink(name, dir_fd=rootfd)
-            for name in dirs:
-                st = os.stat(name, dir_fd=rootfd, follow_symlinks=False)
-                if stat.S_ISDIR(st.st_mode):
-                    os.rmdir(name, dir_fd=rootfd)
-                else:
-                    os.unlink(name, dir_fd=rootfd)
-        os.rmdir(support.TESTFN)
-
 class BytesWalkTests(WalkTests):
     """Tests for os.walk() with bytes."""
     def setUp(self):
         super().setUp()
         self.stack = contextlib.ExitStack()
         if os.name == 'nt':
-            self.stack.enter_context(warnings.catch_warnings())
-            warnings.simplefilter("ignore", DeprecationWarning)
+            self.stack.enter_context(bytes_filename_warn(False))
 
     def tearDown(self):
         self.stack.close()
@@ -1203,8 +1187,7 @@ class RemoveDirsTests(unittest.TestCase):
         os.mkdir(dira)
         dirb = os.path.join(dira, 'dirb')
         os.mkdir(dirb)
-        with open(os.path.join(dira, 'file.txt'), 'w') as f:
-            f.write('text')
+        create_file(os.path.join(dira, 'file.txt'))
         os.removedirs(dirb)
         self.assertFalse(os.path.exists(dirb))
         self.assertTrue(os.path.exists(dira))
@@ -1215,8 +1198,7 @@ class RemoveDirsTests(unittest.TestCase):
         os.mkdir(dira)
         dirb = os.path.join(dira, 'dirb')
         os.mkdir(dirb)
-        with open(os.path.join(dirb, 'file.txt'), 'w') as f:
-            f.write('text')
+        create_file(os.path.join(dirb, 'file.txt'))
         with self.assertRaises(OSError):
             os.removedirs(dirb)
         self.assertTrue(os.path.exists(dirb))
@@ -1226,7 +1208,7 @@ class RemoveDirsTests(unittest.TestCase):
 
 class DevNullTests(unittest.TestCase):
     def test_devnull(self):
-        with open(os.devnull, 'wb') as f:
+        with open(os.devnull, 'wb', 0) as f:
             f.write(b'hello')
             f.close()
         with open(os.devnull, 'rb') as f:
@@ -1313,9 +1295,9 @@ class URandomFDTests(unittest.TestCase):
     def test_urandom_fd_reopened(self):
         # Issue #21207: urandom() should detect its fd to /dev/urandom
         # changed to something else, and reopen it.
-        with open(support.TESTFN, 'wb') as f:
-            f.write(b"x" * 256)
-        self.addCleanup(os.unlink, support.TESTFN)
+        self.addCleanup(support.unlink, support.TESTFN)
+        create_file(support.TESTFN, b"x" * 256)
+
         code = """if 1:
             import os
             import sys
@@ -1444,6 +1426,18 @@ class ExecTests(unittest.TestCase):
 
 @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
 class Win32ErrorTests(unittest.TestCase):
+    def setUp(self):
+        try:
+            os.stat(support.TESTFN)
+        except FileNotFoundError:
+            exists = False
+        except OSError as exc:
+            exists = True
+            self.fail("file %s must not exist; os.stat failed with %s"
+                      % (support.TESTFN, exc))
+        else:
+            self.fail("file %s must not exist" % support.TESTFN)
+
     def test_rename(self):
         self.assertRaises(OSError, os.rename, support.TESTFN, support.TESTFN+".bak")
 
@@ -1454,12 +1448,10 @@ class Win32ErrorTests(unittest.TestCase):
         self.assertRaises(OSError, os.chdir, support.TESTFN)
 
     def test_mkdir(self):
-        f = open(support.TESTFN, "w")
-        try:
+        self.addCleanup(support.unlink, support.TESTFN)
+
+        with open(support.TESTFN, "x") as f:
             self.assertRaises(OSError, os.mkdir, support.TESTFN)
-        finally:
-            f.close()
-            os.unlink(support.TESTFN)
 
     def test_utime(self):
         self.assertRaises(OSError, os.utime, support.TESTFN, None)
@@ -1467,6 +1459,7 @@ class Win32ErrorTests(unittest.TestCase):
     def test_chmod(self):
         self.assertRaises(OSError, os.chmod, support.TESTFN, 0)
 
+
 class TestInvalidFD(unittest.TestCase):
     singles = ["fchdir", "dup", "fdopen", "fdatasync", "fstat",
                "fstatvfs", "fsync", "tcgetpgrp", "ttyname"]
@@ -1578,11 +1571,9 @@ class LinkTests(unittest.TestCase):
                 os.unlink(file)
 
     def _test_link(self, file1, file2):
-        with open(file1, "w") as f1:
-            f1.write("test")
+        create_file(file1)
 
-        with warnings.catch_warnings():
-            warnings.simplefilter("ignore", DeprecationWarning)
+        with bytes_filename_warn(False):
             os.link(file1, file2)
         with open(file1, "r") as f1, open(file2, "r") as f2:
             self.assertTrue(os.path.sameopenfile(f1.fileno(), f2.fileno()))
@@ -1874,10 +1865,12 @@ class Win32ListdirTests(unittest.TestCase):
         self.assertEqual(
                 sorted(os.listdir(support.TESTFN)),
                 self.created_paths)
+
         # bytes
-        self.assertEqual(
-                sorted(os.listdir(os.fsencode(support.TESTFN))),
-                [os.fsencode(path) for path in self.created_paths])
+        with bytes_filename_warn(False):
+            self.assertEqual(
+                    sorted(os.listdir(os.fsencode(support.TESTFN))),
+                    [os.fsencode(path) for path in self.created_paths])
 
     def test_listdir_extended_path(self):
         """Test when the path starts with '\\\\?\\'."""
@@ -1887,11 +1880,13 @@ class Win32ListdirTests(unittest.TestCase):
         self.assertEqual(
                 sorted(os.listdir(path)),
                 self.created_paths)
+
         # bytes
-        path = b'\\\\?\\' + os.fsencode(os.path.abspath(support.TESTFN))
-        self.assertEqual(
-                sorted(os.listdir(path)),
-                [os.fsencode(path) for path in self.created_paths])
+        with bytes_filename_warn(False):
+            path = b'\\\\?\\' + os.fsencode(os.path.abspath(support.TESTFN))
+            self.assertEqual(
+                    sorted(os.listdir(path)),
+                    [os.fsencode(path) for path in self.created_paths])
 
 
 @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
@@ -1966,51 +1961,45 @@ class Win32SymlinkTests(unittest.TestCase):
         self.assertNotEqual(os.lstat(link), os.stat(link))
 
         bytes_link = os.fsencode(link)
-        with warnings.catch_warnings():
-            warnings.simplefilter("ignore", DeprecationWarning)
+        with bytes_filename_warn(True):
             self.assertEqual(os.stat(bytes_link), os.stat(target))
+        with bytes_filename_warn(True):
             self.assertNotEqual(os.lstat(bytes_link), os.stat(bytes_link))
 
     def test_12084(self):
         level1 = os.path.abspath(support.TESTFN)
         level2 = os.path.join(level1, "level2")
         level3 = os.path.join(level2, "level3")
-        try:
-            os.mkdir(level1)
-            os.mkdir(level2)
-            os.mkdir(level3)
+        self.addCleanup(support.rmtree, level1)
 
-            file1 = os.path.abspath(os.path.join(level1, "file1"))
+        os.mkdir(level1)
+        os.mkdir(level2)
+        os.mkdir(level3)
 
-            with open(file1, "w") as f:
-                f.write("file1")
+        file1 = os.path.abspath(os.path.join(level1, "file1"))
+        create_file(file1)
 
-            orig_dir = os.getcwd()
-            try:
-                os.chdir(level2)
-                link = os.path.join(level2, "link")
-                os.symlink(os.path.relpath(file1), "link")
-                self.assertIn("link", os.listdir(os.getcwd()))
-
-                # Check os.stat calls from the same dir as the link
-                self.assertEqual(os.stat(file1), os.stat("link"))
-
-                # Check os.stat calls from a dir below the link
-                os.chdir(level1)
-                self.assertEqual(os.stat(file1),
-                                 os.stat(os.path.relpath(link)))
-
-                # Check os.stat calls from a dir above the link
-                os.chdir(level3)
-                self.assertEqual(os.stat(file1),
-                                 os.stat(os.path.relpath(link)))
-            finally:
-                os.chdir(orig_dir)
-        except OSError as err:
-            self.fail(err)
+        orig_dir = os.getcwd()
+        try:
+            os.chdir(level2)
+            link = os.path.join(level2, "link")
+            os.symlink(os.path.relpath(file1), "link")
+            self.assertIn("link", os.listdir(os.getcwd()))
+
+            # Check os.stat calls from the same dir as the link
+            self.assertEqual(os.stat(file1), os.stat("link"))
+
+            # Check os.stat calls from a dir below the link
+            os.chdir(level1)
+            self.assertEqual(os.stat(file1),
+                             os.stat(os.path.relpath(link)))
+
+            # Check os.stat calls from a dir above the link
+            os.chdir(level3)
+            self.assertEqual(os.stat(file1),
+                             os.stat(os.path.relpath(link)))
         finally:
-            os.remove(file1)
-            shutil.rmtree(level1)
+            os.chdir(orig_dir)
 
 
 @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
@@ -2146,8 +2135,8 @@ class ProgramPriorityTests(unittest.TestCase):
         try:
             new_prio = os.getpriority(os.PRIO_PROCESS, os.getpid())
             if base >= 19 and new_prio <= 19:
-                raise unittest.SkipTest(
-      "unable to reliably test setpriority at current nice level of %s" % base)
+                raise unittest.SkipTest("unable to reliably test setpriority "
+                                        "at current nice level of %s" % base)
             else:
                 self.assertEqual(new_prio, base + 1)
         finally:
@@ -2257,8 +2246,7 @@ class TestSendfile(unittest.TestCase):
     @classmethod
     def setUpClass(cls):
         cls.key = support.threading_setup()
-        with open(support.TESTFN, "wb") as f:
-            f.write(cls.DATA)
+        create_file(support.TESTFN, cls.DATA)
 
     @classmethod
     def tearDownClass(cls):
@@ -2408,10 +2396,11 @@ class TestSendfile(unittest.TestCase):
     def test_trailers(self):
         TESTFN2 = support.TESTFN + "2"
         file_data = b"abcdef"
-        with open(TESTFN2, 'wb') as f:
-            f.write(file_data)
-        with open(TESTFN2, 'rb')as f:
-            self.addCleanup(os.remove, TESTFN2)
+
+        self.addCleanup(support.unlink, TESTFN2)
+        create_file(TESTFN2, file_data)
+
+        with open(TESTFN2, 'rb') as f:
             os.sendfile(self.sockno, f.fileno(), 0, len(file_data),
                         trailers=[b"1234"])
             self.client.close()
@@ -2434,35 +2423,37 @@ class TestSendfile(unittest.TestCase):
 def supports_extended_attributes():
     if not hasattr(os, "setxattr"):
         return False
+
     try:
-        with open(support.TESTFN, "wb") as fp:
+        with open(support.TESTFN, "xb", 0) as fp:
             try:
                 os.setxattr(fp.fileno(), b"user.test", b"")
             except OSError:
                 return False
     finally:
         support.unlink(support.TESTFN)
-    # Kernels < 2.6.39 don't respect setxattr flags.
-    kernel_version = platform.release()
-    m = re.match("2.6.(\d{1,2})", kernel_version)
-    return m is None or int(m.group(1)) >= 39
+
+    return True
 
 
 @unittest.skipUnless(supports_extended_attributes(),
                      "no non-broken extended attribute support")
+# Kernels < 2.6.39 don't respect setxattr flags.
+@support.requires_linux_version(2, 6, 39)
 class ExtendedAttributeTests(unittest.TestCase):
 
-    def tearDown(self):
-        support.unlink(support.TESTFN)
-
     def _check_xattrs_str(self, s, getxattr, setxattr, removexattr, listxattr, **kwargs):
         fn = support.TESTFN
-        open(fn, "wb").close()
+        self.addCleanup(support.unlink, fn)
+        create_file(fn)
+
         with self.assertRaises(OSError) as cm:
             getxattr(fn, s("user.test"), **kwargs)
         self.assertEqual(cm.exception.errno, errno.ENODATA)
+
         init_xattr = listxattr(fn)
         self.assertIsInstance(init_xattr, list)
+
         setxattr(fn, s("user.test"), b"", **kwargs)
         xattr = set(init_xattr)
         xattr.add("user.test")
@@ -2470,19 +2461,24 @@ class ExtendedAttributeTests(unittest.TestCase):
         self.assertEqual(getxattr(fn, b"user.test", **kwargs), b"")
         setxattr(fn, s("user.test"), b"hello", os.XATTR_REPLACE, **kwargs)
         self.assertEqual(getxattr(fn, b"user.test", **kwargs), b"hello")
+
         with self.assertRaises(OSError) as cm:
             setxattr(fn, s("user.test"), b"bye", os.XATTR_CREATE, **kwargs)
         self.assertEqual(cm.exception.errno, errno.EEXIST)
+
         with self.assertRaises(OSError) as cm:
             setxattr(fn, s("user.test2"), b"bye", os.XATTR_REPLACE, **kwargs)
         self.assertEqual(cm.exception.errno, errno.ENODATA)
+
         setxattr(fn, s("user.test2"), b"foo", os.XATTR_CREATE, **kwargs)
         xattr.add("user.test2")
         self.assertEqual(set(listxattr(fn)), xattr)
         removexattr(fn, s("user.test"), **kwargs)
+
         with self.assertRaises(OSError) as cm:
             getxattr(fn, s("user.test"), **kwargs)
         self.assertEqual(cm.exception.errno, errno.ENODATA)
+
         xattr.remove("user.test")
         self.assertEqual(set(listxattr(fn)), xattr)
         self.assertEqual(getxattr(fn, s("user.test2"), **kwargs), b"foo")
@@ -2495,11 +2491,11 @@ class ExtendedAttributeTests(unittest.TestCase):
         self.assertEqual(set(listxattr(fn)), set(init_xattr) | set(many))
 
     def _check_xattrs(self, *args, **kwargs):
-        def make_bytes(s):
-            return bytes(s, "ascii")
         self._check_xattrs_str(str, *args, **kwargs)
         support.unlink(support.TESTFN)
-        self._check_xattrs_str(make_bytes, *args, **kwargs)
+
+        self._check_xattrs_str(os.fsencode, *args, **kwargs)
+        support.unlink(support.TESTFN)
 
     def test_simple(self):
         self._check_xattrs(os.getxattr, os.setxattr, os.removexattr,
@@ -2514,10 +2510,10 @@ class ExtendedAttributeTests(unittest.TestCase):
             with open(path, "rb") as fp:
                 return os.getxattr(fp.fileno(), *args)
         def setxattr(path, *args):
-            with open(path, "wb") as fp:
+            with open(path, "wb", 0) as fp:
                 os.setxattr(fp.fileno(), *args)
         def removexattr(path, *args):
-            with open(path, "wb") as fp:
+            with open(path, "wb", 0) as fp:
                 os.removexattr(fp.fileno(), *args)
         def listxattr(path, *args):
             with open(path, "rb") as fp:
@@ -2530,36 +2526,39 @@ class Win32DeprecatedBytesAPI(unittest.TestCase):
     def test_deprecated(self):
         import nt
         filename = os.fsencode(support.TESTFN)
-        with warnings.catch_warnings():
-            warnings.simplefilter("error", DeprecationWarning)
-            for func, *args in (
-                (nt._getfullpathname, filename),
-                (nt._isdir, filename),
-                (os.access, filename, os.R_OK),
-                (os.chdir, filename),
-                (os.chmod, filename, 0o777),
-                (os.getcwdb,),
-                (os.link, filename, filename),
-                (os.listdir, filename),
-                (os.lstat, filename),
-                (os.mkdir, filename),
-                (os.open, filename, os.O_RDONLY),
-                (os.rename, filename, filename),
-                (os.rmdir, filename),
-                (os.startfile, filename),
-                (os.stat, filename),
-                (os.unlink, filename),
-                (os.utime, filename),
-            ):
-                self.assertRaises(DeprecationWarning, func, *args)
+        for func, *args in (
+            (nt._getfullpathname, filename),
+            (nt._isdir, filename),
+            (os.access, filename, os.R_OK),
+            (os.chdir, filename),
+            (os.chmod, filename, 0o777),
+            (os.getcwdb,),
+            (os.link, filename, filename),
+            (os.listdir, filename),
+            (os.lstat, filename),
+            (os.mkdir, filename),
+            (os.open, filename, os.O_RDONLY),
+            (os.rename, filename, filename),
+            (os.rmdir, filename),
+            (os.startfile, filename),
+            (os.stat, filename),
+            (os.unlink, filename),
+            (os.utime, filename),
+        ):
+            with bytes_filename_warn(True):
+                try:
+                    func(*args)
+                except OSError:
+                    # ignore OSError, we only care about DeprecationWarning
+                    pass
 
     @support.skip_unless_symlink
     def test_symlink(self):
+        self.addCleanup(support.unlink, support.TESTFN)
+
         filename = os.fsencode(support.TESTFN)
-        with warnings.catch_warnings():
-            warnings.simplefilter("error", DeprecationWarning)
-            self.assertRaises(DeprecationWarning,
-                              os.symlink, filename, filename)
+        with bytes_filename_warn(True):
+            os.symlink(filename, filename)
 
 
 @unittest.skipUnless(hasattr(os, 'get_terminal_size'), "requires os.get_terminal_size")
@@ -2697,7 +2696,8 @@ class OSErrorTests(unittest.TestCase):
         for filenames, func, *func_args in funcs:
             for name in filenames:
                 try:
-                    func(name, *func_args)
+                    with bytes_filename_warn(False):
+                        func(name, *func_args)
                 except OSError as err:
                     self.assertIs(err.filename, name)
                 else:
@@ -2820,6 +2820,8 @@ class ExportsTests(unittest.TestCase):
 
 
 class TestScandir(unittest.TestCase):
+    check_no_resource_warning = support.check_no_resource_warning
+
     def setUp(self):
         self.path = os.path.realpath(support.TESTFN)
         self.addCleanup(support.rmtree, self.path)
@@ -2827,8 +2829,7 @@ class TestScandir(unittest.TestCase):
 
     def create_file(self, name="file.txt"):
         filename = os.path.join(self.path, name)
-        with open(filename, "wb") as fp:
-            fp.write(b'python')
+        create_file(filename, b'python')
         return filename
 
     def get_entries(self, names):
@@ -3010,7 +3011,8 @@ class TestScandir(unittest.TestCase):
     def test_bytes(self):
         if os.name == "nt":
             # On Windows, os.scandir(bytes) must raise an exception
-            self.assertRaises(TypeError, os.scandir, b'.')
+            with bytes_filename_warn(True):
+                self.assertRaises(TypeError, os.scandir, b'.')
             return
 
         self.create_file("file.txt")
@@ -3042,6 +3044,108 @@ class TestScandir(unittest.TestCase):
         for obj in [1234, 1.234, {}, []]:
             self.assertRaises(TypeError, os.scandir, obj)
 
+    def test_close(self):
+        self.create_file("file.txt")
+        self.create_file("file2.txt")
+        iterator = os.scandir(self.path)
+        next(iterator)
+        iterator.close()
+        # multiple closes
+        iterator.close()
+        with self.check_no_resource_warning():
+            del iterator
+
+    def test_context_manager(self):
+        self.create_file("file.txt")
+        self.create_file("file2.txt")
+        with os.scandir(self.path) as iterator:
+            next(iterator)
+        with self.check_no_resource_warning():
+            del iterator
+
+    def test_context_manager_close(self):
+        self.create_file("file.txt")
+        self.create_file("file2.txt")
+        with os.scandir(self.path) as iterator:
+            next(iterator)
+            iterator.close()
+
+    def test_context_manager_exception(self):
+        self.create_file("file.txt")
+        self.create_file("file2.txt")
+        with self.assertRaises(ZeroDivisionError):
+            with os.scandir(self.path) as iterator:
+                next(iterator)
+                1/0
+        with self.check_no_resource_warning():
+            del iterator
+
+    def test_resource_warning(self):
+        self.create_file("file.txt")
+        self.create_file("file2.txt")
+        iterator = os.scandir(self.path)
+        next(iterator)
+        with self.assertWarns(ResourceWarning):
+            del iterator
+            support.gc_collect()
+        # exhausted iterator
+        iterator = os.scandir(self.path)
+        list(iterator)
+        with self.check_no_resource_warning():
+            del iterator
+
+
+class TestPEP519(unittest.TestCase):
+    "os.fspath()"
+
+    def test_return_bytes(self):
+        for b in b'hello', b'goodbye', b'some/path/and/file':
+            self.assertEqual(b, os.fspath(b))
+
+    def test_return_string(self):
+        for s in 'hello', 'goodbye', 'some/path/and/file':
+            self.assertEqual(s, os.fspath(s))
+
+    def test_fsencode_fsdecode_return_pathlike(self):
+        class PathLike:
+            def __init__(self, path):
+                self.path = path
+            def __fspath__(self):
+                return self.path
+
+        for p in "path/like/object", b"path/like/object":
+            pathlike = PathLike(p)
+
+            self.assertEqual(p, os.fspath(pathlike))
+            self.assertEqual(b"path/like/object", os.fsencode(pathlike))
+            self.assertEqual("path/like/object", os.fsdecode(pathlike))
+
+    def test_fspathlike(self):
+        class PathLike:
+            def __init__(self, path=''):
+                self.path = path
+            def __fspath__(self):
+                return self.path
+
+        self.assertEqual('#feelthegil', os.fspath(PathLike('#feelthegil')))
+        self.assertTrue(issubclass(PathLike, os.PathLike))
+        self.assertTrue(isinstance(PathLike(), os.PathLike))
+
+        message = 'expected str, bytes or os.PathLike object, not'
+        for fn in (os.fsencode, os.fsdecode):
+            for obj in PathLike(None), None:
+                with self.assertRaisesRegex(TypeError, message):
+                    fn(obj)
+
+    def test_garbage_in_exception_out(self):
+        vapor = type('blah', (), {})
+        for o in int, type, os, vapor():
+            self.assertRaises(TypeError, os.fspath, o)
+
+    def test_argument_required(self):
+        with self.assertRaises(TypeError):
+            os.fspath()
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_parser.py b/Lib/test/test_parser.py
index 3d301b4924..72692067fe 100644
--- a/Lib/test/test_parser.py
+++ b/Lib/test/test_parser.py
@@ -1,6 +1,5 @@
 import parser
 import unittest
-import sys
 import operator
 import struct
 from test import support
diff --git a/Lib/test/test_pathlib.py b/Lib/test/test_pathlib.py
index fa96d9f882..fbbd448f65 100644
--- a/Lib/test/test_pathlib.py
+++ b/Lib/test/test_pathlib.py
@@ -1474,14 +1474,14 @@ class _BasePathTest(object):
         self.assertEqual(set(p.glob("dirA/../file*")), { P(BASE, "dirA/../fileA") })
         self.assertEqual(set(p.glob("../xyzzy")), set())
 
-    def _check_resolve_relative(self, p, expected):
-        q = p.resolve()
-        self.assertEqual(q, expected)
 
-    def _check_resolve_absolute(self, p, expected):
+    def _check_resolve(self, p, expected):
         q = p.resolve()
         self.assertEqual(q, expected)
 
+    # this can be used to check both relative and absolute resolutions
+    _check_resolve_relative = _check_resolve_absolute = _check_resolve
+
     @with_symlinks
     def test_resolve_common(self):
         P = self.cls
diff --git a/Lib/test/test_pdb.py b/Lib/test/test_pdb.py
index 45ba5a9685..a63ccd83ca 100644
--- a/Lib/test/test_pdb.py
+++ b/Lib/test/test_pdb.py
@@ -558,7 +558,6 @@ def test_pdb_continue_in_bottomframe():
 
 def pdb_invoke(method, arg):
     """Run pdb.method(arg)."""
-    import pdb
     getattr(pdb.Pdb(nosigint=True), method)(arg)
 
 
diff --git a/Lib/test/test_peepholer.py b/Lib/test/test_peepholer.py
index 41e5091fab..b0336407c3 100644
--- a/Lib/test/test_peepholer.py
+++ b/Lib/test/test_peepholer.py
@@ -1,9 +1,8 @@
 import dis
 import re
 import sys
-from io import StringIO
+import textwrap
 import unittest
-from math import copysign
 
 from test.bytecode_helper import BytecodeTestCase
 
@@ -30,22 +29,25 @@ class TestTranforms(BytecodeTestCase):
 
     def test_global_as_constant(self):
         # LOAD_GLOBAL None/True/False  -->  LOAD_CONST None/True/False
-        def f(x):
-            None
-            None
+        def f():
+            x = None
+            x = None
             return x
-        def g(x):
-            True
+        def g():
+            x = True
             return x
-        def h(x):
-            False
+        def h():
+            x = False
             return x
+
         for func, elem in ((f, None), (g, True), (h, False)):
             self.assertNotInBytecode(func, 'LOAD_GLOBAL')
             self.assertInBytecode(func, 'LOAD_CONST', elem)
+
         def f():
             'Adding a docstring made this test fail in Py2.5.0'
             return None
+
         self.assertNotInBytecode(f, 'LOAD_GLOBAL')
         self.assertInBytecode(f, 'LOAD_CONST', None)
 
diff --git a/Lib/test/test_pep3151.py b/Lib/test/test_pep3151.py
index 7b0d465425..8649596790 100644
--- a/Lib/test/test_pep3151.py
+++ b/Lib/test/test_pep3151.py
@@ -2,7 +2,6 @@ import builtins
 import os
 import select
 import socket
-import sys
 import unittest
 import errno
 from errno import EEXIST
diff --git a/Lib/test/test_pep352.py b/Lib/test/test_pep352.py
index 7c98c460b9..27d514fe2e 100644
--- a/Lib/test/test_pep352.py
+++ b/Lib/test/test_pep352.py
@@ -1,6 +1,5 @@
 import unittest
 import builtins
-import warnings
 import os
 from platform import system as platform_system
 
diff --git a/Lib/test/test_pickle.py b/Lib/test/test_pickle.py
index ee7a667d06..e2ba1ad77a 100644
--- a/Lib/test/test_pickle.py
+++ b/Lib/test/test_pickle.py
@@ -33,8 +33,6 @@ class PyUnpicklerTests(AbstractUnpickleTests):
 
     unpickler = pickle._Unpickler
     bad_stack_errors = (IndexError,)
-    bad_mark_errors = (IndexError, pickle.UnpicklingError,
-                       TypeError, AttributeError, EOFError)
     truncated_errors = (pickle.UnpicklingError, EOFError,
                         AttributeError, ValueError,
                         struct.error, IndexError, ImportError)
@@ -69,8 +67,6 @@ class InMemoryPickleTests(AbstractPickleTests, AbstractUnpickleTests,
     pickler = pickle._Pickler
     unpickler = pickle._Unpickler
     bad_stack_errors = (pickle.UnpicklingError, IndexError)
-    bad_mark_errors = (pickle.UnpicklingError, IndexError,
-                       TypeError, AttributeError, EOFError)
     truncated_errors = (pickle.UnpicklingError, EOFError,
                         AttributeError, ValueError,
                         struct.error, IndexError, ImportError)
@@ -132,7 +128,6 @@ if has_c_implementation:
     class CUnpicklerTests(PyUnpicklerTests):
         unpickler = _pickle.Unpickler
         bad_stack_errors = (pickle.UnpicklingError,)
-        bad_mark_errors = (EOFError,)
         truncated_errors = (pickle.UnpicklingError, EOFError,
                             AttributeError, ValueError)
 
diff --git a/Lib/test/test_pickletools.py b/Lib/test/test_pickletools.py
index bbe6875545..86bebfa026 100644
--- a/Lib/test/test_pickletools.py
+++ b/Lib/test/test_pickletools.py
@@ -1,9 +1,9 @@
-import struct
 import pickle
 import pickletools
 from test import support
 from test.pickletester import AbstractPickleTests
 from test.pickletester import AbstractPickleModuleTests
+import unittest
 
 class OptimizedPickleTests(AbstractPickleTests, AbstractPickleModuleTests):
 
@@ -59,8 +59,40 @@ class OptimizedPickleTests(AbstractPickleTests, AbstractPickleModuleTests):
         self.assertNotIn(pickle.BINPUT, pickled2)
 
 
+class MiscTestCase(unittest.TestCase):
+    def test__all__(self):
+        blacklist = {'bytes_types',
+                     'UP_TO_NEWLINE', 'TAKEN_FROM_ARGUMENT1',
+                     'TAKEN_FROM_ARGUMENT4', 'TAKEN_FROM_ARGUMENT4U',
+                     'TAKEN_FROM_ARGUMENT8U', 'ArgumentDescriptor',
+                     'read_uint1', 'read_uint2', 'read_int4', 'read_uint4',
+                     'read_uint8', 'read_stringnl', 'read_stringnl_noescape',
+                     'read_stringnl_noescape_pair', 'read_string1',
+                     'read_string4', 'read_bytes1', 'read_bytes4',
+                     'read_bytes8', 'read_unicodestringnl',
+                     'read_unicodestring1', 'read_unicodestring4',
+                     'read_unicodestring8', 'read_decimalnl_short',
+                     'read_decimalnl_long', 'read_floatnl', 'read_float8',
+                     'read_long1', 'read_long4',
+                     'uint1', 'uint2', 'int4', 'uint4', 'uint8', 'stringnl',
+                     'stringnl_noescape', 'stringnl_noescape_pair', 'string1',
+                     'string4', 'bytes1', 'bytes4', 'bytes8',
+                     'unicodestringnl', 'unicodestring1', 'unicodestring4',
+                     'unicodestring8', 'decimalnl_short', 'decimalnl_long',
+                     'floatnl', 'float8', 'long1', 'long4',
+                     'StackObject',
+                     'pyint', 'pylong', 'pyinteger_or_bool', 'pybool', 'pyfloat',
+                     'pybytes_or_str', 'pystring', 'pybytes', 'pyunicode',
+                     'pynone', 'pytuple', 'pylist', 'pydict', 'pyset',
+                     'pyfrozenset', 'anyobject', 'markobject', 'stackslice',
+                     'OpcodeInfo', 'opcodes', 'code2op',
+                     }
+        support.check__all__(self, pickletools, blacklist=blacklist)
+
+
 def test_main():
     support.run_unittest(OptimizedPickleTests)
+    support.run_unittest(MiscTestCase)
     support.run_doctest(pickletools)
 
 
diff --git a/Lib/test/test_pipes.py b/Lib/test/test_pipes.py
index 6a7b45fb46..ad01d08481 100644
--- a/Lib/test/test_pipes.py
+++ b/Lib/test/test_pipes.py
@@ -2,6 +2,7 @@ import pipes
 import os
 import string
 import unittest
+import shutil
 from test.support import TESTFN, run_unittest, unlink, reap_children
 
 if os.name != 'posix':
@@ -18,6 +19,8 @@ class SimplePipeTests(unittest.TestCase):
             unlink(f)
 
     def testSimplePipe1(self):
+        if shutil.which('tr') is None:
+            self.skipTest('tr is not available')
         t = pipes.Template()
         t.append(s_command, pipes.STDIN_STDOUT)
         f = t.open(TESTFN, 'w')
@@ -27,6 +30,8 @@ class SimplePipeTests(unittest.TestCase):
             self.assertEqual(f.read(), 'HELLO WORLD #1')
 
     def testSimplePipe2(self):
+        if shutil.which('tr') is None:
+            self.skipTest('tr is not available')
         with open(TESTFN, 'w') as f:
             f.write('hello world #2')
         t = pipes.Template()
@@ -36,6 +41,8 @@ class SimplePipeTests(unittest.TestCase):
             self.assertEqual(f.read(), 'HELLO WORLD #2')
 
     def testSimplePipe3(self):
+        if shutil.which('tr') is None:
+            self.skipTest('tr is not available')
         with open(TESTFN, 'w') as f:
             f.write('hello world #2')
         t = pipes.Template()
diff --git a/Lib/test/test_plistlib.py b/Lib/test/test_plistlib.py
index 16114f9f6f..60ff9183c2 100644
--- a/Lib/test/test_plistlib.py
+++ b/Lib/test/test_plistlib.py
@@ -7,7 +7,6 @@ import datetime
 import codecs
 import binascii
 import collections
-import struct
 from test import support
 from io import BytesIO
 
@@ -527,8 +526,14 @@ class TestPlistlibDeprecated(unittest.TestCase):
         self.assertEqual(cur, in_data)
 
 
+class MiscTestCase(unittest.TestCase):
+    def test__all__(self):
+        blacklist = {"PlistFormat", "PLISTHEADER"}
+        support.check__all__(self, plistlib, blacklist=blacklist)
+
+
 def test_main():
-    support.run_unittest(TestPlistlib, TestPlistlibDeprecated)
+    support.run_unittest(TestPlistlib, TestPlistlibDeprecated, MiscTestCase)
 
 
 if __name__ == '__main__':
diff --git a/Lib/test/test_poplib.py b/Lib/test/test_poplib.py
index bceeb93ad1..7b9606d359 100644
--- a/Lib/test/test_poplib.py
+++ b/Lib/test/test_poplib.py
@@ -8,7 +8,6 @@ import asyncore
 import asynchat
 import socket
 import os
-import time
 import errno
 
 from unittest import TestCase, skipUnless
diff --git a/Lib/test/test_posix.py b/Lib/test/test_posix.py
index 2a59c38174..6a1c82917a 100644
--- a/Lib/test/test_posix.py
+++ b/Lib/test/test_posix.py
@@ -11,7 +11,6 @@ import time
 import os
 import platform
 import pwd
-import shutil
 import stat
 import tempfile
 import unittest
@@ -411,7 +410,7 @@ class PosixTester(unittest.TestCase):
         self.assertTrue(posix.stat(bytearray(os.fsencode(support.TESTFN))))
 
         self.assertRaisesRegex(TypeError,
-                'can\'t specify None for path argument',
+                'should be string, bytes or integer, not',
                 posix.stat, None)
         self.assertRaisesRegex(TypeError,
                 'should be string, bytes or integer, not',
@@ -863,9 +862,9 @@ class PosixTester(unittest.TestCase):
             self.assertEqual(s1, s2)
             s2 = posix.stat(support.TESTFN, dir_fd=None)
             self.assertEqual(s1, s2)
-            self.assertRaisesRegex(TypeError, 'should be integer, not',
+            self.assertRaisesRegex(TypeError, 'should be integer or None, not',
                     posix.stat, support.TESTFN, dir_fd=posix.getcwd())
-            self.assertRaisesRegex(TypeError, 'should be integer, not',
+            self.assertRaisesRegex(TypeError, 'should be integer or None, not',
                     posix.stat, support.TESTFN, dir_fd=float(f))
             self.assertRaises(OverflowError,
                     posix.stat, support.TESTFN, dir_fd=10**20)
diff --git a/Lib/test/test_posixpath.py b/Lib/test/test_posixpath.py
index acf110204c..4ff445d400 100644
--- a/Lib/test/test_posixpath.py
+++ b/Lib/test/test_posixpath.py
@@ -1,7 +1,5 @@
-import itertools
 import os
 import posixpath
-import sys
 import unittest
 import warnings
 from posixpath import realpath, abspath, dirname, basename
diff --git a/Lib/test/test_pow.py b/Lib/test/test_pow.py
index 6feac409bd..ce99fe6410 100644
--- a/Lib/test/test_pow.py
+++ b/Lib/test/test_pow.py
@@ -1,4 +1,4 @@
-import test.support, unittest
+import unittest
 
 class PowTest(unittest.TestCase):
 
diff --git a/Lib/test/test_pprint.py b/Lib/test/test_pprint.py
index 7ebc298337..2283923cee 100644
--- a/Lib/test/test_pprint.py
+++ b/Lib/test/test_pprint.py
@@ -848,12 +848,11 @@ bytearray(b'\\x00\\x01\\x02\\x03'
 
     def test_default_dict(self):
         d = collections.defaultdict(int)
-        self.assertEqual(pprint.pformat(d, width=1), "defaultdict(<class 'int'>, {})")
+        self.assertRegex(pprint.pformat(d, width=1), r"defaultdict\(<class 'int' at 0x.+>, {}\)")
         words = 'the quick brown fox jumped over a lazy dog'.split()
         d = collections.defaultdict(int, zip(words, itertools.count()))
-        self.assertEqual(pprint.pformat(d),
-"""\
-defaultdict(<class 'int'>,
+        self.assertRegex(pprint.pformat(d),
+r"""defaultdict\(<class 'int' at 0x.+>,
             {'a': 6,
              'brown': 2,
              'dog': 8,
@@ -862,7 +861,7 @@ defaultdict(<class 'int'>,
              'lazy': 7,
              'over': 5,
              'quick': 1,
-             'the': 0})""")
+             'the': 0}\)""")
 
     def test_counter(self):
         d = collections.Counter()
diff --git a/Lib/test/test_pty.py b/Lib/test/test_pty.py
index ef5e99ee26..15f88e4fcd 100644
--- a/Lib/test/test_pty.py
+++ b/Lib/test/test_pty.py
@@ -277,7 +277,6 @@ class SmallPtyTests(unittest.TestCase):
         socketpair = self._socketpair()
         masters = [s.fileno() for s in socketpair]
 
-        os.close(masters[1])
         socketpair[1].close()
         os.close(write_to_stdin_fd)
 
diff --git a/Lib/test/test_pulldom.py b/Lib/test/test_pulldom.py
index 1932c6bb99..3d89e3adda 100644
--- a/Lib/test/test_pulldom.py
+++ b/Lib/test/test_pulldom.py
@@ -1,6 +1,5 @@
 import io
 import unittest
-import sys
 import xml.sax
 
 from xml.sax.xmlreader import AttributesImpl
diff --git a/Lib/test/test_pyclbr.py b/Lib/test/test_pyclbr.py
index 6ffbbbda27..06c10c17af 100644
--- a/Lib/test/test_pyclbr.py
+++ b/Lib/test/test_pyclbr.py
@@ -156,7 +156,7 @@ class PyclbrTest(TestCase):
         # These were once about the 10 longest modules
         cm('random', ignore=('Random',))  # from _random import Random as CoreGenerator
         cm('cgi', ignore=('log',))      # set with = in module
-        cm('pickle')
+        cm('pickle', ignore=('partial',))
         cm('aifc', ignore=('openfp', '_aifc_params'))  # set with = in module
         cm('sre_parse', ignore=('dump', 'groups')) # from sre_constants import *; property
         cm('pdb')
diff --git a/Lib/test/test_pydoc.py b/Lib/test/test_pydoc.py
index 59aa7151ee..9a357da59b 100644
--- a/Lib/test/test_pydoc.py
+++ b/Lib/test/test_pydoc.py
@@ -855,6 +855,22 @@ class TestDescriptions(unittest.TestCase):
         self.assertEqual(self._get_summary_line(t.wrap),
             "wrap(text) method of textwrap.TextWrapper instance")
 
+    def test_field_order_for_named_tuples(self):
+        Person = namedtuple('Person', ['nickname', 'firstname', 'agegroup'])
+        s = pydoc.render_doc(Person)
+        self.assertLess(s.index('nickname'), s.index('firstname'))
+        self.assertLess(s.index('firstname'), s.index('agegroup'))
+
+        class NonIterableFields:
+            _fields = None
+
+        class NonHashableFields:
+            _fields = [[]]
+
+        # Make sure these doesn't fail
+        pydoc.render_doc(NonIterableFields)
+        pydoc.render_doc(NonHashableFields)
+
     @requires_docstrings
     def test_bound_builtin_method(self):
         s = StringIO()
diff --git a/Lib/test/test_quopri.py b/Lib/test/test_quopri.py
index 7cac013446..715544c8a9 100644
--- a/Lib/test/test_quopri.py
+++ b/Lib/test/test_quopri.py
@@ -1,6 +1,6 @@
 import unittest
 
-import sys, os, io, subprocess
+import sys, io, subprocess
 import quopri
 
 
diff --git a/Lib/test/test_range.py b/Lib/test/test_range.py
index 106c732dd9..e03b570dab 100644
--- a/Lib/test/test_range.py
+++ b/Lib/test/test_range.py
@@ -1,6 +1,6 @@
 # Python test set -- built-in functions
 
-import test.support, unittest
+import unittest
 import sys
 import pickle
 import itertools
diff --git a/Lib/test/test_readline.py b/Lib/test/test_readline.py
index 35330ab076..c1864efaab 100644
--- a/Lib/test/test_readline.py
+++ b/Lib/test/test_readline.py
@@ -1,7 +1,12 @@
 """
 Very minimal unittests for parts of the readline module.
 """
+from contextlib import ExitStack
+from errno import EIO
 import os
+import selectors
+import subprocess
+import sys
 import tempfile
 import unittest
 from test.support import import_module, unlink
@@ -96,6 +101,65 @@ class TestReadline(unittest.TestCase):
                                               TERM='xterm-256color')
         self.assertEqual(stdout, b'')
 
+    auto_history_script = """\
+import readline
+readline.set_auto_history({})
+input()
+print("History length:", readline.get_current_history_length())
+"""
+
+    def test_auto_history_enabled(self):
+        output = run_pty(self.auto_history_script.format(True))
+        self.assertIn(b"History length: 1\r\n", output)
+
+    def test_auto_history_disabled(self):
+        output = run_pty(self.auto_history_script.format(False))
+        self.assertIn(b"History length: 0\r\n", output)
+
+
+def run_pty(script, input=b"dummy input\r"):
+    pty = import_module('pty')
+    output = bytearray()
+    [master, slave] = pty.openpty()
+    args = (sys.executable, '-c', script)
+    proc = subprocess.Popen(args, stdin=slave, stdout=slave, stderr=slave)
+    os.close(slave)
+    with ExitStack() as cleanup:
+        cleanup.enter_context(proc)
+        def terminate(proc):
+            try:
+                proc.terminate()
+            except ProcessLookupError:
+                # Workaround for Open/Net BSD bug (Issue 16762)
+                pass
+        cleanup.callback(terminate, proc)
+        cleanup.callback(os.close, master)
+        # Avoid using DefaultSelector and PollSelector. Kqueue() does not
+        # work with pseudo-terminals on OS X < 10.9 (Issue 20365) and Open
+        # BSD (Issue 20667). Poll() does not work with OS X 10.6 or 10.4
+        # either (Issue 20472). Hopefully the file descriptor is low enough
+        # to use with select().
+        sel = cleanup.enter_context(selectors.SelectSelector())
+        sel.register(master, selectors.EVENT_READ | selectors.EVENT_WRITE)
+        os.set_blocking(master, False)
+        while True:
+            for [_, events] in sel.select():
+                if events & selectors.EVENT_READ:
+                    try:
+                        chunk = os.read(master, 0x10000)
+                    except OSError as err:
+                        # Linux raises EIO when the slave is closed
+                        if err.errno != EIO:
+                            raise
+                        chunk = b""
+                    if not chunk:
+                        return output
+                    output.extend(chunk)
+                if events & selectors.EVENT_WRITE:
+                    input = input[os.write(master, input):]
+                    if not input:
+                        sel.modify(master, selectors.EVENT_READ)
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_regrtest.py b/Lib/test/test_regrtest.py
index a398a4f836..c11408df7f 100644
--- a/Lib/test/test_regrtest.py
+++ b/Lib/test/test_regrtest.py
@@ -1,21 +1,48 @@
 """
 Tests of regrtest.py.
+
+Note: test_regrtest cannot be run twice in parallel.
 """
 
-import argparse
+import contextlib
 import faulthandler
-import getopt
+import io
 import os.path
+import platform
+import re
+import subprocess
+import sys
+import sysconfig
+import tempfile
+import textwrap
 import unittest
-from test import regrtest, support
+from test import libregrtest
+from test import support
 
-class ParseArgsTestCase(unittest.TestCase):
 
-    """Test regrtest's argument parsing."""
+Py_DEBUG = hasattr(sys, 'getobjects')
+ROOT_DIR = os.path.join(os.path.dirname(__file__), '..', '..')
+ROOT_DIR = os.path.abspath(os.path.normpath(ROOT_DIR))
+
+TEST_INTERRUPTED = textwrap.dedent("""
+    from signal import SIGINT
+    try:
+        from _testcapi import raise_signal
+        raise_signal(SIGINT)
+    except ImportError:
+        import os
+        os.kill(os.getpid(), SIGINT)
+    """)
+
+
+class ParseArgsTestCase(unittest.TestCase):
+    """
+    Test regrtest's argument parsing, function _parse_args().
+    """
 
     def checkError(self, args, msg):
         with support.captured_stderr() as err, self.assertRaises(SystemExit):
-            regrtest._parse_args(args)
+            libregrtest._parse_args(args)
         self.assertIn(msg, err.getvalue())
 
     def test_help(self):
@@ -23,82 +50,82 @@ class ParseArgsTestCase(unittest.TestCase):
             with self.subTest(opt=opt):
                 with support.captured_stdout() as out, \
                      self.assertRaises(SystemExit):
-                    regrtest._parse_args([opt])
+                    libregrtest._parse_args([opt])
                 self.assertIn('Run Python regression tests.', out.getvalue())
 
     @unittest.skipUnless(hasattr(faulthandler, 'dump_traceback_later'),
                          "faulthandler.dump_traceback_later() required")
     def test_timeout(self):
-        ns = regrtest._parse_args(['--timeout', '4.2'])
+        ns = libregrtest._parse_args(['--timeout', '4.2'])
         self.assertEqual(ns.timeout, 4.2)
         self.checkError(['--timeout'], 'expected one argument')
         self.checkError(['--timeout', 'foo'], 'invalid float value')
 
     def test_wait(self):
-        ns = regrtest._parse_args(['--wait'])
+        ns = libregrtest._parse_args(['--wait'])
         self.assertTrue(ns.wait)
 
     def test_slaveargs(self):
-        ns = regrtest._parse_args(['--slaveargs', '[[], {}]'])
+        ns = libregrtest._parse_args(['--slaveargs', '[[], {}]'])
         self.assertEqual(ns.slaveargs, '[[], {}]')
         self.checkError(['--slaveargs'], 'expected one argument')
 
     def test_start(self):
         for opt in '-S', '--start':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt, 'foo'])
+                ns = libregrtest._parse_args([opt, 'foo'])
                 self.assertEqual(ns.start, 'foo')
                 self.checkError([opt], 'expected one argument')
 
     def test_verbose(self):
-        ns = regrtest._parse_args(['-v'])
+        ns = libregrtest._parse_args(['-v'])
         self.assertEqual(ns.verbose, 1)
-        ns = regrtest._parse_args(['-vvv'])
+        ns = libregrtest._parse_args(['-vvv'])
         self.assertEqual(ns.verbose, 3)
-        ns = regrtest._parse_args(['--verbose'])
+        ns = libregrtest._parse_args(['--verbose'])
         self.assertEqual(ns.verbose, 1)
-        ns = regrtest._parse_args(['--verbose'] * 3)
+        ns = libregrtest._parse_args(['--verbose'] * 3)
         self.assertEqual(ns.verbose, 3)
-        ns = regrtest._parse_args([])
+        ns = libregrtest._parse_args([])
         self.assertEqual(ns.verbose, 0)
 
     def test_verbose2(self):
         for opt in '-w', '--verbose2':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt])
+                ns = libregrtest._parse_args([opt])
                 self.assertTrue(ns.verbose2)
 
     def test_verbose3(self):
         for opt in '-W', '--verbose3':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt])
+                ns = libregrtest._parse_args([opt])
                 self.assertTrue(ns.verbose3)
 
     def test_quiet(self):
         for opt in '-q', '--quiet':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt])
+                ns = libregrtest._parse_args([opt])
                 self.assertTrue(ns.quiet)
                 self.assertEqual(ns.verbose, 0)
 
     def test_slow(self):
         for opt in '-o', '--slow':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt])
+                ns = libregrtest._parse_args([opt])
                 self.assertTrue(ns.print_slow)
 
     def test_header(self):
-        ns = regrtest._parse_args(['--header'])
+        ns = libregrtest._parse_args(['--header'])
         self.assertTrue(ns.header)
 
     def test_randomize(self):
         for opt in '-r', '--randomize':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt])
+                ns = libregrtest._parse_args([opt])
                 self.assertTrue(ns.randomize)
 
     def test_randseed(self):
-        ns = regrtest._parse_args(['--randseed', '12345'])
+        ns = libregrtest._parse_args(['--randseed', '12345'])
         self.assertEqual(ns.random_seed, 12345)
         self.assertTrue(ns.randomize)
         self.checkError(['--randseed'], 'expected one argument')
@@ -107,7 +134,7 @@ class ParseArgsTestCase(unittest.TestCase):
     def test_fromfile(self):
         for opt in '-f', '--fromfile':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt, 'foo'])
+                ns = libregrtest._parse_args([opt, 'foo'])
                 self.assertEqual(ns.fromfile, 'foo')
                 self.checkError([opt], 'expected one argument')
                 self.checkError([opt, 'foo', '-s'], "don't go together")
@@ -115,42 +142,42 @@ class ParseArgsTestCase(unittest.TestCase):
     def test_exclude(self):
         for opt in '-x', '--exclude':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt])
+                ns = libregrtest._parse_args([opt])
                 self.assertTrue(ns.exclude)
 
     def test_single(self):
         for opt in '-s', '--single':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt])
+                ns = libregrtest._parse_args([opt])
                 self.assertTrue(ns.single)
                 self.checkError([opt, '-f', 'foo'], "don't go together")
 
     def test_match(self):
         for opt in '-m', '--match':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt, 'pattern'])
+                ns = libregrtest._parse_args([opt, 'pattern'])
                 self.assertEqual(ns.match_tests, 'pattern')
                 self.checkError([opt], 'expected one argument')
 
     def test_failfast(self):
         for opt in '-G', '--failfast':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt, '-v'])
+                ns = libregrtest._parse_args([opt, '-v'])
                 self.assertTrue(ns.failfast)
-                ns = regrtest._parse_args([opt, '-W'])
+                ns = libregrtest._parse_args([opt, '-W'])
                 self.assertTrue(ns.failfast)
                 self.checkError([opt], '-G/--failfast needs either -v or -W')
 
     def test_use(self):
         for opt in '-u', '--use':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt, 'gui,network'])
+                ns = libregrtest._parse_args([opt, 'gui,network'])
                 self.assertEqual(ns.use_resources, ['gui', 'network'])
-                ns = regrtest._parse_args([opt, 'gui,none,network'])
+                ns = libregrtest._parse_args([opt, 'gui,none,network'])
                 self.assertEqual(ns.use_resources, ['network'])
-                expected = list(regrtest.RESOURCE_NAMES)
+                expected = list(libregrtest.RESOURCE_NAMES)
                 expected.remove('gui')
-                ns = regrtest._parse_args([opt, 'all,-gui'])
+                ns = libregrtest._parse_args([opt, 'all,-gui'])
                 self.assertEqual(ns.use_resources, expected)
                 self.checkError([opt], 'expected one argument')
                 self.checkError([opt, 'foo'], 'invalid resource')
@@ -158,31 +185,31 @@ class ParseArgsTestCase(unittest.TestCase):
     def test_memlimit(self):
         for opt in '-M', '--memlimit':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt, '4G'])
+                ns = libregrtest._parse_args([opt, '4G'])
                 self.assertEqual(ns.memlimit, '4G')
                 self.checkError([opt], 'expected one argument')
 
     def test_testdir(self):
-        ns = regrtest._parse_args(['--testdir', 'foo'])
+        ns = libregrtest._parse_args(['--testdir', 'foo'])
         self.assertEqual(ns.testdir, os.path.join(support.SAVEDCWD, 'foo'))
         self.checkError(['--testdir'], 'expected one argument')
 
     def test_runleaks(self):
         for opt in '-L', '--runleaks':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt])
+                ns = libregrtest._parse_args([opt])
                 self.assertTrue(ns.runleaks)
 
     def test_huntrleaks(self):
         for opt in '-R', '--huntrleaks':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt, ':'])
+                ns = libregrtest._parse_args([opt, ':'])
                 self.assertEqual(ns.huntrleaks, (5, 4, 'reflog.txt'))
-                ns = regrtest._parse_args([opt, '6:'])
+                ns = libregrtest._parse_args([opt, '6:'])
                 self.assertEqual(ns.huntrleaks, (6, 4, 'reflog.txt'))
-                ns = regrtest._parse_args([opt, ':3'])
+                ns = libregrtest._parse_args([opt, ':3'])
                 self.assertEqual(ns.huntrleaks, (5, 3, 'reflog.txt'))
-                ns = regrtest._parse_args([opt, '6:3:leaks.log'])
+                ns = libregrtest._parse_args([opt, '6:3:leaks.log'])
                 self.assertEqual(ns.huntrleaks, (6, 3, 'leaks.log'))
                 self.checkError([opt], 'expected one argument')
                 self.checkError([opt, '6'],
@@ -193,24 +220,23 @@ class ParseArgsTestCase(unittest.TestCase):
     def test_multiprocess(self):
         for opt in '-j', '--multiprocess':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt, '2'])
+                ns = libregrtest._parse_args([opt, '2'])
                 self.assertEqual(ns.use_mp, 2)
                 self.checkError([opt], 'expected one argument')
                 self.checkError([opt, 'foo'], 'invalid int value')
                 self.checkError([opt, '2', '-T'], "don't go together")
                 self.checkError([opt, '2', '-l'], "don't go together")
-                self.checkError([opt, '2', '-M', '4G'], "don't go together")
 
     def test_coverage(self):
         for opt in '-T', '--coverage':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt])
+                ns = libregrtest._parse_args([opt])
                 self.assertTrue(ns.trace)
 
     def test_coverdir(self):
         for opt in '-D', '--coverdir':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt, 'foo'])
+                ns = libregrtest._parse_args([opt, 'foo'])
                 self.assertEqual(ns.coverdir,
                                  os.path.join(support.SAVEDCWD, 'foo'))
                 self.checkError([opt], 'expected one argument')
@@ -218,13 +244,13 @@ class ParseArgsTestCase(unittest.TestCase):
     def test_nocoverdir(self):
         for opt in '-N', '--nocoverdir':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt])
+                ns = libregrtest._parse_args([opt])
                 self.assertIsNone(ns.coverdir)
 
     def test_threshold(self):
         for opt in '-t', '--threshold':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt, '1000'])
+                ns = libregrtest._parse_args([opt, '1000'])
                 self.assertEqual(ns.threshold, 1000)
                 self.checkError([opt], 'expected one argument')
                 self.checkError([opt, 'foo'], 'invalid int value')
@@ -232,13 +258,16 @@ class ParseArgsTestCase(unittest.TestCase):
     def test_nowindows(self):
         for opt in '-n', '--nowindows':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt])
+                with contextlib.redirect_stderr(io.StringIO()) as stderr:
+                    ns = libregrtest._parse_args([opt])
                 self.assertTrue(ns.nowindows)
+                err = stderr.getvalue()
+                self.assertIn('the --nowindows (-n) option is deprecated', err)
 
     def test_forever(self):
         for opt in '-F', '--forever':
             with self.subTest(opt=opt):
-                ns = regrtest._parse_args([opt])
+                ns = libregrtest._parse_args([opt])
                 self.assertTrue(ns.forever)
 
 
@@ -246,30 +275,503 @@ class ParseArgsTestCase(unittest.TestCase):
         self.checkError(['--xxx'], 'usage:')
 
     def test_long_option__partial(self):
-        ns = regrtest._parse_args(['--qui'])
+        ns = libregrtest._parse_args(['--qui'])
         self.assertTrue(ns.quiet)
         self.assertEqual(ns.verbose, 0)
 
     def test_two_options(self):
-        ns = regrtest._parse_args(['--quiet', '--exclude'])
+        ns = libregrtest._parse_args(['--quiet', '--exclude'])
         self.assertTrue(ns.quiet)
         self.assertEqual(ns.verbose, 0)
         self.assertTrue(ns.exclude)
 
     def test_option_with_empty_string_value(self):
-        ns = regrtest._parse_args(['--start', ''])
+        ns = libregrtest._parse_args(['--start', ''])
         self.assertEqual(ns.start, '')
 
     def test_arg(self):
-        ns = regrtest._parse_args(['foo'])
+        ns = libregrtest._parse_args(['foo'])
         self.assertEqual(ns.args, ['foo'])
 
     def test_option_and_arg(self):
-        ns = regrtest._parse_args(['--quiet', 'foo'])
+        ns = libregrtest._parse_args(['--quiet', 'foo'])
         self.assertTrue(ns.quiet)
         self.assertEqual(ns.verbose, 0)
         self.assertEqual(ns.args, ['foo'])
 
 
+class BaseTestCase(unittest.TestCase):
+    TEST_UNIQUE_ID = 1
+    TESTNAME_PREFIX = 'test_regrtest_'
+    TESTNAME_REGEX = r'test_[a-zA-Z0-9_]+'
+
+    def setUp(self):
+        self.testdir = os.path.realpath(os.path.dirname(__file__))
+
+        self.tmptestdir = tempfile.mkdtemp()
+        self.addCleanup(support.rmtree, self.tmptestdir)
+
+    def create_test(self, name=None, code=''):
+        if not name:
+            name = 'noop%s' % BaseTestCase.TEST_UNIQUE_ID
+            BaseTestCase.TEST_UNIQUE_ID += 1
+
+        # test_regrtest cannot be run twice in parallel because
+        # of setUp() and create_test()
+        name = self.TESTNAME_PREFIX + name
+        path = os.path.join(self.tmptestdir, name + '.py')
+
+        self.addCleanup(support.unlink, path)
+        # Use 'x' mode to ensure that we do not override existing tests
+        try:
+            with open(path, 'x', encoding='utf-8') as fp:
+                fp.write(code)
+        except PermissionError as exc:
+            if not sysconfig.is_python_build():
+                self.skipTest("cannot write %s: %s" % (path, exc))
+            raise
+        return name
+
+    def regex_search(self, regex, output):
+        match = re.search(regex, output, re.MULTILINE)
+        if not match:
+            self.fail("%r not found in %r" % (regex, output))
+        return match
+
+    def check_line(self, output, regex):
+        regex = re.compile(r'^' + regex, re.MULTILINE)
+        self.assertRegex(output, regex)
+
+    def parse_executed_tests(self, output):
+        regex = (r'^[0-9]+:[0-9]+:[0-9]+ \[ *[0-9]+(?:/ *[0-9]+)?\] (%s)'
+                 % self.TESTNAME_REGEX)
+        parser = re.finditer(regex, output, re.MULTILINE)
+        return list(match.group(1) for match in parser)
+
+    def check_executed_tests(self, output, tests, skipped=(), failed=(),
+                             omitted=(), randomize=False):
+        if isinstance(tests, str):
+            tests = [tests]
+        if isinstance(skipped, str):
+            skipped = [skipped]
+        if isinstance(failed, str):
+            failed = [failed]
+        if isinstance(omitted, str):
+            omitted = [omitted]
+        ntest = len(tests)
+        nskipped = len(skipped)
+        nfailed = len(failed)
+        nomitted = len(omitted)
+
+        executed = self.parse_executed_tests(output)
+        if randomize:
+            self.assertEqual(set(executed), set(tests), output)
+        else:
+            self.assertEqual(executed, tests, output)
+
+        def plural(count):
+            return 's' if count != 1 else ''
+
+        def list_regex(line_format, tests):
+            count = len(tests)
+            names = ' '.join(sorted(tests))
+            regex = line_format % (count, plural(count))
+            regex = r'%s:\n    %s$' % (regex, names)
+            return regex
+
+        if skipped:
+            regex = list_regex('%s test%s skipped', skipped)
+            self.check_line(output, regex)
+
+        if failed:
+            regex = list_regex('%s test%s failed', failed)
+            self.check_line(output, regex)
+
+        if omitted:
+            regex = list_regex('%s test%s omitted', omitted)
+            self.check_line(output, regex)
+
+        good = ntest - nskipped - nfailed - nomitted
+        if good:
+            regex = r'%s test%s OK\.$' % (good, plural(good))
+            if not skipped and not failed and good > 1:
+                regex = 'All %s' % regex
+            self.check_line(output, regex)
+
+    def parse_random_seed(self, output):
+        match = self.regex_search(r'Using random seed ([0-9]+)', output)
+        randseed = int(match.group(1))
+        self.assertTrue(0 <= randseed <= 10000000, randseed)
+        return randseed
+
+    def run_command(self, args, input=None, exitcode=0, **kw):
+        if not input:
+            input = ''
+        if 'stderr' not in kw:
+            kw['stderr'] = subprocess.PIPE
+        proc = subprocess.run(args,
+                              universal_newlines=True,
+                              input=input,
+                              stdout=subprocess.PIPE,
+                              **kw)
+        if proc.returncode != exitcode:
+            msg = ("Command %s failed with exit code %s\n"
+                   "\n"
+                   "stdout:\n"
+                   "---\n"
+                   "%s\n"
+                   "---\n"
+                   % (str(args), proc.returncode, proc.stdout))
+            if proc.stderr:
+                msg += ("\n"
+                        "stderr:\n"
+                        "---\n"
+                        "%s"
+                        "---\n"
+                        % proc.stderr)
+            self.fail(msg)
+        return proc
+
+
+    def run_python(self, args, **kw):
+        args = [sys.executable, '-X', 'faulthandler', '-I', *args]
+        proc = self.run_command(args, **kw)
+        return proc.stdout
+
+
+class ProgramsTestCase(BaseTestCase):
+    """
+    Test various ways to run the Python test suite. Use options close
+    to options used on the buildbot.
+    """
+
+    NTEST = 4
+
+    def setUp(self):
+        super().setUp()
+
+        # Create NTEST tests doing nothing
+        self.tests = [self.create_test() for index in range(self.NTEST)]
+
+        self.python_args = ['-Wd', '-E', '-bb']
+        self.regrtest_args = ['-uall', '-rwW',
+                              '--testdir=%s' % self.tmptestdir]
+        if hasattr(faulthandler, 'dump_traceback_later'):
+            self.regrtest_args.extend(('--timeout', '3600', '-j4'))
+        if sys.platform == 'win32':
+            self.regrtest_args.append('-n')
+
+    def check_output(self, output):
+        self.parse_random_seed(output)
+        self.check_executed_tests(output, self.tests, randomize=True)
+
+    def run_tests(self, args):
+        output = self.run_python(args)
+        self.check_output(output)
+
+    def test_script_regrtest(self):
+        # Lib/test/regrtest.py
+        script = os.path.join(self.testdir, 'regrtest.py')
+
+        args = [*self.python_args, script, *self.regrtest_args, *self.tests]
+        self.run_tests(args)
+
+    def test_module_test(self):
+        # -m test
+        args = [*self.python_args, '-m', 'test',
+                *self.regrtest_args, *self.tests]
+        self.run_tests(args)
+
+    def test_module_regrtest(self):
+        # -m test.regrtest
+        args = [*self.python_args, '-m', 'test.regrtest',
+                *self.regrtest_args, *self.tests]
+        self.run_tests(args)
+
+    def test_module_autotest(self):
+        # -m test.autotest
+        args = [*self.python_args, '-m', 'test.autotest',
+                *self.regrtest_args, *self.tests]
+        self.run_tests(args)
+
+    def test_module_from_test_autotest(self):
+        # from test import autotest
+        code = 'from test import autotest'
+        args = [*self.python_args, '-c', code,
+                *self.regrtest_args, *self.tests]
+        self.run_tests(args)
+
+    def test_script_autotest(self):
+        # Lib/test/autotest.py
+        script = os.path.join(self.testdir, 'autotest.py')
+        args = [*self.python_args, script, *self.regrtest_args, *self.tests]
+        self.run_tests(args)
+
+    @unittest.skipUnless(sysconfig.is_python_build(),
+                         'run_tests.py script is not installed')
+    def test_tools_script_run_tests(self):
+        # Tools/scripts/run_tests.py
+        script = os.path.join(ROOT_DIR, 'Tools', 'scripts', 'run_tests.py')
+        args = [script, *self.regrtest_args, *self.tests]
+        self.run_tests(args)
+
+    def run_batch(self, *args):
+        proc = self.run_command(args)
+        self.check_output(proc.stdout)
+
+    @unittest.skipUnless(sysconfig.is_python_build(),
+                         'test.bat script is not installed')
+    @unittest.skipUnless(sys.platform == 'win32', 'Windows only')
+    def test_tools_buildbot_test(self):
+        # Tools\buildbot\test.bat
+        script = os.path.join(ROOT_DIR, 'Tools', 'buildbot', 'test.bat')
+        test_args = ['--testdir=%s' % self.tmptestdir]
+        if platform.architecture()[0] == '64bit':
+            test_args.append('-x64')   # 64-bit build
+        if not Py_DEBUG:
+            test_args.append('+d')     # Release build, use python.exe
+        self.run_batch(script, *test_args, *self.tests)
+
+    @unittest.skipUnless(sys.platform == 'win32', 'Windows only')
+    def test_pcbuild_rt(self):
+        # PCbuild\rt.bat
+        script = os.path.join(ROOT_DIR, r'PCbuild\rt.bat')
+        rt_args = ["-q"]             # Quick, don't run tests twice
+        if platform.architecture()[0] == '64bit':
+            rt_args.append('-x64')   # 64-bit build
+        if Py_DEBUG:
+            rt_args.append('-d')     # Debug build, use python_d.exe
+        self.run_batch(script, *rt_args, *self.regrtest_args, *self.tests)
+
+
+class ArgsTestCase(BaseTestCase):
+    """
+    Test arguments of the Python test suite.
+    """
+
+    def run_tests(self, *testargs, **kw):
+        cmdargs = ['-m', 'test', '--testdir=%s' % self.tmptestdir, *testargs]
+        return self.run_python(cmdargs, **kw)
+
+    def test_failing_test(self):
+        # test a failing test
+        code = textwrap.dedent("""
+            import unittest
+
+            class FailingTest(unittest.TestCase):
+                def test_failing(self):
+                    self.fail("bug")
+        """)
+        test_ok = self.create_test('ok')
+        test_failing = self.create_test('failing', code=code)
+        tests = [test_ok, test_failing]
+
+        output = self.run_tests(*tests, exitcode=1)
+        self.check_executed_tests(output, tests, failed=test_failing)
+
+    def test_resources(self):
+        # test -u command line option
+        tests = {}
+        for resource in ('audio', 'network'):
+            code = 'from test import support\nsupport.requires(%r)' % resource
+            tests[resource] = self.create_test(resource, code)
+        test_names = sorted(tests.values())
+
+        # -u all: 2 resources enabled
+        output = self.run_tests('-u', 'all', *test_names)
+        self.check_executed_tests(output, test_names)
+
+        # -u audio: 1 resource enabled
+        output = self.run_tests('-uaudio', *test_names)
+        self.check_executed_tests(output, test_names,
+                                  skipped=tests['network'])
+
+        # no option: 0 resources enabled
+        output = self.run_tests(*test_names)
+        self.check_executed_tests(output, test_names,
+                                  skipped=test_names)
+
+    def test_random(self):
+        # test -r and --randseed command line option
+        code = textwrap.dedent("""
+            import random
+            print("TESTRANDOM: %s" % random.randint(1, 1000))
+        """)
+        test = self.create_test('random', code)
+
+        # first run to get the output with the random seed
+        output = self.run_tests('-r', test)
+        randseed = self.parse_random_seed(output)
+        match = self.regex_search(r'TESTRANDOM: ([0-9]+)', output)
+        test_random = int(match.group(1))
+
+        # try to reproduce with the random seed
+        output = self.run_tests('-r', '--randseed=%s' % randseed, test)
+        randseed2 = self.parse_random_seed(output)
+        self.assertEqual(randseed2, randseed)
+
+        match = self.regex_search(r'TESTRANDOM: ([0-9]+)', output)
+        test_random2 = int(match.group(1))
+        self.assertEqual(test_random2, test_random)
+
+    def test_fromfile(self):
+        # test --fromfile
+        tests = [self.create_test() for index in range(5)]
+
+        # Write the list of files using a format similar to regrtest output:
+        # [1/2] test_1
+        # [2/2] test_2
+        filename = support.TESTFN
+        self.addCleanup(support.unlink, filename)
+
+        # test format '0:00:00 [2/7] test_opcodes -- test_grammar took 0 sec'
+        with open(filename, "w") as fp:
+            previous = None
+            for index, name in enumerate(tests, 1):
+                line = ("00:00:%02i [%s/%s] %s"
+                        % (index, index, len(tests), name))
+                if previous:
+                    line += " -- %s took 0 sec" % previous
+                print(line, file=fp)
+                previous = name
+
+        output = self.run_tests('--fromfile', filename)
+        self.check_executed_tests(output, tests)
+
+        # test format '[2/7] test_opcodes'
+        with open(filename, "w") as fp:
+            for index, name in enumerate(tests, 1):
+                print("[%s/%s] %s" % (index, len(tests), name), file=fp)
+
+        output = self.run_tests('--fromfile', filename)
+        self.check_executed_tests(output, tests)
+
+        # test format 'test_opcodes'
+        with open(filename, "w") as fp:
+            for name in tests:
+                print(name, file=fp)
+
+        output = self.run_tests('--fromfile', filename)
+        self.check_executed_tests(output, tests)
+
+    def test_interrupted(self):
+        code = TEST_INTERRUPTED
+        test = self.create_test('sigint', code=code)
+        output = self.run_tests(test, exitcode=1)
+        self.check_executed_tests(output, test, omitted=test)
+
+    def test_slow(self):
+        # test --slow
+        tests = [self.create_test() for index in range(3)]
+        output = self.run_tests("--slow", *tests)
+        self.check_executed_tests(output, tests)
+        regex = ('10 slowest tests:\n'
+                 '(?:%s: [0-9]+\.[0-9]+s\n){%s}'
+                 % (self.TESTNAME_REGEX, len(tests)))
+        self.check_line(output, regex)
+
+    def test_slow_interrupted(self):
+        # Issue #25373: test --slow with an interrupted test
+        code = TEST_INTERRUPTED
+        test = self.create_test("sigint", code=code)
+
+        for multiprocessing in (False, True):
+            if multiprocessing:
+                args = ("--slow", "-j2", test)
+            else:
+                args = ("--slow", test)
+            output = self.run_tests(*args, exitcode=1)
+            self.check_executed_tests(output, test, omitted=test)
+            regex = ('10 slowest tests:\n')
+            self.check_line(output, regex)
+            self.check_line(output, 'Test suite interrupted by signal SIGINT.')
+
+    def test_coverage(self):
+        # test --coverage
+        test = self.create_test('coverage')
+        output = self.run_tests("--coverage", test)
+        self.check_executed_tests(output, [test])
+        regex = ('lines +cov% +module +\(path\)\n'
+                 '(?: *[0-9]+ *[0-9]{1,2}% *[^ ]+ +\([^)]+\)+)+')
+        self.check_line(output, regex)
+
+    def test_wait(self):
+        # test --wait
+        test = self.create_test('wait')
+        output = self.run_tests("--wait", test, input='key')
+        self.check_line(output, 'Press any key to continue')
+
+    def test_forever(self):
+        # test --forever
+        code = textwrap.dedent("""
+            import builtins
+            import unittest
+
+            class ForeverTester(unittest.TestCase):
+                def test_run(self):
+                    # Store the state in the builtins module, because the test
+                    # module is reload at each run
+                    if 'RUN' in builtins.__dict__:
+                        builtins.__dict__['RUN'] += 1
+                        if builtins.__dict__['RUN'] >= 3:
+                            self.fail("fail at the 3rd runs")
+                    else:
+                        builtins.__dict__['RUN'] = 1
+        """)
+        test = self.create_test('forever', code=code)
+        output = self.run_tests('--forever', test, exitcode=1)
+        self.check_executed_tests(output, [test]*3, failed=test)
+
+    @unittest.skipUnless(Py_DEBUG, 'need a debug build')
+    def test_huntrleaks_fd_leak(self):
+        # test --huntrleaks for file descriptor leak
+        code = textwrap.dedent("""
+            import os
+            import unittest
+
+            # Issue #25306: Disable popups and logs to stderr on assertion
+            # failures in MSCRT
+            try:
+                import msvcrt
+                msvcrt.CrtSetReportMode
+            except (ImportError, AttributeError):
+                # no Windows, o release build
+                pass
+            else:
+                for m in [msvcrt.CRT_WARN, msvcrt.CRT_ERROR, msvcrt.CRT_ASSERT]:
+                    msvcrt.CrtSetReportMode(m, 0)
+
+            class FDLeakTest(unittest.TestCase):
+                def test_leak(self):
+                    fd = os.open(__file__, os.O_RDONLY)
+                    # bug: never cloes the file descriptor
+        """)
+        test = self.create_test('huntrleaks', code=code)
+
+        filename = 'reflog.txt'
+        self.addCleanup(support.unlink, filename)
+        output = self.run_tests('--huntrleaks', '3:3:', test,
+                                exitcode=1,
+                                stderr=subprocess.STDOUT)
+        self.check_executed_tests(output, [test], failed=test)
+
+        line = 'beginning 6 repetitions\n123456\n......\n'
+        self.check_line(output, re.escape(line))
+
+        line2 = '%s leaked [1, 1, 1] file descriptors, sum=3\n' % test
+        self.check_line(output, re.escape(line2))
+
+        with open(filename) as fp:
+            reflog = fp.read()
+            self.assertEqual(reflog, line2)
+
+    def test_list_tests(self):
+        # test --list-tests
+        tests = [self.create_test() for i in range(5)]
+        output = self.run_tests('--list-tests', *tests)
+        self.assertEqual(output.rstrip().splitlines(),
+                         tests)
+
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/Lib/test/test_reprlib.py b/Lib/test/test_reprlib.py
index 4bf91945ea..2ecea0221e 100644
--- a/Lib/test/test_reprlib.py
+++ b/Lib/test/test_reprlib.py
@@ -292,8 +292,8 @@ class foo(object):
 ''')
         importlib.invalidate_caches()
         from areallylongpackageandmodulenametotestreprtruncation.areallylongpackageandmodulenametotestreprtruncation import foo
-        eq(repr(foo.foo),
-               "<class '%s.foo'>" % foo.__name__)
+        self.assertRegex(repr(foo.foo),
+               r"<class '%s.foo' at 0x.+>" % foo.__name__)
 
     @unittest.skip('need a suitable object')
     def test_object(self):
@@ -310,7 +310,7 @@ class bar:
         importlib.invalidate_caches()
         from areallylongpackageandmodulenametotestreprtruncation.areallylongpackageandmodulenametotestreprtruncation import bar
         # Module name may be prefixed with "test.", depending on how run.
-        self.assertEqual(repr(bar.bar), "<class '%s.bar'>" % bar.__name__)
+        self.assertRegex(repr(bar.bar), r"<class '%s.bar' at 0x.+>" % bar.__name__)
 
     def test_instance(self):
         self._check_path_limitations('baz')
diff --git a/Lib/test/test_richcmp.py b/Lib/test/test_richcmp.py
index 1582caad97..58729a9fea 100644
--- a/Lib/test/test_richcmp.py
+++ b/Lib/test/test_richcmp.py
@@ -253,6 +253,31 @@ class MiscTest(unittest.TestCase):
         self.assertTrue(a != b)
         self.assertTrue(a < b)
 
+    def test_exception_message(self):
+        class Spam:
+            pass
+
+        tests = [
+            (lambda: 42 < None, r"'<' .* of 'int' and 'NoneType'"),
+            (lambda: None < 42, r"'<' .* of 'NoneType' and 'int'"),
+            (lambda: 42 > None, r"'>' .* of 'int' and 'NoneType'"),
+            (lambda: "foo" < None, r"'<' .* of 'str' and 'NoneType'"),
+            (lambda: "foo" >= 666, r"'>=' .* of 'str' and 'int'"),
+            (lambda: 42 <= None, r"'<=' .* of 'int' and 'NoneType'"),
+            (lambda: 42 >= None, r"'>=' .* of 'int' and 'NoneType'"),
+            (lambda: 42 < [], r"'<' .* of 'int' and 'list'"),
+            (lambda: () > [], r"'>' .* of 'tuple' and 'list'"),
+            (lambda: None >= None, r"'>=' .* of 'NoneType' and 'NoneType'"),
+            (lambda: Spam() < 42, r"'<' .* of 'Spam' and 'int'"),
+            (lambda: 42 < Spam(), r"'<' .* of 'int' and 'Spam'"),
+            (lambda: Spam() <= Spam(), r"'<=' .* of 'Spam' and 'Spam'"),
+        ]
+        for i, test in enumerate(tests):
+            with self.subTest(test=i):
+                with self.assertRaisesRegex(TypeError, test[1]):
+                    test[0]()
+
+
 class DictTest(unittest.TestCase):
 
     def test_dicts(self):
diff --git a/Lib/test/test_rlcompleter.py b/Lib/test/test_rlcompleter.py
index 853e77330a..0dc1080ca3 100644
--- a/Lib/test/test_rlcompleter.py
+++ b/Lib/test/test_rlcompleter.py
@@ -1,11 +1,12 @@
 import unittest
-import unittest.mock
+from unittest.mock import patch
 import builtins
 import rlcompleter
 
 class CompleteMe:
     """ Trivial class used in testing rlcompleter.Completer. """
     spam = 1
+    _ham = 2
 
 
 class TestRlcompleter(unittest.TestCase):
@@ -52,18 +53,32 @@ class TestRlcompleter(unittest.TestCase):
                          ['str.{}('.format(x) for x in dir(str)
                           if x.startswith('s')])
         self.assertEqual(self.stdcompleter.attr_matches('tuple.foospamegg'), [])
+        expected = sorted({'None.%s%s' % (x, '(' if x != '__doc__' else '')
+                           for x in dir(None)})
+        self.assertEqual(self.stdcompleter.attr_matches('None.'), expected)
+        self.assertEqual(self.stdcompleter.attr_matches('None._'), expected)
+        self.assertEqual(self.stdcompleter.attr_matches('None.__'), expected)
 
         # test with a customized namespace
         self.assertEqual(self.completer.attr_matches('CompleteMe.sp'),
                          ['CompleteMe.spam'])
         self.assertEqual(self.completer.attr_matches('Completeme.egg'), [])
+        self.assertEqual(self.completer.attr_matches('CompleteMe.'),
+                         ['CompleteMe.mro(', 'CompleteMe.spam'])
+        self.assertEqual(self.completer.attr_matches('CompleteMe._'),
+                         ['CompleteMe._ham'])
+        matches = self.completer.attr_matches('CompleteMe.__')
+        for x in matches:
+            self.assertTrue(x.startswith('CompleteMe.__'), x)
+        self.assertIn('CompleteMe.__name__', matches)
+        self.assertIn('CompleteMe.__new__(', matches)
 
-        CompleteMe.me = CompleteMe
-        self.assertEqual(self.completer.attr_matches('CompleteMe.me.me.sp'),
-                         ['CompleteMe.me.me.spam'])
-        self.assertEqual(self.completer.attr_matches('egg.s'),
-                         ['egg.{}('.format(x) for x in dir(str)
-                          if x.startswith('s')])
+        with patch.object(CompleteMe, "me", CompleteMe, create=True):
+            self.assertEqual(self.completer.attr_matches('CompleteMe.me.me.sp'),
+                             ['CompleteMe.me.me.spam'])
+            self.assertEqual(self.completer.attr_matches('egg.s'),
+                             ['egg.{}('.format(x) for x in dir(str)
+                              if x.startswith('s')])
 
     def test_excessive_getattr(self):
         # Ensure getattr() is invoked no more than once per attribute
@@ -78,14 +93,27 @@ class TestRlcompleter(unittest.TestCase):
         self.assertEqual(completer.complete('f.b', 0), 'f.bar')
         self.assertEqual(f.calls, 1)
 
+    def test_uncreated_attr(self):
+        # Attributes like properties and slots should be completed even when
+        # they haven't been created on an instance
+        class Foo:
+            __slots__ = ("bar",)
+        completer = rlcompleter.Completer(dict(f=Foo()))
+        self.assertEqual(completer.complete('f.', 0), 'f.bar')
+
     @unittest.mock.patch('rlcompleter._readline_available', False)
     def test_complete(self):
         completer = rlcompleter.Completer()
         self.assertEqual(completer.complete('', 0), '\t')
-        self.assertEqual(completer.complete('a', 0), 'and')
-        self.assertEqual(completer.complete('a', 1), 'as')
-        self.assertEqual(completer.complete('as', 2), 'assert')
-        self.assertEqual(completer.complete('an', 0), 'and')
+        self.assertEqual(completer.complete('a', 0), 'and ')
+        self.assertEqual(completer.complete('a', 1), 'as ')
+        self.assertEqual(completer.complete('as', 2), 'assert ')
+        self.assertEqual(completer.complete('an', 0), 'and ')
+        self.assertEqual(completer.complete('pa', 0), 'pass')
+        self.assertEqual(completer.complete('Fa', 0), 'False')
+        self.assertEqual(completer.complete('el', 0), 'elif ')
+        self.assertEqual(completer.complete('el', 1), 'else')
+        self.assertEqual(completer.complete('tr', 0), 'try:')
 
     def test_duplicate_globals(self):
         namespace = {
@@ -98,9 +126,10 @@ class TestRlcompleter(unittest.TestCase):
         completer = rlcompleter.Completer(namespace)
         self.assertEqual(completer.complete('False', 0), 'False')
         self.assertIsNone(completer.complete('False', 1))  # No duplicates
-        self.assertEqual(completer.complete('assert', 0), 'assert')
+        # Space or colon added due to being a reserved keyword
+        self.assertEqual(completer.complete('assert', 0), 'assert ')
         self.assertIsNone(completer.complete('assert', 1))
-        self.assertEqual(completer.complete('try', 0), 'try')
+        self.assertEqual(completer.complete('try', 0), 'try:')
         self.assertIsNone(completer.complete('try', 1))
         # No opening bracket "(" because we overrode the built-in class
         self.assertEqual(completer.complete('memoryview', 0), 'memoryview')
diff --git a/Lib/test/test_robotparser.py b/Lib/test/test_robotparser.py
index d01266f330..76f4f7c614 100644
--- a/Lib/test/test_robotparser.py
+++ b/Lib/test/test_robotparser.py
@@ -1,8 +1,7 @@
 import io
 import unittest
 import urllib.robotparser
-from urllib.error import URLError, HTTPError
-from urllib.request import urlopen
+from collections import namedtuple
 from test import support
 from http.server import BaseHTTPRequestHandler, HTTPServer
 try:
@@ -12,7 +11,8 @@ except ImportError:
 
 
 class RobotTestCase(unittest.TestCase):
-    def __init__(self, index=None, parser=None, url=None, good=None, agent=None):
+    def __init__(self, index=None, parser=None, url=None, good=None,
+                 agent=None, request_rate=None, crawl_delay=None):
         # workaround to make unittest discovery work (see #17066)
         if not isinstance(index, int):
             return
@@ -25,6 +25,8 @@ class RobotTestCase(unittest.TestCase):
         self.url = url
         self.good = good
         self.agent = agent
+        self.request_rate = request_rate
+        self.crawl_delay = crawl_delay
 
     def runTest(self):
         if isinstance(self.url, tuple):
@@ -34,6 +36,18 @@ class RobotTestCase(unittest.TestCase):
             agent = self.agent
         if self.good:
             self.assertTrue(self.parser.can_fetch(agent, url))
+            self.assertEqual(self.parser.crawl_delay(agent), self.crawl_delay)
+            # if we have actual values for request rate
+            if self.request_rate and self.parser.request_rate(agent):
+                self.assertEqual(
+                    self.parser.request_rate(agent).requests,
+                    self.request_rate.requests
+                )
+                self.assertEqual(
+                    self.parser.request_rate(agent).seconds,
+                    self.request_rate.seconds
+                )
+            self.assertEqual(self.parser.request_rate(agent), self.request_rate)
         else:
             self.assertFalse(self.parser.can_fetch(agent, url))
 
@@ -43,15 +57,17 @@ class RobotTestCase(unittest.TestCase):
 tests = unittest.TestSuite()
 
 def RobotTest(index, robots_txt, good_urls, bad_urls,
-              agent="test_robotparser"):
+              request_rate, crawl_delay, agent="test_robotparser"):
 
     lines = io.StringIO(robots_txt).readlines()
     parser = urllib.robotparser.RobotFileParser()
     parser.parse(lines)
     for url in good_urls:
-        tests.addTest(RobotTestCase(index, parser, url, 1, agent))
+        tests.addTest(RobotTestCase(index, parser, url, 1, agent,
+                      request_rate, crawl_delay))
     for url in bad_urls:
-        tests.addTest(RobotTestCase(index, parser, url, 0, agent))
+        tests.addTest(RobotTestCase(index, parser, url, 0, agent,
+                      request_rate, crawl_delay))
 
 # Examples from http://www.robotstxt.org/wc/norobots.html (fetched 2002)
 
@@ -65,14 +81,18 @@ Disallow: /foo.html
 
 good = ['/','/test.html']
 bad = ['/cyberworld/map/index.html','/tmp/xxx','/foo.html']
+request_rate = None
+crawl_delay = None
 
-RobotTest(1, doc, good, bad)
+RobotTest(1, doc, good, bad, request_rate, crawl_delay)
 
 # 2.
 doc = """
 # robots.txt for http://www.example.com/
 
 User-agent: *
+Crawl-delay: 1
+Request-rate: 3/15
 Disallow: /cyberworld/map/ # This is an infinite virtual URL space
 
 # Cybermapper knows where to go.
@@ -83,8 +103,10 @@ Disallow:
 
 good = ['/','/test.html',('cybermapper','/cyberworld/map/index.html')]
 bad = ['/cyberworld/map/index.html']
+request_rate = None  # The parameters should be equal to None since they
+crawl_delay = None   # don't apply to the cybermapper user agent
 
-RobotTest(2, doc, good, bad)
+RobotTest(2, doc, good, bad, request_rate, crawl_delay)
 
 # 3.
 doc = """
@@ -95,14 +117,18 @@ Disallow: /
 
 good = []
 bad = ['/cyberworld/map/index.html','/','/tmp/']
+request_rate = None
+crawl_delay = None
 
-RobotTest(3, doc, good, bad)
+RobotTest(3, doc, good, bad, request_rate, crawl_delay)
 
 # Examples from http://www.robotstxt.org/wc/norobots-rfc.html (fetched 2002)
 
 # 4.
 doc = """
 User-agent: figtree
+Crawl-delay: 3
+Request-rate: 9/30
 Disallow: /tmp
 Disallow: /a%3cd.html
 Disallow: /a%2fb.html
@@ -115,8 +141,17 @@ bad = ['/tmp','/tmp.html','/tmp/a.html',
        '/~joe/index.html'
        ]
 
-RobotTest(4, doc, good, bad, 'figtree')
-RobotTest(5, doc, good, bad, 'FigTree Robot libwww-perl/5.04')
+request_rate = namedtuple('req_rate', 'requests seconds')
+request_rate.requests = 9
+request_rate.seconds = 30
+crawl_delay = 3
+request_rate_bad = None  # not actually tested, but we still need to parse it
+crawl_delay_bad = None  # in order to accommodate the input parameters
+
+
+RobotTest(4, doc, good, bad, request_rate, crawl_delay, 'figtree' )
+RobotTest(5, doc, good, bad, request_rate_bad, crawl_delay_bad,
+          'FigTree Robot libwww-perl/5.04')
 
 # 6.
 doc = """
@@ -125,14 +160,18 @@ Disallow: /tmp/
 Disallow: /a%3Cd.html
 Disallow: /a/b.html
 Disallow: /%7ejoe/index.html
+Crawl-delay: 3
+Request-rate: 9/banana
 """
 
 good = ['/tmp',] # XFAIL: '/a%2fb.html'
 bad = ['/tmp/','/tmp/a.html',
        '/a%3cd.html','/a%3Cd.html',"/a/b.html",
        '/%7Ejoe/index.html']
+crawl_delay = 3
+request_rate = None  # since request rate has invalid syntax, return None
 
-RobotTest(6, doc, good, bad)
+RobotTest(6, doc, good, bad, None, None)
 
 # From bug report #523041
 
@@ -140,12 +179,16 @@ RobotTest(6, doc, good, bad)
 doc = """
 User-Agent: *
 Disallow: /.
+Crawl-delay: pears
 """
 
 good = ['/foo.html']
-bad = [] # Bug report says "/" should be denied, but that is not in the RFC
+bad = []  # bug report says "/" should be denied, but that is not in the RFC
+
+crawl_delay = None  # since crawl delay has invalid syntax, return None
+request_rate = None
 
-RobotTest(7, doc, good, bad)
+RobotTest(7, doc, good, bad, crawl_delay, request_rate)
 
 # From Google: http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=40364
 
@@ -154,12 +197,15 @@ doc = """
 User-agent: Googlebot
 Allow: /folder1/myfile.html
 Disallow: /folder1/
+Request-rate: whale/banana
 """
 
 good = ['/folder1/myfile.html']
 bad = ['/folder1/anotherfile.html']
+crawl_delay = None
+request_rate = None  # invalid syntax, return none
 
-RobotTest(8, doc, good, bad, agent="Googlebot")
+RobotTest(8, doc, good, bad, crawl_delay, request_rate, agent="Googlebot")
 
 # 9.  This file is incorrect because "Googlebot" is a substring of
 #     "Googlebot-Mobile", so test 10 works just like test 9.
@@ -174,12 +220,12 @@ Allow: /
 good = []
 bad = ['/something.jpg']
 
-RobotTest(9, doc, good, bad, agent="Googlebot")
+RobotTest(9, doc, good, bad, None, None, agent="Googlebot")
 
 good = []
 bad = ['/something.jpg']
 
-RobotTest(10, doc, good, bad, agent="Googlebot-Mobile")
+RobotTest(10, doc, good, bad, None, None, agent="Googlebot-Mobile")
 
 # 11.  Get the order correct.
 doc = """
@@ -193,12 +239,12 @@ Disallow: /
 good = []
 bad = ['/something.jpg']
 
-RobotTest(11, doc, good, bad, agent="Googlebot")
+RobotTest(11, doc, good, bad, None, None, agent="Googlebot")
 
 good = ['/something.jpg']
 bad = []
 
-RobotTest(12, doc, good, bad, agent="Googlebot-Mobile")
+RobotTest(12, doc, good, bad, None, None, agent="Googlebot-Mobile")
 
 
 # 13.  Google also got the order wrong in #8.  You need to specify the
@@ -212,7 +258,7 @@ Disallow: /folder1/
 good = ['/folder1/myfile.html']
 bad = ['/folder1/anotherfile.html']
 
-RobotTest(13, doc, good, bad, agent="googlebot")
+RobotTest(13, doc, good, bad, None, None, agent="googlebot")
 
 
 # 14. For issue #6325 (query string support)
@@ -224,7 +270,7 @@ Disallow: /some/path?name=value
 good = ['/some/path']
 bad = ['/some/path?name=value']
 
-RobotTest(14, doc, good, bad)
+RobotTest(14, doc, good, bad, None, None)
 
 # 15. For issue #4108 (obey first * entry)
 doc = """
@@ -238,7 +284,7 @@ Disallow: /another/path
 good = ['/another/path']
 bad = ['/some/path']
 
-RobotTest(15, doc, good, bad)
+RobotTest(15, doc, good, bad, None, None)
 
 # 16. Empty query (issue #17403). Normalizing the url first.
 doc = """
@@ -250,7 +296,7 @@ Disallow: /another/path?
 good = ['/some/path?']
 bad = ['/another/path?']
 
-RobotTest(16, doc, good, bad)
+RobotTest(16, doc, good, bad, None, None)
 
 
 class RobotHandler(BaseHTTPRequestHandler):
diff --git a/Lib/test/test_sched.py b/Lib/test/test_sched.py
index fe8e785092..f86f599afc 100644
--- a/Lib/test/test_sched.py
+++ b/Lib/test/test_sched.py
@@ -2,7 +2,6 @@ import queue
 import sched
 import time
 import unittest
-from test import support
 try:
     import threading
 except ImportError:
diff --git a/Lib/test/test_secrets.py b/Lib/test/test_secrets.py
new file mode 100644
index 0000000000..4c65cf00cd
--- /dev/null
+++ b/Lib/test/test_secrets.py
@@ -0,0 +1,123 @@
+"""Test the secrets module.
+
+As most of the functions in secrets are thin wrappers around functions
+defined elsewhere, we don't need to test them exhaustively.
+"""
+
+
+import secrets
+import unittest
+import string
+
+
+# === Unit tests ===
+
+class Compare_Digest_Tests(unittest.TestCase):
+    """Test secrets.compare_digest function."""
+
+    def test_equal(self):
+        # Test compare_digest functionality with equal (byte/text) strings.
+        for s in ("a", "bcd", "xyz123"):
+            a = s*100
+            b = s*100
+            self.assertTrue(secrets.compare_digest(a, b))
+            self.assertTrue(secrets.compare_digest(a.encode('utf-8'), b.encode('utf-8')))
+
+    def test_unequal(self):
+        # Test compare_digest functionality with unequal (byte/text) strings.
+        self.assertFalse(secrets.compare_digest("abc", "abcd"))
+        self.assertFalse(secrets.compare_digest(b"abc", b"abcd"))
+        for s in ("x", "mn", "a1b2c3"):
+            a = s*100 + "q"
+            b = s*100 + "k"
+            self.assertFalse(secrets.compare_digest(a, b))
+            self.assertFalse(secrets.compare_digest(a.encode('utf-8'), b.encode('utf-8')))
+
+    def test_bad_types(self):
+        # Test that compare_digest raises with mixed types.
+        a = 'abcde'
+        b = a.encode('utf-8')
+        assert isinstance(a, str)
+        assert isinstance(b, bytes)
+        self.assertRaises(TypeError, secrets.compare_digest, a, b)
+        self.assertRaises(TypeError, secrets.compare_digest, b, a)
+
+    def test_bool(self):
+        # Test that compare_digest returns a bool.
+        self.assertIsInstance(secrets.compare_digest("abc", "abc"), bool)
+        self.assertIsInstance(secrets.compare_digest("abc", "xyz"), bool)
+
+
+class Random_Tests(unittest.TestCase):
+    """Test wrappers around SystemRandom methods."""
+
+    def test_randbits(self):
+        # Test randbits.
+        errmsg = "randbits(%d) returned %d"
+        for numbits in (3, 12, 30):
+            for i in range(6):
+                n = secrets.randbits(numbits)
+                self.assertTrue(0 <= n < 2**numbits, errmsg % (numbits, n))
+
+    def test_choice(self):
+        # Test choice.
+        items = [1, 2, 4, 8, 16, 32, 64]
+        for i in range(10):
+            self.assertTrue(secrets.choice(items) in items)
+
+    def test_randbelow(self):
+        # Test randbelow.
+        for i in range(2, 10):
+            self.assertIn(secrets.randbelow(i), range(i))
+        self.assertRaises(ValueError, secrets.randbelow, 0)
+
+
+class Token_Tests(unittest.TestCase):
+    """Test token functions."""
+
+    def test_token_defaults(self):
+        # Test that token_* functions handle default size correctly.
+        for func in (secrets.token_bytes, secrets.token_hex,
+                     secrets.token_urlsafe):
+            with self.subTest(func=func):
+                name = func.__name__
+                try:
+                    func()
+                except TypeError:
+                    self.fail("%s cannot be called with no argument" % name)
+                try:
+                    func(None)
+                except TypeError:
+                    self.fail("%s cannot be called with None" % name)
+        size = secrets.DEFAULT_ENTROPY
+        self.assertEqual(len(secrets.token_bytes(None)), size)
+        self.assertEqual(len(secrets.token_hex(None)), 2*size)
+
+    def test_token_bytes(self):
+        # Test token_bytes.
+        for n in (1, 8, 17, 100):
+            with self.subTest(n=n):
+                self.assertIsInstance(secrets.token_bytes(n), bytes)
+                self.assertEqual(len(secrets.token_bytes(n)), n)
+
+    def test_token_hex(self):
+        # Test token_hex.
+        for n in (1, 12, 25, 90):
+            with self.subTest(n=n):
+                s = secrets.token_hex(n)
+                self.assertIsInstance(s, str)
+                self.assertEqual(len(s), 2*n)
+                self.assertTrue(all(c in string.hexdigits for c in s))
+
+    def test_token_urlsafe(self):
+        # Test token_urlsafe.
+        legal = string.ascii_letters + string.digits + '-_'
+        for n in (1, 11, 28, 76):
+            with self.subTest(n=n):
+                s = secrets.token_urlsafe(n)
+                self.assertIsInstance(s, str)
+                self.assertTrue(all(c in legal for c in s))
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/Lib/test/test_set.py b/Lib/test/test_set.py
index 1a49edf231..49abfb3e71 100644
--- a/Lib/test/test_set.py
+++ b/Lib/test/test_set.py
@@ -6,10 +6,11 @@ import operator
 import copy
 import pickle
 from random import randrange, shuffle
-import sys
 import warnings
 import collections
 import collections.abc
+import itertools
+import string
 
 class PassThru(Exception):
     pass
@@ -714,6 +715,28 @@ class TestFrozenSet(TestJointOps, unittest.TestCase):
             addhashvalue(hash(frozenset([e for e, m in elemmasks if m&i])))
         self.assertEqual(len(hashvalues), 2**n)
 
+        def letter_range(n):
+            return string.ascii_letters[:n]
+
+        def zf_range(n):
+            # https://en.wikipedia.org/wiki/Set-theoretic_definition_of_natural_numbers
+            nums = [frozenset()]
+            for i in range(n-1):
+                num = frozenset(nums)
+                nums.append(num)
+            return nums[:n]
+
+        def powerset(s):
+            for i in range(len(s)+1):
+                yield from map(frozenset, itertools.combinations(s, i))
+
+        for n in range(18):
+            t = 2 ** n
+            mask = t - 1
+            for nums in (range, letter_range, zf_range):
+                u = len({h & mask for h in map(hash, powerset(nums(n)))})
+                self.assertGreater(4*u, t)
+
 class FrozenSetSubclass(frozenset):
     pass
 
diff --git a/Lib/test/test_signal.py b/Lib/test/test_signal.py
index 1b80ff0963..ab42ed70cc 100644
--- a/Lib/test/test_signal.py
+++ b/Lib/test/test_signal.py
@@ -22,29 +22,6 @@ except ImportError:
     _testcapi = None
 
 
-class HandlerBCalled(Exception):
-    pass
-
-
-def exit_subprocess():
-    """Use os._exit(0) to exit the current subprocess.
-
-    Otherwise, the test catches the SystemExit and continues executing
-    in parallel with the original test, so you wind up with an
-    exponential number of tests running concurrently.
-    """
-    os._exit(0)
-
-
-def ignoring_eintr(__func, *args, **kwargs):
-    try:
-        return __func(*args, **kwargs)
-    except OSError as e:
-        if e.errno != errno.EINTR:
-            raise
-        return None
-
-
 class GenericTests(unittest.TestCase):
 
     @unittest.skipIf(threading is None, "test needs threading module")
@@ -63,145 +40,6 @@ class GenericTests(unittest.TestCase):
 
 
 @unittest.skipIf(sys.platform == "win32", "Not valid on Windows")
-class InterProcessSignalTests(unittest.TestCase):
-    MAX_DURATION = 20   # Entire test should last at most 20 sec.
-
-    def setUp(self):
-        self.using_gc = gc.isenabled()
-        gc.disable()
-
-    def tearDown(self):
-        if self.using_gc:
-            gc.enable()
-
-    def format_frame(self, frame, limit=None):
-        return ''.join(traceback.format_stack(frame, limit=limit))
-
-    def handlerA(self, signum, frame):
-        self.a_called = True
-
-    def handlerB(self, signum, frame):
-        self.b_called = True
-        raise HandlerBCalled(signum, self.format_frame(frame))
-
-    def wait(self, child):
-        """Wait for child to finish, ignoring EINTR."""
-        while True:
-            try:
-                child.wait()
-                return
-            except OSError as e:
-                if e.errno != errno.EINTR:
-                    raise
-
-    def run_test(self):
-        # Install handlers. This function runs in a sub-process, so we
-        # don't worry about re-setting the default handlers.
-        signal.signal(signal.SIGHUP, self.handlerA)
-        signal.signal(signal.SIGUSR1, self.handlerB)
-        signal.signal(signal.SIGUSR2, signal.SIG_IGN)
-        signal.signal(signal.SIGALRM, signal.default_int_handler)
-
-        # Variables the signals will modify:
-        self.a_called = False
-        self.b_called = False
-
-        # Let the sub-processes know who to send signals to.
-        pid = os.getpid()
-
-        child = ignoring_eintr(subprocess.Popen, ['kill', '-HUP', str(pid)])
-        if child:
-            self.wait(child)
-            if not self.a_called:
-                time.sleep(1)  # Give the signal time to be delivered.
-        self.assertTrue(self.a_called)
-        self.assertFalse(self.b_called)
-        self.a_called = False
-
-        # Make sure the signal isn't delivered while the previous
-        # Popen object is being destroyed, because __del__ swallows
-        # exceptions.
-        del child
-        try:
-            child = subprocess.Popen(['kill', '-USR1', str(pid)])
-            # This wait should be interrupted by the signal's exception.
-            self.wait(child)
-            time.sleep(1)  # Give the signal time to be delivered.
-            self.fail('HandlerBCalled exception not raised')
-        except HandlerBCalled:
-            self.assertTrue(self.b_called)
-            self.assertFalse(self.a_called)
-
-        child = ignoring_eintr(subprocess.Popen, ['kill', '-USR2', str(pid)])
-        if child:
-            self.wait(child)  # Nothing should happen.
-
-        try:
-            signal.alarm(1)
-            # The race condition in pause doesn't matter in this case,
-            # since alarm is going to raise a KeyboardException, which
-            # will skip the call.
-            signal.pause()
-            # But if another signal arrives before the alarm, pause
-            # may return early.
-            time.sleep(1)
-        except KeyboardInterrupt:
-            pass
-        except:
-            self.fail("Some other exception woke us from pause: %s" %
-                      traceback.format_exc())
-        else:
-            self.fail("pause returned of its own accord, and the signal"
-                      " didn't arrive after another second.")
-
-    # Issue 3864, unknown if this affects earlier versions of freebsd also
-    @unittest.skipIf(sys.platform=='freebsd6',
-        'inter process signals not reliable (do not mix well with threading) '
-        'on freebsd6')
-    def test_main(self):
-        # This function spawns a child process to insulate the main
-        # test-running process from all the signals. It then
-        # communicates with that child process over a pipe and
-        # re-raises information about any exceptions the child
-        # raises. The real work happens in self.run_test().
-        os_done_r, os_done_w = os.pipe()
-        with closing(os.fdopen(os_done_r, 'rb')) as done_r, \
-             closing(os.fdopen(os_done_w, 'wb')) as done_w:
-            child = os.fork()
-            if child == 0:
-                # In the child process; run the test and report results
-                # through the pipe.
-                try:
-                    done_r.close()
-                    # Have to close done_w again here because
-                    # exit_subprocess() will skip the enclosing with block.
-                    with closing(done_w):
-                        try:
-                            self.run_test()
-                        except:
-                            pickle.dump(traceback.format_exc(), done_w)
-                        else:
-                            pickle.dump(None, done_w)
-                except:
-                    print('Uh oh, raised from pickle.')
-                    traceback.print_exc()
-                finally:
-                    exit_subprocess()
-
-            done_w.close()
-            # Block for up to MAX_DURATION seconds for the test to finish.
-            r, w, x = select.select([done_r], [], [], self.MAX_DURATION)
-            if done_r in r:
-                tb = pickle.load(done_r)
-                if tb:
-                    self.fail(tb)
-            else:
-                os.kill(child, signal.SIGKILL)
-                self.fail('Test deadlocked after %d seconds.' %
-                          self.MAX_DURATION)
-
-
-@unittest.skipIf(sys.platform == "win32", "Not valid on Windows")
 class PosixTests(unittest.TestCase):
     def trivial_signal_handler(self, *args):
         pass
@@ -224,6 +62,15 @@ class PosixTests(unittest.TestCase):
         signal.signal(signal.SIGHUP, hup)
         self.assertEqual(signal.getsignal(signal.SIGHUP), hup)
 
+    # Issue 3864, unknown if this affects earlier versions of freebsd also
+    @unittest.skipIf(sys.platform=='freebsd6',
+        'inter process signals not reliable (do not mix well with threading) '
+        'on freebsd6')
+    def test_interprocess_signal(self):
+        dirname = os.path.dirname(__file__)
+        script = os.path.join(dirname, 'signalinterproctester.py')
+        assert_python_ok(script)
+
 
 @unittest.skipUnless(sys.platform == "win32", "Windows specific")
 class WindowsSignalTests(unittest.TestCase):
diff --git a/Lib/test/test_site.py b/Lib/test/test_site.py
index da20a3d21a..f698927f37 100644
--- a/Lib/test/test_site.py
+++ b/Lib/test/test_site.py
@@ -75,7 +75,7 @@ class HelperFunctionsTests(unittest.TestCase):
     def test_init_pathinfo(self):
         dir_set = site._init_pathinfo()
         for entry in [site.makepath(path)[1] for path in sys.path
-                        if path and os.path.isdir(path)]:
+                        if path and os.path.exists(path)]:
             self.assertIn(entry, dir_set,
                           "%s from sys.path not found in set returned "
                           "by _init_pathinfo(): %s" % (entry, dir_set))
@@ -243,13 +243,14 @@ class HelperFunctionsTests(unittest.TestCase):
             self.assertEqual(len(dirs), 2)
             wanted = os.path.join('/Library',
                                   sysconfig.get_config_var("PYTHONFRAMEWORK"),
-                                  sys.version[:3],
+                                  '%d.%d' % sys.version_info[:2],
                                   'site-packages')
             self.assertEqual(dirs[1], wanted)
         elif os.sep == '/':
             # OS X non-framwework builds, Linux, FreeBSD, etc
             self.assertEqual(len(dirs), 1)
-            wanted = os.path.join('xoxo', 'lib', 'python' + sys.version[:3],
+            wanted = os.path.join('xoxo', 'lib',
+                                  'python%d.%d' % sys.version_info[:2],
                                   'site-packages')
             self.assertEqual(dirs[0], wanted)
         else:
diff --git a/Lib/test/test_smtpd.py b/Lib/test/test_smtpd.py
index 88dbfdf6f0..3eebe948ad 100644
--- a/Lib/test/test_smtpd.py
+++ b/Lib/test/test_smtpd.py
@@ -53,10 +53,6 @@ class SMTPDServerTest(unittest.TestCase):
         write_line(b'DATA')
         self.assertRaises(NotImplementedError, write_line, b'spam\r\n.\r\n')
 
-    def test_decode_data_default_warns(self):
-        with self.assertWarns(DeprecationWarning):
-            smtpd.SMTPServer((support.HOST, 0), ('b', 0))
-
     def test_decode_data_and_enable_SMTPUTF8_raises(self):
         self.assertRaises(
             ValueError,
@@ -108,10 +104,9 @@ class DebuggingServerTest(unittest.TestCase):
              """))
 
     def test_process_message_with_decode_data_false(self):
-        server = smtpd.DebuggingServer((support.HOST, 0), ('b', 0),
-                                       decode_data=False)
+        server = smtpd.DebuggingServer((support.HOST, 0), ('b', 0))
         conn, addr = server.accept()
-        channel = smtpd.SMTPChannel(server, conn, addr, decode_data=False)
+        channel = smtpd.SMTPChannel(server, conn, addr)
         with support.captured_stdout() as s:
             self.send_data(channel, b'From: test\n\nh\xc3\xa9llo\xff\n')
         stdout = s.getvalue()
@@ -175,13 +170,11 @@ class TestFamilyDetection(unittest.TestCase):
 
     @unittest.skipUnless(support.IPV6_ENABLED, "IPv6 not enabled")
     def test_socket_uses_IPv6(self):
-        server = smtpd.SMTPServer((support.HOSTv6, 0), (support.HOST, 0),
-                                  decode_data=False)
+        server = smtpd.SMTPServer((support.HOSTv6, 0), (support.HOST, 0))
         self.assertEqual(server.socket.family, socket.AF_INET6)
 
     def test_socket_uses_IPv4(self):
-        server = smtpd.SMTPServer((support.HOST, 0), (support.HOSTv6, 0),
-                                  decode_data=False)
+        server = smtpd.SMTPServer((support.HOST, 0), (support.HOSTv6, 0))
         self.assertEqual(server.socket.family, socket.AF_INET)
 
 
@@ -204,18 +197,18 @@ class TestRcptOptionParsing(unittest.TestCase):
         channel.handle_read()
 
     def test_params_rejected(self):
-        server = DummyServer((support.HOST, 0), ('b', 0), decode_data=False)
+        server = DummyServer((support.HOST, 0), ('b', 0))
         conn, addr = server.accept()
-        channel = smtpd.SMTPChannel(server, conn, addr, decode_data=False)
+        channel = smtpd.SMTPChannel(server, conn, addr)
         self.write_line(channel, b'EHLO example')
         self.write_line(channel, b'MAIL from: <foo@example.com> size=20')
         self.write_line(channel, b'RCPT to: <foo@example.com> foo=bar')
         self.assertEqual(channel.socket.last, self.error_response)
 
     def test_nothing_accepted(self):
-        server = DummyServer((support.HOST, 0), ('b', 0), decode_data=False)
+        server = DummyServer((support.HOST, 0), ('b', 0))
         conn, addr = server.accept()
-        channel = smtpd.SMTPChannel(server, conn, addr, decode_data=False)
+        channel = smtpd.SMTPChannel(server, conn, addr)
         self.write_line(channel, b'EHLO example')
         self.write_line(channel, b'MAIL from: <foo@example.com> size=20')
         self.write_line(channel, b'RCPT to: <foo@example.com>')
@@ -257,9 +250,9 @@ class TestMailOptionParsing(unittest.TestCase):
         self.assertEqual(channel.socket.last, b'250 OK\r\n')
 
     def test_with_decode_data_false(self):
-        server = DummyServer((support.HOST, 0), ('b', 0), decode_data=False)
+        server = DummyServer((support.HOST, 0), ('b', 0))
         conn, addr = server.accept()
-        channel = smtpd.SMTPChannel(server, conn, addr, decode_data=False)
+        channel = smtpd.SMTPChannel(server, conn, addr)
         self.write_line(channel, b'EHLO example')
         for line in [
             b'MAIL from: <foo@example.com> size=20 SMTPUTF8',
@@ -765,13 +758,6 @@ class SMTPDChannelTest(unittest.TestCase):
         with support.check_warnings(('', DeprecationWarning)):
             self.channel._SMTPChannel__addr = 'spam'
 
-    def test_decode_data_default_warning(self):
-        with self.assertWarns(DeprecationWarning):
-            server = DummyServer((support.HOST, 0), ('b', 0))
-        conn, addr = self.server.accept()
-        with self.assertWarns(DeprecationWarning):
-            smtpd.SMTPChannel(server, conn, addr)
-
 @unittest.skipUnless(support.IPV6_ENABLED, "IPv6 not enabled")
 class SMTPDChannelIPv6Test(SMTPDChannelTest):
     def setUp(self):
@@ -845,12 +831,9 @@ class SMTPDChannelWithDecodeDataFalse(unittest.TestCase):
         smtpd.socket = asyncore.socket = mock_socket
         self.old_debugstream = smtpd.DEBUGSTREAM
         self.debug = smtpd.DEBUGSTREAM = io.StringIO()
-        self.server = DummyServer((support.HOST, 0), ('b', 0),
-                                  decode_data=False)
+        self.server = DummyServer((support.HOST, 0), ('b', 0))
         conn, addr = self.server.accept()
-        # Set decode_data to False
-        self.channel = smtpd.SMTPChannel(self.server, conn, addr,
-                decode_data=False)
+        self.channel = smtpd.SMTPChannel(self.server, conn, addr)
 
     def tearDown(self):
         asyncore.close_all()
@@ -1015,5 +998,16 @@ class SMTPDChannelTestWithEnableSMTPUTF8True(unittest.TestCase):
             self.write_line(b'test\r\n.')
             self.assertEqual(self.channel.socket.last[0:3], b'250')
 
+
+class MiscTestCase(unittest.TestCase):
+    def test__all__(self):
+        blacklist = {
+            "program", "Devnull", "DEBUGSTREAM", "NEWLINE", "COMMASPACE",
+            "DATA_SIZE_DEFAULT", "usage", "Options", "parseargs",
+
+        }
+        support.check__all__(self, smtpd, blacklist=blacklist)
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
index c151a50dcb..1ddd6044b9 100644
--- a/Lib/test/test_socket.py
+++ b/Lib/test/test_socket.py
@@ -13,7 +13,6 @@ import queue
 import sys
 import os
 import array
-import platform
 import contextlib
 from weakref import proxy
 import signal
@@ -1161,6 +1160,17 @@ class GeneralModuleTests(unittest.TestCase):
         sock.close()
         self.assertRaises(OSError, sock.send, b"spam")
 
+    def testCloseException(self):
+        sock = socket.socket()
+        socket.socket(fileno=sock.fileno()).close()
+        try:
+            sock.close()
+        except OSError as err:
+            # Winsock apparently raises ENOTSOCK
+            self.assertIn(err.errno, (errno.EBADF, errno.ENOTSOCK))
+        else:
+            self.fail("close() should raise EBADF/ENOTSOCK")
+
     def testNewAttributes(self):
         # testing .family, .type and .protocol
 
@@ -2823,6 +2833,7 @@ class SCMRightsTest(SendrecvmsgServerTimeoutBase):
             nbytes = self.sendmsgToServer([msg])
         self.assertEqual(nbytes, len(msg))
 
+    @unittest.skipIf(sys.platform == "darwin", "see issue #24725")
     def testFDPassEmpty(self):
         # Try to pass an empty FD array.  Can receive either no array
         # or an empty array.
diff --git a/Lib/test/test_socketserver.py b/Lib/test/test_socketserver.py
index 0d0f86fca4..9a907292aa 100644
--- a/Lib/test/test_socketserver.py
+++ b/Lib/test/test_socketserver.py
@@ -7,8 +7,6 @@ import os
 import select
 import signal
 import socket
-import select
-import errno
 import tempfile
 import unittest
 import socketserver
@@ -46,7 +44,7 @@ def receive(sock, n, timeout=20):
     else:
         raise RuntimeError("timed out on %r" % (sock,))
 
-if HAVE_UNIX_SOCKETS:
+if HAVE_UNIX_SOCKETS and HAVE_FORKING:
     class ForkingUnixStreamServer(socketserver.ForkingMixIn,
                                   socketserver.UnixStreamServer):
         pass
@@ -58,6 +56,7 @@ if HAVE_UNIX_SOCKETS:
 
 @contextlib.contextmanager
 def simple_subprocess(testcase):
+    """Tests that a custom child process is not waited on (Issue 1540386)"""
     pid = os.fork()
     if pid == 0:
         # Don't raise an exception; it would be caught by the test harness.
@@ -103,7 +102,6 @@ class SocketServerTest(unittest.TestCase):
         class MyServer(svrcls):
             def handle_error(self, request, client_address):
                 self.close_request(request)
-                self.server_close()
                 raise
 
         class MyHandler(hdlrbase):
@@ -279,6 +277,104 @@ class SocketServerTest(unittest.TestCase):
                 socketserver.TCPServer((HOST, -1),
                                        socketserver.StreamRequestHandler)
 
+    def test_context_manager(self):
+        with socketserver.TCPServer((HOST, 0),
+                                    socketserver.StreamRequestHandler) as server:
+            pass
+        self.assertEqual(-1, server.socket.fileno())
+
+
+class ErrorHandlerTest(unittest.TestCase):
+    """Test that the servers pass normal exceptions from the handler to
+    handle_error(), and that exiting exceptions like SystemExit and
+    KeyboardInterrupt are not passed."""
+
+    def tearDown(self):
+        test.support.unlink(test.support.TESTFN)
+
+    def test_sync_handled(self):
+        BaseErrorTestServer(ValueError)
+        self.check_result(handled=True)
+
+    def test_sync_not_handled(self):
+        with self.assertRaises(SystemExit):
+            BaseErrorTestServer(SystemExit)
+        self.check_result(handled=False)
+
+    @unittest.skipUnless(threading, 'Threading required for this test.')
+    def test_threading_handled(self):
+        ThreadingErrorTestServer(ValueError)
+        self.check_result(handled=True)
+
+    @unittest.skipUnless(threading, 'Threading required for this test.')
+    def test_threading_not_handled(self):
+        ThreadingErrorTestServer(SystemExit)
+        self.check_result(handled=False)
+
+    @requires_forking
+    def test_forking_handled(self):
+        ForkingErrorTestServer(ValueError)
+        self.check_result(handled=True)
+
+    @requires_forking
+    def test_forking_not_handled(self):
+        ForkingErrorTestServer(SystemExit)
+        self.check_result(handled=False)
+
+    def check_result(self, handled):
+        with open(test.support.TESTFN) as log:
+            expected = 'Handler called\n' + 'Error handled\n' * handled
+            self.assertEqual(log.read(), expected)
+
+
+class BaseErrorTestServer(socketserver.TCPServer):
+    def __init__(self, exception):
+        self.exception = exception
+        super().__init__((HOST, 0), BadHandler)
+        with socket.create_connection(self.server_address):
+            pass
+        try:
+            self.handle_request()
+        finally:
+            self.server_close()
+        self.wait_done()
+
+    def handle_error(self, request, client_address):
+        with open(test.support.TESTFN, 'a') as log:
+            log.write('Error handled\n')
+
+    def wait_done(self):
+        pass
+
+
+class BadHandler(socketserver.BaseRequestHandler):
+    def handle(self):
+        with open(test.support.TESTFN, 'a') as log:
+            log.write('Handler called\n')
+        raise self.server.exception('Test error')
+
+
+class ThreadingErrorTestServer(socketserver.ThreadingMixIn,
+        BaseErrorTestServer):
+    def __init__(self, *pos, **kw):
+        self.done = threading.Event()
+        super().__init__(*pos, **kw)
+
+    def shutdown_request(self, *pos, **kw):
+        super().shutdown_request(*pos, **kw)
+        self.done.set()
+
+    def wait_done(self):
+        self.done.wait()
+
+
+if HAVE_FORKING:
+    class ForkingErrorTestServer(socketserver.ForkingMixIn, BaseErrorTestServer):
+        def wait_done(self):
+            [child] = self.active_children
+            os.waitpid(child, 0)
+            self.active_children.clear()
+
 
 class MiscTestCase(unittest.TestCase):
 
diff --git a/Lib/test/test_sort.py b/Lib/test/test_sort.py
index a5d0ebfd5a..98ccab5c39 100644
--- a/Lib/test/test_sort.py
+++ b/Lib/test/test_sort.py
@@ -1,6 +1,5 @@
 from test import support
 import random
-import sys
 import unittest
 from functools import cmp_to_key
 
diff --git a/Lib/test/test_spwd.py b/Lib/test/test_spwd.py
index bea7ab1ba5..e893f3a847 100644
--- a/Lib/test/test_spwd.py
+++ b/Lib/test/test_spwd.py
@@ -56,5 +56,20 @@ class TestSpwdRoot(unittest.TestCase):
             self.assertRaises(TypeError, spwd.getspnam, bytes_name)
 
 
+@unittest.skipUnless(hasattr(os, 'geteuid') and os.geteuid() != 0,
+                     'non-root user required')
+class TestSpwdNonRoot(unittest.TestCase):
+
+    def test_getspnam_exception(self):
+        name = 'bin'
+        try:
+            with self.assertRaises(PermissionError) as cm:
+                spwd.getspnam(name)
+        except KeyError as exc:
+            self.skipTest("spwd entry %r doesn't exist: %s" % (name, exc))
+        else:
+            self.assertEqual(str(cm.exception), '[Errno 13] Permission denied')
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index 645ec8d100..00d437a951 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -21,6 +21,13 @@ import functools
 
 ssl = support.import_module("ssl")
 
+try:
+    import threading
+except ImportError:
+    _have_threads = False
+else:
+    _have_threads = True
+
 PROTOCOLS = sorted(ssl._PROTOCOL_NAMES)
 HOST = support.HOST
 
@@ -53,10 +60,10 @@ CRLFILE = data_file("revocation.crl")
 # Two keys and certs signed by the same CA (for SNI tests)
 SIGNED_CERTFILE = data_file("keycert3.pem")
 SIGNED_CERTFILE2 = data_file("keycert4.pem")
-SIGNING_CA = data_file("pycacert.pem")
+# Same certificate as pycacert.pem, but without extra text in file
+SIGNING_CA = data_file("capath", "ceff1710.0")
 
 REMOTE_HOST = "self-signed.pythontest.net"
-REMOTE_ROOT_CERT = data_file("selfsigned_pythontestdotnet.pem")
 
 EMPTYCERT = data_file("nullcert.pem")
 BADCERT = data_file("badcert.pem")
@@ -328,7 +335,7 @@ class BasicSocketTests(unittest.TestCase):
         wr = weakref.ref(ss)
         with support.check_warnings(("", ResourceWarning)):
             del ss
-            self.assertEqual(wr(), None)
+        self.assertEqual(wr(), None)
 
     def test_wrapped_unconnected(self):
         # Methods on an unconnected SSLSocket propagate the original
@@ -783,6 +790,22 @@ class BasicSocketTests(unittest.TestCase):
         self.cert_time_ok("Feb  9 00:00:00 2007 GMT", 1170979200.0)
         self.cert_time_fail(local_february_name() + "  9 00:00:00 2007 GMT")
 
+    def test_connect_ex_error(self):
+        server = socket.socket(socket.AF_INET)
+        self.addCleanup(server.close)
+        port = support.bind_port(server)  # Reserve port but don't listen
+        s = ssl.wrap_socket(socket.socket(socket.AF_INET),
+                            cert_reqs=ssl.CERT_REQUIRED)
+        self.addCleanup(s.close)
+        rc = s.connect_ex((HOST, port))
+        # Issue #19919: Windows machines or VMs hosted on Windows
+        # machines sometimes return EWOULDBLOCK.
+        errors = (
+            errno.ECONNREFUSED, errno.EHOSTUNREACH, errno.ETIMEDOUT,
+            errno.EWOULDBLOCK,
+        )
+        self.assertIn(rc, errors)
+
 
 class ContextTests(unittest.TestCase):
 
@@ -1368,140 +1391,103 @@ class MemoryBIOTests(unittest.TestCase):
         self.assertRaises(TypeError, bio.write, 1)
 
 
-class NetworkedTests(unittest.TestCase):
+@unittest.skipUnless(_have_threads, "Needs threading module")
+class SimpleBackgroundTests(unittest.TestCase):
 
-    def test_connect(self):
-        with support.transient_internet(REMOTE_HOST):
-            s = ssl.wrap_socket(socket.socket(socket.AF_INET),
-                                cert_reqs=ssl.CERT_NONE)
-            try:
-                s.connect((REMOTE_HOST, 443))
-                self.assertEqual({}, s.getpeercert())
-            finally:
-                s.close()
+    """Tests that connect to a simple server running in the background"""
 
-            # this should fail because we have no verification certs
-            s = ssl.wrap_socket(socket.socket(socket.AF_INET),
-                                cert_reqs=ssl.CERT_REQUIRED)
-            self.assertRaisesRegex(ssl.SSLError, "certificate verify failed",
-                                   s.connect, (REMOTE_HOST, 443))
-            s.close()
+    def setUp(self):
+        server = ThreadedEchoServer(SIGNED_CERTFILE)
+        self.server_addr = (HOST, server.port)
+        server.__enter__()
+        self.addCleanup(server.__exit__, None, None, None)
 
-            # this should succeed because we specify the root cert
-            s = ssl.wrap_socket(socket.socket(socket.AF_INET),
-                                cert_reqs=ssl.CERT_REQUIRED,
-                                ca_certs=REMOTE_ROOT_CERT)
-            try:
-                s.connect((REMOTE_HOST, 443))
-                self.assertTrue(s.getpeercert())
-            finally:
-                s.close()
+    def test_connect(self):
+        with ssl.wrap_socket(socket.socket(socket.AF_INET),
+                            cert_reqs=ssl.CERT_NONE) as s:
+            s.connect(self.server_addr)
+            self.assertEqual({}, s.getpeercert())
+
+        # this should succeed because we specify the root cert
+        with ssl.wrap_socket(socket.socket(socket.AF_INET),
+                            cert_reqs=ssl.CERT_REQUIRED,
+                            ca_certs=SIGNING_CA) as s:
+            s.connect(self.server_addr)
+            self.assertTrue(s.getpeercert())
+
+    def test_connect_fail(self):
+        # This should fail because we have no verification certs. Connection
+        # failure crashes ThreadedEchoServer, so run this in an independent
+        # test method.
+        s = ssl.wrap_socket(socket.socket(socket.AF_INET),
+                            cert_reqs=ssl.CERT_REQUIRED)
+        self.addCleanup(s.close)
+        self.assertRaisesRegex(ssl.SSLError, "certificate verify failed",
+                               s.connect, self.server_addr)
 
     def test_connect_ex(self):
         # Issue #11326: check connect_ex() implementation
-        with support.transient_internet(REMOTE_HOST):
-            s = ssl.wrap_socket(socket.socket(socket.AF_INET),
-                                cert_reqs=ssl.CERT_REQUIRED,
-                                ca_certs=REMOTE_ROOT_CERT)
-            try:
-                self.assertEqual(0, s.connect_ex((REMOTE_HOST, 443)))
-                self.assertTrue(s.getpeercert())
-            finally:
-                s.close()
+        s = ssl.wrap_socket(socket.socket(socket.AF_INET),
+                            cert_reqs=ssl.CERT_REQUIRED,
+                            ca_certs=SIGNING_CA)
+        self.addCleanup(s.close)
+        self.assertEqual(0, s.connect_ex(self.server_addr))
+        self.assertTrue(s.getpeercert())
 
     def test_non_blocking_connect_ex(self):
         # Issue #11326: non-blocking connect_ex() should allow handshake
         # to proceed after the socket gets ready.
-        with support.transient_internet(REMOTE_HOST):
-            s = ssl.wrap_socket(socket.socket(socket.AF_INET),
-                                cert_reqs=ssl.CERT_REQUIRED,
-                                ca_certs=REMOTE_ROOT_CERT,
-                                do_handshake_on_connect=False)
+        s = ssl.wrap_socket(socket.socket(socket.AF_INET),
+                            cert_reqs=ssl.CERT_REQUIRED,
+                            ca_certs=SIGNING_CA,
+                            do_handshake_on_connect=False)
+        self.addCleanup(s.close)
+        s.setblocking(False)
+        rc = s.connect_ex(self.server_addr)
+        # EWOULDBLOCK under Windows, EINPROGRESS elsewhere
+        self.assertIn(rc, (0, errno.EINPROGRESS, errno.EWOULDBLOCK))
+        # Wait for connect to finish
+        select.select([], [s], [], 5.0)
+        # Non-blocking handshake
+        while True:
             try:
-                s.setblocking(False)
-                rc = s.connect_ex((REMOTE_HOST, 443))
-                # EWOULDBLOCK under Windows, EINPROGRESS elsewhere
-                self.assertIn(rc, (0, errno.EINPROGRESS, errno.EWOULDBLOCK))
-                # Wait for connect to finish
+                s.do_handshake()
+                break
+            except ssl.SSLWantReadError:
+                select.select([s], [], [], 5.0)
+            except ssl.SSLWantWriteError:
                 select.select([], [s], [], 5.0)
-                # Non-blocking handshake
-                while True:
-                    try:
-                        s.do_handshake()
-                        break
-                    except ssl.SSLWantReadError:
-                        select.select([s], [], [], 5.0)
-                    except ssl.SSLWantWriteError:
-                        select.select([], [s], [], 5.0)
-                # SSL established
-                self.assertTrue(s.getpeercert())
-            finally:
-                s.close()
-
-    def test_timeout_connect_ex(self):
-        # Issue #12065: on a timeout, connect_ex() should return the original
-        # errno (mimicking the behaviour of non-SSL sockets).
-        with support.transient_internet(REMOTE_HOST):
-            s = ssl.wrap_socket(socket.socket(socket.AF_INET),
-                                cert_reqs=ssl.CERT_REQUIRED,
-                                ca_certs=REMOTE_ROOT_CERT,
-                                do_handshake_on_connect=False)
-            try:
-                s.settimeout(0.0000001)
-                rc = s.connect_ex((REMOTE_HOST, 443))
-                if rc == 0:
-                    self.skipTest("REMOTE_HOST responded too quickly")
-                self.assertIn(rc, (errno.EAGAIN, errno.EWOULDBLOCK))
-            finally:
-                s.close()
-
-    def test_connect_ex_error(self):
-        with support.transient_internet(REMOTE_HOST):
-            s = ssl.wrap_socket(socket.socket(socket.AF_INET),
-                                cert_reqs=ssl.CERT_REQUIRED,
-                                ca_certs=REMOTE_ROOT_CERT)
-            try:
-                rc = s.connect_ex((REMOTE_HOST, 444))
-                # Issue #19919: Windows machines or VMs hosted on Windows
-                # machines sometimes return EWOULDBLOCK.
-                errors = (
-                    errno.ECONNREFUSED, errno.EHOSTUNREACH, errno.ETIMEDOUT,
-                    errno.EWOULDBLOCK,
-                )
-                self.assertIn(rc, errors)
-            finally:
-                s.close()
+        # SSL established
+        self.assertTrue(s.getpeercert())
 
     def test_connect_with_context(self):
-        with support.transient_internet(REMOTE_HOST):
-            # Same as test_connect, but with a separately created context
-            ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
-            s = ctx.wrap_socket(socket.socket(socket.AF_INET))
-            s.connect((REMOTE_HOST, 443))
-            try:
-                self.assertEqual({}, s.getpeercert())
-            finally:
-                s.close()
-            # Same with a server hostname
-            s = ctx.wrap_socket(socket.socket(socket.AF_INET),
-                                server_hostname=REMOTE_HOST)
-            s.connect((REMOTE_HOST, 443))
-            s.close()
-            # This should fail because we have no verification certs
-            ctx.verify_mode = ssl.CERT_REQUIRED
-            s = ctx.wrap_socket(socket.socket(socket.AF_INET))
-            self.assertRaisesRegex(ssl.SSLError, "certificate verify failed",
-                                    s.connect, (REMOTE_HOST, 443))
-            s.close()
-            # This should succeed because we specify the root cert
-            ctx.load_verify_locations(REMOTE_ROOT_CERT)
-            s = ctx.wrap_socket(socket.socket(socket.AF_INET))
-            s.connect((REMOTE_HOST, 443))
-            try:
-                cert = s.getpeercert()
-                self.assertTrue(cert)
-            finally:
-                s.close()
+        # Same as test_connect, but with a separately created context
+        ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
+        with ctx.wrap_socket(socket.socket(socket.AF_INET)) as s:
+            s.connect(self.server_addr)
+            self.assertEqual({}, s.getpeercert())
+        # Same with a server hostname
+        with ctx.wrap_socket(socket.socket(socket.AF_INET),
+                            server_hostname="dummy") as s:
+            s.connect(self.server_addr)
+        ctx.verify_mode = ssl.CERT_REQUIRED
+        # This should succeed because we specify the root cert
+        ctx.load_verify_locations(SIGNING_CA)
+        with ctx.wrap_socket(socket.socket(socket.AF_INET)) as s:
+            s.connect(self.server_addr)
+            cert = s.getpeercert()
+            self.assertTrue(cert)
+
+    def test_connect_with_context_fail(self):
+        # This should fail because we have no verification certs. Connection
+        # failure crashes ThreadedEchoServer, so run this in an independent
+        # test method.
+        ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
+        ctx.verify_mode = ssl.CERT_REQUIRED
+        s = ctx.wrap_socket(socket.socket(socket.AF_INET))
+        self.addCleanup(s.close)
+        self.assertRaisesRegex(ssl.SSLError, "certificate verify failed",
+                                s.connect, self.server_addr)
 
     def test_connect_capath(self):
         # Verify server certificates using the `capath` argument
@@ -1509,198 +1495,130 @@ class NetworkedTests(unittest.TestCase):
         # OpenSSL 0.9.8n and 1.0.0, as a result the capath directory must
         # contain both versions of each certificate (same content, different
         # filename) for this test to be portable across OpenSSL releases.
-        with support.transient_internet(REMOTE_HOST):
-            ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
-            ctx.verify_mode = ssl.CERT_REQUIRED
-            ctx.load_verify_locations(capath=CAPATH)
-            s = ctx.wrap_socket(socket.socket(socket.AF_INET))
-            s.connect((REMOTE_HOST, 443))
-            try:
-                cert = s.getpeercert()
-                self.assertTrue(cert)
-            finally:
-                s.close()
-            # Same with a bytes `capath` argument
-            ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
-            ctx.verify_mode = ssl.CERT_REQUIRED
-            ctx.load_verify_locations(capath=BYTES_CAPATH)
-            s = ctx.wrap_socket(socket.socket(socket.AF_INET))
-            s.connect((REMOTE_HOST, 443))
-            try:
-                cert = s.getpeercert()
-                self.assertTrue(cert)
-            finally:
-                s.close()
+        ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
+        ctx.verify_mode = ssl.CERT_REQUIRED
+        ctx.load_verify_locations(capath=CAPATH)
+        with ctx.wrap_socket(socket.socket(socket.AF_INET)) as s:
+            s.connect(self.server_addr)
+            cert = s.getpeercert()
+            self.assertTrue(cert)
+        # Same with a bytes `capath` argument
+        ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
+        ctx.verify_mode = ssl.CERT_REQUIRED
+        ctx.load_verify_locations(capath=BYTES_CAPATH)
+        with ctx.wrap_socket(socket.socket(socket.AF_INET)) as s:
+            s.connect(self.server_addr)
+            cert = s.getpeercert()
+            self.assertTrue(cert)
 
     def test_connect_cadata(self):
-        with open(REMOTE_ROOT_CERT) as f:
+        with open(SIGNING_CA) as f:
             pem = f.read()
         der = ssl.PEM_cert_to_DER_cert(pem)
-        with support.transient_internet(REMOTE_HOST):
-            ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
-            ctx.verify_mode = ssl.CERT_REQUIRED
-            ctx.load_verify_locations(cadata=pem)
-            with ctx.wrap_socket(socket.socket(socket.AF_INET)) as s:
-                s.connect((REMOTE_HOST, 443))
-                cert = s.getpeercert()
-                self.assertTrue(cert)
+        ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
+        ctx.verify_mode = ssl.CERT_REQUIRED
+        ctx.load_verify_locations(cadata=pem)
+        with ctx.wrap_socket(socket.socket(socket.AF_INET)) as s:
+            s.connect(self.server_addr)
+            cert = s.getpeercert()
+            self.assertTrue(cert)
 
-            # same with DER
-            ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
-            ctx.verify_mode = ssl.CERT_REQUIRED
-            ctx.load_verify_locations(cadata=der)
-            with ctx.wrap_socket(socket.socket(socket.AF_INET)) as s:
-                s.connect((REMOTE_HOST, 443))
-                cert = s.getpeercert()
-                self.assertTrue(cert)
+        # same with DER
+        ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
+        ctx.verify_mode = ssl.CERT_REQUIRED
+        ctx.load_verify_locations(cadata=der)
+        with ctx.wrap_socket(socket.socket(socket.AF_INET)) as s:
+            s.connect(self.server_addr)
+            cert = s.getpeercert()
+            self.assertTrue(cert)
 
     @unittest.skipIf(os.name == "nt", "Can't use a socket as a file under Windows")
     def test_makefile_close(self):
         # Issue #5238: creating a file-like object with makefile() shouldn't
         # delay closing the underlying "real socket" (here tested with its
         # file descriptor, hence skipping the test under Windows).
-        with support.transient_internet(REMOTE_HOST):
-            ss = ssl.wrap_socket(socket.socket(socket.AF_INET))
-            ss.connect((REMOTE_HOST, 443))
-            fd = ss.fileno()
-            f = ss.makefile()
-            f.close()
-            # The fd is still open
+        ss = ssl.wrap_socket(socket.socket(socket.AF_INET))
+        ss.connect(self.server_addr)
+        fd = ss.fileno()
+        f = ss.makefile()
+        f.close()
+        # The fd is still open
+        os.read(fd, 0)
+        # Closing the SSL socket should close the fd too
+        ss.close()
+        gc.collect()
+        with self.assertRaises(OSError) as e:
             os.read(fd, 0)
-            # Closing the SSL socket should close the fd too
-            ss.close()
-            gc.collect()
-            with self.assertRaises(OSError) as e:
-                os.read(fd, 0)
-            self.assertEqual(e.exception.errno, errno.EBADF)
+        self.assertEqual(e.exception.errno, errno.EBADF)
 
     def test_non_blocking_handshake(self):
-        with support.transient_internet(REMOTE_HOST):
-            s = socket.socket(socket.AF_INET)
-            s.connect((REMOTE_HOST, 443))
-            s.setblocking(False)
-            s = ssl.wrap_socket(s,
-                                cert_reqs=ssl.CERT_NONE,
-                                do_handshake_on_connect=False)
-            count = 0
-            while True:
-                try:
-                    count += 1
-                    s.do_handshake()
-                    break
-                except ssl.SSLWantReadError:
-                    select.select([s], [], [])
-                except ssl.SSLWantWriteError:
-                    select.select([], [s], [])
-            s.close()
-            if support.verbose:
-                sys.stdout.write("\nNeeded %d calls to do_handshake() to establish session.\n" % count)
+        s = socket.socket(socket.AF_INET)
+        s.connect(self.server_addr)
+        s.setblocking(False)
+        s = ssl.wrap_socket(s,
+                            cert_reqs=ssl.CERT_NONE,
+                            do_handshake_on_connect=False)
+        self.addCleanup(s.close)
+        count = 0
+        while True:
+            try:
+                count += 1
+                s.do_handshake()
+                break
+            except ssl.SSLWantReadError:
+                select.select([s], [], [])
+            except ssl.SSLWantWriteError:
+                select.select([], [s], [])
+        if support.verbose:
+            sys.stdout.write("\nNeeded %d calls to do_handshake() to establish session.\n" % count)
 
     def test_get_server_certificate(self):
-        def _test_get_server_certificate(host, port, cert=None):
-            with support.transient_internet(host):
-                pem = ssl.get_server_certificate((host, port))
-                if not pem:
-                    self.fail("No server certificate on %s:%s!" % (host, port))
-
-                try:
-                    pem = ssl.get_server_certificate((host, port),
-                                                     ca_certs=CERTFILE)
-                except ssl.SSLError as x:
-                    #should fail
-                    if support.verbose:
-                        sys.stdout.write("%s\n" % x)
-                else:
-                    self.fail("Got server certificate %s for %s:%s!" % (pem, host, port))
-
-                pem = ssl.get_server_certificate((host, port),
-                                                 ca_certs=cert)
-                if not pem:
-                    self.fail("No server certificate on %s:%s!" % (host, port))
-                if support.verbose:
-                    sys.stdout.write("\nVerified certificate for %s:%s is\n%s\n" % (host, port ,pem))
+        _test_get_server_certificate(self, *self.server_addr, cert=SIGNING_CA)
 
-        _test_get_server_certificate(REMOTE_HOST, 443, REMOTE_ROOT_CERT)
-        if support.IPV6_ENABLED:
-            _test_get_server_certificate('ipv6.google.com', 443)
+    def test_get_server_certificate_fail(self):
+        # Connection failure crashes ThreadedEchoServer, so run this in an
+        # independent test method
+        _test_get_server_certificate_fail(self, *self.server_addr)
 
     def test_ciphers(self):
-        remote = (REMOTE_HOST, 443)
-        with support.transient_internet(remote[0]):
-            with ssl.wrap_socket(socket.socket(socket.AF_INET),
-                                 cert_reqs=ssl.CERT_NONE, ciphers="ALL") as s:
-                s.connect(remote)
-            with ssl.wrap_socket(socket.socket(socket.AF_INET),
-                                 cert_reqs=ssl.CERT_NONE, ciphers="DEFAULT") as s:
-                s.connect(remote)
-            # Error checking can happen at instantiation or when connecting
-            with self.assertRaisesRegex(ssl.SSLError, "No cipher can be selected"):
-                with socket.socket(socket.AF_INET) as sock:
-                    s = ssl.wrap_socket(sock,
-                                        cert_reqs=ssl.CERT_NONE, ciphers="^$:,;?*'dorothyx")
-                    s.connect(remote)
-
-    def test_algorithms(self):
-        # Issue #8484: all algorithms should be available when verifying a
-        # certificate.
-        # SHA256 was added in OpenSSL 0.9.8
-        if ssl.OPENSSL_VERSION_INFO < (0, 9, 8, 0, 15):
-            self.skipTest("SHA256 not available on %r" % ssl.OPENSSL_VERSION)
-        # sha256.tbs-internet.com needs SNI to use the correct certificate
-        if not ssl.HAS_SNI:
-            self.skipTest("SNI needed for this test")
-        # https://sha2.hboeck.de/ was used until 2011-01-08 (no route to host)
-        remote = ("sha256.tbs-internet.com", 443)
-        sha256_cert = os.path.join(os.path.dirname(__file__), "sha256.pem")
-        with support.transient_internet("sha256.tbs-internet.com"):
-            ctx = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
-            ctx.verify_mode = ssl.CERT_REQUIRED
-            ctx.load_verify_locations(sha256_cert)
-            s = ctx.wrap_socket(socket.socket(socket.AF_INET),
-                                server_hostname="sha256.tbs-internet.com")
-            try:
-                s.connect(remote)
-                if support.verbose:
-                    sys.stdout.write("\nCipher with %r is %r\n" %
-                                     (remote, s.cipher()))
-                    sys.stdout.write("Certificate is:\n%s\n" %
-                                     pprint.pformat(s.getpeercert()))
-            finally:
-                s.close()
+        with ssl.wrap_socket(socket.socket(socket.AF_INET),
+                             cert_reqs=ssl.CERT_NONE, ciphers="ALL") as s:
+            s.connect(self.server_addr)
+        with ssl.wrap_socket(socket.socket(socket.AF_INET),
+                             cert_reqs=ssl.CERT_NONE, ciphers="DEFAULT") as s:
+            s.connect(self.server_addr)
+        # Error checking can happen at instantiation or when connecting
+        with self.assertRaisesRegex(ssl.SSLError, "No cipher can be selected"):
+            with socket.socket(socket.AF_INET) as sock:
+                s = ssl.wrap_socket(sock,
+                                    cert_reqs=ssl.CERT_NONE, ciphers="^$:,;?*'dorothyx")
+                s.connect(self.server_addr)
 
     def test_get_ca_certs_capath(self):
         # capath certs are loaded on request
-        with support.transient_internet(REMOTE_HOST):
-            ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
-            ctx.verify_mode = ssl.CERT_REQUIRED
-            ctx.load_verify_locations(capath=CAPATH)
-            self.assertEqual(ctx.get_ca_certs(), [])
-            s = ctx.wrap_socket(socket.socket(socket.AF_INET))
-            s.connect((REMOTE_HOST, 443))
-            try:
-                cert = s.getpeercert()
-                self.assertTrue(cert)
-            finally:
-                s.close()
-            self.assertEqual(len(ctx.get_ca_certs()), 1)
+        ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
+        ctx.verify_mode = ssl.CERT_REQUIRED
+        ctx.load_verify_locations(capath=CAPATH)
+        self.assertEqual(ctx.get_ca_certs(), [])
+        with ctx.wrap_socket(socket.socket(socket.AF_INET)) as s:
+            s.connect(self.server_addr)
+            cert = s.getpeercert()
+            self.assertTrue(cert)
+        self.assertEqual(len(ctx.get_ca_certs()), 1)
 
     @needs_sni
     def test_context_setget(self):
         # Check that the context of a connected socket can be replaced.
-        with support.transient_internet(REMOTE_HOST):
-            ctx1 = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
-            ctx2 = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
-            s = socket.socket(socket.AF_INET)
-            with ctx1.wrap_socket(s) as ss:
-                ss.connect((REMOTE_HOST, 443))
-                self.assertIs(ss.context, ctx1)
-                self.assertIs(ss._sslobj.context, ctx1)
-                ss.context = ctx2
-                self.assertIs(ss.context, ctx2)
-                self.assertIs(ss._sslobj.context, ctx2)
-
-
-class NetworkedBIOTests(unittest.TestCase):
+        ctx1 = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
+        ctx2 = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
+        s = socket.socket(socket.AF_INET)
+        with ctx1.wrap_socket(s) as ss:
+            ss.connect(self.server_addr)
+            self.assertIs(ss.context, ctx1)
+            self.assertIs(ss._sslobj.context, ctx1)
+            ss.context = ctx2
+            self.assertIs(ss.context, ctx2)
+            self.assertIs(ss._sslobj.context, ctx2)
 
     def ssl_io_loop(self, sock, incoming, outgoing, func, *args, **kwargs):
         # A simple IO loop. Call func(*args) depending on the error we get
@@ -1736,64 +1654,128 @@ class NetworkedBIOTests(unittest.TestCase):
                              % (count, func.__name__))
         return ret
 
-    def test_handshake(self):
+    def test_bio_handshake(self):
+        sock = socket.socket(socket.AF_INET)
+        self.addCleanup(sock.close)
+        sock.connect(self.server_addr)
+        incoming = ssl.MemoryBIO()
+        outgoing = ssl.MemoryBIO()
+        ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
+        ctx.verify_mode = ssl.CERT_REQUIRED
+        ctx.load_verify_locations(SIGNING_CA)
+        ctx.check_hostname = True
+        sslobj = ctx.wrap_bio(incoming, outgoing, False, 'localhost')
+        self.assertIs(sslobj._sslobj.owner, sslobj)
+        self.assertIsNone(sslobj.cipher())
+        self.assertIsNone(sslobj.shared_ciphers())
+        self.assertRaises(ValueError, sslobj.getpeercert)
+        if 'tls-unique' in ssl.CHANNEL_BINDING_TYPES:
+            self.assertIsNone(sslobj.get_channel_binding('tls-unique'))
+        self.ssl_io_loop(sock, incoming, outgoing, sslobj.do_handshake)
+        self.assertTrue(sslobj.cipher())
+        self.assertIsNone(sslobj.shared_ciphers())
+        self.assertTrue(sslobj.getpeercert())
+        if 'tls-unique' in ssl.CHANNEL_BINDING_TYPES:
+            self.assertTrue(sslobj.get_channel_binding('tls-unique'))
+        try:
+            self.ssl_io_loop(sock, incoming, outgoing, sslobj.unwrap)
+        except ssl.SSLSyscallError:
+            # If the server shuts down the TCP connection without sending a
+            # secure shutdown message, this is reported as SSL_ERROR_SYSCALL
+            pass
+        self.assertRaises(ssl.SSLError, sslobj.write, b'foo')
+
+    def test_bio_read_write_data(self):
+        sock = socket.socket(socket.AF_INET)
+        self.addCleanup(sock.close)
+        sock.connect(self.server_addr)
+        incoming = ssl.MemoryBIO()
+        outgoing = ssl.MemoryBIO()
+        ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
+        ctx.verify_mode = ssl.CERT_NONE
+        sslobj = ctx.wrap_bio(incoming, outgoing, False)
+        self.ssl_io_loop(sock, incoming, outgoing, sslobj.do_handshake)
+        req = b'FOO\n'
+        self.ssl_io_loop(sock, incoming, outgoing, sslobj.write, req)
+        buf = self.ssl_io_loop(sock, incoming, outgoing, sslobj.read, 1024)
+        self.assertEqual(buf, b'foo\n')
+        self.ssl_io_loop(sock, incoming, outgoing, sslobj.unwrap)
+
+
+class NetworkedTests(unittest.TestCase):
+
+    def test_timeout_connect_ex(self):
+        # Issue #12065: on a timeout, connect_ex() should return the original
+        # errno (mimicking the behaviour of non-SSL sockets).
         with support.transient_internet(REMOTE_HOST):
-            sock = socket.socket(socket.AF_INET)
-            sock.connect((REMOTE_HOST, 443))
-            incoming = ssl.MemoryBIO()
-            outgoing = ssl.MemoryBIO()
-            ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
+            s = ssl.wrap_socket(socket.socket(socket.AF_INET),
+                                cert_reqs=ssl.CERT_REQUIRED,
+                                do_handshake_on_connect=False)
+            self.addCleanup(s.close)
+            s.settimeout(0.0000001)
+            rc = s.connect_ex((REMOTE_HOST, 443))
+            if rc == 0:
+                self.skipTest("REMOTE_HOST responded too quickly")
+            self.assertIn(rc, (errno.EAGAIN, errno.EWOULDBLOCK))
+
+    @unittest.skipUnless(support.IPV6_ENABLED, 'Needs IPv6')
+    def test_get_server_certificate_ipv6(self):
+        with support.transient_internet('ipv6.google.com'):
+            _test_get_server_certificate(self, 'ipv6.google.com', 443)
+            _test_get_server_certificate_fail(self, 'ipv6.google.com', 443)
+
+    def test_algorithms(self):
+        # Issue #8484: all algorithms should be available when verifying a
+        # certificate.
+        # SHA256 was added in OpenSSL 0.9.8
+        if ssl.OPENSSL_VERSION_INFO < (0, 9, 8, 0, 15):
+            self.skipTest("SHA256 not available on %r" % ssl.OPENSSL_VERSION)
+        # sha256.tbs-internet.com needs SNI to use the correct certificate
+        if not ssl.HAS_SNI:
+            self.skipTest("SNI needed for this test")
+        # https://sha2.hboeck.de/ was used until 2011-01-08 (no route to host)
+        remote = ("sha256.tbs-internet.com", 443)
+        sha256_cert = os.path.join(os.path.dirname(__file__), "sha256.pem")
+        with support.transient_internet("sha256.tbs-internet.com"):
+            ctx = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
             ctx.verify_mode = ssl.CERT_REQUIRED
-            ctx.load_verify_locations(REMOTE_ROOT_CERT)
-            ctx.check_hostname = True
-            sslobj = ctx.wrap_bio(incoming, outgoing, False, REMOTE_HOST)
-            self.assertIs(sslobj._sslobj.owner, sslobj)
-            self.assertIsNone(sslobj.cipher())
-            self.assertIsNone(sslobj.shared_ciphers())
-            self.assertRaises(ValueError, sslobj.getpeercert)
-            if 'tls-unique' in ssl.CHANNEL_BINDING_TYPES:
-                self.assertIsNone(sslobj.get_channel_binding('tls-unique'))
-            self.ssl_io_loop(sock, incoming, outgoing, sslobj.do_handshake)
-            self.assertTrue(sslobj.cipher())
-            self.assertIsNone(sslobj.shared_ciphers())
-            self.assertTrue(sslobj.getpeercert())
-            if 'tls-unique' in ssl.CHANNEL_BINDING_TYPES:
-                self.assertTrue(sslobj.get_channel_binding('tls-unique'))
+            ctx.load_verify_locations(sha256_cert)
+            s = ctx.wrap_socket(socket.socket(socket.AF_INET),
+                                server_hostname="sha256.tbs-internet.com")
             try:
-                self.ssl_io_loop(sock, incoming, outgoing, sslobj.unwrap)
-            except ssl.SSLSyscallError:
-                # self-signed.pythontest.net probably shuts down the TCP
-                # connection without sending a secure shutdown message, and
-                # this is reported as SSL_ERROR_SYSCALL
-                pass
-            self.assertRaises(ssl.SSLError, sslobj.write, b'foo')
-            sock.close()
+                s.connect(remote)
+                if support.verbose:
+                    sys.stdout.write("\nCipher with %r is %r\n" %
+                                     (remote, s.cipher()))
+                    sys.stdout.write("Certificate is:\n%s\n" %
+                                     pprint.pformat(s.getpeercert()))
+            finally:
+                s.close()
 
-    def test_read_write_data(self):
-        with support.transient_internet(REMOTE_HOST):
-            sock = socket.socket(socket.AF_INET)
-            sock.connect((REMOTE_HOST, 443))
-            incoming = ssl.MemoryBIO()
-            outgoing = ssl.MemoryBIO()
-            ctx = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
-            ctx.verify_mode = ssl.CERT_NONE
-            sslobj = ctx.wrap_bio(incoming, outgoing, False)
-            self.ssl_io_loop(sock, incoming, outgoing, sslobj.do_handshake)
-            req = b'GET / HTTP/1.0\r\n\r\n'
-            self.ssl_io_loop(sock, incoming, outgoing, sslobj.write, req)
-            buf = self.ssl_io_loop(sock, incoming, outgoing, sslobj.read, 1024)
-            self.assertEqual(buf[:5], b'HTTP/')
-            self.ssl_io_loop(sock, incoming, outgoing, sslobj.unwrap)
-            sock.close()
 
+def _test_get_server_certificate(test, host, port, cert=None):
+    pem = ssl.get_server_certificate((host, port))
+    if not pem:
+        test.fail("No server certificate on %s:%s!" % (host, port))
 
-try:
-    import threading
-except ImportError:
-    _have_threads = False
-else:
-    _have_threads = True
+    pem = ssl.get_server_certificate((host, port), ca_certs=cert)
+    if not pem:
+        test.fail("No server certificate on %s:%s!" % (host, port))
+    if support.verbose:
+        sys.stdout.write("\nVerified certificate for %s:%s is\n%s\n" % (host, port ,pem))
 
+def _test_get_server_certificate_fail(test, host, port):
+    try:
+        pem = ssl.get_server_certificate((host, port), ca_certs=CERTFILE)
+    except ssl.SSLError as x:
+        #should fail
+        if support.verbose:
+            sys.stdout.write("%s\n" % x)
+    else:
+        test.fail("Got server certificate %s for %s:%s!" % (pem, host, port))
+
+
+if _have_threads:
     from test.ssl_servers import make_https_server
 
     class ThreadedEchoServer(threading.Thread):
@@ -1881,6 +1863,15 @@ else:
                         if not stripped:
                             # eof, so quit this handler
                             self.running = False
+                            try:
+                                self.sock = self.sslconn.unwrap()
+                            except OSError:
+                                # Many tests shut the TCP connection down
+                                # without an SSL shutdown. This causes
+                                # unwrap() to raise OSError with errno=0!
+                                pass
+                            else:
+                                self.sslconn = None
                             self.close()
                         elif stripped == b'over':
                             if support.verbose and self.server.connectionchatty:
@@ -2718,12 +2709,13 @@ else:
                     count, addr = s.recvfrom_into(b)
                     return b[:count]
 
-                # (name, method, whether to expect success, *args)
+                # (name, method, expect success?, *args, return value func)
                 send_methods = [
-                    ('send', s.send, True, []),
-                    ('sendto', s.sendto, False, ["some.address"]),
-                    ('sendall', s.sendall, True, []),
+                    ('send', s.send, True, [], len),
+                    ('sendto', s.sendto, False, ["some.address"], len),
+                    ('sendall', s.sendall, True, [], lambda x: None),
                 ]
+                # (name, method, whether to expect success, *args)
                 recv_methods = [
                     ('recv', s.recv, True, []),
                     ('recvfrom', s.recvfrom, False, ["some.address"]),
@@ -2732,10 +2724,13 @@ else:
                 ]
                 data_prefix = "PREFIX_"
 
-                for meth_name, send_meth, expect_success, args in send_methods:
+                for (meth_name, send_meth, expect_success, args,
+                        ret_val_meth) in send_methods:
                     indata = (data_prefix + meth_name).encode('ascii')
                     try:
-                        send_meth(indata, *args)
+                        ret = send_meth(indata, *args)
+                        msg = "sending with {}".format(meth_name)
+                        self.assertEqual(ret, ret_val_meth(indata), msg=msg)
                         outdata = s.read()
                         if outdata != indata.lower():
                             self.fail(
@@ -3360,18 +3355,20 @@ def test_main(verbose=False):
             pass
 
     for filename in [
-        CERTFILE, REMOTE_ROOT_CERT, BYTES_CERTFILE,
+        CERTFILE, BYTES_CERTFILE,
         ONLYCERT, ONLYKEY, BYTES_ONLYCERT, BYTES_ONLYKEY,
         SIGNED_CERTFILE, SIGNED_CERTFILE2, SIGNING_CA,
         BADCERT, BADKEY, EMPTYCERT]:
         if not os.path.exists(filename):
             raise support.TestFailed("Can't read certificate file %r" % filename)
 
-    tests = [ContextTests, BasicSocketTests, SSLErrorTests, MemoryBIOTests]
+    tests = [
+        ContextTests, BasicSocketTests, SSLErrorTests, MemoryBIOTests,
+        SimpleBackgroundTests,
+    ]
 
     if support.is_resource_enabled('network'):
         tests.append(NetworkedTests)
-        tests.append(NetworkedBIOTests)
 
     if _have_threads:
         thread_info = support.threading_setup()
diff --git a/Lib/test/test_statistics.py b/Lib/test/test_statistics.py
index 0089ae8dc6..5dd50483f2 100644
--- a/Lib/test/test_statistics.py
+++ b/Lib/test/test_statistics.py
@@ -659,7 +659,7 @@ class DocTests(unittest.TestCase):
     @unittest.skipIf(sys.flags.optimize >= 2,
                      "Docstrings are omitted with -OO and above")
     def test_doc_tests(self):
-        failed, tried = doctest.testmod(statistics)
+        failed, tried = doctest.testmod(statistics, optionflags=doctest.ELLIPSIS)
         self.assertGreater(tried, 0)
         self.assertEqual(failed, 0)
 
@@ -702,9 +702,9 @@ class ExactRatioTest(unittest.TestCase):
     def test_decimal(self):
         D = Decimal
         _exact_ratio = statistics._exact_ratio
-        self.assertEqual(_exact_ratio(D("0.125")), (125, 1000))
-        self.assertEqual(_exact_ratio(D("12.345")), (12345, 1000))
-        self.assertEqual(_exact_ratio(D("-1.98")), (-198, 100))
+        self.assertEqual(_exact_ratio(D("0.125")), (1, 8))
+        self.assertEqual(_exact_ratio(D("12.345")), (2469, 200))
+        self.assertEqual(_exact_ratio(D("-1.98")), (-99, 50))
 
     def test_inf(self):
         INF = float("INF")
@@ -743,18 +743,18 @@ class ExactRatioTest(unittest.TestCase):
 
 
 class DecimalToRatioTest(unittest.TestCase):
-    # Test _decimal_to_ratio private function.
+    # Test _exact_ratio private function.
 
     def test_infinity(self):
         # Test that INFs are handled correctly.
         inf = Decimal('INF')
-        self.assertEqual(statistics._decimal_to_ratio(inf), (inf, None))
-        self.assertEqual(statistics._decimal_to_ratio(-inf), (-inf, None))
+        self.assertEqual(statistics._exact_ratio(inf), (inf, None))
+        self.assertEqual(statistics._exact_ratio(-inf), (-inf, None))
 
     def test_nan(self):
         # Test that NANs are handled correctly.
         for nan in (Decimal('NAN'), Decimal('sNAN')):
-            num, den = statistics._decimal_to_ratio(nan)
+            num, den = statistics._exact_ratio(nan)
             # Because NANs always compare non-equal, we cannot use assertEqual.
             # Nor can we use an identity test, as we don't guarantee anything
             # about the object identity.
@@ -767,30 +767,30 @@ class DecimalToRatioTest(unittest.TestCase):
         for d in numbers:
             # First test positive decimals.
             assert d > 0
-            num, den = statistics._decimal_to_ratio(d)
+            num, den = statistics._exact_ratio(d)
             self.assertGreaterEqual(num, 0)
             self.assertGreater(den, 0)
             # Then test negative decimals.
-            num, den = statistics._decimal_to_ratio(-d)
+            num, den = statistics._exact_ratio(-d)
             self.assertLessEqual(num, 0)
             self.assertGreater(den, 0)
 
     def test_negative_exponent(self):
         # Test result when the exponent is negative.
-        t = statistics._decimal_to_ratio(Decimal("0.1234"))
-        self.assertEqual(t, (1234, 10000))
+        t = statistics._exact_ratio(Decimal("0.1234"))
+        self.assertEqual(t, (617, 5000))
 
     def test_positive_exponent(self):
         # Test results when the exponent is positive.
-        t = statistics._decimal_to_ratio(Decimal("1.234e7"))
+        t = statistics._exact_ratio(Decimal("1.234e7"))
         self.assertEqual(t, (12340000, 1))
 
     def test_regression_20536(self):
         # Regression test for issue 20536.
         # See http://bugs.python.org/issue20536
-        t = statistics._decimal_to_ratio(Decimal("1e2"))
+        t = statistics._exact_ratio(Decimal("1e2"))
         self.assertEqual(t, (100, 1))
-        t = statistics._decimal_to_ratio(Decimal("1.47e5"))
+        t = statistics._exact_ratio(Decimal("1.47e5"))
         self.assertEqual(t, (147000, 1))
 
 
diff --git a/Lib/test/test_strptime.py b/Lib/test/test_strptime.py
index 85126e6e53..8c8f97ba50 100644
--- a/Lib/test/test_strptime.py
+++ b/Lib/test/test_strptime.py
@@ -5,7 +5,6 @@ import time
 import locale
 import re
 import os
-import sys
 from test import support
 from datetime import date as datetime_date
 
@@ -153,8 +152,8 @@ class TimeRETests(unittest.TestCase):
                          "'%s' using '%s'; group 'a' = '%s', group 'b' = %s'" %
                          (found.string, found.re.pattern, found.group('a'),
                           found.group('b')))
-        for directive in ('a','A','b','B','c','d','H','I','j','m','M','p','S',
-                          'U','w','W','x','X','y','Y','Z','%'):
+        for directive in ('a','A','b','B','c','d','G','H','I','j','m','M','p',
+                          'S','u','U','V','w','W','x','X','y','Y','Z','%'):
             compiled = self.time_re.compile("%" + directive)
             found = compiled.match(time.strftime("%" + directive))
             self.assertTrue(found, "Matching failed on '%s' using '%s' regex" %
@@ -219,6 +218,26 @@ class StrptimeTests(unittest.TestCase):
             else:
                 self.fail("'%s' did not raise ValueError" % bad_format)
 
+        # Ambiguous or incomplete cases using ISO year/week/weekday directives
+        # 1. ISO week (%V) is specified, but the year is specified with %Y
+        # instead of %G
+        with self.assertRaises(ValueError):
+            _strptime._strptime("1999 50", "%Y %V")
+        # 2. ISO year (%G) and ISO week (%V) are specified, but weekday is not
+        with self.assertRaises(ValueError):
+            _strptime._strptime("1999 51", "%G %V")
+        # 3. ISO year (%G) and weekday are specified, but ISO week (%V) is not
+        for w in ('A', 'a', 'w', 'u'):
+            with self.assertRaises(ValueError):
+                _strptime._strptime("1999 51","%G %{}".format(w))
+        # 4. ISO year is specified alone (e.g. time.strptime('2015', '%G'))
+        with self.assertRaises(ValueError):
+            _strptime._strptime("2015", "%G")
+        # 5. Julian/ordinal day (%j) is specified with %G, but not %Y
+        with self.assertRaises(ValueError):
+            _strptime._strptime("1999 256", "%G %j")
+
+
     def test_strptime_exception_context(self):
         # check that this doesn't chain exceptions needlessly (see #17572)
         with self.assertRaises(ValueError) as e:
@@ -290,7 +309,7 @@ class StrptimeTests(unittest.TestCase):
 
     def test_weekday(self):
         # Test weekday directives
-        for directive in ('A', 'a', 'w'):
+        for directive in ('A', 'a', 'w', 'u'):
             self.helper(directive,6)
 
     def test_julian(self):
@@ -457,16 +476,20 @@ class CalculationTests(unittest.TestCase):
         # Should be able to infer date if given year, week of year (%U or %W)
         # and day of the week
         def test_helper(ymd_tuple, test_reason):
-            for directive in ('W', 'U'):
-                format_string = "%%Y %%%s %%w" % directive
-                dt_date = datetime_date(*ymd_tuple)
-                strp_input = dt_date.strftime(format_string)
-                strp_output = _strptime._strptime_time(strp_input, format_string)
-                self.assertTrue(strp_output[:3] == ymd_tuple,
-                        "%s(%s) test failed w/ '%s': %s != %s (%s != %s)" %
-                            (test_reason, directive, strp_input,
-                                strp_output[:3], ymd_tuple,
-                                strp_output[7], dt_date.timetuple()[7]))
+            for year_week_format in ('%Y %W', '%Y %U', '%G %V'):
+                for weekday_format in ('%w', '%u', '%a', '%A'):
+                    format_string = year_week_format + ' ' + weekday_format
+                    with self.subTest(test_reason,
+                                      date=ymd_tuple,
+                                      format=format_string):
+                        dt_date = datetime_date(*ymd_tuple)
+                        strp_input = dt_date.strftime(format_string)
+                        strp_output = _strptime._strptime_time(strp_input,
+                                                               format_string)
+                        msg = "%r: %s != %s" % (strp_input,
+                                                strp_output[7],
+                                                dt_date.timetuple()[7])
+                        self.assertEqual(strp_output[:3], ymd_tuple, msg)
         test_helper((1901, 1, 3), "week 0")
         test_helper((1901, 1, 8), "common case")
         test_helper((1901, 1, 13), "day on Sunday")
@@ -498,33 +521,48 @@ class CalculationTests(unittest.TestCase):
             self.assertEqual(_strptime._strptime_time(value, format)[:-1], expected)
         check('2015 0 0', '%Y %U %w', 2014, 12, 28, 0, 0, 0, 6, 362)
         check('2015 0 0', '%Y %W %w', 2015, 1, 4, 0, 0, 0, 6, 4)
+        check('2015 1 1', '%G %V %u', 2014, 12, 29, 0, 0, 0, 0, 363)
         check('2015 0 1', '%Y %U %w', 2014, 12, 29, 0, 0, 0, 0, 363)
         check('2015 0 1', '%Y %W %w', 2014, 12, 29, 0, 0, 0, 0, 363)
+        check('2015 1 2', '%G %V %u', 2014, 12, 30, 0, 0, 0, 1, 364)
         check('2015 0 2', '%Y %U %w', 2014, 12, 30, 0, 0, 0, 1, 364)
         check('2015 0 2', '%Y %W %w', 2014, 12, 30, 0, 0, 0, 1, 364)
+        check('2015 1 3', '%G %V %u', 2014, 12, 31, 0, 0, 0, 2, 365)
         check('2015 0 3', '%Y %U %w', 2014, 12, 31, 0, 0, 0, 2, 365)
         check('2015 0 3', '%Y %W %w', 2014, 12, 31, 0, 0, 0, 2, 365)
+        check('2015 1 4', '%G %V %u', 2015, 1, 1, 0, 0, 0, 3, 1)
         check('2015 0 4', '%Y %U %w', 2015, 1, 1, 0, 0, 0, 3, 1)
         check('2015 0 4', '%Y %W %w', 2015, 1, 1, 0, 0, 0, 3, 1)
+        check('2015 1 5', '%G %V %u', 2015, 1, 2, 0, 0, 0, 4, 2)
         check('2015 0 5', '%Y %U %w', 2015, 1, 2, 0, 0, 0, 4, 2)
         check('2015 0 5', '%Y %W %w', 2015, 1, 2, 0, 0, 0, 4, 2)
+        check('2015 1 6', '%G %V %u', 2015, 1, 3, 0, 0, 0, 5, 3)
         check('2015 0 6', '%Y %U %w', 2015, 1, 3, 0, 0, 0, 5, 3)
         check('2015 0 6', '%Y %W %w', 2015, 1, 3, 0, 0, 0, 5, 3)
+        check('2015 1 7', '%G %V %u', 2015, 1, 4, 0, 0, 0, 6, 4)
 
         check('2009 0 0', '%Y %U %w', 2008, 12, 28, 0, 0, 0, 6, 363)
         check('2009 0 0', '%Y %W %w', 2009, 1, 4, 0, 0, 0, 6, 4)
+        check('2009 1 1', '%G %V %u', 2008, 12, 29, 0, 0, 0, 0, 364)
         check('2009 0 1', '%Y %U %w', 2008, 12, 29, 0, 0, 0, 0, 364)
         check('2009 0 1', '%Y %W %w', 2008, 12, 29, 0, 0, 0, 0, 364)
+        check('2009 1 2', '%G %V %u', 2008, 12, 30, 0, 0, 0, 1, 365)
         check('2009 0 2', '%Y %U %w', 2008, 12, 30, 0, 0, 0, 1, 365)
         check('2009 0 2', '%Y %W %w', 2008, 12, 30, 0, 0, 0, 1, 365)
+        check('2009 1 3', '%G %V %u', 2008, 12, 31, 0, 0, 0, 2, 366)
         check('2009 0 3', '%Y %U %w', 2008, 12, 31, 0, 0, 0, 2, 366)
         check('2009 0 3', '%Y %W %w', 2008, 12, 31, 0, 0, 0, 2, 366)
+        check('2009 1 4', '%G %V %u', 2009, 1, 1, 0, 0, 0, 3, 1)
         check('2009 0 4', '%Y %U %w', 2009, 1, 1, 0, 0, 0, 3, 1)
         check('2009 0 4', '%Y %W %w', 2009, 1, 1, 0, 0, 0, 3, 1)
+        check('2009 1 5', '%G %V %u', 2009, 1, 2, 0, 0, 0, 4, 2)
         check('2009 0 5', '%Y %U %w', 2009, 1, 2, 0, 0, 0, 4, 2)
         check('2009 0 5', '%Y %W %w', 2009, 1, 2, 0, 0, 0, 4, 2)
+        check('2009 1 6', '%G %V %u', 2009, 1, 3, 0, 0, 0, 5, 3)
         check('2009 0 6', '%Y %U %w', 2009, 1, 3, 0, 0, 0, 5, 3)
         check('2009 0 6', '%Y %W %w', 2009, 1, 3, 0, 0, 0, 5, 3)
+        check('2009 1 7', '%G %V %u', 2009, 1, 4, 0, 0, 0, 6, 4)
+
 
 class CacheTests(unittest.TestCase):
     """Test that caching works properly."""
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index 4704d49062..ba91bbc081 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -1,20 +1,16 @@
 import unittest
 from unittest import mock
-from test.support import script_helper
 from test import support
 import subprocess
 import sys
 import signal
 import io
-import locale
 import os
 import errno
 import tempfile
 import time
-import re
 import selectors
 import sysconfig
-import warnings
 import select
 import shutil
 import gc
@@ -448,8 +444,8 @@ class ProcessTestCase(BaseTestCase):
         p = subprocess.Popen([sys.executable, "-c",
                           'import sys; sys.stdout.write("orange")'],
                          stdout=subprocess.PIPE)
-        self.addCleanup(p.stdout.close)
-        self.assertEqual(p.stdout.read(), b"orange")
+        with p:
+            self.assertEqual(p.stdout.read(), b"orange")
 
     def test_stdout_filedes(self):
         # stdout is set to open file descriptor
@@ -479,8 +475,8 @@ class ProcessTestCase(BaseTestCase):
         p = subprocess.Popen([sys.executable, "-c",
                           'import sys; sys.stderr.write("strawberry")'],
                          stderr=subprocess.PIPE)
-        self.addCleanup(p.stderr.close)
-        self.assertStderrEqual(p.stderr.read(), b"strawberry")
+        with p:
+            self.assertStderrEqual(p.stderr.read(), b"strawberry")
 
     def test_stderr_filedes(self):
         # stderr is set to open file descriptor
@@ -535,8 +531,8 @@ class ProcessTestCase(BaseTestCase):
                               'sys.stderr.write("orange")'],
                              stdout=subprocess.PIPE,
                              stderr=subprocess.STDOUT)
-        self.addCleanup(p.stdout.close)
-        self.assertStderrEqual(p.stdout.read(), b"appleorange")
+        with p:
+            self.assertStderrEqual(p.stdout.read(), b"appleorange")
 
     def test_stdout_stderr_file(self):
         # capture stdout and stderr to the same open file
@@ -794,18 +790,19 @@ class ProcessTestCase(BaseTestCase):
                              stdin=subprocess.PIPE,
                              stdout=subprocess.PIPE,
                              universal_newlines=1)
-        p.stdin.write("line1\n")
-        p.stdin.flush()
-        self.assertEqual(p.stdout.readline(), "line1\n")
-        p.stdin.write("line3\n")
-        p.stdin.close()
-        self.addCleanup(p.stdout.close)
-        self.assertEqual(p.stdout.readline(),
-                         "line2\n")
-        self.assertEqual(p.stdout.read(6),
-                         "line3\n")
-        self.assertEqual(p.stdout.read(),
-                         "line4\nline5\nline6\nline7\nline8")
+        with p:
+            p.stdin.write("line1\n")
+            p.stdin.flush()
+            self.assertEqual(p.stdout.readline(), "line1\n")
+            p.stdin.write("line3\n")
+            p.stdin.close()
+            self.addCleanup(p.stdout.close)
+            self.assertEqual(p.stdout.readline(),
+                             "line2\n")
+            self.assertEqual(p.stdout.read(6),
+                             "line3\n")
+            self.assertEqual(p.stdout.read(),
+                             "line4\nline5\nline6\nline7\nline8")
 
     def test_universal_newlines_communicate(self):
         # universal newlines through communicate()
@@ -1431,6 +1428,27 @@ class POSIXProcessTestCase(BaseTestCase):
             p.wait()
         self.assertEqual(-p.returncode, signal.SIGABRT)
 
+    def test_CalledProcessError_str_signal(self):
+        err = subprocess.CalledProcessError(-int(signal.SIGABRT), "fake cmd")
+        error_string = str(err)
+        # We're relying on the repr() of the signal.Signals intenum to provide
+        # the word signal, the signal name and the numeric value.
+        self.assertIn("signal", error_string.lower())
+        # We're not being specific about the signal name as some signals have
+        # multiple names and which name is revealed can vary.
+        self.assertIn("SIG", error_string)
+        self.assertIn(str(signal.SIGABRT), error_string)
+
+    def test_CalledProcessError_str_unknown_signal(self):
+        err = subprocess.CalledProcessError(-9876543, "fake cmd")
+        error_string = str(err)
+        self.assertIn("unknown signal 9876543.", error_string)
+
+    def test_CalledProcessError_str_non_zero(self):
+        err = subprocess.CalledProcessError(2, "fake cmd")
+        error_string = str(err)
+        self.assertIn("non-zero exit status 2.", error_string)
+
     def test_preexec(self):
         # DISCLAIMER: Setting environment variables is *not* a good use
         # of a preexec_fn.  This is merely a test.
@@ -1439,8 +1457,8 @@ class POSIXProcessTestCase(BaseTestCase):
                               'sys.stdout.write(os.getenv("FRUIT"))'],
                              stdout=subprocess.PIPE,
                              preexec_fn=lambda: os.putenv("FRUIT", "apple"))
-        self.addCleanup(p.stdout.close)
-        self.assertEqual(p.stdout.read(), b"apple")
+        with p:
+            self.assertEqual(p.stdout.read(), b"apple")
 
     def test_preexec_exception(self):
         def raise_it():
@@ -1588,8 +1606,8 @@ class POSIXProcessTestCase(BaseTestCase):
         p = subprocess.Popen(["echo $FRUIT"], shell=1,
                              stdout=subprocess.PIPE,
                              env=newenv)
-        self.addCleanup(p.stdout.close)
-        self.assertEqual(p.stdout.read().strip(b" \t\r\n\f"), b"apple")
+        with p:
+            self.assertEqual(p.stdout.read().strip(b" \t\r\n\f"), b"apple")
 
     def test_shell_string(self):
         # Run command through the shell (string)
@@ -1598,8 +1616,8 @@ class POSIXProcessTestCase(BaseTestCase):
         p = subprocess.Popen("echo $FRUIT", shell=1,
                              stdout=subprocess.PIPE,
                              env=newenv)
-        self.addCleanup(p.stdout.close)
-        self.assertEqual(p.stdout.read().strip(b" \t\r\n\f"), b"apple")
+        with p:
+            self.assertEqual(p.stdout.read().strip(b" \t\r\n\f"), b"apple")
 
     def test_call_string(self):
         # call() function with string argument on UNIX
@@ -1631,8 +1649,8 @@ class POSIXProcessTestCase(BaseTestCase):
         for sh in shells:
             p = subprocess.Popen("echo $0", executable=sh, shell=True,
                                  stdout=subprocess.PIPE)
-            self.addCleanup(p.stdout.close)
-            self.assertEqual(p.stdout.read().strip(), bytes(sh, 'ascii'))
+            with p:
+                self.assertEqual(p.stdout.read().strip(), bytes(sh, 'ascii'))
 
     def _kill_process(self, method, *args):
         # Do not inherit file handles from the parent.
@@ -2290,7 +2308,9 @@ class POSIXProcessTestCase(BaseTestCase):
         self.addCleanup(p.stderr.close)
         ident = id(p)
         pid = p.pid
-        del p
+        with support.check_warnings(('', ResourceWarning)):
+            p = None
+
         # check that p is in the active processes list
         self.assertIn(ident, [id(o) for o in subprocess._active])
 
@@ -2309,7 +2329,9 @@ class POSIXProcessTestCase(BaseTestCase):
         self.addCleanup(p.stderr.close)
         ident = id(p)
         pid = p.pid
-        del p
+        with support.check_warnings(('', ResourceWarning)):
+            p = None
+
         os.kill(pid, signal.SIGKILL)
         # check that p is in the active processes list
         self.assertIn(ident, [id(o) for o in subprocess._active])
@@ -2501,8 +2523,8 @@ class Win32ProcessTestCase(BaseTestCase):
         p = subprocess.Popen(["set"], shell=1,
                              stdout=subprocess.PIPE,
                              env=newenv)
-        self.addCleanup(p.stdout.close)
-        self.assertIn(b"physalis", p.stdout.read())
+        with p:
+            self.assertIn(b"physalis", p.stdout.read())
 
     def test_shell_string(self):
         # Run command through the shell (string)
@@ -2511,8 +2533,8 @@ class Win32ProcessTestCase(BaseTestCase):
         p = subprocess.Popen("set", shell=1,
                              stdout=subprocess.PIPE,
                              env=newenv)
-        self.addCleanup(p.stdout.close)
-        self.assertIn(b"physalis", p.stdout.read())
+        with p:
+            self.assertIn(b"physalis", p.stdout.read())
 
     def test_call_string(self):
         # call() function with string argument on Windows
@@ -2531,16 +2553,14 @@ class Win32ProcessTestCase(BaseTestCase):
                              stdin=subprocess.PIPE,
                              stdout=subprocess.PIPE,
                              stderr=subprocess.PIPE)
-        self.addCleanup(p.stdout.close)
-        self.addCleanup(p.stderr.close)
-        self.addCleanup(p.stdin.close)
-        # Wait for the interpreter to be completely initialized before
-        # sending any signal.
-        p.stdout.read(1)
-        getattr(p, method)(*args)
-        _, stderr = p.communicate()
-        self.assertStderrEqual(stderr, b'')
-        returncode = p.wait()
+        with p:
+            # Wait for the interpreter to be completely initialized before
+            # sending any signal.
+            p.stdout.read(1)
+            getattr(p, method)(*args)
+            _, stderr = p.communicate()
+            self.assertStderrEqual(stderr, b'')
+            returncode = p.wait()
         self.assertNotEqual(returncode, 0)
 
     def _kill_dead_process(self, method, *args):
@@ -2553,19 +2573,17 @@ class Win32ProcessTestCase(BaseTestCase):
                              stdin=subprocess.PIPE,
                              stdout=subprocess.PIPE,
                              stderr=subprocess.PIPE)
-        self.addCleanup(p.stdout.close)
-        self.addCleanup(p.stderr.close)
-        self.addCleanup(p.stdin.close)
-        # Wait for the interpreter to be completely initialized before
-        # sending any signal.
-        p.stdout.read(1)
-        # The process should end after this
-        time.sleep(1)
-        # This shouldn't raise even though the child is now dead
-        getattr(p, method)(*args)
-        _, stderr = p.communicate()
-        self.assertStderrEqual(stderr, b'')
-        rc = p.wait()
+        with p:
+            # Wait for the interpreter to be completely initialized before
+            # sending any signal.
+            p.stdout.read(1)
+            # The process should end after this
+            time.sleep(1)
+            # This shouldn't raise even though the child is now dead
+            getattr(p, method)(*args)
+            _, stderr = p.communicate()
+            self.assertStderrEqual(stderr, b'')
+            rc = p.wait()
         self.assertEqual(rc, 42)
 
     def test_send_signal(self):
@@ -2608,8 +2626,7 @@ class MiscTests(unittest.TestCase):
 
     def test__all__(self):
         """Ensure that __all__ is populated properly."""
-        # STARTUPINFO added to __all__ in 3.6
-        intentionally_excluded = {"list2cmdline", "STARTUPINFO", "Handle"}
+        intentionally_excluded = {"list2cmdline", "Handle"}
         exported = set(subprocess.__all__)
         possible_exports = set()
         import types
@@ -2654,11 +2671,11 @@ class CommandsWithSpaces (BaseTestCase):
     def with_spaces(self, *args, **kwargs):
         kwargs['stdout'] = subprocess.PIPE
         p = subprocess.Popen(*args, **kwargs)
-        self.addCleanup(p.stdout.close)
-        self.assertEqual(
-          p.stdout.read ().decode("mbcs"),
-          "2 [%r, 'ab cd']" % self.fname
-        )
+        with p:
+            self.assertEqual(
+              p.stdout.read ().decode("mbcs"),
+              "2 [%r, 'ab cd']" % self.fname
+            )
 
     def test_shell_string_with_spaces(self):
         # call() function with string argument with spaces on Windows
diff --git a/Lib/test/test_sunau.py b/Lib/test/test_sunau.py
index 0f4134e982..bc1f46c0eb 100644
--- a/Lib/test/test_sunau.py
+++ b/Lib/test/test_sunau.py
@@ -1,4 +1,3 @@
-from test.support import TESTFN
 import unittest
 from test import audiotests
 from audioop import byteswap
diff --git a/Lib/test/test_support.py b/Lib/test/test_support.py
index 2c00417414..269d9bf2b6 100644
--- a/Lib/test/test_support.py
+++ b/Lib/test/test_support.py
@@ -9,13 +9,11 @@ import errno
 from test import support
 
 TESTFN = support.TESTFN
-TESTDIRN = os.path.basename(tempfile.mkdtemp(dir='.'))
 
 
 class TestSupport(unittest.TestCase):
     def setUp(self):
         support.unlink(TESTFN)
-        support.rmtree(TESTDIRN)
     tearDown = setUp
 
     def test_import_module(self):
@@ -48,6 +46,10 @@ class TestSupport(unittest.TestCase):
         support.unlink(TESTFN)
 
     def test_rmtree(self):
+        TESTDIRN = os.path.basename(tempfile.mkdtemp(dir='.'))
+        self.addCleanup(support.rmtree, TESTDIRN)
+        support.rmtree(TESTDIRN)
+
         os.mkdir(TESTDIRN)
         os.mkdir(os.path.join(TESTDIRN, TESTDIRN))
         support.rmtree(TESTDIRN)
@@ -228,7 +230,8 @@ class TestSupport(unittest.TestCase):
 
     def test_check_syntax_error(self):
         support.check_syntax_error(self, "def class")
-        self.assertRaises(AssertionError, support.check_syntax_error, self, "1")
+        with self.assertRaises(AssertionError):
+            support.check_syntax_error(self, "x=1")
 
     def test_CleanImport(self):
         import importlib
@@ -312,6 +315,28 @@ class TestSupport(unittest.TestCase):
                 self.OtherClass, self.RefClass, ignore=ignore)
         self.assertEqual(set(), missing_items)
 
+    def test_check__all__(self):
+        extra = {'tempdir'}
+        blacklist = {'template'}
+        support.check__all__(self,
+                             tempfile,
+                             extra=extra,
+                             blacklist=blacklist)
+
+        extra = {'TextTestResult', 'installHandler'}
+        blacklist = {'load_tests', "TestProgram", "BaseTestSuite"}
+
+        support.check__all__(self,
+                             unittest,
+                             ("unittest.result", "unittest.case",
+                              "unittest.suite", "unittest.loader",
+                              "unittest.main", "unittest.runner",
+                              "unittest.signals"),
+                             extra=extra,
+                             blacklist=blacklist)
+
+        self.assertRaises(AssertionError, support.check__all__, self, unittest)
+
     # XXX -follows a list of untested API
     # make_legacy_pyc
     # is_resource_enabled
diff --git a/Lib/test/test_symbol.py b/Lib/test/test_symbol.py
new file mode 100644
index 0000000000..c1306f5432
--- /dev/null
+++ b/Lib/test/test_symbol.py
@@ -0,0 +1,54 @@
+import unittest
+from test import support
+import os
+import sys
+import subprocess
+
+
+SYMBOL_FILE              = support.findfile('symbol.py')
+GRAMMAR_FILE             = os.path.join(os.path.dirname(__file__),
+                                        '..', '..', 'Include', 'graminit.h')
+TEST_PY_FILE             = 'symbol_test.py'
+
+
+class TestSymbolGeneration(unittest.TestCase):
+
+    def _copy_file_without_generated_symbols(self, source_file, dest_file):
+        with open(source_file) as fp:
+            lines = fp.readlines()
+        with open(dest_file, 'w') as fp:
+            fp.writelines(lines[:lines.index("#--start constants--\n") + 1])
+            fp.writelines(lines[lines.index("#--end constants--\n"):])
+
+    def _generate_symbols(self, grammar_file, target_symbol_py_file):
+        proc = subprocess.Popen([sys.executable,
+                                 SYMBOL_FILE,
+                                 grammar_file,
+                                 target_symbol_py_file], stderr=subprocess.PIPE)
+        stderr = proc.communicate()[1]
+        return proc.returncode, stderr
+
+    def compare_files(self, file1, file2):
+        with open(file1) as fp:
+            lines1 = fp.readlines()
+        with open(file2) as fp:
+            lines2 = fp.readlines()
+        self.assertEqual(lines1, lines2)
+
+    @unittest.skipIf(not os.path.exists(GRAMMAR_FILE),
+                     'test only works from source build directory')
+    def test_real_grammar_and_symbol_file(self):
+        output = support.TESTFN
+        self.addCleanup(support.unlink, output)
+
+        self._copy_file_without_generated_symbols(SYMBOL_FILE, output)
+
+        exitcode, stderr = self._generate_symbols(GRAMMAR_FILE, output)
+        self.assertEqual(b'', stderr)
+        self.assertEqual(0, exitcode)
+
+        self.compare_files(SYMBOL_FILE, output)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
index 057441c83c..38fc417524 100644
--- a/Lib/test/test_syntax.py
+++ b/Lib/test/test_syntax.py
@@ -35,14 +35,6 @@ SyntaxError: invalid syntax
 Traceback (most recent call last):
 SyntaxError: can't assign to keyword
 
-It's a syntax error to assign to the empty tuple.  Why isn't it an
-error to assign to the empty list?  It will always raise some error at
-runtime.
-
->>> () = 1
-Traceback (most recent call last):
-SyntaxError: can't assign to ()
-
 >>> f() = 1
 Traceback (most recent call last):
 SyntaxError: can't assign to function call
@@ -491,10 +483,6 @@ Traceback (most recent call last):
    ...
 SyntaxError: keyword argument repeated
 
->>> del ()
-Traceback (most recent call last):
-SyntaxError: can't delete ()
-
 >>> {1, 2, 3} = 42
 Traceback (most recent call last):
 SyntaxError: can't assign to literal
diff --git a/Lib/test/test_sys_settrace.py b/Lib/test/test_sys_settrace.py
index 509bc3e505..25c5835fd6 100644
--- a/Lib/test/test_sys_settrace.py
+++ b/Lib/test/test_sys_settrace.py
@@ -338,8 +338,8 @@ class TraceTestCase(unittest.TestCase):
 
     def test_14_onliner_if(self):
         def onliners():
-            if True: False
-            else: True
+            if True: x=False
+            else: x=True
             return 0
         self.run_and_compare(
             onliners,
diff --git a/Lib/test/test_tarfile.py b/Lib/test/test_tarfile.py
index abfb34dfb8..d7785ceada 100644
--- a/Lib/test/test_tarfile.py
+++ b/Lib/test/test_tarfile.py
@@ -2074,6 +2074,24 @@ class MiscTest(unittest.TestCase):
         with self.assertRaises(ValueError):
             tarfile.itn(0x10000000000, 6, tarfile.GNU_FORMAT)
 
+    def test__all__(self):
+        blacklist = {'version', 'grp', 'pwd', 'symlink_exception',
+                     'NUL', 'BLOCKSIZE', 'RECORDSIZE', 'GNU_MAGIC',
+                     'POSIX_MAGIC', 'LENGTH_NAME', 'LENGTH_LINK',
+                     'LENGTH_PREFIX', 'REGTYPE', 'AREGTYPE', 'LNKTYPE',
+                     'SYMTYPE', 'CHRTYPE', 'BLKTYPE', 'DIRTYPE', 'FIFOTYPE',
+                     'CONTTYPE', 'GNUTYPE_LONGNAME', 'GNUTYPE_LONGLINK',
+                     'GNUTYPE_SPARSE', 'XHDTYPE', 'XGLTYPE', 'SOLARIS_XHDTYPE',
+                     'SUPPORTED_TYPES', 'REGULAR_TYPES', 'GNU_TYPES',
+                     'PAX_FIELDS', 'PAX_NAME_FIELDS', 'PAX_NUMBER_FIELDS',
+                     'stn', 'nts', 'nti', 'itn', 'calc_chksums', 'copyfileobj',
+                     'filemode',
+                     'EmptyHeaderError', 'TruncatedHeaderError',
+                     'EOFHeaderError', 'InvalidHeaderError',
+                     'SubsequentHeaderError', 'ExFileObject',
+                     'main'}
+        support.check__all__(self, tarfile, blacklist=blacklist)
+
 
 class CommandLineTest(unittest.TestCase):
 
diff --git a/Lib/test/test_telnetlib.py b/Lib/test/test_telnetlib.py
index 8e219f4217..51d82e1158 100644
--- a/Lib/test/test_telnetlib.py
+++ b/Lib/test/test_telnetlib.py
@@ -1,7 +1,6 @@
 import socket
 import selectors
 import telnetlib
-import time
 import contextlib
 
 from test import support
@@ -42,6 +41,11 @@ class GeneralTests(unittest.TestCase):
         telnet = telnetlib.Telnet(HOST, self.port)
         telnet.sock.close()
 
+    def testContextManager(self):
+        with telnetlib.Telnet(HOST, self.port) as tn:
+            self.assertIsNotNone(tn.get_socket())
+        self.assertIsNone(tn.get_socket())
+
     def testTimeoutDefault(self):
         self.assertTrue(socket.getdefaulttimeout() is None)
         socket.setdefaulttimeout(30)
diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index b49a9615f0..d6317c71bf 100644
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -3,11 +3,10 @@ Tests for the threading module.
 """
 
 import test.support
-from test.support import verbose, strip_python_stderr, import_module, cpython_only
+from test.support import verbose, import_module, cpython_only
 from test.support.script_helper import assert_python_ok, assert_python_failure
 
 import random
-import re
 import sys
 _thread = import_module('_thread')
 threading = import_module('threading')
@@ -18,6 +17,7 @@ import os
 import subprocess
 
 from test import lock_tests
+from test import support
 
 
 # Between fork() and exec(), only async-safe functions are allowed (issues
@@ -1097,5 +1097,12 @@ class BoundedSemaphoreTests(lock_tests.BoundedSemaphoreTests):
 class BarrierTests(lock_tests.BarrierTests):
     barriertype = staticmethod(threading.Barrier)
 
+class MiscTestCase(unittest.TestCase):
+    def test__all__(self):
+        extra = {"ThreadError"}
+        blacklist = {'currentThread', 'activeCount'}
+        support.check__all__(self, threading, ('threading', '_thread'),
+                             extra=extra, blacklist=blacklist)
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_time.py b/Lib/test/test_time.py
index 76b894eece..f883c45d04 100644
--- a/Lib/test/test_time.py
+++ b/Lib/test/test_time.py
@@ -1,6 +1,8 @@
 from test import support
+import decimal
 import enum
 import locale
+import math
 import platform
 import sys
 import sysconfig
@@ -21,17 +23,27 @@ SIZEOF_INT = sysconfig.get_config_var('SIZEOF_INT') or 4
 TIME_MAXYEAR = (1 << 8 * SIZEOF_INT - 1) - 1
 TIME_MINYEAR = -TIME_MAXYEAR - 1
 
+SEC_TO_US = 10 ** 6
 US_TO_NS = 10 ** 3
 MS_TO_NS = 10 ** 6
 SEC_TO_NS = 10 ** 9
+NS_TO_SEC = 10 ** 9
 
 class _PyTime(enum.IntEnum):
     # Round towards minus infinity (-inf)
     ROUND_FLOOR = 0
     # Round towards infinity (+inf)
     ROUND_CEILING = 1
+    # Round to nearest with ties going to nearest even integer
+    ROUND_HALF_EVEN = 2
 
-ALL_ROUNDING_METHODS = (_PyTime.ROUND_FLOOR, _PyTime.ROUND_CEILING)
+# Rounding modes supported by PyTime
+ROUNDING_MODES = (
+    # (PyTime rounding method, decimal rounding method)
+    (_PyTime.ROUND_FLOOR, decimal.ROUND_FLOOR),
+    (_PyTime.ROUND_CEILING, decimal.ROUND_CEILING),
+    (_PyTime.ROUND_HALF_EVEN, decimal.ROUND_HALF_EVEN),
+)
 
 
 class TimeTestCase(unittest.TestCase):
@@ -607,79 +619,6 @@ class TestStrftime4dyear(_TestStrftimeYear, _Test4dYear, unittest.TestCase):
 
 
 class TestPytime(unittest.TestCase):
-    def setUp(self):
-        self.invalid_values = (
-            -(2 ** 100), 2 ** 100,
-            -(2.0 ** 100.0), 2.0 ** 100.0,
-        )
-
-    @support.cpython_only
-    def test_time_t(self):
-        from _testcapi import pytime_object_to_time_t
-        for obj, time_t, rnd in (
-            # Round towards minus infinity (-inf)
-            (0, 0, _PyTime.ROUND_FLOOR),
-            (-1, -1, _PyTime.ROUND_FLOOR),
-            (-1.0, -1, _PyTime.ROUND_FLOOR),
-            (-1.9, -2, _PyTime.ROUND_FLOOR),
-            (1.0, 1, _PyTime.ROUND_FLOOR),
-            (1.9, 1, _PyTime.ROUND_FLOOR),
-            # Round towards infinity (+inf)
-            (0, 0, _PyTime.ROUND_CEILING),
-            (-1, -1, _PyTime.ROUND_CEILING),
-            (-1.0, -1, _PyTime.ROUND_CEILING),
-            (-1.9, -1, _PyTime.ROUND_CEILING),
-            (1.0, 1, _PyTime.ROUND_CEILING),
-            (1.9, 2, _PyTime.ROUND_CEILING),
-        ):
-            self.assertEqual(pytime_object_to_time_t(obj, rnd), time_t)
-
-        rnd = _PyTime.ROUND_FLOOR
-        for invalid in self.invalid_values:
-            self.assertRaises(OverflowError,
-                              pytime_object_to_time_t, invalid, rnd)
-
-    @support.cpython_only
-    def test_timespec(self):
-        from _testcapi import pytime_object_to_timespec
-        for obj, timespec, rnd in (
-            # Round towards minus infinity (-inf)
-            (0, (0, 0), _PyTime.ROUND_FLOOR),
-            (-1, (-1, 0), _PyTime.ROUND_FLOOR),
-            (-1.0, (-1, 0), _PyTime.ROUND_FLOOR),
-            (1e-9, (0, 1), _PyTime.ROUND_FLOOR),
-            (1e-10, (0, 0), _PyTime.ROUND_FLOOR),
-            (-1e-9, (-1, 999999999), _PyTime.ROUND_FLOOR),
-            (-1e-10, (-1, 999999999), _PyTime.ROUND_FLOOR),
-            (-1.2, (-2, 800000000), _PyTime.ROUND_FLOOR),
-            (0.9999999999, (0, 999999999), _PyTime.ROUND_FLOOR),
-            (1.1234567890, (1, 123456789), _PyTime.ROUND_FLOOR),
-            (1.1234567899, (1, 123456789), _PyTime.ROUND_FLOOR),
-            (-1.1234567890, (-2, 876543211), _PyTime.ROUND_FLOOR),
-            (-1.1234567891, (-2, 876543210), _PyTime.ROUND_FLOOR),
-            # Round towards infinity (+inf)
-            (0, (0, 0), _PyTime.ROUND_CEILING),
-            (-1, (-1, 0), _PyTime.ROUND_CEILING),
-            (-1.0, (-1, 0), _PyTime.ROUND_CEILING),
-            (1e-9, (0, 1), _PyTime.ROUND_CEILING),
-            (1e-10, (0, 1), _PyTime.ROUND_CEILING),
-            (-1e-9, (-1, 999999999), _PyTime.ROUND_CEILING),
-            (-1e-10, (0, 0), _PyTime.ROUND_CEILING),
-            (-1.2, (-2, 800000000), _PyTime.ROUND_CEILING),
-            (0.9999999999, (1, 0), _PyTime.ROUND_CEILING),
-            (1.1234567890, (1, 123456790), _PyTime.ROUND_CEILING),
-            (1.1234567899, (1, 123456790), _PyTime.ROUND_CEILING),
-            (-1.1234567890, (-2, 876543211), _PyTime.ROUND_CEILING),
-            (-1.1234567891, (-2, 876543211), _PyTime.ROUND_CEILING),
-        ):
-            with self.subTest(obj=obj, round=rnd, timespec=timespec):
-                self.assertEqual(pytime_object_to_timespec(obj, rnd), timespec)
-
-        rnd = _PyTime.ROUND_FLOOR
-        for invalid in self.invalid_values:
-            self.assertRaises(OverflowError,
-                              pytime_object_to_timespec, invalid, rnd)
-
     @unittest.skipUnless(time._STRUCT_TM_ITEMS == 11, "needs tm_zone support")
     def test_localtime_timezone(self):
 
@@ -734,266 +673,291 @@ class TestPytime(unittest.TestCase):
         self.assertIs(lt.tm_zone, None)
 
 
-@unittest.skipUnless(_testcapi is not None,
-                     'need the _testcapi module')
-class TestPyTime_t(unittest.TestCase):
+@unittest.skipIf(_testcapi is None, 'need the _testcapi module')
+class CPyTimeTestCase:
+    """
+    Base class to test the C _PyTime_t API.
+    """
+    OVERFLOW_SECONDS = None
+
+    def setUp(self):
+        from _testcapi import SIZEOF_TIME_T
+        bits = SIZEOF_TIME_T * 8 - 1
+        self.time_t_min = -2 ** bits
+        self.time_t_max = 2 ** bits - 1
+
+    def time_t_filter(self, seconds):
+        return (self.time_t_min <= seconds <= self.time_t_max)
+
+    def _rounding_values(self, use_float):
+        "Build timestamps used to test rounding."
+
+        units = [1, US_TO_NS, MS_TO_NS, SEC_TO_NS]
+        if use_float:
+            # picoseconds are only tested to pytime_converter accepting floats
+            units.append(1e-3)
+
+        values = (
+            # small values
+            1, 2, 5, 7, 123, 456, 1234,
+            # 10^k - 1
+            9,
+            99,
+            999,
+            9999,
+            99999,
+            999999,
+            # test half even rounding near 0.5, 1.5, 2.5, 3.5, 4.5
+            499, 500, 501,
+            1499, 1500, 1501,
+            2500,
+            3500,
+            4500,
+        )
+
+        ns_timestamps = [0]
+        for unit in units:
+            for value in values:
+                ns = value * unit
+                ns_timestamps.extend((-ns, ns))
+        for pow2 in (0, 5, 10, 15, 22, 23, 24, 30, 33):
+            ns = (2 ** pow2) * SEC_TO_NS
+            ns_timestamps.extend((
+                -ns-1, -ns, -ns+1,
+                ns-1, ns, ns+1
+            ))
+        for seconds in (_testcapi.INT_MIN, _testcapi.INT_MAX):
+            ns_timestamps.append(seconds * SEC_TO_NS)
+        if use_float:
+            # numbers with an extract representation in IEEE 754 (base 2)
+            for pow2 in (3, 7, 10, 15):
+                ns = 2.0 ** (-pow2)
+                ns_timestamps.extend((-ns, ns))
+
+        # seconds close to _PyTime_t type limit
+        ns = (2 ** 63 // SEC_TO_NS) * SEC_TO_NS
+        ns_timestamps.extend((-ns, ns))
+
+        return ns_timestamps
+
+    def _check_rounding(self, pytime_converter, expected_func,
+                        use_float, unit_to_sec, value_filter=None):
+
+        def convert_values(ns_timestamps):
+            if use_float:
+                unit_to_ns = SEC_TO_NS / float(unit_to_sec)
+                values = [ns / unit_to_ns for ns in ns_timestamps]
+            else:
+                unit_to_ns = SEC_TO_NS // unit_to_sec
+                values = [ns // unit_to_ns for ns in ns_timestamps]
+
+            if value_filter:
+                values = filter(value_filter, values)
+
+            # remove duplicates and sort
+            return sorted(set(values))
+
+        # test rounding
+        ns_timestamps = self._rounding_values(use_float)
+        valid_values = convert_values(ns_timestamps)
+        for time_rnd, decimal_rnd in ROUNDING_MODES :
+            context = decimal.getcontext()
+            context.rounding = decimal_rnd
+
+            for value in valid_values:
+                debug_info = {'value': value, 'rounding': decimal_rnd}
+                try:
+                    result = pytime_converter(value, time_rnd)
+                    expected = expected_func(value)
+                except Exception as exc:
+                    self.fail("Error on timestamp conversion: %s" % debug_info)
+                self.assertEqual(result,
+                                 expected,
+                                 debug_info)
+
+        # test overflow
+        ns = self.OVERFLOW_SECONDS * SEC_TO_NS
+        ns_timestamps = (-ns, ns)
+        overflow_values = convert_values(ns_timestamps)
+        for time_rnd, _ in ROUNDING_MODES :
+            for value in overflow_values:
+                debug_info = {'value': value, 'rounding': time_rnd}
+                with self.assertRaises(OverflowError, msg=debug_info):
+                    pytime_converter(value, time_rnd)
+
+    def check_int_rounding(self, pytime_converter, expected_func,
+                           unit_to_sec=1, value_filter=None):
+        self._check_rounding(pytime_converter, expected_func,
+                             False, unit_to_sec, value_filter)
+
+    def check_float_rounding(self, pytime_converter, expected_func,
+                             unit_to_sec=1, value_filter=None):
+        self._check_rounding(pytime_converter, expected_func,
+                             True, unit_to_sec, value_filter)
+
+    def decimal_round(self, x):
+        d = decimal.Decimal(x)
+        d = d.quantize(1)
+        return int(d)
+
+
+class TestCPyTime(CPyTimeTestCase, unittest.TestCase):
+    """
+    Test the C _PyTime_t API.
+    """
+    # _PyTime_t is a 64-bit signed integer
+    OVERFLOW_SECONDS = math.ceil((2**63 + 1) / SEC_TO_NS)
+
     def test_FromSeconds(self):
         from _testcapi import PyTime_FromSeconds
-        for seconds in (0, 3, -456, _testcapi.INT_MAX, _testcapi.INT_MIN):
-            with self.subTest(seconds=seconds):
-                self.assertEqual(PyTime_FromSeconds(seconds),
-                                 seconds * SEC_TO_NS)
+
+        # PyTime_FromSeconds() expects a C int, reject values out of range
+        def c_int_filter(secs):
+            return (_testcapi.INT_MIN <= secs <= _testcapi.INT_MAX)
+
+        self.check_int_rounding(lambda secs, rnd: PyTime_FromSeconds(secs),
+                                lambda secs: secs * SEC_TO_NS,
+                                value_filter=c_int_filter)
 
     def test_FromSecondsObject(self):
         from _testcapi import PyTime_FromSecondsObject
 
-        # Conversion giving the same result for all rounding methods
-        for rnd in ALL_ROUNDING_METHODS:
-            for obj, ts in (
-                # integers
-                (0, 0),
-                (1, SEC_TO_NS),
-                (-3, -3 * SEC_TO_NS),
-
-                # float: subseconds
-                (0.0, 0),
-                (1e-9, 1),
-                (1e-6, 10 ** 3),
-                (1e-3, 10 ** 6),
-
-                # float: seconds
-                (2.0, 2 * SEC_TO_NS),
-                (123.0, 123 * SEC_TO_NS),
-                (-7.0, -7 * SEC_TO_NS),
-
-                # nanosecond are kept for value <= 2^23 seconds
-                (2**22 - 1e-9,  4194303999999999),
-                (2**22,         4194304000000000),
-                (2**22 + 1e-9,  4194304000000001),
-                (2**23 - 1e-9,  8388607999999999),
-                (2**23,         8388608000000000),
-
-                # start losing precision for value > 2^23 seconds
-                (2**23 + 1e-9,  8388608000000002),
-
-                # nanoseconds are lost for value > 2^23 seconds
-                (2**24 - 1e-9, 16777215999999998),
-                (2**24,        16777216000000000),
-                (2**24 + 1e-9, 16777216000000000),
-                (2**25 - 1e-9, 33554432000000000),
-                (2**25       , 33554432000000000),
-                (2**25 + 1e-9, 33554432000000000),
-
-                # close to 2^63 nanoseconds (_PyTime_t limit)
-                (9223372036, 9223372036 * SEC_TO_NS),
-                (9223372036.0, 9223372036 * SEC_TO_NS),
-                (-9223372036, -9223372036 * SEC_TO_NS),
-                (-9223372036.0, -9223372036 * SEC_TO_NS),
-            ):
-                with self.subTest(obj=obj, round=rnd, timestamp=ts):
-                    self.assertEqual(PyTime_FromSecondsObject(obj, rnd), ts)
-
-            with self.subTest(round=rnd):
-                with self.assertRaises(OverflowError):
-                    PyTime_FromSecondsObject(9223372037, rnd)
-                    PyTime_FromSecondsObject(9223372037.0, rnd)
-                    PyTime_FromSecondsObject(-9223372037, rnd)
-                    PyTime_FromSecondsObject(-9223372037.0, rnd)
-
-        # Conversion giving different results depending on the rounding method
-        FLOOR = _PyTime.ROUND_FLOOR
-        CEILING = _PyTime.ROUND_CEILING
-        for obj, ts, rnd in (
-            # close to zero
-            ( 1e-10,  0, FLOOR),
-            ( 1e-10,  1, CEILING),
-            (-1e-10, -1, FLOOR),
-            (-1e-10,  0, CEILING),
-
-            # test rounding of the last nanosecond
-            ( 1.1234567899,  1123456789, FLOOR),
-            ( 1.1234567899,  1123456790, CEILING),
-            (-1.1234567899, -1123456790, FLOOR),
-            (-1.1234567899, -1123456789, CEILING),
-
-            # close to 1 second
-            ( 0.9999999999,   999999999, FLOOR),
-            ( 0.9999999999,  1000000000, CEILING),
-            (-0.9999999999, -1000000000, FLOOR),
-            (-0.9999999999,  -999999999, CEILING),
-        ):
-            with self.subTest(obj=obj, round=rnd, timestamp=ts):
-                self.assertEqual(PyTime_FromSecondsObject(obj, rnd), ts)
+        self.check_int_rounding(
+            PyTime_FromSecondsObject,
+            lambda secs: secs * SEC_TO_NS)
+
+        self.check_float_rounding(
+            PyTime_FromSecondsObject,
+            lambda ns: self.decimal_round(ns * SEC_TO_NS))
 
     def test_AsSecondsDouble(self):
         from _testcapi import PyTime_AsSecondsDouble
 
-        for nanoseconds, seconds in (
-            # near 1 nanosecond
-            ( 0,  0.0),
-            ( 1,  1e-9),
-            (-1, -1e-9),
-
-            # near 1 second
-            (SEC_TO_NS + 1, 1.0 + 1e-9),
-            (SEC_TO_NS,     1.0),
-            (SEC_TO_NS - 1, 1.0 - 1e-9),
-
-            # a few seconds
-            (123 * SEC_TO_NS, 123.0),
-            (-567 * SEC_TO_NS, -567.0),
-
-            # nanosecond are kept for value <= 2^23 seconds
-            (4194303999999999, 2**22 - 1e-9),
-            (4194304000000000, 2**22),
-            (4194304000000001, 2**22 + 1e-9),
-
-            # start losing precision for value > 2^23 seconds
-            (8388608000000002, 2**23 + 1e-9),
-
-            # nanoseconds are lost for value > 2^23 seconds
-            (16777215999999998, 2**24 - 1e-9),
-            (16777215999999999, 2**24 - 1e-9),
-            (16777216000000000, 2**24       ),
-            (16777216000000001, 2**24       ),
-            (16777216000000002, 2**24 + 2e-9),
-
-            (33554432000000000, 2**25       ),
-            (33554432000000002, 2**25       ),
-            (33554432000000004, 2**25 + 4e-9),
-
-            # close to 2^63 nanoseconds (_PyTime_t limit)
-            (9223372036 * SEC_TO_NS, 9223372036.0),
-            (-9223372036 * SEC_TO_NS, -9223372036.0),
-        ):
-            with self.subTest(nanoseconds=nanoseconds, seconds=seconds):
-                self.assertEqual(PyTime_AsSecondsDouble(nanoseconds),
-                                 seconds)
-
-    def test_timeval(self):
+        def float_converter(ns):
+            if abs(ns) % SEC_TO_NS == 0:
+                return float(ns // SEC_TO_NS)
+            else:
+                return float(ns) / SEC_TO_NS
+
+        self.check_int_rounding(lambda ns, rnd: PyTime_AsSecondsDouble(ns),
+                                float_converter,
+                                NS_TO_SEC)
+
+    def create_decimal_converter(self, denominator):
+        denom = decimal.Decimal(denominator)
+
+        def converter(value):
+            d = decimal.Decimal(value) / denom
+            return self.decimal_round(d)
+
+        return converter
+
+    def test_AsTimeval(self):
         from _testcapi import PyTime_AsTimeval
-        for rnd in ALL_ROUNDING_METHODS:
-            for ns, tv in (
-                # microseconds
-                (0, (0, 0)),
-                (1000, (0, 1)),
-                (-1000, (-1, 999999)),
-
-                # seconds
-                (2 * SEC_TO_NS, (2, 0)),
-                (-3 * SEC_TO_NS, (-3, 0)),
-            ):
-                with self.subTest(nanoseconds=ns, timeval=tv, round=rnd):
-                    self.assertEqual(PyTime_AsTimeval(ns, rnd), tv)
-
-        FLOOR = _PyTime.ROUND_FLOOR
-        CEILING = _PyTime.ROUND_CEILING
-        for ns, tv, rnd in (
-            # nanoseconds
-            (1, (0, 0), FLOOR),
-            (1, (0, 1), CEILING),
-            (-1, (-1, 999999), FLOOR),
-            (-1, (0, 0), CEILING),
-
-            # seconds + nanoseconds
-            (1234567001, (1, 234567), FLOOR),
-            (1234567001, (1, 234568), CEILING),
-            (-1234567001, (-2, 765432), FLOOR),
-            (-1234567001, (-2, 765433), CEILING),
-        ):
-            with self.subTest(nanoseconds=ns, timeval=tv, round=rnd):
-                self.assertEqual(PyTime_AsTimeval(ns, rnd), tv)
+
+        us_converter = self.create_decimal_converter(US_TO_NS)
+
+        def timeval_converter(ns):
+            us = us_converter(ns)
+            return divmod(us, SEC_TO_US)
+
+        if sys.platform == 'win32':
+            from _testcapi import LONG_MIN, LONG_MAX
+
+            # On Windows, timeval.tv_sec type is a C long
+            def seconds_filter(secs):
+                return LONG_MIN <= secs <= LONG_MAX
+        else:
+            seconds_filter = self.time_t_filter
+
+        self.check_int_rounding(PyTime_AsTimeval,
+                                timeval_converter,
+                                NS_TO_SEC,
+                                value_filter=seconds_filter)
 
     @unittest.skipUnless(hasattr(_testcapi, 'PyTime_AsTimespec'),
                          'need _testcapi.PyTime_AsTimespec')
-    def test_timespec(self):
+    def test_AsTimespec(self):
         from _testcapi import PyTime_AsTimespec
-        for ns, ts in (
-            # nanoseconds
-            (0, (0, 0)),
-            (1, (0, 1)),
-            (-1, (-1, 999999999)),
-
-            # seconds
-            (2 * SEC_TO_NS, (2, 0)),
-            (-3 * SEC_TO_NS, (-3, 0)),
-
-            # seconds + nanoseconds
-            (1234567890, (1, 234567890)),
-            (-1234567890, (-2, 765432110)),
-        ):
-            with self.subTest(nanoseconds=ns, timespec=ts):
-                self.assertEqual(PyTime_AsTimespec(ns), ts)
-
-    def test_milliseconds(self):
+
+        def timespec_converter(ns):
+            return divmod(ns, SEC_TO_NS)
+
+        self.check_int_rounding(lambda ns, rnd: PyTime_AsTimespec(ns),
+                                timespec_converter,
+                                NS_TO_SEC,
+                                value_filter=self.time_t_filter)
+
+    def test_AsMilliseconds(self):
         from _testcapi import PyTime_AsMilliseconds
-        for rnd in ALL_ROUNDING_METHODS:
-            for ns, tv in (
-                # milliseconds
-                (1 * MS_TO_NS, 1),
-                (-2 * MS_TO_NS, -2),
-
-                # seconds
-                (2 * SEC_TO_NS, 2000),
-                (-3 * SEC_TO_NS, -3000),
-            ):
-                with self.subTest(nanoseconds=ns, timeval=tv, round=rnd):
-                    self.assertEqual(PyTime_AsMilliseconds(ns, rnd), tv)
-
-        FLOOR = _PyTime.ROUND_FLOOR
-        CEILING = _PyTime.ROUND_CEILING
-        for ns, ms, rnd in (
-            # nanoseconds
-            (1, 0, FLOOR),
-            (1, 1, CEILING),
-            (-1, -1, FLOOR),
-            (-1, 0, CEILING),
-
-            # seconds + nanoseconds
-            (1234 * MS_TO_NS + 1, 1234, FLOOR),
-            (1234 * MS_TO_NS + 1, 1235, CEILING),
-            (-1234 * MS_TO_NS - 1, -1235, FLOOR),
-            (-1234 * MS_TO_NS - 1, -1234, CEILING),
-        ):
-            with self.subTest(nanoseconds=ns, milliseconds=ms, round=rnd):
-                self.assertEqual(PyTime_AsMilliseconds(ns, rnd), ms)
-
-    def test_microseconds(self):
+
+        self.check_int_rounding(PyTime_AsMilliseconds,
+                                self.create_decimal_converter(MS_TO_NS),
+                                NS_TO_SEC)
+
+    def test_AsMicroseconds(self):
         from _testcapi import PyTime_AsMicroseconds
-        for rnd in ALL_ROUNDING_METHODS:
-            for ns, tv in (
-                # microseconds
-                (1 * US_TO_NS, 1),
-                (-2 * US_TO_NS, -2),
-
-                # milliseconds
-                (1 * MS_TO_NS, 1000),
-                (-2 * MS_TO_NS, -2000),
-
-                # seconds
-                (2 * SEC_TO_NS, 2000000),
-                (-3 * SEC_TO_NS, -3000000),
-            ):
-                with self.subTest(nanoseconds=ns, timeval=tv, round=rnd):
-                    self.assertEqual(PyTime_AsMicroseconds(ns, rnd), tv)
-
-        FLOOR = _PyTime.ROUND_FLOOR
-        CEILING = _PyTime.ROUND_CEILING
-        for ns, ms, rnd in (
-            # nanoseconds
-            (1, 0, FLOOR),
-            (1, 1, CEILING),
-            (-1, -1, FLOOR),
-            (-1, 0, CEILING),
-
-            # seconds + nanoseconds
-            (1234 * US_TO_NS + 1, 1234, FLOOR),
-            (1234 * US_TO_NS + 1, 1235, CEILING),
-            (-1234 * US_TO_NS - 1, -1235, FLOOR),
-            (-1234 * US_TO_NS - 1, -1234, CEILING),
-        ):
-            with self.subTest(nanoseconds=ns, milliseconds=ms, round=rnd):
-                self.assertEqual(PyTime_AsMicroseconds(ns, rnd), ms)
+
+        self.check_int_rounding(PyTime_AsMicroseconds,
+                                self.create_decimal_converter(US_TO_NS),
+                                NS_TO_SEC)
+
+
+class TestOldPyTime(CPyTimeTestCase, unittest.TestCase):
+    """
+    Test the old C _PyTime_t API: _PyTime_ObjectToXXX() functions.
+    """
+
+    # time_t is a 32-bit or 64-bit signed integer
+    OVERFLOW_SECONDS = 2 ** 64
+
+    def test_object_to_time_t(self):
+        from _testcapi import pytime_object_to_time_t
+
+        self.check_int_rounding(pytime_object_to_time_t,
+                                lambda secs: secs,
+                                value_filter=self.time_t_filter)
+
+        self.check_float_rounding(pytime_object_to_time_t,
+                                  self.decimal_round,
+                                  value_filter=self.time_t_filter)
+
+    def create_converter(self, sec_to_unit):
+        def converter(secs):
+            floatpart, intpart = math.modf(secs)
+            intpart = int(intpart)
+            floatpart *= sec_to_unit
+            floatpart = self.decimal_round(floatpart)
+            if floatpart < 0:
+                floatpart += sec_to_unit
+                intpart -= 1
+            elif floatpart >= sec_to_unit:
+                floatpart -= sec_to_unit
+                intpart += 1
+            return (intpart, floatpart)
+        return converter
+
+    def test_object_to_timeval(self):
+        from _testcapi import pytime_object_to_timeval
+
+        self.check_int_rounding(pytime_object_to_timeval,
+                                lambda secs: (secs, 0),
+                                value_filter=self.time_t_filter)
+
+        self.check_float_rounding(pytime_object_to_timeval,
+                                  self.create_converter(SEC_TO_US),
+                                  value_filter=self.time_t_filter)
+
+    def test_object_to_timespec(self):
+        from _testcapi import pytime_object_to_timespec
+
+        self.check_int_rounding(pytime_object_to_timespec,
+                                lambda secs: (secs, 0),
+                                value_filter=self.time_t_filter)
+
+        self.check_float_rounding(pytime_object_to_timespec,
+                                  self.create_converter(SEC_TO_NS),
+                                  value_filter=self.time_t_filter)
 
 
 if __name__ == "__main__":
diff --git a/Lib/test/test_tokenize.py b/Lib/test/test_tokenize.py
index 3b17ca6329..90438e7d30 100644
--- a/Lib/test/test_tokenize.py
+++ b/Lib/test/test_tokenize.py
@@ -24,8 +24,7 @@ class TokenizeTest(TestCase):
             if type == ENDMARKER:
                 break
             type = tok_name[type]
-            result.append("    %(type)-10.10s %(token)-13.13r %(start)s %(end)s" %
-                          locals())
+            result.append(f"    {type:10} {token!r:13} {start} {end}")
         self.assertEqual(result,
                          ["    ENCODING   'utf-8'       (0, 0) (0, 0)"] +
                          expected.rstrip().splitlines())
@@ -132,18 +131,18 @@ def k(x):
         self.check_tokenize("x = 0xfffffffffff", """\
     NAME       'x'           (1, 0) (1, 1)
     OP         '='           (1, 2) (1, 3)
-    NUMBER     '0xffffffffff (1, 4) (1, 17)
+    NUMBER     '0xfffffffffff' (1, 4) (1, 17)
     """)
         self.check_tokenize("x = 123141242151251616110", """\
     NAME       'x'           (1, 0) (1, 1)
     OP         '='           (1, 2) (1, 3)
-    NUMBER     '123141242151 (1, 4) (1, 25)
+    NUMBER     '123141242151251616110' (1, 4) (1, 25)
     """)
         self.check_tokenize("x = -15921590215012591", """\
     NAME       'x'           (1, 0) (1, 1)
     OP         '='           (1, 2) (1, 3)
     OP         '-'           (1, 4) (1, 5)
-    NUMBER     '159215902150 (1, 5) (1, 22)
+    NUMBER     '15921590215012591' (1, 5) (1, 22)
     """)
 
     def test_float(self):
@@ -307,6 +306,50 @@ def k(x):
     OP         '+'           (1, 28) (1, 29)
     STRING     'RB"abc"'     (1, 30) (1, 37)
     """)
+        # Check 0, 1, and 2 character string prefixes.
+        self.check_tokenize(r'"a\
+de\
+fg"', """\
+    STRING     '"a\\\\\\nde\\\\\\nfg"\' (1, 0) (3, 3)
+    """)
+        self.check_tokenize(r'u"a\
+de"', """\
+    STRING     'u"a\\\\\\nde"\'  (1, 0) (2, 3)
+    """)
+        self.check_tokenize(r'rb"a\
+d"', """\
+    STRING     'rb"a\\\\\\nd"\'  (1, 0) (2, 2)
+    """)
+        self.check_tokenize(r'"""a\
+b"""', """\
+    STRING     '\"\""a\\\\\\nb\"\""' (1, 0) (2, 4)
+    """)
+        self.check_tokenize(r'u"""a\
+b"""', """\
+    STRING     'u\"\""a\\\\\\nb\"\""' (1, 0) (2, 4)
+    """)
+        self.check_tokenize(r'rb"""a\
+b\
+c"""', """\
+    STRING     'rb"\""a\\\\\\nb\\\\\\nc"\""' (1, 0) (3, 4)
+    """)
+        self.check_tokenize('f"abc"', """\
+    STRING     'f"abc"'      (1, 0) (1, 6)
+    """)
+        self.check_tokenize('fR"a{b}c"', """\
+    STRING     'fR"a{b}c"'   (1, 0) (1, 9)
+    """)
+        self.check_tokenize('f"""abc"""', """\
+    STRING     'f\"\"\"abc\"\"\"'  (1, 0) (1, 10)
+    """)
+        self.check_tokenize(r'f"abc\
+def"', """\
+    STRING     'f"abc\\\\\\ndef"' (1, 0) (2, 4)
+    """)
+        self.check_tokenize(r'Rf"abc\
+def"', """\
+    STRING     'Rf"abc\\\\\\ndef"' (1, 0) (2, 4)
+    """)
 
     def test_function(self):
         self.check_tokenize("def d22(a, b, c=2, d=2, *k): pass", """\
@@ -505,7 +548,7 @@ def k(x):
         # Methods
         self.check_tokenize("@staticmethod\ndef foo(x,y): pass", """\
     OP         '@'           (1, 0) (1, 1)
-    NAME       'staticmethod (1, 1) (1, 13)
+    NAME       'staticmethod' (1, 1) (1, 13)
     NEWLINE    '\\n'          (1, 13) (1, 14)
     NAME       'def'         (2, 0) (2, 3)
     NAME       'foo'         (2, 4) (2, 7)
diff --git a/Lib/test/test_tools/__init__.py b/Lib/test/test_tools/__init__.py
index 04c8726e11..4d0fca330a 100644
--- a/Lib/test/test_tools/__init__.py
+++ b/Lib/test/test_tools/__init__.py
@@ -3,7 +3,6 @@ import os
 import unittest
 import importlib
 from test import support
-from fnmatch import fnmatch
 
 basepath = os.path.dirname(                 # <src/install dir>
                 os.path.dirname(                # Lib
diff --git a/Lib/test/test_tools/test_gprof2html.py b/Lib/test/test_tools/test_gprof2html.py
index 0c294ec0c4..9489ed91f9 100644
--- a/Lib/test/test_tools/test_gprof2html.py
+++ b/Lib/test/test_tools/test_gprof2html.py
@@ -2,12 +2,11 @@
 
 import os
 import sys
-import importlib
 import unittest
 from unittest import mock
 import tempfile
 
-from test.test_tools import scriptsdir, skip_if_missing, import_tool
+from test.test_tools import skip_if_missing, import_tool
 
 skip_if_missing()
 
diff --git a/Lib/test/test_tools/test_md5sum.py b/Lib/test/test_tools/test_md5sum.py
index 1305295ef1..fb565b7377 100644
--- a/Lib/test/test_tools/test_md5sum.py
+++ b/Lib/test/test_tools/test_md5sum.py
@@ -1,12 +1,11 @@
 """Tests for the md5sum script in the Tools directory."""
 
 import os
-import sys
 import unittest
 from test import support
 from test.support.script_helper import assert_python_ok, assert_python_failure
 
-from test.test_tools import scriptsdir, import_tool, skip_if_missing
+from test.test_tools import scriptsdir, skip_if_missing
 
 skip_if_missing()
 
diff --git a/Lib/test/test_tools/test_pdeps.py b/Lib/test/test_tools/test_pdeps.py
index 091fa6a06d..27cbfe215d 100644
--- a/Lib/test/test_tools/test_pdeps.py
+++ b/Lib/test/test_tools/test_pdeps.py
@@ -1,12 +1,10 @@
 """Tests for the pdeps script in the Tools directory."""
 
 import os
-import sys
 import unittest
 import tempfile
-from test import support
 
-from test.test_tools import scriptsdir, skip_if_missing, import_tool
+from test.test_tools import skip_if_missing, import_tool
 
 skip_if_missing()
 
diff --git a/Lib/test/test_tools/test_unparse.py b/Lib/test/test_tools/test_unparse.py
index 734bbc215a..d91ade9228 100644
--- a/Lib/test/test_tools/test_unparse.py
+++ b/Lib/test/test_tools/test_unparse.py
@@ -134,6 +134,15 @@ class ASTTestCase(unittest.TestCase):
 class UnparseTestCase(ASTTestCase):
     # Tests for specific bugs found in earlier versions of unparse
 
+    def test_fstrings(self):
+        # See issue 25180
+        self.check_roundtrip(r"""f'{f"{0}"*3}'""")
+        self.check_roundtrip(r"""f'{f"{y}"*3}'""")
+        self.check_roundtrip(r"""f'{f"{\'x\'}"*3}'""")
+
+        self.check_roundtrip(r'''f"{r'x' f'{\"s\"}'}"''')
+        self.check_roundtrip(r'''f"{r'x'rf'{\"s\"}'}"''')
+
     def test_del_statement(self):
         self.check_roundtrip("del x, y, z")
 
diff --git a/Lib/test/test_trace.py b/Lib/test/test_trace.py
index 03dff8432d..1d894aaf84 100644
--- a/Lib/test/test_trace.py
+++ b/Lib/test/test_trace.py
@@ -1,11 +1,11 @@
 import os
-import io
 import sys
 from test.support import TESTFN, rmtree, unlink, captured_stdout
+from test.support.script_helper import assert_python_ok, assert_python_failure
 import unittest
 
 import trace
-from trace import CoverageResults, Trace
+from trace import Trace
 
 from test.tracedmodules import testmod
 
@@ -365,51 +365,27 @@ class Test_Ignore(unittest.TestCase):
         # Matched before.
         self.assertTrue(ignore.names(jn('bar', 'baz.py'), 'baz'))
 
-
-class TestDeprecatedMethods(unittest.TestCase):
-
-    def test_deprecated_usage(self):
-        sio = io.StringIO()
-        with self.assertWarns(DeprecationWarning):
-            trace.usage(sio)
-        self.assertIn('Usage:', sio.getvalue())
-
-    def test_deprecated_Ignore(self):
-        with self.assertWarns(DeprecationWarning):
-            trace.Ignore()
-
-    def test_deprecated_modname(self):
-        with self.assertWarns(DeprecationWarning):
-            self.assertEqual("spam", trace.modname("spam"))
-
-    def test_deprecated_fullmodname(self):
-        with self.assertWarns(DeprecationWarning):
-            self.assertEqual("spam", trace.fullmodname("spam"))
-
-    def test_deprecated_find_lines_from_code(self):
-        with self.assertWarns(DeprecationWarning):
-            def foo():
-                pass
-            trace.find_lines_from_code(foo.__code__, ["eggs"])
-
-    def test_deprecated_find_lines(self):
-        with self.assertWarns(DeprecationWarning):
-            def foo():
-                pass
-            trace.find_lines(foo.__code__, ["eggs"])
-
-    def test_deprecated_find_strings(self):
-        with open(TESTFN, 'w') as fd:
-            self.addCleanup(unlink, TESTFN)
-        with self.assertWarns(DeprecationWarning):
-            trace.find_strings(fd.name)
-
-    def test_deprecated_find_executable_linenos(self):
+class TestCommandLine(unittest.TestCase):
+
+    def test_failures(self):
+        _errors = (
+            (b'filename is missing: required with the main options', '-l', '-T'),
+            (b'cannot specify both --listfuncs and (--trace or --count)', '-lc'),
+            (b'argument -R/--no-report: not allowed with argument -r/--report', '-rR'),
+            (b'must specify one of --trace, --count, --report, --listfuncs, or --trackcalls', '-g'),
+            (b'-r/--report requires -f/--file', '-r'),
+            (b'--summary can only be used with --count or --report', '-sT'),
+            (b'unrecognized arguments: -y', '-y'))
+        for message, *args in _errors:
+            *_, stderr = assert_python_failure('-m', 'trace', *args)
+            self.assertIn(message, stderr)
+
+    def test_listfuncs_flag_success(self):
         with open(TESTFN, 'w') as fd:
             self.addCleanup(unlink, TESTFN)
-        with self.assertWarns(DeprecationWarning):
-            trace.find_executable_linenos(fd.name)
-
+            fd.write("a = 1\n")
+            status, stdout, stderr = assert_python_ok('-m', 'trace', '-l', TESTFN)
+            self.assertIn(b'functions called:', stdout)
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
index b7695d6eb4..5e4b6a27e5 100644
--- a/Lib/test/test_traceback.py
+++ b/Lib/test/test_traceback.py
@@ -129,12 +129,12 @@ class SyntaxTracebackCases(unittest.TestCase):
         def do_test(firstlines, message, charset, lineno):
             # Raise the message in a subprocess, and catch the output
             try:
-                output = open(TESTFN, "w", encoding=charset)
-                output.write("""{0}if 1:
-                    import traceback;
-                    raise RuntimeError('{1}')
-                    """.format(firstlines, message))
-                output.close()
+                with open(TESTFN, "w", encoding=charset) as output:
+                    output.write("""{0}if 1:
+                        import traceback;
+                        raise RuntimeError('{1}')
+                        """.format(firstlines, message))
+
                 process = subprocess.Popen([sys.executable, TESTFN],
                     stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
                 stdout, stderr = process.communicate()
@@ -175,8 +175,8 @@ class SyntaxTracebackCases(unittest.TestCase):
                     text, charset, 5)
             do_test(" \t\f\n# coding: {0}\n".format(charset),
                     text, charset, 5)
-        # Issue #18960: coding spec should has no effect
-        do_test("0\n# coding: GBK\n", "h\xe9 ho", 'utf-8', 5)
+        # Issue #18960: coding spec should have no effect
+        do_test("x=0\n# coding: GBK\n", "h\xe9 ho", 'utf-8', 5)
 
     def test_print_traceback_at_exit(self):
         # Issue #22599: Ensure that it is possible to use the traceback module
diff --git a/Lib/test/test_tracemalloc.py b/Lib/test/test_tracemalloc.py
index da89a9a871..790ab7ee60 100644
--- a/Lib/test/test_tracemalloc.py
+++ b/Lib/test/test_tracemalloc.py
@@ -11,9 +11,15 @@ try:
     import threading
 except ImportError:
     threading = None
+try:
+    import _testcapi
+except ImportError:
+    _testcapi = None
+
 
 EMPTY_STRING_SIZE = sys.getsizeof(b'')
 
+
 def get_frames(nframe, lineno_delta):
     frames = []
     frame = sys._getframe(1)
@@ -37,28 +43,31 @@ def allocate_bytes(size):
 def create_snapshots():
     traceback_limit = 2
 
+    # _tracemalloc._get_traces() returns a list of (domain, size,
+    # traceback_frames) tuples. traceback_frames is a tuple of (filename,
+    # line_number) tuples.
     raw_traces = [
-        (10, (('a.py', 2), ('b.py', 4))),
-        (10, (('a.py', 2), ('b.py', 4))),
-        (10, (('a.py', 2), ('b.py', 4))),
+        (0, 10, (('a.py', 2), ('b.py', 4))),
+        (0, 10, (('a.py', 2), ('b.py', 4))),
+        (0, 10, (('a.py', 2), ('b.py', 4))),
 
-        (2, (('a.py', 5), ('b.py', 4))),
+        (1, 2, (('a.py', 5), ('b.py', 4))),
 
-        (66, (('b.py', 1),)),
+        (2, 66, (('b.py', 1),)),
 
-        (7, (('<unknown>', 0),)),
+        (3, 7, (('<unknown>', 0),)),
     ]
     snapshot = tracemalloc.Snapshot(raw_traces, traceback_limit)
 
     raw_traces2 = [
-        (10, (('a.py', 2), ('b.py', 4))),
-        (10, (('a.py', 2), ('b.py', 4))),
-        (10, (('a.py', 2), ('b.py', 4))),
+        (0, 10, (('a.py', 2), ('b.py', 4))),
+        (0, 10, (('a.py', 2), ('b.py', 4))),
+        (0, 10, (('a.py', 2), ('b.py', 4))),
 
-        (2, (('a.py', 5), ('b.py', 4))),
-        (5000, (('a.py', 5), ('b.py', 4))),
+        (2, 2, (('a.py', 5), ('b.py', 4))),
+        (2, 5000, (('a.py', 5), ('b.py', 4))),
 
-        (400, (('c.py', 578),)),
+        (4, 400, (('c.py', 578),)),
     ]
     snapshot2 = tracemalloc.Snapshot(raw_traces2, traceback_limit)
 
@@ -126,7 +135,7 @@ class TestTracemallocEnabled(unittest.TestCase):
 
     def find_trace(self, traces, traceback):
         for trace in traces:
-            if trace[1] == traceback._frames:
+            if trace[2] == traceback._frames:
                 return trace
 
         self.fail("trace not found")
@@ -140,7 +149,7 @@ class TestTracemallocEnabled(unittest.TestCase):
         trace = self.find_trace(traces, obj_traceback)
 
         self.assertIsInstance(trace, tuple)
-        size, traceback = trace
+        domain, size, traceback = trace
         self.assertEqual(size, obj_size)
         self.assertEqual(traceback, obj_traceback._frames)
 
@@ -167,9 +176,8 @@ class TestTracemallocEnabled(unittest.TestCase):
 
         trace1 = self.find_trace(traces, obj1_traceback)
         trace2 = self.find_trace(traces, obj2_traceback)
-        size1, traceback1 = trace1
-        size2, traceback2 = trace2
-        self.assertEqual(traceback2, traceback1)
+        domain1, size1, traceback1 = trace1
+        domain2, size2, traceback2 = trace2
         self.assertIs(traceback2, traceback1)
 
     def test_get_traced_memory(self):
@@ -292,7 +300,7 @@ class TestSnapshot(unittest.TestCase):
     maxDiff = 4000
 
     def test_create_snapshot(self):
-        raw_traces = [(5, (('a.py', 2),))]
+        raw_traces = [(0, 5, (('a.py', 2),))]
 
         with contextlib.ExitStack() as stack:
             stack.enter_context(patch.object(tracemalloc, 'is_tracing',
@@ -322,11 +330,11 @@ class TestSnapshot(unittest.TestCase):
         # exclude b.py
         snapshot3 = snapshot.filter_traces((filter1,))
         self.assertEqual(snapshot3.traces._traces, [
-            (10, (('a.py', 2), ('b.py', 4))),
-            (10, (('a.py', 2), ('b.py', 4))),
-            (10, (('a.py', 2), ('b.py', 4))),
-            (2, (('a.py', 5), ('b.py', 4))),
-            (7, (('<unknown>', 0),)),
+            (0, 10, (('a.py', 2), ('b.py', 4))),
+            (0, 10, (('a.py', 2), ('b.py', 4))),
+            (0, 10, (('a.py', 2), ('b.py', 4))),
+            (1, 2, (('a.py', 5), ('b.py', 4))),
+            (3, 7, (('<unknown>', 0),)),
         ])
 
         # filter_traces() must not touch the original snapshot
@@ -335,10 +343,10 @@ class TestSnapshot(unittest.TestCase):
         # only include two lines of a.py
         snapshot4 = snapshot3.filter_traces((filter2, filter3))
         self.assertEqual(snapshot4.traces._traces, [
-            (10, (('a.py', 2), ('b.py', 4))),
-            (10, (('a.py', 2), ('b.py', 4))),
-            (10, (('a.py', 2), ('b.py', 4))),
-            (2, (('a.py', 5), ('b.py', 4))),
+            (0, 10, (('a.py', 2), ('b.py', 4))),
+            (0, 10, (('a.py', 2), ('b.py', 4))),
+            (0, 10, (('a.py', 2), ('b.py', 4))),
+            (1, 2, (('a.py', 5), ('b.py', 4))),
         ])
 
         # No filter: just duplicate the snapshot
@@ -349,6 +357,54 @@ class TestSnapshot(unittest.TestCase):
 
         self.assertRaises(TypeError, snapshot.filter_traces, filter1)
 
+    def test_filter_traces_domain(self):
+        snapshot, snapshot2 = create_snapshots()
+        filter1 = tracemalloc.Filter(False, "a.py", domain=1)
+        filter2 = tracemalloc.Filter(True, "a.py", domain=1)
+
+        original_traces = list(snapshot.traces._traces)
+
+        # exclude a.py of domain 1
+        snapshot3 = snapshot.filter_traces((filter1,))
+        self.assertEqual(snapshot3.traces._traces, [
+            (0, 10, (('a.py', 2), ('b.py', 4))),
+            (0, 10, (('a.py', 2), ('b.py', 4))),
+            (0, 10, (('a.py', 2), ('b.py', 4))),
+            (2, 66, (('b.py', 1),)),
+            (3, 7, (('<unknown>', 0),)),
+        ])
+
+        # include domain 1
+        snapshot3 = snapshot.filter_traces((filter1,))
+        self.assertEqual(snapshot3.traces._traces, [
+            (0, 10, (('a.py', 2), ('b.py', 4))),
+            (0, 10, (('a.py', 2), ('b.py', 4))),
+            (0, 10, (('a.py', 2), ('b.py', 4))),
+            (2, 66, (('b.py', 1),)),
+            (3, 7, (('<unknown>', 0),)),
+        ])
+
+    def test_filter_traces_domain_filter(self):
+        snapshot, snapshot2 = create_snapshots()
+        filter1 = tracemalloc.DomainFilter(False, domain=3)
+        filter2 = tracemalloc.DomainFilter(True, domain=3)
+
+        # exclude domain 2
+        snapshot3 = snapshot.filter_traces((filter1,))
+        self.assertEqual(snapshot3.traces._traces, [
+            (0, 10, (('a.py', 2), ('b.py', 4))),
+            (0, 10, (('a.py', 2), ('b.py', 4))),
+            (0, 10, (('a.py', 2), ('b.py', 4))),
+            (1, 2, (('a.py', 5), ('b.py', 4))),
+            (2, 66, (('b.py', 1),)),
+        ])
+
+        # include domain 2
+        snapshot3 = snapshot.filter_traces((filter2,))
+        self.assertEqual(snapshot3.traces._traces, [
+            (3, 7, (('<unknown>', 0),)),
+        ])
+
     def test_snapshot_group_by_line(self):
         snapshot, snapshot2 = create_snapshots()
         tb_0 = traceback_lineno('<unknown>', 0)
@@ -816,12 +872,121 @@ class TestCommandLine(unittest.TestCase):
         assert_python_ok('-X', 'tracemalloc', '-c', code)
 
 
+@unittest.skipIf(_testcapi is None, 'need _testcapi')
+class TestCAPI(unittest.TestCase):
+    maxDiff = 80 * 20
+
+    def setUp(self):
+        if tracemalloc.is_tracing():
+            self.skipTest("tracemalloc must be stopped before the test")
+
+        self.domain = 5
+        self.size = 123
+        self.obj = allocate_bytes(self.size)[0]
+
+        # for the type "object", id(obj) is the address of its memory block.
+        # This type is not tracked by the garbage collector
+        self.ptr = id(self.obj)
+
+    def tearDown(self):
+        tracemalloc.stop()
+
+    def get_traceback(self):
+        frames = _testcapi.tracemalloc_get_traceback(self.domain, self.ptr)
+        if frames is not None:
+            return tracemalloc.Traceback(frames)
+        else:
+            return None
+
+    def track(self, release_gil=False, nframe=1):
+        frames = get_frames(nframe, 2)
+        _testcapi.tracemalloc_track(self.domain, self.ptr, self.size,
+                                    release_gil)
+        return frames
+
+    def untrack(self):
+        _testcapi.tracemalloc_untrack(self.domain, self.ptr)
+
+    def get_traced_memory(self):
+        # Get the traced size in the domain
+        snapshot = tracemalloc.take_snapshot()
+        domain_filter = tracemalloc.DomainFilter(True, self.domain)
+        snapshot = snapshot.filter_traces([domain_filter])
+        return sum(trace.size for trace in snapshot.traces)
+
+    def check_track(self, release_gil):
+        nframe = 5
+        tracemalloc.start(nframe)
+
+        size = tracemalloc.get_traced_memory()[0]
+
+        frames = self.track(release_gil, nframe)
+        self.assertEqual(self.get_traceback(),
+                         tracemalloc.Traceback(frames))
+
+        self.assertEqual(self.get_traced_memory(), self.size)
+
+    def test_track(self):
+        self.check_track(False)
+
+    def test_track_without_gil(self):
+        # check that calling _PyTraceMalloc_Track() without holding the GIL
+        # works too
+        self.check_track(True)
+
+    def test_track_already_tracked(self):
+        nframe = 5
+        tracemalloc.start(nframe)
+
+        # track a first time
+        self.track()
+
+        # calling _PyTraceMalloc_Track() must remove the old trace and add
+        # a new trace with the new traceback
+        frames = self.track(nframe=nframe)
+        self.assertEqual(self.get_traceback(),
+                         tracemalloc.Traceback(frames))
+
+    def test_untrack(self):
+        tracemalloc.start()
+
+        self.track()
+        self.assertIsNotNone(self.get_traceback())
+        self.assertEqual(self.get_traced_memory(), self.size)
+
+        # untrack must remove the trace
+        self.untrack()
+        self.assertIsNone(self.get_traceback())
+        self.assertEqual(self.get_traced_memory(), 0)
+
+        # calling _PyTraceMalloc_Untrack() multiple times must not crash
+        self.untrack()
+        self.untrack()
+
+    def test_stop_track(self):
+        tracemalloc.start()
+        tracemalloc.stop()
+
+        with self.assertRaises(RuntimeError):
+            self.track()
+        self.assertIsNone(self.get_traceback())
+
+    def test_stop_untrack(self):
+        tracemalloc.start()
+        self.track()
+
+        tracemalloc.stop()
+        with self.assertRaises(RuntimeError):
+            self.untrack()
+
+
 def test_main():
     support.run_unittest(
         TestTracemallocEnabled,
         TestSnapshot,
         TestFilters,
         TestCommandLine,
+        TestCAPI,
     )
 
 if __name__ == "__main__":
diff --git a/Lib/test/test_ttk_guionly.py b/Lib/test/test_ttk_guionly.py
index 490e72337f..462665db5f 100644
--- a/Lib/test/test_ttk_guionly.py
+++ b/Lib/test/test_ttk_guionly.py
@@ -1,4 +1,3 @@
-import os
 import unittest
 from test import support
 
diff --git a/Lib/test/test_ttk_textonly.py b/Lib/test/test_ttk_textonly.py
index 566fc9d09a..7540a43103 100644
--- a/Lib/test/test_ttk_textonly.py
+++ b/Lib/test/test_ttk_textonly.py
@@ -1,4 +1,3 @@
-import os
 from test import support
 
 # Skip this test if _tkinter does not exist.
diff --git a/Lib/test/test_unpack.py b/Lib/test/test_unpack.py
index d1ccb38937..3fcb18fb43 100644
--- a/Lib/test/test_unpack.py
+++ b/Lib/test/test_unpack.py
@@ -117,6 +117,27 @@ error)
       ...
     test.test_unpack.BozoError
 
+Allow unpacking empty iterables
+
+    >>> () = []
+    >>> [] = ()
+    >>> [] = []
+    >>> () = ()
+
+Unpacking non-iterables should raise TypeError
+
+    >>> () = 42
+    Traceback (most recent call last):
+      ...
+    TypeError: 'int' object is not iterable
+
+Unpacking to an empty iterable should raise ValueError
+
+    >>> () = [42]
+    Traceback (most recent call last):
+      ...
+    ValueError: too many values to unpack (expected 0)
+
 """
 
 __test__ = {'doctests' : doctests}
diff --git a/Lib/test/test_unpack_ex.py b/Lib/test/test_unpack_ex.py
index d27eef0397..f426e5afd7 100644
--- a/Lib/test/test_unpack_ex.py
+++ b/Lib/test/test_unpack_ex.py
@@ -352,7 +352,6 @@ Some size constraints (all fail.)
 __test__ = {'doctests' : doctests}
 
 def test_main(verbose=False):
-    import sys
     from test import support
     from test import test_unpack_ex
     support.run_doctest(test_unpack_ex, verbose)
diff --git a/Lib/test/test_urllib2_localnet.py b/Lib/test/test_urllib2_localnet.py
index c8b37eecea..e9564fde62 100644
--- a/Lib/test/test_urllib2_localnet.py
+++ b/Lib/test/test_urllib2_localnet.py
@@ -289,12 +289,12 @@ class BasicAuthTests(unittest.TestCase):
         def http_server_with_basic_auth_handler(*args, **kwargs):
             return BasicAuthHandler(*args, **kwargs)
         self.server = LoopbackHttpServerThread(http_server_with_basic_auth_handler)
+        self.addCleanup(self.server.stop)
         self.server_url = 'http://127.0.0.1:%s' % self.server.port
         self.server.start()
         self.server.ready.wait()
 
     def tearDown(self):
-        self.server.stop()
         super(BasicAuthTests, self).tearDown()
 
     def test_basic_auth_success(self):
@@ -438,17 +438,13 @@ class TestUrlopen(unittest.TestCase):
 
     def setUp(self):
         super(TestUrlopen, self).setUp()
+
         # Ignore proxies for localhost tests.
-        self.old_environ = os.environ.copy()
+        def restore_environ(old_environ):
+            os.environ.clear()
+            os.environ.update(old_environ)
+        self.addCleanup(restore_environ, os.environ.copy())
         os.environ['NO_PROXY'] = '*'
-        self.server = None
-
-    def tearDown(self):
-        if self.server is not None:
-            self.server.stop()
-        os.environ.clear()
-        os.environ.update(self.old_environ)
-        super(TestUrlopen, self).tearDown()
 
     def urlopen(self, url, data=None, **kwargs):
         l = []
@@ -469,6 +465,7 @@ class TestUrlopen(unittest.TestCase):
         handler = GetRequestHandler(responses)
 
         self.server = LoopbackHttpServerThread(handler)
+        self.addCleanup(self.server.stop)
         self.server.start()
         self.server.ready.wait()
         port = self.server.port
@@ -592,7 +589,8 @@ class TestUrlopen(unittest.TestCase):
         handler = self.start_server()
         req = urllib.request.Request("http://localhost:%s/" % handler.port,
                                      headers={"Range": "bytes=20-39"})
-        urllib.request.urlopen(req)
+        with urllib.request.urlopen(req):
+            pass
         self.assertEqual(handler.headers_received["Range"], "bytes=20-39")
 
     def test_basic(self):
@@ -608,22 +606,21 @@ class TestUrlopen(unittest.TestCase):
 
     def test_info(self):
         handler = self.start_server()
-        try:
-            open_url = urllib.request.urlopen(
-                "http://localhost:%s" % handler.port)
+        open_url = urllib.request.urlopen(
+            "http://localhost:%s" % handler.port)
+        with open_url:
             info_obj = open_url.info()
-            self.assertIsInstance(info_obj, email.message.Message,
-                                  "object returned by 'info' is not an "
-                                  "instance of email.message.Message")
-            self.assertEqual(info_obj.get_content_subtype(), "plain")
-        finally:
-            self.server.stop()
+        self.assertIsInstance(info_obj, email.message.Message,
+                              "object returned by 'info' is not an "
+                              "instance of email.message.Message")
+        self.assertEqual(info_obj.get_content_subtype(), "plain")
 
     def test_geturl(self):
         # Make sure same URL as opened is returned by geturl.
         handler = self.start_server()
         open_url = urllib.request.urlopen("http://localhost:%s" % handler.port)
-        url = open_url.geturl()
+        with open_url:
+            url = open_url.geturl()
         self.assertEqual(url, "http://localhost:%s" % handler.port)
 
     def test_iteration(self):
diff --git a/Lib/test/test_urllibnet.py b/Lib/test/test_urllibnet.py
index b811930bbc..949716c2b5 100644
--- a/Lib/test/test_urllibnet.py
+++ b/Lib/test/test_urllibnet.py
@@ -4,7 +4,6 @@ from test import support
 import contextlib
 import socket
 import urllib.request
-import sys
 import os
 import email.message
 import time
diff --git a/Lib/test/test_urlparse.py b/Lib/test/test_urlparse.py
index 829997fd6a..9165d73e82 100644
--- a/Lib/test/test_urlparse.py
+++ b/Lib/test/test_urlparse.py
@@ -605,29 +605,27 @@ class UrlParseTestCase(unittest.TestCase):
         self.assertEqual(p.port, 80)
         self.assertEqual(p.geturl(), url)
 
-        # Verify an illegal port is returned as None
+        # Verify an illegal port raises ValueError
         url = b"HTTP://WWW.PYTHON.ORG:65536/doc/#frag"
         p = urllib.parse.urlsplit(url)
-        self.assertEqual(p.port, None)
+        with self.assertRaisesRegex(ValueError, "out of range"):
+            p.port
 
     def test_attributes_bad_port(self):
-        """Check handling of non-integer ports."""
-        p = urllib.parse.urlsplit("http://www.example.net:foo")
-        self.assertEqual(p.netloc, "www.example.net:foo")
-        self.assertRaises(ValueError, lambda: p.port)
-
-        p = urllib.parse.urlparse("http://www.example.net:foo")
-        self.assertEqual(p.netloc, "www.example.net:foo")
-        self.assertRaises(ValueError, lambda: p.port)
-
-        # Once again, repeat ourselves to test bytes
-        p = urllib.parse.urlsplit(b"http://www.example.net:foo")
-        self.assertEqual(p.netloc, b"www.example.net:foo")
-        self.assertRaises(ValueError, lambda: p.port)
-
-        p = urllib.parse.urlparse(b"http://www.example.net:foo")
-        self.assertEqual(p.netloc, b"www.example.net:foo")
-        self.assertRaises(ValueError, lambda: p.port)
+        """Check handling of invalid ports."""
+        for bytes in (False, True):
+            for parse in (urllib.parse.urlsplit, urllib.parse.urlparse):
+                for port in ("foo", "1.5", "-1", "0x10"):
+                    with self.subTest(bytes=bytes, parse=parse, port=port):
+                        netloc = "www.example.net:" + port
+                        url = "http://" + netloc
+                        if bytes:
+                            netloc = netloc.encode("ascii")
+                            url = url.encode("ascii")
+                        p = parse(url)
+                        self.assertEqual(p.netloc, netloc)
+                        with self.assertRaises(ValueError):
+                            p.port
 
     def test_attributes_without_netloc(self):
         # This example is straight from RFC 3261.  It looks like it
diff --git a/Lib/test/test_userdict.py b/Lib/test/test_userdict.py
index 8357f8bcd1..662c7f641a 100644
--- a/Lib/test/test_userdict.py
+++ b/Lib/test/test_userdict.py
@@ -1,6 +1,6 @@
 # Check every path through every method of UserDict
 
-from test import support, mapping_tests
+from test import mapping_tests
 import unittest
 import collections
 
@@ -30,7 +30,7 @@ class UserDictTest(mapping_tests.TestHashMappingProtocol):
         self.assertEqual(collections.UserDict(one=1, two=2), d2)
         # item sequence constructor
         self.assertEqual(collections.UserDict([('one',1), ('two',2)]), d2)
-        with self.assertWarnsRegex(PendingDeprecationWarning, "'dict'"):
+        with self.assertWarnsRegex(DeprecationWarning, "'dict'"):
             self.assertEqual(collections.UserDict(dict=[('one',1), ('two',2)]), d2)
         # both together
         self.assertEqual(collections.UserDict([('one',1), ('two',2)], two=3, three=5), d3)
@@ -149,7 +149,7 @@ class UserDictTest(mapping_tests.TestHashMappingProtocol):
                          [('dict', 42)])
         self.assertEqual(list(collections.UserDict({}, dict=None).items()),
                          [('dict', None)])
-        with self.assertWarnsRegex(PendingDeprecationWarning, "'dict'"):
+        with self.assertWarnsRegex(DeprecationWarning, "'dict'"):
             self.assertEqual(list(collections.UserDict(dict={'a': 42}).items()),
                              [('a', 42)])
         self.assertRaises(TypeError, collections.UserDict, 42)
diff --git a/Lib/test/test_userlist.py b/Lib/test/test_userlist.py
index f92e4d385e..8de6c14e39 100644
--- a/Lib/test/test_userlist.py
+++ b/Lib/test/test_userlist.py
@@ -1,7 +1,7 @@
 # Check every path through every method of UserList
 
 from collections import UserList
-from test import support, list_tests
+from test import list_tests
 import unittest
 
 class UserListTest(list_tests.CommonTest):
diff --git a/Lib/test/test_userstring.py b/Lib/test/test_userstring.py
index 9bc8edd99d..71528223d3 100644
--- a/Lib/test/test_userstring.py
+++ b/Lib/test/test_userstring.py
@@ -1,9 +1,8 @@
 # UserString is a wrapper around the native builtin string type.
 # UserString instances should behave similar to builtin string objects.
 
-import string
 import unittest
-from test import support, string_tests
+from test import string_tests
 
 from collections import UserString
 
diff --git a/Lib/test/test_uu.py b/Lib/test/test_uu.py
index 25fffbf993..ad2f2c59c1 100644
--- a/Lib/test/test_uu.py
+++ b/Lib/test/test_uu.py
@@ -8,7 +8,6 @@ from test import support
 
 import sys, os
 import uu
-from io import BytesIO
 import io
 
 plaintext = b"The smooth-scaled python crept over the sleeping dog\n"
diff --git a/Lib/test/test_venv.py b/Lib/test/test_venv.py
index d2c986e71e..a2842b0217 100644
--- a/Lib/test/test_venv.py
+++ b/Lib/test/test_venv.py
@@ -15,7 +15,6 @@ import sys
 import tempfile
 from test.support import (captured_stdout, captured_stderr,
                           can_symlink, EnvironmentVarGuard, rmtree)
-import textwrap
 import unittest
 import venv
 
@@ -31,18 +30,17 @@ try:
 except ImportError:
     threading = None
 
+try:
+    import ctypes
+except ImportError:
+    ctypes = None
+
 skipInVenv = unittest.skipIf(sys.prefix != sys.base_prefix,
                              'Test not appropriate in a venv')
 
-# os.path.exists('nul') is False: http://bugs.python.org/issue20541
-if os.devnull.lower() == 'nul':
-    failsOnWindows = unittest.expectedFailure
-else:
-    def failsOnWindows(f):
-        return f
-
 class BaseTest(unittest.TestCase):
     """Base class for venv tests."""
+    maxDiff = 80 * 50
 
     def setUp(self):
         self.env_dir = os.path.realpath(tempfile.mkdtemp())
@@ -52,7 +50,7 @@ class BaseTest(unittest.TestCase):
             self.include = 'Include'
         else:
             self.bindir = 'bin'
-            self.lib = ('lib', 'python%s' % sys.version[:3])
+            self.lib = ('lib', 'python%d.%d' % sys.version_info[:2])
             self.include = 'include'
         if sys.platform == 'darwin' and '__PYVENV_LAUNCHER__' in os.environ:
             executable = os.environ['__PYVENV_LAUNCHER__']
@@ -313,20 +311,27 @@ class EnsurePipTest(BaseTest):
         self.run_with_capture(venv.create, self.env_dir, with_pip=False)
         self.assert_pip_not_installed()
 
-    @failsOnWindows
-    def test_devnull_exists_and_is_empty(self):
+    def test_devnull(self):
         # Fix for issue #20053 uses os.devnull to force a config file to
         # appear empty. However http://bugs.python.org/issue20541 means
         # that doesn't currently work properly on Windows. Once that is
         # fixed, the "win_location" part of test_with_pip should be restored
-        self.assertTrue(os.path.exists(os.devnull))
         with open(os.devnull, "rb") as f:
             self.assertEqual(f.read(), b"")
 
+        # Issue #20541: os.path.exists('nul') is False on Windows
+        if os.devnull.lower() == 'nul':
+            self.assertFalse(os.path.exists(os.devnull))
+        else:
+            self.assertTrue(os.path.exists(os.devnull))
+
+
     # Requesting pip fails without SSL (http://bugs.python.org/issue19744)
     @unittest.skipIf(ssl is None, ensurepip._MISSING_SSL_MESSAGE)
     @unittest.skipUnless(threading, 'some dependencies of pip import threading'
                                     ' module unconditionally')
+    # Issue #26610: pip/pep425tags.py requires ctypes
+    @unittest.skipUnless(ctypes, 'pip requires ctypes')
     def test_with_pip(self):
         rmtree(self.env_dir)
         with EnvironmentVarGuard() as envvars:
diff --git a/Lib/test/test_warnings/__init__.py b/Lib/test/test_warnings/__init__.py
index 72fcc73661..497c5cc94b 100644
--- a/Lib/test/test_warnings/__init__.py
+++ b/Lib/test/test_warnings/__init__.py
@@ -2,7 +2,9 @@ from contextlib import contextmanager
 import linecache
 import os
 from io import StringIO
+import re
 import sys
+import textwrap
 import unittest
 from test import support
 from test.support.script_helper import assert_python_ok, assert_python_failure
@@ -708,6 +710,17 @@ class _WarningsTests(BaseTest, unittest.TestCase):
                 result = stream.getvalue()
         self.assertIn(text, result)
 
+    def test_showwarnmsg_missing(self):
+        # Test that _showwarnmsg() missing is okay.
+        text = 'del _showwarnmsg test'
+        with original_warnings.catch_warnings(module=self.module):
+            self.module.filterwarnings("always", category=UserWarning)
+            del self.module._showwarnmsg
+            with support.captured_output('stderr') as stream:
+                self.module.warn(text)
+                result = stream.getvalue()
+        self.assertIn(text, result)
+
     def test_showwarning_not_callable(self):
         with original_warnings.catch_warnings(module=self.module):
             self.module.filterwarnings("always", category=UserWarning)
@@ -809,12 +822,44 @@ class WarningsDisplayTests(BaseTest):
                                 file_object, expected_file_line)
         self.assertEqual(expect, file_object.getvalue())
 
+
 class CWarningsDisplayTests(WarningsDisplayTests, unittest.TestCase):
     module = c_warnings
 
 class PyWarningsDisplayTests(WarningsDisplayTests, unittest.TestCase):
     module = py_warnings
 
+    def test_tracemalloc(self):
+        self.addCleanup(support.unlink, support.TESTFN)
+
+        with open(support.TESTFN, 'w') as fp:
+            fp.write(textwrap.dedent("""
+                def func():
+                    f = open(__file__)
+                    # Emit ResourceWarning
+                    f = None
+
+                func()
+            """))
+
+        res = assert_python_ok('-Wd', '-X', 'tracemalloc=2', support.TESTFN)
+
+        stderr = res.err.decode('ascii', 'replace')
+        # normalize newlines
+        stderr = '\n'.join(stderr.splitlines())
+        stderr = re.sub('<.*>', '<...>', stderr)
+        expected = textwrap.dedent('''
+            {fname}:5: ResourceWarning: unclosed file <...>
+              f = None
+            Object allocated at (most recent call first):
+              File "{fname}", lineno 3
+                f = open(__file__)
+              File "{fname}", lineno 7
+                func()
+        ''')
+        expected = expected.format(fname=support.TESTFN).strip()
+        self.assertEqual(stderr, expected)
+
 
 class CatchWarningTests(BaseTest):
 
diff --git a/Lib/test/test_wave.py b/Lib/test/test_wave.py
index 3eff773bca..8666f7269c 100644
--- a/Lib/test/test_wave.py
+++ b/Lib/test/test_wave.py
@@ -1,6 +1,6 @@
-from test.support import TESTFN
 import unittest
 from test import audiotests
+from test import support
 from audioop import byteswap
 import sys
 import wave
@@ -103,5 +103,11 @@ class WavePCM32Test(WaveTest, unittest.TestCase):
         frames = byteswap(frames, 4)
 
 
+class MiscTestCase(unittest.TestCase):
+    def test__all__(self):
+        blacklist = {'WAVE_FORMAT_PCM'}
+        support.check__all__(self, wave, blacklist=blacklist)
+
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/Lib/test/test_weakset.py b/Lib/test/test_weakset.py
index 9ce672b815..691b95e77c 100644
--- a/Lib/test/test_weakset.py
+++ b/Lib/test/test_weakset.py
@@ -1,13 +1,6 @@
 import unittest
-from weakref import proxy, ref, WeakSet
-import operator
-import copy
+from weakref import WeakSet
 import string
-import os
-from random import randrange, shuffle
-import sys
-import warnings
-import collections
 from collections import UserString as ustr
 import gc
 import contextlib
diff --git a/Lib/test/test_winreg.py b/Lib/test/test_winreg.py
index 2c4ac08f39..ef40e8bc37 100644
--- a/Lib/test/test_winreg.py
+++ b/Lib/test/test_winreg.py
@@ -37,6 +37,7 @@ test_reflect_key_name = "SOFTWARE\\Classes\\" + test_key_base
 
 test_data = [
     ("Int Value",     45,                                      REG_DWORD),
+    ("Qword Value",   0x1122334455667788,                      REG_QWORD),
     ("String Val",    "A string value",                        REG_SZ),
     ("StringExpand",  "The path is %path%",                    REG_EXPAND_SZ),
     ("Multi-string",  ["Lots", "of", "string", "values"],      REG_MULTI_SZ),
diff --git a/Lib/test/test_with.py b/Lib/test/test_with.py
index e8d789bc2c..e247ff6a61 100644
--- a/Lib/test/test_with.py
+++ b/Lib/test/test_with.py
@@ -140,11 +140,6 @@ class FailureTestCase(unittest.TestCase):
             'with mock as (None):\n'
             '  pass')
 
-    def testAssignmentToEmptyTupleError(self):
-        self.assertRaisesSyntaxError(
-            'with mock as ():\n'
-            '  pass')
-
     def testAssignmentToTupleOnlyContainingNoneError(self):
         self.assertRaisesSyntaxError('with mock as None,:\n  pass')
         self.assertRaisesSyntaxError(
@@ -454,7 +449,7 @@ class ExceptionalTestCase(ContextmanagerAssertionMixin, unittest.TestCase):
             with cm():
                 raise StopIteration("from with")
 
-        with self.assertWarnsRegex(PendingDeprecationWarning, "StopIteration"):
+        with self.assertWarnsRegex(DeprecationWarning, "StopIteration"):
             self.assertRaises(StopIteration, shouldThrow)
 
     def testRaisedStopIteration2(self):
@@ -482,7 +477,7 @@ class ExceptionalTestCase(ContextmanagerAssertionMixin, unittest.TestCase):
             with cm():
                 raise next(iter([]))
 
-        with self.assertWarnsRegex(PendingDeprecationWarning, "StopIteration"):
+        with self.assertWarnsRegex(DeprecationWarning, "StopIteration"):
             self.assertRaises(StopIteration, shouldThrow)
 
     def testRaisedGeneratorExit1(self):
diff --git a/Lib/test/test_wsgiref.py b/Lib/test/test_wsgiref.py
index 61a750c622..3c5a27a12e 100644
--- a/Lib/test/test_wsgiref.py
+++ b/Lib/test/test_wsgiref.py
@@ -165,10 +165,10 @@ class IntegrationTests(TestCase):
         self.assertTrue(out.endswith(
             b"A server error occurred.  Please contact the administrator."
         ))
-        self.assertEqual(
+        self.assertRegex(
             err.splitlines()[-2],
-            "AssertionError: Headers (('Content-Type', 'text/plain')) must"
-            " be of type list: <class 'tuple'>"
+            r"AssertionError: Headers \(\('Content-Type', 'text/plain'\)\) must"
+            r" be of type list: <class 'tuple' at 0x.+>"
         )
 
     def test_status_validation_errors(self):
diff --git a/Lib/test/test_xml_etree.py b/Lib/test/test_xml_etree.py
index 44e3142dc9..a56f1582b6 100644
--- a/Lib/test/test_xml_etree.py
+++ b/Lib/test/test_xml_etree.py
@@ -91,8 +91,6 @@ ENTITY_XML = """\
 
 
 class ModuleTest(unittest.TestCase):
-    # TODO: this should be removed once we get rid of the global module vars
-
     def test_sanity(self):
         # Import sanity.
 
@@ -100,6 +98,10 @@ class ModuleTest(unittest.TestCase):
         from xml.etree import ElementInclude
         from xml.etree import ElementPath
 
+    def test_all(self):
+        names = ("xml.etree.ElementTree", "_elementtree")
+        support.check__all__(self, ET, names, blacklist=("HTML_EMPTY",))
+
 
 def serialize(elem, to_string=True, encoding='unicode', **options):
     if encoding != 'unicode':
@@ -182,10 +184,12 @@ class ElementTreeTest(unittest.TestCase):
 
         def check_element(element):
             self.assertTrue(ET.iselement(element), msg="not an element")
-            self.assertTrue(hasattr(element, "tag"), msg="no tag member")
-            self.assertTrue(hasattr(element, "attrib"), msg="no attrib member")
-            self.assertTrue(hasattr(element, "text"), msg="no text member")
-            self.assertTrue(hasattr(element, "tail"), msg="no tail member")
+            direlem = dir(element)
+            for attr in 'tag', 'attrib', 'text', 'tail':
+                self.assertTrue(hasattr(element, attr),
+                        msg='no %s member' % attr)
+                self.assertIn(attr, direlem,
+                        msg='no %s visible by dir' % attr)
 
             check_string(element.tag)
             check_mapping(element.attrib)
diff --git a/Lib/test/test_xml_etree_c.py b/Lib/test/test_xml_etree_c.py
index 96b446e32e..87f3f27abc 100644
--- a/Lib/test/test_xml_etree_c.py
+++ b/Lib/test/test_xml_etree_c.py
@@ -1,5 +1,5 @@
 # xml.etree test for cElementTree
-import sys, struct
+import struct
 from test import support
 from test.support import import_fresh_module
 import types
@@ -108,7 +108,7 @@ class SizeofTest(unittest.TestCase):
                              struct.calcsize('8P'))
 
 def test_main():
-    from test import test_xml_etree, test_xml_etree_c
+    from test import test_xml_etree
 
     # Run the tests specific to the C implementation
     support.run_unittest(
diff --git a/Lib/test/test_xmlrpc.py b/Lib/test/test_xmlrpc.py
index 02d9f5c650..f2fdc44cbe 100644
--- a/Lib/test/test_xmlrpc.py
+++ b/Lib/test/test_xmlrpc.py
@@ -9,7 +9,6 @@ import xmlrpc.server
 import http.client
 import http, http.server
 import socket
-import os
 import re
 import io
 import contextlib
@@ -776,8 +775,8 @@ class SimpleServerTestCase(BaseServerTestCase):
             #   'method "this_is_not_exists" is not supported'>}]
 
             self.assertEqual(result.results[0]['faultCode'], 1)
-            self.assertEqual(result.results[0]['faultString'],
-                '<class \'Exception\'>:method "this_is_not_exists" '
+            self.assertRegex(result.results[0]['faultString'],
+                '<class \'Exception\' at 0x.+>:method "this_is_not_exists" '
                 'is not supported')
         except (xmlrpclib.ProtocolError, OSError) as e:
             # ignore failures due to non-blocking socket 'unavailable' errors
@@ -1147,7 +1146,6 @@ def captured_stdout(encoding='utf-8'):
     """A variation on support.captured_stdout() which gives a text stream
     having a `buffer` attribute.
     """
-    import io
     orig_stdout = sys.stdout
     sys.stdout = io.TextIOWrapper(io.BytesIO(), encoding=encoding)
     try:
diff --git a/Lib/test/test_xmlrpc_net.py b/Lib/test/test_xmlrpc_net.py
index b60b82f3e2..ae0a28e721 100644
--- a/Lib/test/test_xmlrpc_net.py
+++ b/Lib/test/test_xmlrpc_net.py
@@ -1,7 +1,4 @@
 import collections.abc
-import errno
-import socket
-import sys
 import unittest
 from test import support
 
diff --git a/Lib/test/test_zipfile.py b/Lib/test/test_zipfile.py
index d278e06a45..6a77d6c91f 100644
--- a/Lib/test/test_zipfile.py
+++ b/Lib/test/test_zipfile.py
@@ -1,8 +1,8 @@
 import contextlib
 import io
 import os
-import sys
 import importlib.util
+import posixpath
 import time
 import struct
 import zipfile
@@ -61,6 +61,9 @@ class AbstractTestsWithSourceFile:
             zipfp.write(TESTFN, "another.name")
             zipfp.write(TESTFN, TESTFN)
             zipfp.writestr("strfile", self.data)
+            with zipfp.open('written-open-w', mode='w') as f:
+                for line in self.line_gen:
+                    f.write(line)
 
     def zip_test(self, f, compression):
         self.make_test_archive(f, compression)
@@ -76,7 +79,7 @@ class AbstractTestsWithSourceFile:
             zipfp.printdir(file=fp)
             directory = fp.getvalue()
             lines = directory.splitlines()
-            self.assertEqual(len(lines), 4) # Number of files + header
+            self.assertEqual(len(lines), 5) # Number of files + header
 
             self.assertIn('File Name', lines[0])
             self.assertIn('Modified', lines[0])
@@ -90,23 +93,25 @@ class AbstractTestsWithSourceFile:
 
             # Check the namelist
             names = zipfp.namelist()
-            self.assertEqual(len(names), 3)
+            self.assertEqual(len(names), 4)
             self.assertIn(TESTFN, names)
             self.assertIn("another.name", names)
             self.assertIn("strfile", names)
+            self.assertIn("written-open-w", names)
 
             # Check infolist
             infos = zipfp.infolist()
             names = [i.filename for i in infos]
-            self.assertEqual(len(names), 3)
+            self.assertEqual(len(names), 4)
             self.assertIn(TESTFN, names)
             self.assertIn("another.name", names)
             self.assertIn("strfile", names)
+            self.assertIn("written-open-w", names)
             for i in infos:
                 self.assertEqual(i.file_size, len(self.data))
 
             # check getinfo
-            for nm in (TESTFN, "another.name", "strfile"):
+            for nm in (TESTFN, "another.name", "strfile", "written-open-w"):
                 info = zipfp.getinfo(nm)
                 self.assertEqual(info.filename, nm)
                 self.assertEqual(info.file_size, len(self.data))
@@ -372,14 +377,18 @@ class StoredTestsWithSourceFile(AbstractTestsWithSourceFile,
     test_low_compression = None
 
     def zip_test_writestr_permissions(self, f, compression):
-        # Make sure that writestr creates files with mode 0600,
-        # when it is passed a name rather than a ZipInfo instance.
+        # Make sure that writestr and open(... mode='w') create files with
+        # mode 0600, when they are passed a name rather than a ZipInfo
+        # instance.
 
         self.make_test_archive(f, compression)
         with zipfile.ZipFile(f, "r") as zipfp:
             zinfo = zipfp.getinfo('strfile')
             self.assertEqual(zinfo.external_attr, 0o600 << 16)
 
+            zinfo2 = zipfp.getinfo('written-open-w')
+            self.assertEqual(zinfo2.external_attr, 0o600 << 16)
+
     def test_writestr_permissions(self):
         for f in get_files(self):
             self.zip_test_writestr_permissions(f, zipfile.ZIP_STORED)
@@ -451,6 +460,10 @@ class StoredTestsWithSourceFile(AbstractTestsWithSourceFile,
         with zipfile.ZipFile(TESTFN2, mode="r") as zipfp:
             self.assertRaises(RuntimeError, zipfp.write, TESTFN)
 
+        with zipfile.ZipFile(TESTFN2, mode="r") as zipfp:
+            with self.assertRaises(RuntimeError):
+                zipfp.open(TESTFN, mode='w')
+
     def test_add_file_before_1980(self):
         # Set atime and mtime to 1970-01-01
         os.utime(TESTFN, (0, 0))
@@ -1428,6 +1441,35 @@ class OtherTests(unittest.TestCase):
             # testzip returns the name of the first corrupt file, or None
             self.assertIsNone(zipf.testzip())
 
+    def test_open_conflicting_handles(self):
+        # It's only possible to open one writable file handle at a time
+        msg1 = b"It's fun to charter an accountant!"
+        msg2 = b"And sail the wide accountant sea"
+        msg3 = b"To find, explore the funds offshore"
+        with zipfile.ZipFile(TESTFN2, 'w', zipfile.ZIP_STORED) as zipf:
+            with zipf.open('foo', mode='w') as w2:
+                w2.write(msg1)
+            with zipf.open('bar', mode='w') as w1:
+                with self.assertRaises(RuntimeError):
+                    zipf.open('handle', mode='w')
+                with self.assertRaises(RuntimeError):
+                    zipf.open('foo', mode='r')
+                with self.assertRaises(RuntimeError):
+                    zipf.writestr('str', 'abcde')
+                with self.assertRaises(RuntimeError):
+                    zipf.write(__file__, 'file')
+                with self.assertRaises(RuntimeError):
+                    zipf.close()
+                w1.write(msg2)
+            with zipf.open('baz', mode='w') as w2:
+                w2.write(msg3)
+
+        with zipfile.ZipFile(TESTFN2, 'r') as zipf:
+            self.assertEqual(zipf.read('foo'), msg1)
+            self.assertEqual(zipf.read('bar'), msg2)
+            self.assertEqual(zipf.read('baz'), msg3)
+            self.assertEqual(zipf.namelist(), ['foo', 'bar', 'baz'])
+
     def tearDown(self):
         unlink(TESTFN)
         unlink(TESTFN2)
@@ -1761,6 +1803,22 @@ class UnseekableTests(unittest.TestCase):
                     with zipf.open('twos') as zopen:
                         self.assertEqual(zopen.read(), b'222')
 
+    def test_open_write(self):
+        for wrapper in (lambda f: f), Tellable, Unseekable:
+            with self.subTest(wrapper=wrapper):
+                f = io.BytesIO()
+                f.write(b'abc')
+                bf = io.BufferedWriter(f)
+                with zipfile.ZipFile(wrapper(bf), 'w', zipfile.ZIP_STORED) as zipf:
+                    with zipf.open('ones', 'w') as zopen:
+                        zopen.write(b'111')
+                    with zipf.open('twos', 'w') as zopen:
+                        zopen.write(b'222')
+                self.assertEqual(f.getvalue()[:5], b'abcPK')
+                with zipfile.ZipFile(f) as zipf:
+                    self.assertEqual(zipf.read('ones'), b'111')
+                    self.assertEqual(zipf.read('twos'), b'222')
+
 
 @requires_zlib
 class TestsWithMultipleOpens(unittest.TestCase):
@@ -1871,6 +1929,19 @@ class TestsWithMultipleOpens(unittest.TestCase):
         with open(os.devnull) as f:
             self.assertLess(f.fileno(), 100)
 
+    def test_write_while_reading(self):
+        with zipfile.ZipFile(TESTFN2, 'w', zipfile.ZIP_DEFLATED) as zipf:
+            zipf.writestr('ones', self.data1)
+        with zipfile.ZipFile(TESTFN2, 'a', zipfile.ZIP_DEFLATED) as zipf:
+            with zipf.open('ones', 'r') as r1:
+                data1 = r1.read(500)
+                with zipf.open('twos', 'w') as w1:
+                    w1.write(self.data2)
+                data1 += r1.read()
+        self.assertEqual(data1, self.data1)
+        with zipfile.ZipFile(TESTFN2) as zipf:
+            self.assertEqual(zipf.read('twos'), self.data2)
+
     def tearDown(self):
         unlink(TESTFN2)
 
@@ -2072,5 +2143,19 @@ class LzmaUniversalNewlineTests(AbstractUniversalNewlineTests,
                                 unittest.TestCase):
     compression = zipfile.ZIP_LZMA
 
+class ZipInfoTests(unittest.TestCase):
+    def test_from_file(self):
+        zi = zipfile.ZipInfo.from_file(__file__)
+        self.assertEqual(posixpath.basename(zi.filename), 'test_zipfile.py')
+        self.assertFalse(zi.is_dir())
+
+    def test_from_dir(self):
+        dirpath = os.path.dirname(os.path.abspath(__file__))
+        zi = zipfile.ZipInfo.from_file(dirpath, 'stdlib_tests')
+        self.assertEqual(zi.filename, 'stdlib_tests/')
+        self.assertTrue(zi.is_dir())
+        self.assertEqual(zi.compress_type, zipfile.ZIP_STORED)
+        self.assertEqual(zi.file_size, 0)
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_zipimport.py b/Lib/test/test_zipimport.py
index 0da5906f28..1f10095f43 100644
--- a/Lib/test/test_zipimport.py
+++ b/Lib/test/test_zipimport.py
@@ -398,7 +398,8 @@ class UncompressedZipImportTestCase(ImportHooksBaseTestCase):
         packdir2 = packdir + TESTPACK2 + os.sep
         files = {packdir + "__init__" + pyc_ext: (NOW, test_pyc),
                  packdir2 + "__init__" + pyc_ext: (NOW, test_pyc),
-                 packdir2 + TESTMOD + pyc_ext: (NOW, test_pyc)}
+                 packdir2 + TESTMOD + pyc_ext: (NOW, test_pyc),
+                 "spam" + pyc_ext: (NOW, test_pyc)}
 
         z = ZipFile(TEMP_ZIP, "w")
         try:
@@ -412,6 +413,14 @@ class UncompressedZipImportTestCase(ImportHooksBaseTestCase):
             zi = zipimport.zipimporter(TEMP_ZIP)
             self.assertEqual(zi.archive, TEMP_ZIP)
             self.assertEqual(zi.is_package(TESTPACK), True)
+
+            find_mod = zi.find_module('spam')
+            self.assertIsNotNone(find_mod)
+            self.assertIsInstance(find_mod, zipimport.zipimporter)
+            self.assertFalse(find_mod.is_package('spam'))
+            load_mod = find_mod.load_module('spam')
+            self.assertEqual(find_mod.get_filename('spam'), load_mod.__file__)
+
             mod = zi.load_module(TESTPACK)
             self.assertEqual(zi.get_filename(TESTPACK), mod.__file__)
 
@@ -471,6 +480,16 @@ class UncompressedZipImportTestCase(ImportHooksBaseTestCase):
             self.assertEqual(
                 zi.is_package(TESTPACK2 + os.sep + TESTMOD), False)
 
+            pkg_path = TEMP_ZIP + os.sep + packdir + TESTPACK2
+            zi2 = zipimport.zipimporter(pkg_path)
+            find_mod_dotted = zi2.find_module(TESTMOD)
+            self.assertIsNotNone(find_mod_dotted)
+            self.assertIsInstance(find_mod_dotted, zipimport.zipimporter)
+            self.assertFalse(zi2.is_package(TESTMOD))
+            load_mod = find_mod_dotted.load_module(TESTMOD)
+            self.assertEqual(
+                find_mod_dotted.get_filename(TESTMOD), load_mod.__file__)
+
             mod_path = TESTPACK2 + os.sep + TESTMOD
             mod_name = module_path_to_dotted_name(mod_path)
             mod = importlib.import_module(mod_name)
diff --git a/Lib/test/test_zipimport_support.py b/Lib/test/test_zipimport_support.py
index 5913622f56..84d526c3db 100644
--- a/Lib/test/test_zipimport_support.py
+++ b/Lib/test/test_zipimport_support.py
@@ -12,7 +12,6 @@ import zipimport
 import doctest
 import inspect
 import linecache
-import pdb
 import unittest
 from test.support.script_helper import (spawn_python, kill_python, assert_python_ok,
                                         make_script, make_zip_script)
diff --git a/Lib/test/test_zlib.py b/Lib/test/test_zlib.py
index 78ecade950..4d3611c4a6 100644
--- a/Lib/test/test_zlib.py
+++ b/Lib/test/test_zlib.py
@@ -162,6 +162,10 @@ class CompressTestCase(BaseCompressTestCase, unittest.TestCase):
         x = zlib.compress(HAMLET_SCENE)
         self.assertEqual(zlib.decompress(x), HAMLET_SCENE)
 
+    def test_keywords(self):
+        x = zlib.compress(data=HAMLET_SCENE, level=3)
+        self.assertEqual(zlib.decompress(x), HAMLET_SCENE)
+
     def test_speech128(self):
         # compress more data
         data = HAMLET_SCENE * 128
diff --git a/Lib/threading.py b/Lib/threading.py
index c9f8cb64ee..d09fcae4e8 100644
--- a/Lib/threading.py
+++ b/Lib/threading.py
@@ -22,9 +22,11 @@ except ImportError:
 # with the multiprocessing module, which doesn't provide the old
 # Java inspired names.
 
-__all__ = ['active_count', 'Condition', 'current_thread', 'enumerate', 'Event',
-           'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore', 'Thread', 'Barrier',
-           'Timer', 'ThreadError', 'setprofile', 'settrace', 'local', 'stack_size']
+__all__ = ['get_ident', 'active_count', 'Condition', 'current_thread',
+           'enumerate', 'main_thread', 'TIMEOUT_MAX',
+           'Event', 'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore', 'Thread',
+           'Barrier', 'BrokenBarrierError', 'Timer', 'ThreadError',
+           'setprofile', 'settrace', 'local', 'stack_size']
 
 # Rename some stuff so "from threading import *" is safe
 _start_new_thread = _thread.start_new_thread
diff --git a/Lib/timeit.py b/Lib/timeit.py
index 2de88f7271..98cb3eb89a 100755..100644
--- a/Lib/timeit.py
+++ b/Lib/timeit.py
@@ -317,20 +317,26 @@ def main(args=None, *, _wrap_timer=None):
     print("%d loops," % number, end=' ')
     usec = best * 1e6 / number
     if time_unit is not None:
-        print("best of %d: %.*g %s per loop" % (repeat, precision,
-                                             usec/units[time_unit], time_unit))
+        scale = units[time_unit]
     else:
-        if usec < 1000:
-            print("best of %d: %.*g usec per loop" % (repeat, precision, usec))
-        else:
-            msec = usec / 1000
-            if msec < 1000:
-                print("best of %d: %.*g msec per loop" % (repeat,
-                                                          precision, msec))
-            else:
-                sec = msec / 1000
-                print("best of %d: %.*g sec per loop" % (repeat,
-                                                         precision, sec))
+        scales = [(scale, unit) for unit, scale in units.items()]
+        scales.sort(reverse=True)
+        for scale, time_unit in scales:
+            if usec >= scale:
+                break
+    print("best of %d: %.*g %s per loop" % (repeat, precision,
+                                            usec/scale, time_unit))
+    best = min(r)
+    usec = best * 1e6 / number
+    worst = max(r)
+    if worst >= best * 4:
+        usec = worst * 1e6 / number
+        import warnings
+        warnings.warn_explicit(
+            "The test results are likely unreliable. The worst\n"
+            "time (%.*g %s) was more than four times slower than the best time." %
+            (precision, usec/scale, time_unit),
+             UserWarning, '', 0)
     return None
 
 if __name__ == "__main__":
diff --git a/Lib/tkinter/__init__.py b/Lib/tkinter/__init__.py
index aa646dc8ed..174e04e89e 100644
--- a/Lib/tkinter/__init__.py
+++ b/Lib/tkinter/__init__.py
@@ -468,12 +468,6 @@ class Misc:
         disabledForeground, insertBackground, troughColor."""
         self.tk.call(('tk_setPalette',)
               + _flatten(args) + _flatten(list(kw.items())))
-    def tk_menuBar(self, *args):
-        """Do not use. Needed in Tk 3.6 and earlier."""
-        # obsolete since Tk 4.0
-        import warnings
-        warnings.warn('tk_menuBar() does nothing and will be removed in 3.6',
-                      DeprecationWarning, stacklevel=2)
     def wait_variable(self, name='PY_VAR'):
         """Wait until the variable is modified.
 
@@ -845,8 +839,7 @@ class Misc:
             self.tk.call('winfo', 'height', self._w))
     def winfo_id(self):
         """Return identifier ID for this widget."""
-        return self.tk.getint(
-            self.tk.call('winfo', 'id', self._w))
+        return int(self.tk.call('winfo', 'id', self._w), 0)
     def winfo_interps(self, displayof=0):
         """Return the name of all Tcl interpreters for this display."""
         args = ('winfo', 'interps') + self._displayof(displayof)
@@ -1888,9 +1881,6 @@ class Tk(Misc, Wm):
         if tcl_version != _tkinter.TCL_VERSION:
             raise RuntimeError("tcl.h version (%s) doesn't match libtcl.a version (%s)" \
                                % (_tkinter.TCL_VERSION, tcl_version))
-        if TkVersion < 4.0:
-            raise RuntimeError("Tk 4.0 or higher is required; found Tk %s"
-                               % str(TkVersion))
         # Create and register the tkerror and exit commands
         # We need to inline parts of _register here, _ register
         # would register differently-named commands.
@@ -2709,12 +2699,6 @@ class Menu(Widget):
     def tk_popup(self, x, y, entry=""):
         """Post the menu at position X,Y with entry ENTRY."""
         self.tk.call('tk_popup', self._w, x, y, entry)
-    def tk_bindForTraversal(self):
-        # obsolete since Tk 4.0
-        import warnings
-        warnings.warn('tk_bindForTraversal() does nothing and '
-                      'will be removed in 3.6',
-                      DeprecationWarning, stacklevel=2)
     def activate(self, index):
         """Activate entry at INDEX."""
         self.tk.call(self._w, 'activate', index)
diff --git a/Lib/tkinter/commondialog.py b/Lib/tkinter/commondialog.py
index d2688dba9b..1e75cae689 100644
--- a/Lib/tkinter/commondialog.py
+++ b/Lib/tkinter/commondialog.py
@@ -15,11 +15,6 @@ class Dialog:
     command  = None
 
     def __init__(self, master=None, **options):
-
-        # FIXME: should this be placed on the module level instead?
-        if TkVersion < 4.2:
-            raise TclError("this module requires Tk 4.2 or newer")
-
         self.master  = master
         self.options = options
         if not master and options.get('parent'):
diff --git a/Lib/tkinter/dialog.py b/Lib/tkinter/dialog.py
index be085abe1d..f61c5f7fa9 100644
--- a/Lib/tkinter/dialog.py
+++ b/Lib/tkinter/dialog.py
@@ -3,10 +3,7 @@
 from tkinter import *
 from tkinter import _cnfmerge
 
-if TkVersion <= 3.6:
-    DIALOG_ICON = 'warning'
-else:
-    DIALOG_ICON = 'questhead'
+DIALOG_ICON = 'questhead'
 
 
 class Dialog(Widget):
diff --git a/Lib/tkinter/test/runtktests.py b/Lib/tkinter/test/runtktests.py
index dbe5e88c14..33dc54a137 100644
--- a/Lib/tkinter/test/runtktests.py
+++ b/Lib/tkinter/test/runtktests.py
@@ -7,8 +7,6 @@ Extensions also should live in packages following the same rule as above.
 """
 
 import os
-import sys
-import unittest
 import importlib
 import test.support
 
diff --git a/Lib/tkinter/test/test_tkinter/test_widgets.py b/Lib/tkinter/test/test_tkinter/test_widgets.py
index c924d55937..81b52eafea 100644
--- a/Lib/tkinter/test/test_tkinter/test_widgets.py
+++ b/Lib/tkinter/test/test_tkinter/test_widgets.py
@@ -91,9 +91,10 @@ class ToplevelTest(AbstractToplevelTest, unittest.TestCase):
         widget = self.create()
         self.assertEqual(widget['use'], '')
         parent = self.create(container=True)
-        wid = parent.winfo_id()
-        widget2 = self.create(use=wid)
-        self.assertEqual(int(widget2['use']), wid)
+        wid = hex(parent.winfo_id())
+        with self.subTest(wid=wid):
+            widget2 = self.create(use=wid)
+            self.assertEqual(widget2['use'], wid)
 
 
 @add_standard_options(StandardOptionsTests)
diff --git a/Lib/tkinter/test/test_ttk/test_functions.py b/Lib/tkinter/test/test_ttk/test_functions.py
index c68a650559..a1b7cdfcd1 100644
--- a/Lib/tkinter/test/test_ttk/test_functions.py
+++ b/Lib/tkinter/test/test_ttk/test_functions.py
@@ -1,6 +1,5 @@
 # -*- encoding: utf-8 -*-
 import unittest
-import tkinter
 from tkinter import ttk
 
 class MockTkApp:
diff --git a/Lib/tkinter/tix.py b/Lib/tkinter/tix.py
index f667933a1e..a283cf120a 100644
--- a/Lib/tkinter/tix.py
+++ b/Lib/tkinter/tix.py
@@ -29,10 +29,6 @@
 from tkinter import *
 from tkinter import _cnfmerge, _default_root
 
-# WARNING - TkVersion is a limited precision floating point number
-if TkVersion < 3.999:
-    raise ImportError("This version of Tix.py requires Tk 4.0 or higher")
-
 import _tkinter # If this fails your Python may not be configured for Tk
 
 # Some more constants (for consistency with Tkinter)
diff --git a/Lib/tkinter/ttk.py b/Lib/tkinter/ttk.py
index 8f9369b060..8f217bf3f1 100644
--- a/Lib/tkinter/ttk.py
+++ b/Lib/tkinter/ttk.py
@@ -381,7 +381,9 @@ class Style(object):
         a sequence identifying the value for that option."""
         if query_opt is not None:
             kw[query_opt] = None
-        return _val_or_dict(self.tk, kw, self._name, "configure", style)
+        result = _val_or_dict(self.tk, kw, self._name, "configure", style)
+        if result or query_opt:
+            return result
 
 
     def map(self, style, query_opt=None, **kw):
@@ -466,12 +468,14 @@ class Style(object):
 
     def element_names(self):
         """Returns the list of elements defined in the current theme."""
-        return self.tk.splitlist(self.tk.call(self._name, "element", "names"))
+        return tuple(n.lstrip('-') for n in self.tk.splitlist(
+            self.tk.call(self._name, "element", "names")))
 
 
     def element_options(self, elementname):
         """Return the list of elementname's options."""
-        return self.tk.splitlist(self.tk.call(self._name, "element", "options", elementname))
+        return tuple(o.lstrip('-') for o in self.tk.splitlist(
+            self.tk.call(self._name, "element", "options", elementname)))
 
 
     def theme_create(self, themename, parent=None, settings=None):
diff --git a/Lib/tokenize.py b/Lib/tokenize.py
index b1d0c83263..ec79ec886d 100644
--- a/Lib/tokenize.py
+++ b/Lib/tokenize.py
@@ -29,6 +29,7 @@ from codecs import lookup, BOM_UTF8
 import collections
 from io import TextIOWrapper
 from itertools import chain
+import itertools as _itertools
 import re
 import sys
 from token import *
@@ -131,7 +132,28 @@ Floatnumber = group(Pointfloat, Expfloat)
 Imagnumber = group(r'[0-9]+[jJ]', Floatnumber + r'[jJ]')
 Number = group(Imagnumber, Floatnumber, Intnumber)
 
-StringPrefix = r'(?:[bB][rR]?|[rR][bB]?|[uU])?'
+# Return the empty string, plus all of the valid string prefixes.
+def _all_string_prefixes():
+    # The valid string prefixes. Only contain the lower case versions,
+    #  and don't contain any permuations (include 'fr', but not
+    #  'rf'). The various permutations will be generated.
+    _valid_string_prefixes = ['b', 'r', 'u', 'f', 'br', 'fr']
+    # if we add binary f-strings, add: ['fb', 'fbr']
+    result = set([''])
+    for prefix in _valid_string_prefixes:
+        for t in _itertools.permutations(prefix):
+            # create a list with upper and lower versions of each
+            #  character
+            for u in _itertools.product(*[(c, c.upper()) for c in t]):
+                result.add(''.join(u))
+    return result
+
+def _compile(expr):
+    return re.compile(expr, re.UNICODE)
+
+# Note that since _all_string_prefixes includes the empty string,
+#  StringPrefix can be the empty string (making it optional).
+StringPrefix = group(*_all_string_prefixes())
 
 # Tail end of ' string.
 Single = r"[^'\\]*(?:\\.[^'\\]*)*'"
@@ -169,50 +191,25 @@ ContStr = group(StringPrefix + r"'[^\n'\\]*(?:\\.[^\n'\\]*)*" +
 PseudoExtras = group(r'\\\r?\n|\Z', Comment, Triple)
 PseudoToken = Whitespace + group(PseudoExtras, Number, Funny, ContStr, Name)
 
-def _compile(expr):
-    return re.compile(expr, re.UNICODE)
-
-endpats = {"'": Single, '"': Double,
-           "'''": Single3, '"""': Double3,
-           "r'''": Single3, 'r"""': Double3,
-           "b'''": Single3, 'b"""': Double3,
-           "R'''": Single3, 'R"""': Double3,
-           "B'''": Single3, 'B"""': Double3,
-           "br'''": Single3, 'br"""': Double3,
-           "bR'''": Single3, 'bR"""': Double3,
-           "Br'''": Single3, 'Br"""': Double3,
-           "BR'''": Single3, 'BR"""': Double3,
-           "rb'''": Single3, 'rb"""': Double3,
-           "Rb'''": Single3, 'Rb"""': Double3,
-           "rB'''": Single3, 'rB"""': Double3,
-           "RB'''": Single3, 'RB"""': Double3,
-           "u'''": Single3, 'u"""': Double3,
-           "U'''": Single3, 'U"""': Double3,
-           'r': None, 'R': None, 'b': None, 'B': None,
-           'u': None, 'U': None}
-
-triple_quoted = {}
-for t in ("'''", '"""',
-          "r'''", 'r"""', "R'''", 'R"""',
-          "b'''", 'b"""', "B'''", 'B"""',
-          "br'''", 'br"""', "Br'''", 'Br"""',
-          "bR'''", 'bR"""', "BR'''", 'BR"""',
-          "rb'''", 'rb"""', "rB'''", 'rB"""',
-          "Rb'''", 'Rb"""', "RB'''", 'RB"""',
-          "u'''", 'u"""', "U'''", 'U"""',
-          ):
-    triple_quoted[t] = t
-single_quoted = {}
-for t in ("'", '"',
-          "r'", 'r"', "R'", 'R"',
-          "b'", 'b"', "B'", 'B"',
-          "br'", 'br"', "Br'", 'Br"',
-          "bR'", 'bR"', "BR'", 'BR"' ,
-          "rb'", 'rb"', "rB'", 'rB"',
-          "Rb'", 'Rb"', "RB'", 'RB"' ,
-          "u'", 'u"', "U'", 'U"',
-          ):
-    single_quoted[t] = t
+# For a given string prefix plus quotes, endpats maps it to a regex
+#  to match the remainder of that string. _prefix can be empty, for
+#  a normal single or triple quoted string (with no prefix).
+endpats = {}
+for _prefix in _all_string_prefixes():
+    endpats[_prefix + "'"] = Single
+    endpats[_prefix + '"'] = Double
+    endpats[_prefix + "'''"] = Single3
+    endpats[_prefix + '"""'] = Double3
+
+# A set of all of the single and triple quoted string prefixes,
+#  including the opening quotes.
+single_quoted = set()
+triple_quoted = set()
+for t in _all_string_prefixes():
+    for u in (t + '"', t + "'"):
+        single_quoted.add(u)
+    for u in (t + '"""', t + "'''"):
+        triple_quoted.add(u)
 
 tabsize = 8
 
@@ -626,6 +623,7 @@ def _tokenize(readline, encoding):
                         yield stashed
                         stashed = None
                     yield TokenInfo(COMMENT, token, spos, epos, line)
+
                 elif token in triple_quoted:
                     endprog = _compile(endpats[token])
                     endmatch = endprog.match(line, pos)
@@ -638,19 +636,37 @@ def _tokenize(readline, encoding):
                         contstr = line[start:]
                         contline = line
                         break
-                elif initial in single_quoted or \
-                    token[:2] in single_quoted or \
-                    token[:3] in single_quoted:
+
+                # Check up to the first 3 chars of the token to see if
+                #  they're in the single_quoted set. If so, they start
+                #  a string.
+                # We're using the first 3, because we're looking for
+                #  "rb'" (for example) at the start of the token. If
+                #  we switch to longer prefixes, this needs to be
+                #  adjusted.
+                # Note that initial == token[:1].
+                # Also note that single quote checking must come after
+                #  triple quote checking (above).
+                elif (initial in single_quoted or
+                      token[:2] in single_quoted or
+                      token[:3] in single_quoted):
                     if token[-1] == '\n':                  # continued string
                         strstart = (lnum, start)
-                        endprog = _compile(endpats[initial] or
-                                           endpats[token[1]] or
-                                           endpats[token[2]])
+                        # Again, using the first 3 chars of the
+                        #  token. This is looking for the matching end
+                        #  regex for the correct type of quote
+                        #  character. So it's really looking for
+                        #  endpats["'"] or endpats['"'], by trying to
+                        #  skip string prefix characters, if any.
+                        endprog = _compile(endpats.get(initial) or
+                                           endpats.get(token[1]) or
+                                           endpats.get(token[2]))
                         contstr, needcont = line[start:], 1
                         contline = line
                         break
                     else:                                  # ordinary string
                         yield TokenInfo(STRING, token, spos, epos, line)
+
                 elif initial.isidentifier():               # ordinary name
                     if token in ('async', 'await'):
                         if async_def:
diff --git a/Lib/trace.py b/Lib/trace.py
index f108266816..ae154615fa 100755
--- a/Lib/trace.py
+++ b/Lib/trace.py
@@ -48,6 +48,7 @@ Sample use, programmatically
   r.write_results(show_missing=True, coverdir="/tmp")
 """
 __all__ = ['Trace', 'CoverageResults']
+import argparse
 import linecache
 import os
 import re
@@ -58,7 +59,6 @@ import inspect
 import gc
 import dis
 import pickle
-from warnings import warn as _warn
 from time import monotonic as _time
 
 try:
@@ -77,51 +77,6 @@ else:
         sys.settrace(None)
         threading.settrace(None)
 
-def _usage(outfile):
-    outfile.write("""Usage: %s [OPTIONS] <file> [ARGS]
-
-Meta-options:
---help                Display this help then exit.
---version             Output version information then exit.
-
-Otherwise, exactly one of the following three options must be given:
--t, --trace           Print each line to sys.stdout before it is executed.
--c, --count           Count the number of times each line is executed
-                      and write the counts to <module>.cover for each
-                      module executed, in the module's directory.
-                      See also `--coverdir', `--file', `--no-report' below.
--l, --listfuncs       Keep track of which functions are executed at least
-                      once and write the results to sys.stdout after the
-                      program exits.
--T, --trackcalls      Keep track of caller/called pairs and write the
-                      results to sys.stdout after the program exits.
--r, --report          Generate a report from a counts file; do not execute
-                      any code.  `--file' must specify the results file to
-                      read, which must have been created in a previous run
-                      with `--count --file=FILE'.
-
-Modifiers:
--f, --file=<file>     File to accumulate counts over several runs.
--R, --no-report       Do not generate the coverage report files.
-                      Useful if you want to accumulate over several runs.
--C, --coverdir=<dir>  Directory where the report files.  The coverage
-                      report for <package>.<module> is written to file
-                      <dir>/<package>/<module>.cover.
--m, --missing         Annotate executable lines that were not executed
-                      with '>>>>>> '.
--s, --summary         Write a brief summary on stdout for each file.
-                      (Can only be used with --count or --report.)
--g, --timing          Prefix each line with the time since the program started.
-                      Only used while tracing.
-
-Filters, may be repeated multiple times:
---ignore-module=<mod> Ignore the given module(s) and its submodules
-                      (if it is a package).  Accepts comma separated
-                      list of module names
---ignore-dir=<dir>    Ignore files in the given directory (multiple
-                      directories can be joined by os.pathsep).
-""" % sys.argv[0])
-
 PRAGMA_NOCOVER = "#pragma NO COVER"
 
 # Simple rx to find lines with no code.
@@ -265,7 +220,13 @@ class CoverageResults:
 
     def write_results(self, show_missing=True, summary=False, coverdir=None):
         """
-        @param coverdir
+        Write the coverage results.
+
+        :param show_missing: Show lines that had no hits.
+        :param summary: Include coverage summary per module.
+        :param coverdir: If None, the results of each module are placed in its
+                         directory, otherwise it is included in the directory
+                         specified.
         """
         if self.calledfuncs:
             print()
@@ -647,210 +608,135 @@ class Trace:
                                calledfuncs=self._calledfuncs,
                                callers=self._callers)
 
-def _err_exit(msg):
-    sys.stderr.write("%s: %s\n" % (sys.argv[0], msg))
-    sys.exit(1)
-
-def main(argv=None):
-    import getopt
-
-    if argv is None:
-        argv = sys.argv
+def main():
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--version', action='version', version='trace 2.0')
+
+    grp = parser.add_argument_group('Main options',
+            'One of these (or --report) must be given')
+
+    grp.add_argument('-c', '--count', action='store_true',
+            help='Count the number of times each line is executed and write '
+                 'the counts to <module>.cover for each module executed, in '
+                 'the module\'s directory. See also --coverdir, --file, '
+                 '--no-report below.')
+    grp.add_argument('-t', '--trace', action='store_true',
+            help='Print each line to sys.stdout before it is executed')
+    grp.add_argument('-l', '--listfuncs', action='store_true',
+            help='Keep track of which functions are executed at least once '
+                 'and write the results to sys.stdout after the program exits. '
+                 'Cannot be specified alongside --trace or --count.')
+    grp.add_argument('-T', '--trackcalls', action='store_true',
+            help='Keep track of caller/called pairs and write the results to '
+                 'sys.stdout after the program exits.')
+
+    grp = parser.add_argument_group('Modifiers')
+
+    _grp = grp.add_mutually_exclusive_group()
+    _grp.add_argument('-r', '--report', action='store_true',
+            help='Generate a report from a counts file; does not execute any '
+                 'code. --file must specify the results file to read, which '
+                 'must have been created in a previous run with --count '
+                 '--file=FILE')
+    _grp.add_argument('-R', '--no-report', action='store_true',
+            help='Do not generate the coverage report files. '
+                 'Useful if you want to accumulate over several runs.')
+
+    grp.add_argument('-f', '--file',
+            help='File to accumulate counts over several runs')
+    grp.add_argument('-C', '--coverdir',
+            help='Directory where the report files go. The coverage report '
+                 'for <package>.<module> will be written to file '
+                 '<dir>/<package>/<module>.cover')
+    grp.add_argument('-m', '--missing', action='store_true',
+            help='Annotate executable lines that were not executed with '
+                 '">>>>>> "')
+    grp.add_argument('-s', '--summary', action='store_true',
+            help='Write a brief summary for each file to sys.stdout. '
+                 'Can only be used with --count or --report')
+    grp.add_argument('-g', '--timing', action='store_true',
+            help='Prefix each line with the time since the program started. '
+                 'Only used while tracing')
+
+    grp = parser.add_argument_group('Filters',
+            'Can be specified multiple times')
+    grp.add_argument('--ignore-module', action='append', default=[],
+            help='Ignore the given module(s) and its submodules'
+                 '(if it is a package). Accepts comma separated list of '
+                 'module names.')
+    grp.add_argument('--ignore-dir', action='append', default=[],
+            help='Ignore files in the given directory '
+                 '(multiple directories can be joined by os.pathsep).')
+
+    parser.add_argument('filename', nargs='?',
+            help='file to run as main program')
+    parser.add_argument('arguments', nargs=argparse.REMAINDER,
+            help='arguments to the program')
+
+    opts = parser.parse_args()
+
+    if opts.ignore_dir:
+        rel_path = 'lib', 'python{0.major}.{0.minor}'.format(sys.version_info)
+        _prefix = os.path.join(sys.base_prefix, *rel_path)
+        _exec_prefix = os.path.join(sys.base_exec_prefix, *rel_path)
+
+    def parse_ignore_dir(s):
+        s = os.path.expanduser(os.path.expandvars(s))
+        s = s.replace('$prefix', _prefix).replace('$exec_prefix', _exec_prefix)
+        return os.path.normpath(s)
+
+    opts.ignore_module = [mod.strip()
+                          for i in opts.ignore_module for mod in i.split(',')]
+    opts.ignore_dir = [parse_ignore_dir(s)
+                       for i in opts.ignore_dir for s in i.split(os.pathsep)]
+
+    if opts.report:
+        if not opts.file:
+            parser.error('-r/--report requires -f/--file')
+        results = CoverageResults(infile=opts.file, outfile=opts.file)
+        return results.write_results(opts.missing, opts.summary, opts.coverdir)
+
+    if not any([opts.trace, opts.count, opts.listfuncs, opts.trackcalls]):
+        parser.error('must specify one of --trace, --count, --report, '
+                     '--listfuncs, or --trackcalls')
+
+    if opts.listfuncs and (opts.count or opts.trace):
+        parser.error('cannot specify both --listfuncs and (--trace or --count)')
+
+    if opts.summary and not opts.count:
+        parser.error('--summary can only be used with --count or --report')
+
+    if opts.filename is None:
+        parser.error('filename is missing: required with the main options')
+
+    sys.argv = opts.filename, *opts.arguments
+    sys.path[0] = os.path.dirname(opts.filename)
+
+    t = Trace(opts.count, opts.trace, countfuncs=opts.listfuncs,
+              countcallers=opts.trackcalls, ignoremods=opts.ignore_module,
+              ignoredirs=opts.ignore_dir, infile=opts.file,
+              outfile=opts.file, timing=opts.timing)
     try:
-        opts, prog_argv = getopt.getopt(argv[1:], "tcrRf:d:msC:lTg",
-                                        ["help", "version", "trace", "count",
-                                         "report", "no-report", "summary",
-                                         "file=", "missing",
-                                         "ignore-module=", "ignore-dir=",
-                                         "coverdir=", "listfuncs",
-                                         "trackcalls", "timing"])
-
-    except getopt.error as msg:
-        sys.stderr.write("%s: %s\n" % (sys.argv[0], msg))
-        sys.stderr.write("Try `%s --help' for more information\n"
-                         % sys.argv[0])
-        sys.exit(1)
-
-    trace = 0
-    count = 0
-    report = 0
-    no_report = 0
-    counts_file = None
-    missing = 0
-    ignore_modules = []
-    ignore_dirs = []
-    coverdir = None
-    summary = 0
-    listfuncs = False
-    countcallers = False
-    timing = False
-
-    for opt, val in opts:
-        if opt == "--help":
-            _usage(sys.stdout)
-            sys.exit(0)
-
-        if opt == "--version":
-            sys.stdout.write("trace 2.0\n")
-            sys.exit(0)
-
-        if opt == "-T" or opt == "--trackcalls":
-            countcallers = True
-            continue
-
-        if opt == "-l" or opt == "--listfuncs":
-            listfuncs = True
-            continue
-
-        if opt == "-g" or opt == "--timing":
-            timing = True
-            continue
-
-        if opt == "-t" or opt == "--trace":
-            trace = 1
-            continue
-
-        if opt == "-c" or opt == "--count":
-            count = 1
-            continue
-
-        if opt == "-r" or opt == "--report":
-            report = 1
-            continue
-
-        if opt == "-R" or opt == "--no-report":
-            no_report = 1
-            continue
-
-        if opt == "-f" or opt == "--file":
-            counts_file = val
-            continue
-
-        if opt == "-m" or opt == "--missing":
-            missing = 1
-            continue
-
-        if opt == "-C" or opt == "--coverdir":
-            coverdir = val
-            continue
-
-        if opt == "-s" or opt == "--summary":
-            summary = 1
-            continue
-
-        if opt == "--ignore-module":
-            for mod in val.split(","):
-                ignore_modules.append(mod.strip())
-            continue
-
-        if opt == "--ignore-dir":
-            for s in val.split(os.pathsep):
-                s = os.path.expandvars(s)
-                # should I also call expanduser? (after all, could use $HOME)
-
-                s = s.replace("$prefix",
-                              os.path.join(sys.base_prefix, "lib",
-                                           "python" + sys.version[:3]))
-                s = s.replace("$exec_prefix",
-                              os.path.join(sys.base_exec_prefix, "lib",
-                                           "python" + sys.version[:3]))
-                s = os.path.normpath(s)
-                ignore_dirs.append(s)
-            continue
-
-        assert 0, "Should never get here"
-
-    if listfuncs and (count or trace):
-        _err_exit("cannot specify both --listfuncs and (--trace or --count)")
-
-    if not (count or trace or report or listfuncs or countcallers):
-        _err_exit("must specify one of --trace, --count, --report, "
-                  "--listfuncs, or --trackcalls")
-
-    if report and no_report:
-        _err_exit("cannot specify both --report and --no-report")
-
-    if report and not counts_file:
-        _err_exit("--report requires a --file")
-
-    if no_report and len(prog_argv) == 0:
-        _err_exit("missing name of file to run")
-
-    # everything is ready
-    if report:
-        results = CoverageResults(infile=counts_file, outfile=counts_file)
-        results.write_results(missing, summary=summary, coverdir=coverdir)
-    else:
-        sys.argv = prog_argv
-        progname = prog_argv[0]
-        sys.path[0] = os.path.split(progname)[0]
-
-        t = Trace(count, trace, countfuncs=listfuncs,
-                  countcallers=countcallers, ignoremods=ignore_modules,
-                  ignoredirs=ignore_dirs, infile=counts_file,
-                  outfile=counts_file, timing=timing)
-        try:
-            with open(progname) as fp:
-                code = compile(fp.read(), progname, 'exec')
-            # try to emulate __main__ namespace as much as possible
-            globs = {
-                '__file__': progname,
-                '__name__': '__main__',
-                '__package__': None,
-                '__cached__': None,
-            }
-            t.runctx(code, globs, globs)
-        except OSError as err:
-            _err_exit("Cannot run file %r because: %s" % (sys.argv[0], err))
-        except SystemExit:
-            pass
-
-        results = t.results()
-
-        if not no_report:
-            results.write_results(missing, summary=summary, coverdir=coverdir)
-
-#  Deprecated API
-def usage(outfile):
-    _warn("The trace.usage() function is deprecated",
-         DeprecationWarning, 2)
-    _usage(outfile)
-
-class Ignore(_Ignore):
-    def __init__(self, modules=None, dirs=None):
-        _warn("The class trace.Ignore is deprecated",
-             DeprecationWarning, 2)
-        _Ignore.__init__(self, modules, dirs)
-
-def modname(path):
-    _warn("The trace.modname() function is deprecated",
-         DeprecationWarning, 2)
-    return _modname(path)
-
-def fullmodname(path):
-    _warn("The trace.fullmodname() function is deprecated",
-         DeprecationWarning, 2)
-    return _fullmodname(path)
-
-def find_lines_from_code(code, strs):
-    _warn("The trace.find_lines_from_code() function is deprecated",
-         DeprecationWarning, 2)
-    return _find_lines_from_code(code, strs)
-
-def find_lines(code, strs):
-    _warn("The trace.find_lines() function is deprecated",
-         DeprecationWarning, 2)
-    return _find_lines(code, strs)
+        with open(opts.filename) as fp:
+            code = compile(fp.read(), opts.filename, 'exec')
+        # try to emulate __main__ namespace as much as possible
+        globs = {
+            '__file__': opts.filename,
+            '__name__': '__main__',
+            '__package__': None,
+            '__cached__': None,
+        }
+        t.runctx(code, globs, globs)
+    except OSError as err:
+        sys.exit("Cannot run file %r because: %s" % (sys.argv[0], err))
+    except SystemExit:
+        pass
 
-def find_strings(filename, encoding=None):
-    _warn("The trace.find_strings() function is deprecated",
-         DeprecationWarning, 2)
-    return _find_strings(filename, encoding=None)
+    results = t.results()
 
-def find_executable_linenos(filename):
-    _warn("The trace.find_executable_linenos() function is deprecated",
-         DeprecationWarning, 2)
-    return _find_executable_linenos(filename)
+    if not opts.no_report:
+        results.write_results(opts.missing, opts.summary, opts.coverdir)
 
 if __name__=='__main__':
     main()
diff --git a/Lib/traceback.py b/Lib/traceback.py
index a2eb539c02..3b46c0b050 100644
--- a/Lib/traceback.py
+++ b/Lib/traceback.py
@@ -487,10 +487,9 @@ class TracebackException:
             self._load_lines()
 
     @classmethod
-    def from_exception(self, exc, *args, **kwargs):
+    def from_exception(cls, exc, *args, **kwargs):
         """Create a TracebackException from an exception."""
-        return TracebackException(
-            type(exc), exc, exc.__traceback__, *args, **kwargs)
+        return cls(type(exc), exc, exc.__traceback__, *args, **kwargs)
 
     def _load_lines(self):
         """Private API. force all lines in the stack to be loaded."""
diff --git a/Lib/tracemalloc.py b/Lib/tracemalloc.py
index 6288da8409..75b391891f 100644
--- a/Lib/tracemalloc.py
+++ b/Lib/tracemalloc.py
@@ -244,17 +244,21 @@ class Trace:
     __slots__ = ("_trace",)
 
     def __init__(self, trace):
-        # trace is a tuple: (size, traceback), see Traceback constructor
-        # for the format of the traceback tuple
+        # trace is a tuple: (domain: int, size: int, traceback: tuple).
+        # See Traceback constructor for the format of the traceback tuple.
         self._trace = trace
 
     @property
-    def size(self):
+    def domain(self):
         return self._trace[0]
 
     @property
+    def size(self):
+        return self._trace[1]
+
+    @property
     def traceback(self):
-        return Traceback(self._trace[1])
+        return Traceback(self._trace[2])
 
     def __eq__(self, other):
         return (self._trace == other._trace)
@@ -266,8 +270,8 @@ class Trace:
         return "%s: %s" % (self.traceback, _format_size(self.size, False))
 
     def __repr__(self):
-        return ("<Trace size=%s, traceback=%r>"
-                % (_format_size(self.size, False), self.traceback))
+        return ("<Trace domain=%s size=%s, traceback=%r>"
+                % (self.domain, _format_size(self.size, False), self.traceback))
 
 
 class _Traces(Sequence):
@@ -302,19 +306,29 @@ def _normalize_filename(filename):
     return filename
 
 
-class Filter:
+class BaseFilter:
+    def __init__(self, inclusive):
+        self.inclusive = inclusive
+
+    def _match(self, trace):
+        raise NotImplementedError
+
+
+class Filter(BaseFilter):
     def __init__(self, inclusive, filename_pattern,
-                 lineno=None, all_frames=False):
+                 lineno=None, all_frames=False, domain=None):
+        super().__init__(inclusive)
         self.inclusive = inclusive
         self._filename_pattern = _normalize_filename(filename_pattern)
         self.lineno = lineno
         self.all_frames = all_frames
+        self.domain = domain
 
     @property
     def filename_pattern(self):
         return self._filename_pattern
 
-    def __match_frame(self, filename, lineno):
+    def _match_frame_impl(self, filename, lineno):
         filename = _normalize_filename(filename)
         if not fnmatch.fnmatch(filename, self._filename_pattern):
             return False
@@ -324,11 +338,11 @@ class Filter:
             return (lineno == self.lineno)
 
     def _match_frame(self, filename, lineno):
-        return self.__match_frame(filename, lineno) ^ (not self.inclusive)
+        return self._match_frame_impl(filename, lineno) ^ (not self.inclusive)
 
     def _match_traceback(self, traceback):
         if self.all_frames:
-            if any(self.__match_frame(filename, lineno)
+            if any(self._match_frame_impl(filename, lineno)
                    for filename, lineno in traceback):
                 return self.inclusive
             else:
@@ -337,6 +351,30 @@ class Filter:
             filename, lineno = traceback[0]
             return self._match_frame(filename, lineno)
 
+    def _match(self, trace):
+        domain, size, traceback = trace
+        res = self._match_traceback(traceback)
+        if self.domain is not None:
+            if self.inclusive:
+                return res and (domain == self.domain)
+            else:
+                return res or (domain != self.domain)
+        return res
+
+
+class DomainFilter(BaseFilter):
+    def __init__(self, inclusive, domain):
+        super().__init__(inclusive)
+        self._domain = domain
+
+    @property
+    def domain(self):
+        return self._domain
+
+    def _match(self, trace):
+        domain, size, traceback = trace
+        return (domain == self.domain) ^ (not self.inclusive)
+
 
 class Snapshot:
     """
@@ -365,13 +403,12 @@ class Snapshot:
             return pickle.load(fp)
 
     def _filter_trace(self, include_filters, exclude_filters, trace):
-        traceback = trace[1]
         if include_filters:
-            if not any(trace_filter._match_traceback(traceback)
+            if not any(trace_filter._match(trace)
                        for trace_filter in include_filters):
                 return False
         if exclude_filters:
-            if any(not trace_filter._match_traceback(traceback)
+            if any(not trace_filter._match(trace)
                    for trace_filter in exclude_filters):
                 return False
         return True
@@ -379,8 +416,8 @@ class Snapshot:
     def filter_traces(self, filters):
         """
         Create a new Snapshot instance with a filtered traces sequence, filters
-        is a list of Filter instances.  If filters is an empty list, return a
-        new Snapshot instance with a copy of the traces.
+        is a list of Filter or DomainFilter instances.  If filters is an empty
+        list, return a new Snapshot instance with a copy of the traces.
         """
         if not isinstance(filters, Iterable):
             raise TypeError("filters must be a list of filters, not %s"
@@ -412,7 +449,7 @@ class Snapshot:
         tracebacks = {}
         if not cumulative:
             for trace in self.traces._traces:
-                size, trace_traceback = trace
+                domain, size, trace_traceback = trace
                 try:
                     traceback = tracebacks[trace_traceback]
                 except KeyError:
@@ -433,7 +470,7 @@ class Snapshot:
         else:
             # cumulative statistics
             for trace in self.traces._traces:
-                size, trace_traceback = trace
+                domain, size, trace_traceback = trace
                 for frame in trace_traceback:
                     try:
                         traceback = tracebacks[frame]
diff --git a/Lib/turtledemo/__main__.py b/Lib/turtledemo/__main__.py
index 711d0abf2e..0a58332a66 100644
--- a/Lib/turtledemo/__main__.py
+++ b/Lib/turtledemo/__main__.py
@@ -89,13 +89,12 @@ import sys
 import os
 
 from tkinter import *
-from idlelib.ColorDelegator import ColorDelegator, color_config
-from idlelib.Percolator import Percolator
-from idlelib.textView import view_text
+from idlelib.colorizer import ColorDelegator, color_config
+from idlelib.percolator import Percolator
+from idlelib.textview import view_text
 from turtledemo import __doc__ as about_turtledemo
 
 import turtle
-import time
 
 demo_dir = os.path.dirname(os.path.abspath(__file__))
 darwin = sys.platform == 'darwin'
diff --git a/Lib/turtledemo/bytedesign.py b/Lib/turtledemo/bytedesign.py
index 64b1d7d5b0..b3b095b768 100755
--- a/Lib/turtledemo/bytedesign.py
+++ b/Lib/turtledemo/bytedesign.py
@@ -22,7 +22,6 @@ to 0, this animation runs in "line per line"
 mode as fast as possible.
 """
 
-import math
 from turtle import Turtle, mainloop
 from time import clock
 
diff --git a/Lib/turtledemo/planet_and_moon.py b/Lib/turtledemo/planet_and_moon.py
index 26abfdb069..021ff99383 100755
--- a/Lib/turtledemo/planet_and_moon.py
+++ b/Lib/turtledemo/planet_and_moon.py
@@ -18,7 +18,6 @@ mouse over the scrollbar of the canvas.
 
 """
 from turtle import Shape, Turtle, mainloop, Vec2D as Vec
-from time import sleep
 
 G = 8
 
diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index 86a5a3dfeb..be215f3552 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -523,7 +523,7 @@ class NonCallableMock(Base):
     side_effect = property(__get_side_effect, __set_side_effect)
 
 
-    def reset_mock(self, visited=None):
+    def reset_mock(self,  visited=None,*, return_value=False, side_effect=False):
         "Restore the mock object to its initial state."
         if visited is None:
             visited = []
@@ -538,6 +538,11 @@ class NonCallableMock(Base):
         self.call_args_list = _CallList()
         self.method_calls = _CallList()
 
+        if return_value:
+            self._mock_return_value = DEFAULT
+        if side_effect:
+            self._mock_side_effect = None
+
         for child in self._mock_children.values():
             if isinstance(child, _SpecState):
                 continue
@@ -772,6 +777,24 @@ class NonCallableMock(Base):
                    (self._mock_name or 'mock', self.call_count))
             raise AssertionError(msg)
 
+    def assert_called(_mock_self):
+        """assert that the mock was called at least once
+        """
+        self = _mock_self
+        if self.call_count == 0:
+            msg = ("Expected '%s' to have been called." %
+                   self._mock_name or 'mock')
+            raise AssertionError(msg)
+
+    def assert_called_once(_mock_self):
+        """assert that the mock was called only once.
+        """
+        self = _mock_self
+        if not self.call_count == 1:
+            msg = ("Expected '%s' to have been called once. Called %s times." %
+                   (self._mock_name or 'mock', self.call_count))
+            raise AssertionError(msg)
+
     def assert_called_with(_mock_self, *args, **kwargs):
         """assert that the mock was called with the specified arguments.
 
@@ -820,7 +843,7 @@ class NonCallableMock(Base):
             if expected not in all_calls:
                 raise AssertionError(
                     'Calls not found.\nExpected: %r\n'
-                    'Actual: %r' % (calls, self.mock_calls)
+                    'Actual: %r' % (_CallList(calls), self.mock_calls)
                 ) from cause
             return
 
diff --git a/Lib/unittest/test/testmock/support.py b/Lib/unittest/test/testmock/support.py
index f4738793b3..205431adca 100644
--- a/Lib/unittest/test/testmock/support.py
+++ b/Lib/unittest/test/testmock/support.py
@@ -1,5 +1,3 @@
-import sys
-
 def is_instance(obj, klass):
     """Version of is_instance that doesn't access __class__"""
     return issubclass(type(obj), klass)
diff --git a/Lib/unittest/test/testmock/testmagicmethods.py b/Lib/unittest/test/testmock/testmagicmethods.py
index bb9b956bb2..24569b532d 100644
--- a/Lib/unittest/test/testmock/testmagicmethods.py
+++ b/Lib/unittest/test/testmock/testmagicmethods.py
@@ -1,5 +1,4 @@
 import unittest
-import inspect
 import sys
 from unittest.mock import Mock, MagicMock, _magics
 
diff --git a/Lib/unittest/test/testmock/testmock.py b/Lib/unittest/test/testmock/testmock.py
index 5f82b82966..b07a7cc318 100644
--- a/Lib/unittest/test/testmock/testmock.py
+++ b/Lib/unittest/test/testmock/testmock.py
@@ -1239,6 +1239,27 @@ class MockTest(unittest.TestCase):
         with self.assertRaises(AssertionError):
             m.hello.assert_not_called()
 
+    def test_assert_called(self):
+        m = Mock()
+        with self.assertRaises(AssertionError):
+            m.hello.assert_called()
+        m.hello()
+        m.hello.assert_called()
+
+        m.hello()
+        m.hello.assert_called()
+
+    def test_assert_called_once(self):
+        m = Mock()
+        with self.assertRaises(AssertionError):
+            m.hello.assert_called_once()
+        m.hello()
+        m.hello.assert_called_once()
+
+        m.hello()
+        with self.assertRaises(AssertionError):
+            m.hello.assert_called_once()
+
     #Issue21256 printout of keyword args should be in deterministic order
     def test_sorted_call_signature(self):
         m = Mock()
@@ -1256,6 +1277,24 @@ class MockTest(unittest.TestCase):
         self.assertEqual(m.method_calls[0], c)
         self.assertEqual(m.method_calls[1], i)
 
+    def test_reset_return_sideeffect(self):
+        m = Mock(return_value=10, side_effect=[2,3])
+        m.reset_mock(return_value=True, side_effect=True)
+        self.assertIsInstance(m.return_value, Mock)
+        self.assertEqual(m.side_effect, None)
+
+    def test_reset_return(self):
+        m = Mock(return_value=10, side_effect=[2,3])
+        m.reset_mock(return_value=True)
+        self.assertIsInstance(m.return_value, Mock)
+        self.assertNotEqual(m.side_effect, None)
+
+    def test_reset_sideeffect(self):
+        m = Mock(return_value=10, side_effect=[2,3])
+        m.reset_mock(side_effect=True)
+        self.assertEqual(m.return_value, 10)
+        self.assertEqual(m.side_effect, None)
+
     def test_mock_add_spec(self):
         class _One(object):
             one = 1
diff --git a/Lib/unittest/test/testmock/testpatch.py b/Lib/unittest/test/testmock/testpatch.py
index dfce3696d6..2e0c08f35f 100644
--- a/Lib/unittest/test/testmock/testpatch.py
+++ b/Lib/unittest/test/testmock/testpatch.py
@@ -10,9 +10,9 @@ from unittest.test.testmock import support
 from unittest.test.testmock.support import SomeClass, is_instance
 
 from unittest.mock import (
-    NonCallableMock, CallableMixin, patch, sentinel,
+    NonCallableMock, CallableMixin, sentinel,
     MagicMock, Mock, NonCallableMagicMock, patch, _patch,
-    DEFAULT, call, _get_target, _patch
+    DEFAULT, call, _get_target
 )
 
 
diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index 4d7fcec94b..99a6977ebf 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -156,9 +156,8 @@ class _NetlocResultMixinBase(object):
         port = self._hostinfo[1]
         if port is not None:
             port = int(port, 10)
-            # Return None on an illegal port
             if not ( 0 <= port <= 65535):
-                return None
+                raise ValueError("Port out of range 0-65535")
         return port
 
 
@@ -225,8 +224,71 @@ class _NetlocResultMixinBytes(_NetlocResultMixinBase, _ResultMixinBytes):
 from collections import namedtuple
 
 _DefragResultBase = namedtuple('DefragResult', 'url fragment')
-_SplitResultBase = namedtuple('SplitResult', 'scheme netloc path query fragment')
-_ParseResultBase = namedtuple('ParseResult', 'scheme netloc path params query fragment')
+_SplitResultBase = namedtuple(
+    'SplitResult', 'scheme netloc path query fragment')
+_ParseResultBase = namedtuple(
+    'ParseResult', 'scheme netloc path params query fragment')
+
+_DefragResultBase.__doc__ = """
+DefragResult(url, fragment)
+
+A 2-tuple that contains the url without fragment identifier and the fragment
+identifier as a separate argument.
+"""
+
+_DefragResultBase.url.__doc__ = """The URL with no fragment identifier."""
+
+_DefragResultBase.fragment.__doc__ = """
+Fragment identifier separated from URL, that allows indirect identification of a
+secondary resource by reference to a primary resource and additional identifying
+information.
+"""
+
+_SplitResultBase.__doc__ = """
+SplitResult(scheme, netloc, path, query, fragment)
+
+A 5-tuple that contains the different components of a URL. Similar to
+ParseResult, but does not split params.
+"""
+
+_SplitResultBase.scheme.__doc__ = """Specifies URL scheme for the request."""
+
+_SplitResultBase.netloc.__doc__ = """
+Network location where the request is made to.
+"""
+
+_SplitResultBase.path.__doc__ = """
+The hierarchical path, such as the path to a file to download.
+"""
+
+_SplitResultBase.query.__doc__ = """
+The query component, that contains non-hierarchical data, that along with data
+in path component, identifies a resource in the scope of URI's scheme and
+network location.
+"""
+
+_SplitResultBase.fragment.__doc__ = """
+Fragment identifier, that allows indirect identification of a secondary resource
+by reference to a primary resource and additional identifying information.
+"""
+
+_ParseResultBase.__doc__ = """
+ParseResult(scheme, netloc, path, params,  query, fragment)
+
+A 6-tuple that contains components of a parsed URL.
+"""
+
+_ParseResultBase.scheme.__doc__ = _SplitResultBase.scheme.__doc__
+_ParseResultBase.netloc.__doc__ = _SplitResultBase.netloc.__doc__
+_ParseResultBase.path.__doc__ = _SplitResultBase.path.__doc__
+_ParseResultBase.params.__doc__ = """
+Parameters for last path element used to dereference the URI in order to provide
+access to perform some operation on the resource.
+"""
+
+_ParseResultBase.query.__doc__ = _SplitResultBase.query.__doc__
+_ParseResultBase.fragment.__doc__ = _SplitResultBase.fragment.__doc__
+
 
 # For backwards compatibility, alias _NetlocResultMixinStr
 # ResultBase is no longer part of the documented API, but it is
diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py
index 1731fe3df1..67e73f9ef8 100644
--- a/Lib/urllib/request.py
+++ b/Lib/urllib/request.py
@@ -134,11 +134,76 @@ __all__ = [
 ]
 
 # used in User-Agent header sent
-__version__ = sys.version[:3]
+__version__ = '%d.%d' % sys.version_info[:2]
 
 _opener = None
 def urlopen(url, data=None, timeout=socket._GLOBAL_DEFAULT_TIMEOUT,
             *, cafile=None, capath=None, cadefault=False, context=None):
+    '''Open the URL url, which can be either a string or a Request object.
+
+    *data* must be a bytes object specifying additional data to be sent to the
+    server, or None if no such data is needed. data may also be an iterable
+    object and in that case Content-Length value must be specified in the
+    headers. Currently HTTP requests are the only ones that use data; the HTTP
+    request will be a POST instead of a GET when the data parameter is
+    provided.
+
+    *data* should be a buffer in the standard application/x-www-form-urlencoded
+    format. The urllib.parse.urlencode() function takes a mapping or sequence
+    of 2-tuples and returns an ASCII text string in this format. It should be
+    encoded to bytes before being used as the data parameter.
+
+    urllib.request module uses HTTP/1.1 and includes a "Connection:close"
+    header in its HTTP requests.
+
+    The optional *timeout* parameter specifies a timeout in seconds for
+    blocking operations like the connection attempt (if not specified, the
+    global default timeout setting will be used). This only works for HTTP,
+    HTTPS and FTP connections.
+
+    If *context* is specified, it must be a ssl.SSLContext instance describing
+    the various SSL options. See HTTPSConnection for more details.
+
+    The optional *cafile* and *capath* parameters specify a set of trusted CA
+    certificates for HTTPS requests. cafile should point to a single file
+    containing a bundle of CA certificates, whereas capath should point to a
+    directory of hashed certificate files. More information can be found in
+    ssl.SSLContext.load_verify_locations().
+
+    The *cadefault* parameter is ignored.
+
+    This function always returns an object which can work as a context
+    manager and has methods such as
+
+    * geturl() - return the URL of the resource retrieved, commonly used to
+      determine if a redirect was followed
+
+    * info() - return the meta-information of the page, such as headers, in the
+      form of an email.message_from_string() instance (see Quick Reference to
+      HTTP Headers)
+
+    * getcode() - return the HTTP status code of the response.  Raises URLError
+      on errors.
+
+    For HTTP and HTTPS URLs, this function returns a http.client.HTTPResponse
+    object slightly modified. In addition to the three new methods above, the
+    msg attribute contains the same information as the reason attribute ---
+    the reason phrase returned by the server --- instead of the response
+    headers as it is specified in the documentation for HTTPResponse.
+
+    For FTP, file, and data URLs and requests explicitly handled by legacy
+    URLopener and FancyURLopener classes, this function returns a
+    urllib.response.addinfourl object.
+
+    Note that None may be returned if no handler handles the request (though
+    the default installed global OpenerDirector uses UnknownHandler to ensure
+    this never happens).
+
+    In addition, if proxy settings are detected (for example, when a *_proxy
+    environment variable like http_proxy is set), ProxyHandler is default
+    installed and makes sure the requests are handled through the proxy.
+
+    '''
     global _opener
     if cafile or capath or cadefault:
         if context is not None:
diff --git a/Lib/urllib/robotparser.py b/Lib/urllib/robotparser.py
index 8b69fd985e..85add1624a 100644
--- a/Lib/urllib/robotparser.py
+++ b/Lib/urllib/robotparser.py
@@ -10,7 +10,9 @@
     http://www.robotstxt.org/norobots-rfc.txt
 """
 
-import urllib.parse, urllib.request
+import collections
+import urllib.parse
+import urllib.request
 
 __all__ = ["RobotFileParser"]
 
@@ -120,10 +122,29 @@ class RobotFileParser:
                     if state != 0:
                         entry.rulelines.append(RuleLine(line[1], True))
                         state = 2
+                elif line[0] == "crawl-delay":
+                    if state != 0:
+                        # before trying to convert to int we need to make
+                        # sure that robots.txt has valid syntax otherwise
+                        # it will crash
+                        if line[1].strip().isdigit():
+                            entry.delay = int(line[1])
+                        state = 2
+                elif line[0] == "request-rate":
+                    if state != 0:
+                        numbers = line[1].split('/')
+                        # check if all values are sane
+                        if (len(numbers) == 2 and numbers[0].strip().isdigit()
+                            and numbers[1].strip().isdigit()):
+                            req_rate = collections.namedtuple('req_rate',
+                                                              'requests seconds')
+                            entry.req_rate = req_rate
+                            entry.req_rate.requests = int(numbers[0])
+                            entry.req_rate.seconds = int(numbers[1])
+                        state = 2
         if state == 2:
             self._add_entry(entry)
 
-
     def can_fetch(self, useragent, url):
         """using the parsed robots.txt decide if useragent can fetch url"""
         if self.disallow_all:
@@ -153,6 +174,18 @@ class RobotFileParser:
         # agent not found ==> access granted
         return True
 
+    def crawl_delay(self, useragent):
+        for entry in self.entries:
+            if entry.applies_to(useragent):
+                return entry.delay
+        return None
+
+    def request_rate(self, useragent):
+        for entry in self.entries:
+            if entry.applies_to(useragent):
+                return entry.req_rate
+        return None
+
     def __str__(self):
         return ''.join([str(entry) + "\n" for entry in self.entries])
 
@@ -180,6 +213,8 @@ class Entry:
     def __init__(self):
         self.useragents = []
         self.rulelines = []
+        self.delay = None
+        self.req_rate = None
 
     def __str__(self):
         ret = []
diff --git a/Lib/uuid.py b/Lib/uuid.py
index e96e7e034c..200c800b34 100644
--- a/Lib/uuid.py
+++ b/Lib/uuid.py
@@ -487,7 +487,6 @@ try:
     # Assume that the uuid_generate functions are broken from 10.5 onward,
     # the test can be adjusted when a later version is fixed.
     if sys.platform == 'darwin':
-        import os
         if int(os.uname().release.split('.')[0]) >= 9:
             _uuid_generate_time = None
 
diff --git a/Lib/venv/__init__.py b/Lib/venv/__init__.py
index 74245abbb2..fa3d2a3056 100644
--- a/Lib/venv/__init__.py
+++ b/Lib/venv/__init__.py
@@ -3,28 +3,6 @@ Virtual environment (venv) package for Python. Based on PEP 405.
 
 Copyright (C) 2011-2014 Vinay Sajip.
 Licensed to the PSF under a contributor agreement.
-
-usage: python -m venv [-h] [--system-site-packages] [--symlinks] [--clear]
-            [--upgrade]
-            ENV_DIR [ENV_DIR ...]
-
-Creates virtual Python environments in one or more target directories.
-
-positional arguments:
-  ENV_DIR               A directory to create the environment in.
-
-optional arguments:
-  -h, --help            show this help message and exit
-  --system-site-packages
-                        Give the virtual environment access to the system
-                        site-packages dir.
-  --symlinks            Attempt to symlink rather than copy.
-  --clear               Delete the contents of the environment directory if it
-                        already exists, before environment creation.
-  --upgrade             Upgrade the environment directory to use this version
-                        of Python, assuming Python has been upgraded in-place.
-  --without-pip         Skips installing or upgrading pip in the virtual
-                        environment (pip is bootstrapped by default)
 """
 import logging
 import os
@@ -349,23 +327,7 @@ class EnvBuilder:
 
 def create(env_dir, system_site_packages=False, clear=False,
                     symlinks=False, with_pip=False):
-    """
-    Create a virtual environment in a directory.
-
-    By default, makes the system (global) site-packages dir *un*available to
-    the created environment, and uses copying rather than symlinking for files
-    obtained from the source Python installation.
-
-    :param env_dir: The target directory to create an environment in.
-    :param system_site_packages: If True, the system (global) site-packages
-                                 dir is available to the environment.
-    :param clear: If True, delete the contents of the environment directory if
-                  it already exists, before environment creation.
-    :param symlinks: If True, attempt to symlink rather than copy files into
-                     virtual environment.
-    :param with_pip: If True, ensure pip is installed in the virtual
-                     environment
-    """
+    """Create a virtual environment in a directory."""
     builder = EnvBuilder(system_site_packages=system_site_packages,
                          clear=clear, symlinks=symlinks, with_pip=with_pip)
     builder.create(env_dir)
diff --git a/Lib/warnings.py b/Lib/warnings.py
index c6631fcbf4..2b407ffed9 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -2,39 +2,112 @@
 
 import sys
 
+
 __all__ = ["warn", "warn_explicit", "showwarning",
            "formatwarning", "filterwarnings", "simplefilter",
            "resetwarnings", "catch_warnings"]
 
-
 def showwarning(message, category, filename, lineno, file=None, line=None):
     """Hook to write a warning to a file; replace if you like."""
+    msg = WarningMessage(message, category, filename, lineno, file, line)
+    _showwarnmsg_impl(msg)
+
+def formatwarning(message, category, filename, lineno, line=None):
+    """Function to format a warning the standard way."""
+    msg = WarningMessage(message, category, filename, lineno, None, line)
+    return _formatwarnmsg_impl(msg)
+
+def _showwarnmsg_impl(msg):
+    file = msg.file
     if file is None:
         file = sys.stderr
         if file is None:
-            # sys.stderr is None when run with pythonw.exe - warnings get lost
+            # sys.stderr is None when run with pythonw.exe:
+            # warnings get lost
             return
+    text = _formatwarnmsg(msg)
     try:
-        file.write(formatwarning(message, category, filename, lineno, line))
+        file.write(text)
     except OSError:
-        pass # the file (probably stderr) is invalid - this warning gets lost.
+        # the file (probably stderr) is invalid - this warning gets lost.
+        pass
 
-def formatwarning(message, category, filename, lineno, line=None):
-    """Function to format a warning the standard way."""
-    s =  "%s:%s: %s: %s\n" % (filename, lineno, category.__name__, message)
-    if line is None:
+def _formatwarnmsg_impl(msg):
+    s =  ("%s:%s: %s: %s\n"
+          % (msg.filename, msg.lineno, msg.category.__name__,
+             msg.message))
+
+    if msg.line is None:
         try:
             import linecache
-            line = linecache.getline(filename, lineno)
+            line = linecache.getline(msg.filename, msg.lineno)
         except Exception:
             # When a warning is logged during Python shutdown, linecache
             # and the import machinery don't work anymore
             line = None
+            linecache = None
+    else:
+        line = msg.line
     if line:
         line = line.strip()
         s += "  %s\n" % line
+
+    if msg.source is not None:
+        try:
+            import tracemalloc
+            tb = tracemalloc.get_object_traceback(msg.source)
+        except Exception:
+            # When a warning is logged during Python shutdown, tracemalloc
+            # and the import machinery don't work anymore
+            tb = None
+
+        if tb is not None:
+            s += 'Object allocated at (most recent call first):\n'
+            for frame in tb:
+                s += ('  File "%s", lineno %s\n'
+                      % (frame.filename, frame.lineno))
+
+                try:
+                    if linecache is not None:
+                        line = linecache.getline(frame.filename, frame.lineno)
+                    else:
+                        line = None
+                except Exception:
+                    line = None
+                if line:
+                    line = line.strip()
+                    s += '    %s\n' % line
     return s
 
+# Keep a reference to check if the function was replaced
+_showwarning = showwarning
+
+def _showwarnmsg(msg):
+    """Hook to write a warning to a file; replace if you like."""
+    showwarning = globals().get('showwarning', _showwarning)
+    if showwarning is not _showwarning:
+        # warnings.showwarning() was replaced
+        if not callable(showwarning):
+            raise TypeError("warnings.showwarning() must be set to a "
+                            "function or method")
+
+        showwarning(msg.message, msg.category, msg.filename, msg.lineno,
+                    msg.file, msg.line)
+        return
+    _showwarnmsg_impl(msg)
+
+# Keep a reference to check if the function was replaced
+_formatwarning = formatwarning
+
+def _formatwarnmsg(msg):
+    """Function to format a warning the standard way."""
+    formatwarning = globals().get('formatwarning', _formatwarning)
+    if formatwarning is not _formatwarning:
+        # warnings.formatwarning() was replaced
+        return formatwarning(msg.message, msg.category,
+                             msg.filename, msg.lineno, line=msg.line)
+    return _formatwarnmsg_impl(msg)
+
 def filterwarnings(action, message="", category=Warning, module="", lineno=0,
                    append=False):
     """Insert an entry into the list of warnings filters (at the front).
@@ -185,7 +258,7 @@ def _next_external_frame(frame):
 
 
 # Code typically replaced by _warnings
-def warn(message, category=None, stacklevel=1):
+def warn(message, category=None, stacklevel=1, source=None):
     """Issue a warning, or maybe ignore it or raise an exception."""
     # Check if message is already a Warning object
     if isinstance(message, Warning):
@@ -235,10 +308,11 @@ def warn(message, category=None, stacklevel=1):
             filename = module
     registry = globals.setdefault("__warningregistry__", {})
     warn_explicit(message, category, filename, lineno, module, registry,
-                  globals)
+                  globals, source)
 
 def warn_explicit(message, category, filename, lineno,
-                  module=None, registry=None, module_globals=None):
+                  module=None, registry=None, module_globals=None,
+                  source=None):
     lineno = int(lineno)
     if module is None:
         module = filename or "<unknown>"
@@ -303,22 +377,18 @@ def warn_explicit(message, category, filename, lineno,
         raise RuntimeError(
               "Unrecognized action (%r) in warnings.filters:\n %s" %
               (action, item))
-    if not callable(showwarning):
-        raise TypeError("warnings.showwarning() must be set to a "
-                        "function or method")
     # Print message and context
-    showwarning(message, category, filename, lineno)
+    msg = WarningMessage(message, category, filename, lineno, source)
+    _showwarnmsg(msg)
 
 
 class WarningMessage(object):
 
-    """Holds the result of a single showwarning() call."""
-
     _WARNING_DETAILS = ("message", "category", "filename", "lineno", "file",
-                        "line")
+                        "line", "source")
 
     def __init__(self, message, category, filename, lineno, file=None,
-                    line=None):
+                 line=None, source=None):
         local_values = locals()
         for attr in self._WARNING_DETAILS:
             setattr(self, attr, local_values[attr])
@@ -376,11 +446,12 @@ class catch_warnings(object):
         self._module.filters = self._filters[:]
         self._module._filters_mutated()
         self._showwarning = self._module.showwarning
+        self._showwarnmsg = self._module._showwarnmsg
         if self._record:
             log = []
-            def showwarning(*args, **kwargs):
-                log.append(WarningMessage(*args, **kwargs))
-            self._module.showwarning = showwarning
+            def showarnmsg(msg):
+                log.append(msg)
+            self._module._showwarnmsg = showarnmsg
             return log
         else:
             return None
@@ -391,6 +462,7 @@ class catch_warnings(object):
         self._module.filters = self._filters
         self._module._filters_mutated()
         self._module.showwarning = self._showwarning
+        self._module._showwarnmsg = self._showwarnmsg
 
 
 # filters contains a sequence of filter 5-tuples
diff --git a/Lib/wave.py b/Lib/wave.py
index 8a101e320b..f71f7e5bf9 100644
--- a/Lib/wave.py
+++ b/Lib/wave.py
@@ -73,7 +73,7 @@ is destroyed.
 
 import builtins
 
-__all__ = ["open", "openfp", "Error"]
+__all__ = ["open", "openfp", "Error", "Wave_read", "Wave_write"]
 
 class Error(Exception):
     pass
diff --git a/Lib/wsgiref/simple_server.py b/Lib/wsgiref/simple_server.py
index 7fddbe822c..da74d7b47a 100644
--- a/Lib/wsgiref/simple_server.py
+++ b/Lib/wsgiref/simple_server.py
@@ -163,10 +163,9 @@ def make_server(
 
 
 if __name__ == '__main__':
-    httpd = make_server('', 8000, demo_app)
-    sa = httpd.socket.getsockname()
-    print("Serving HTTP on", sa[0], "port", sa[1], "...")
-    import webbrowser
-    webbrowser.open('http://localhost:8000/xyz?abc')
-    httpd.handle_request()  # serve one request, then exit
-    httpd.server_close()
+    with make_server('', 8000, demo_app) as httpd:
+        sa = httpd.socket.getsockname()
+        print("Serving HTTP on", sa[0], "port", sa[1], "...")
+        import webbrowser
+        webbrowser.open('http://localhost:8000/xyz?abc')
+        httpd.handle_request()  # serve one request, then exit
diff --git a/Lib/xml/etree/ElementTree.py b/Lib/xml/etree/ElementTree.py
index 6d1b0ab864..67b7f2ba70 100644
--- a/Lib/xml/etree/ElementTree.py
+++ b/Lib/xml/etree/ElementTree.py
@@ -85,7 +85,7 @@ __all__ = [
     "TreeBuilder",
     "VERSION",
     "XML", "XMLID",
-    "XMLParser",
+    "XMLParser", "XMLPullParser",
     "register_namespace",
     ]
 
@@ -95,6 +95,7 @@ import sys
 import re
 import warnings
 import io
+import collections
 import contextlib
 
 from . import ElementPath
@@ -1200,16 +1201,37 @@ def iterparse(source, events=None, parser=None):
     Returns an iterator providing (event, elem) pairs.
 
     """
+    # Use the internal, undocumented _parser argument for now; When the
+    # parser argument of iterparse is removed, this can be killed.
+    pullparser = XMLPullParser(events=events, _parser=parser)
+    def iterator():
+        try:
+            while True:
+                yield from pullparser.read_events()
+                # load event buffer
+                data = source.read(16 * 1024)
+                if not data:
+                    break
+                pullparser.feed(data)
+            root = pullparser._close_and_return_root()
+            yield from pullparser.read_events()
+            it.root = root
+        finally:
+            if close_source:
+                source.close()
+
+    class IterParseIterator(collections.Iterator):
+        __next__ = iterator().__next__
+    it = IterParseIterator()
+    it.root = None
+    del iterator, IterParseIterator
+
     close_source = False
     if not hasattr(source, "read"):
         source = open(source, "rb")
         close_source = True
-    try:
-        return _IterParseIterator(source, events, parser, close_source)
-    except:
-        if close_source:
-            source.close()
-        raise
+
+    return it
 
 
 class XMLPullParser:
@@ -1219,9 +1241,7 @@ class XMLPullParser:
         # upon in user code. It will be removed in a future release.
         # See http://bugs.python.org/issue17741 for more details.
 
-        # _elementtree.c expects a list, not a deque
-        self._events_queue = []
-        self._index = 0
+        self._events_queue = collections.deque()
         self._parser = _parser or XMLParser(target=TreeBuilder())
         # wire up the parser for event reporting
         if events is None:
@@ -1259,64 +1279,14 @@ class XMLPullParser:
         retrieved from the iterator.
         """
         events = self._events_queue
-        while True:
-            index = self._index
-            try:
-                event = events[self._index]
-                # Avoid retaining references to past events
-                events[self._index] = None
-            except IndexError:
-                break
-            index += 1
-            # Compact the list in a O(1) amortized fashion
-            # As noted above, _elementree.c needs a list, not a deque
-            if index * 2 >= len(events):
-                events[:index] = []
-                self._index = 0
-            else:
-                self._index = index
+        while events:
+            event = events.popleft()
             if isinstance(event, Exception):
                 raise event
             else:
                 yield event
 
 
-class _IterParseIterator:
-
-    def __init__(self, source, events, parser, close_source=False):
-        # Use the internal, undocumented _parser argument for now; When the
-        # parser argument of iterparse is removed, this can be killed.
-        self._parser = XMLPullParser(events=events, _parser=parser)
-        self._file = source
-        self._close_file = close_source
-        self.root = self._root = None
-
-    def __next__(self):
-        try:
-            while 1:
-                for event in self._parser.read_events():
-                    return event
-                if self._parser._parser is None:
-                    break
-                # load event buffer
-                data = self._file.read(16 * 1024)
-                if data:
-                    self._parser.feed(data)
-                else:
-                    self._root = self._parser._close_and_return_root()
-            self.root = self._root
-        except:
-            if self._close_file:
-                self._file.close()
-            raise
-        if self._close_file:
-            self._file.close()
-        raise StopIteration
-
-    def __iter__(self):
-        return self
-
-
 def XML(text, parser=None):
     """Parse XML document from string constant.
 
diff --git a/Lib/xmlrpc/client.py b/Lib/xmlrpc/client.py
index bbf9ee63f7..581a3b92ac 100644
--- a/Lib/xmlrpc/client.py
+++ b/Lib/xmlrpc/client.py
@@ -151,7 +151,7 @@ def escape(s):
     return s.replace(">", "&gt;",)
 
 # used in User-Agent header sent
-__version__ = sys.version[:3]
+__version__ = '%d.%d' % sys.version_info[:2]
 
 # xmlrpc integer limits
 MAXINT =  2**31-1
diff --git a/Lib/xmlrpc/server.py b/Lib/xmlrpc/server.py
index 5b5bf7c405..78728f271c 100644
--- a/Lib/xmlrpc/server.py
+++ b/Lib/xmlrpc/server.py
@@ -971,16 +971,15 @@ if __name__ == '__main__':
             def getCurrentTime():
                 return datetime.datetime.now()
 
-    server = SimpleXMLRPCServer(("localhost", 8000))
-    server.register_function(pow)
-    server.register_function(lambda x,y: x+y, 'add')
-    server.register_instance(ExampleService(), allow_dotted_names=True)
-    server.register_multicall_functions()
-    print('Serving XML-RPC on localhost port 8000')
-    print('It is advisable to run this example server within a secure, closed network.')
-    try:
-        server.serve_forever()
-    except KeyboardInterrupt:
-        print("\nKeyboard interrupt received, exiting.")
-        server.server_close()
-        sys.exit(0)
+    with SimpleXMLRPCServer(("localhost", 8000)) as server:
+        server.register_function(pow)
+        server.register_function(lambda x,y: x+y, 'add')
+        server.register_instance(ExampleService(), allow_dotted_names=True)
+        server.register_multicall_functions()
+        print('Serving XML-RPC on localhost port 8000')
+        print('It is advisable to run this example server within a secure, closed network.')
+        try:
+            server.serve_forever()
+        except KeyboardInterrupt:
+            print("\nKeyboard interrupt received, exiting.")
+            sys.exit(0)
diff --git a/Lib/zipfile.py b/Lib/zipfile.py
index 56a2479fb3..27a4c713e7 100644
--- a/Lib/zipfile.py
+++ b/Lib/zipfile.py
@@ -371,7 +371,7 @@ class ZipInfo (object):
             result.append(' filemode=%r' % stat.filemode(hi))
         if lo:
             result.append(' external_attr=%#x' % lo)
-        isdir = self.filename[-1:] == '/'
+        isdir = self.is_dir()
         if not isdir or self.file_size:
             result.append(' file_size=%r' % self.file_size)
         if ((not isdir or self.compress_size) and
@@ -469,6 +469,42 @@ class ZipInfo (object):
 
             extra = extra[ln+4:]
 
+    @classmethod
+    def from_file(cls, filename, arcname=None):
+        """Construct an appropriate ZipInfo for a file on the filesystem.
+
+        filename should be the path to a file or directory on the filesystem.
+
+        arcname is the name which it will have within the archive (by default,
+        this will be the same as filename, but without a drive letter and with
+        leading path separators removed).
+        """
+        st = os.stat(filename)
+        isdir = stat.S_ISDIR(st.st_mode)
+        mtime = time.localtime(st.st_mtime)
+        date_time = mtime[0:6]
+        # Create ZipInfo instance to store file information
+        if arcname is None:
+            arcname = filename
+        arcname = os.path.normpath(os.path.splitdrive(arcname)[1])
+        while arcname[0] in (os.sep, os.altsep):
+            arcname = arcname[1:]
+        if isdir:
+            arcname += '/'
+        zinfo = cls(arcname, date_time)
+        zinfo.external_attr = (st.st_mode & 0xFFFF) << 16  # Unix attributes
+        if isdir:
+            zinfo.file_size = 0
+            zinfo.external_attr |= 0x10  # MS-DOS directory flag
+        else:
+            zinfo.file_size = st.st_size
+
+        return zinfo
+
+    def is_dir(self):
+        """Return True if this archive member is a directory."""
+        return self.filename[-1] == '/'
+
 
 class _ZipDecrypter:
     """Class to handle decryption of files stored within a ZIP archive.
@@ -651,14 +687,19 @@ def _get_decompressor(compress_type):
 
 
 class _SharedFile:
-    def __init__(self, file, pos, close, lock):
+    def __init__(self, file, pos, close, lock, writing):
         self._file = file
         self._pos = pos
         self._close = close
         self._lock = lock
+        self._writing = writing
 
     def read(self, n=-1):
         with self._lock:
+            if self._writing():
+                raise RuntimeError("Can't read from the ZIP file while there "
+                        "is an open writing handle on it. "
+                        "Close the writing handle before trying to read.")
             self._file.seek(self._pos)
             data = self._file.read(n)
             self._pos = self._file.tell()
@@ -958,6 +999,76 @@ class ZipExtFile(io.BufferedIOBase):
             super().close()
 
 
+class _ZipWriteFile(io.BufferedIOBase):
+    def __init__(self, zf, zinfo, zip64):
+        self._zinfo = zinfo
+        self._zip64 = zip64
+        self._zipfile = zf
+        self._compressor = _get_compressor(zinfo.compress_type)
+        self._file_size = 0
+        self._compress_size = 0
+        self._crc = 0
+
+    @property
+    def _fileobj(self):
+        return self._zipfile.fp
+
+    def writable(self):
+        return True
+
+    def write(self, data):
+        nbytes = len(data)
+        self._file_size += nbytes
+        self._crc = crc32(data, self._crc)
+        if self._compressor:
+            data = self._compressor.compress(data)
+            self._compress_size += len(data)
+        self._fileobj.write(data)
+        return nbytes
+
+    def close(self):
+        super().close()
+        # Flush any data from the compressor, and update header info
+        if self._compressor:
+            buf = self._compressor.flush()
+            self._compress_size += len(buf)
+            self._fileobj.write(buf)
+            self._zinfo.compress_size = self._compress_size
+        else:
+            self._zinfo.compress_size = self._file_size
+        self._zinfo.CRC = self._crc
+        self._zinfo.file_size = self._file_size
+
+        # Write updated header info
+        if self._zinfo.flag_bits & 0x08:
+            # Write CRC and file sizes after the file data
+            fmt = '<LQQ' if self._zip64 else '<LLL'
+            self._fileobj.write(struct.pack(fmt, self._zinfo.CRC,
+                self._zinfo.compress_size, self._zinfo.file_size))
+            self._zipfile.start_dir = self._fileobj.tell()
+        else:
+            if not self._zip64:
+                if self._file_size > ZIP64_LIMIT:
+                    raise RuntimeError('File size unexpectedly exceeded ZIP64 '
+                                       'limit')
+                if self._compress_size > ZIP64_LIMIT:
+                    raise RuntimeError('Compressed size unexpectedly exceeded '
+                                       'ZIP64 limit')
+            # Seek backwards and write file header (which will now include
+            # correct CRC and file sizes)
+
+            # Preserve current position in file
+            self._zipfile.start_dir = self._fileobj.tell()
+            self._fileobj.seek(self._zinfo.header_offset)
+            self._fileobj.write(self._zinfo.FileHeader(self._zip64))
+            self._fileobj.seek(self._zipfile.start_dir)
+
+        self._zipfile._writing = False
+
+        # Successfully written: Add file to our caches
+        self._zipfile.filelist.append(self._zinfo)
+        self._zipfile.NameToInfo[self._zinfo.filename] = self._zinfo
+
 class ZipFile:
     """ Class with methods to open, read, write, close, list zip files.
 
@@ -1020,6 +1131,7 @@ class ZipFile:
         self._fileRefCnt = 1
         self._lock = threading.RLock()
         self._seekable = True
+        self._writing = False
 
         try:
             if mode == 'r':
@@ -1232,30 +1344,59 @@ class ZipFile:
         with self.open(name, "r", pwd) as fp:
             return fp.read()
 
-    def open(self, name, mode="r", pwd=None):
-        """Return file-like object for 'name'."""
-        if mode not in ("r", "U", "rU"):
-            raise RuntimeError('open() requires mode "r", "U", or "rU"')
+    def open(self, name, mode="r", pwd=None, *, force_zip64=False):
+        """Return file-like object for 'name'.
+
+        name is a string for the file name within the ZIP file, or a ZipInfo
+        object.
+
+        mode should be 'r' to read a file already in the ZIP file, or 'w' to
+        write to a file newly added to the archive.
+
+        pwd is the password to decrypt files (only used for reading).
+
+        When writing, if the file size is not known in advance but may exceed
+        2 GiB, pass force_zip64 to use the ZIP64 format, which can handle large
+        files.  If the size is known in advance, it is best to pass a ZipInfo
+        instance for name, with zinfo.file_size set.
+        """
+        if mode not in {"r", "w", "U", "rU"}:
+            raise RuntimeError('open() requires mode "r", "w", "U", or "rU"')
         if 'U' in mode:
             import warnings
             warnings.warn("'U' mode is deprecated",
                           DeprecationWarning, 2)
         if pwd and not isinstance(pwd, bytes):
             raise TypeError("pwd: expected bytes, got %s" % type(pwd))
+        if pwd and (mode == "w"):
+            raise ValueError("pwd is only supported for reading files")
         if not self.fp:
             raise RuntimeError(
-                "Attempt to read ZIP archive that was already closed")
+                "Attempt to use ZIP archive that was already closed")
 
         # Make sure we have an info object
         if isinstance(name, ZipInfo):
             # 'name' is already an info object
             zinfo = name
+        elif mode == 'w':
+            zinfo = ZipInfo(name)
+            zinfo.compress_type = self.compression
         else:
             # Get info object for name
             zinfo = self.getinfo(name)
 
+        if mode == 'w':
+            return self._open_to_write(zinfo, force_zip64=force_zip64)
+
+        if self._writing:
+            raise RuntimeError("Can't read from the ZIP file while there "
+                    "is an open writing handle on it. "
+                    "Close the writing handle before trying to read.")
+
+        # Open for reading:
         self._fileRefCnt += 1
-        zef_file = _SharedFile(self.fp, zinfo.header_offset, self._fpclose, self._lock)
+        zef_file = _SharedFile(self.fp, zinfo.header_offset,
+                               self._fpclose, self._lock, lambda: self._writing)
         try:
             # Skip the file header:
             fheader = zef_file.read(sizeFileHeader)
@@ -1320,6 +1461,49 @@ class ZipFile:
             zef_file.close()
             raise
 
+    def _open_to_write(self, zinfo, force_zip64=False):
+        if force_zip64 and not self._allowZip64:
+            raise ValueError(
+                "force_zip64 is True, but allowZip64 was False when opening "
+                "the ZIP file."
+            )
+        if self._writing:
+            raise RuntimeError("Can't write to the ZIP file while there is "
+                               "another write handle open on it. "
+                               "Close the first handle before opening another.")
+
+        # Sizes and CRC are overwritten with correct data after processing the file
+        if not hasattr(zinfo, 'file_size'):
+            zinfo.file_size = 0
+        zinfo.compress_size = 0
+        zinfo.CRC = 0
+
+        zinfo.flag_bits = 0x00
+        if zinfo.compress_type == ZIP_LZMA:
+            # Compressed data includes an end-of-stream (EOS) marker
+            zinfo.flag_bits |= 0x02
+        if not self._seekable:
+            zinfo.flag_bits |= 0x08
+
+        if not zinfo.external_attr:
+            zinfo.external_attr = 0o600 << 16  # permissions: ?rw-------
+
+        # Compressed size can be larger than uncompressed size
+        zip64 = self._allowZip64 and \
+                (force_zip64 or zinfo.file_size * 1.05 > ZIP64_LIMIT)
+
+        if self._seekable:
+            self.fp.seek(self.start_dir)
+        zinfo.header_offset = self.fp.tell()
+
+        self._writecheck(zinfo)
+        self._didModify = True
+
+        self.fp.write(zinfo.FileHeader(zip64))
+
+        self._writing = True
+        return _ZipWriteFile(self, zinfo, zip64)
+
     def extract(self, member, path=None, pwd=None):
         """Extract a member from the archive to the current working directory,
            using its full name. Its file information is extracted as accurately
@@ -1389,7 +1573,7 @@ class ZipFile:
         if upperdirs and not os.path.exists(upperdirs):
             os.makedirs(upperdirs)
 
-        if member.filename[-1] == '/':
+        if member.is_dir():
             if not os.path.isdir(targetpath):
                 os.mkdir(targetpath)
             return targetpath
@@ -1429,103 +1613,41 @@ class ZipFile:
         if not self.fp:
             raise RuntimeError(
                 "Attempt to write to ZIP archive that was already closed")
+        if self._writing:
+            raise RuntimeError(
+                "Can't write to ZIP archive while an open writing handle exists"
+            )
 
-        st = os.stat(filename)
-        isdir = stat.S_ISDIR(st.st_mode)
-        mtime = time.localtime(st.st_mtime)
-        date_time = mtime[0:6]
-        # Create ZipInfo instance to store file information
-        if arcname is None:
-            arcname = filename
-        arcname = os.path.normpath(os.path.splitdrive(arcname)[1])
-        while arcname[0] in (os.sep, os.altsep):
-            arcname = arcname[1:]
-        if isdir:
-            arcname += '/'
-        zinfo = ZipInfo(arcname, date_time)
-        zinfo.external_attr = (st[0] & 0xFFFF) << 16      # Unix attributes
-        if isdir:
-            zinfo.compress_type = ZIP_STORED
-        elif compress_type is None:
-            zinfo.compress_type = self.compression
+        zinfo = ZipInfo.from_file(filename, arcname)
+
+        if zinfo.is_dir():
+            zinfo.compress_size = 0
+            zinfo.CRC = 0
         else:
-            zinfo.compress_type = compress_type
+            if compress_type is not None:
+                zinfo.compress_type = compress_type
+            else:
+                zinfo.compress_type = self.compression
 
-        zinfo.file_size = st.st_size
-        zinfo.flag_bits = 0x00
-        with self._lock:
-            if self._seekable:
-                self.fp.seek(self.start_dir)
-            zinfo.header_offset = self.fp.tell()    # Start of header bytes
-            if zinfo.compress_type == ZIP_LZMA:
+        if zinfo.is_dir():
+            with self._lock:
+                if self._seekable:
+                    self.fp.seek(self.start_dir)
+                zinfo.header_offset = self.fp.tell()  # Start of header bytes
+                if zinfo.compress_type == ZIP_LZMA:
                 # Compressed data includes an end-of-stream (EOS) marker
-                zinfo.flag_bits |= 0x02
+                    zinfo.flag_bits |= 0x02
 
-            self._writecheck(zinfo)
-            self._didModify = True
+                self._writecheck(zinfo)
+                self._didModify = True
 
-            if isdir:
-                zinfo.file_size = 0
-                zinfo.compress_size = 0
-                zinfo.CRC = 0
-                zinfo.external_attr |= 0x10  # MS-DOS directory flag
                 self.filelist.append(zinfo)
                 self.NameToInfo[zinfo.filename] = zinfo
                 self.fp.write(zinfo.FileHeader(False))
                 self.start_dir = self.fp.tell()
-                return
-
-            cmpr = _get_compressor(zinfo.compress_type)
-            if not self._seekable:
-                zinfo.flag_bits |= 0x08
-            with open(filename, "rb") as fp:
-                # Must overwrite CRC and sizes with correct data later
-                zinfo.CRC = CRC = 0
-                zinfo.compress_size = compress_size = 0
-                # Compressed size can be larger than uncompressed size
-                zip64 = self._allowZip64 and \
-                    zinfo.file_size * 1.05 > ZIP64_LIMIT
-                self.fp.write(zinfo.FileHeader(zip64))
-                file_size = 0
-                while 1:
-                    buf = fp.read(1024 * 8)
-                    if not buf:
-                        break
-                    file_size = file_size + len(buf)
-                    CRC = crc32(buf, CRC)
-                    if cmpr:
-                        buf = cmpr.compress(buf)
-                        compress_size = compress_size + len(buf)
-                    self.fp.write(buf)
-            if cmpr:
-                buf = cmpr.flush()
-                compress_size = compress_size + len(buf)
-                self.fp.write(buf)
-                zinfo.compress_size = compress_size
-            else:
-                zinfo.compress_size = file_size
-            zinfo.CRC = CRC
-            zinfo.file_size = file_size
-            if zinfo.flag_bits & 0x08:
-                # Write CRC and file sizes after the file data
-                fmt = '<LQQ' if zip64 else '<LLL'
-                self.fp.write(struct.pack(fmt, zinfo.CRC, zinfo.compress_size,
-                                          zinfo.file_size))
-                self.start_dir = self.fp.tell()
-            else:
-                if not zip64 and self._allowZip64:
-                    if file_size > ZIP64_LIMIT:
-                        raise RuntimeError('File size has increased during compressing')
-                    if compress_size > ZIP64_LIMIT:
-                        raise RuntimeError('Compressed size larger than uncompressed size')
-                # Seek backwards and write file header (which will now include
-                # correct CRC and file sizes)
-                self.start_dir = self.fp.tell() # Preserve current position in file
-                self.fp.seek(zinfo.header_offset)
-                self.fp.write(zinfo.FileHeader(zip64))
-                self.fp.seek(self.start_dir)
-            self.filelist.append(zinfo)
-            self.NameToInfo[zinfo.filename] = zinfo
+        else:
+            with open(filename, "rb") as src, self.open(zinfo, 'w') as dest:
+                shutil.copyfileobj(src, dest, 1024*8)
 
     def writestr(self, zinfo_or_arcname, data, compress_type=None):
         """Write a file into the archive.  The contents is 'data', which
@@ -1550,45 +1672,18 @@ class ZipFile:
         if not self.fp:
             raise RuntimeError(
                 "Attempt to write to ZIP archive that was already closed")
+        if self._writing:
+            raise RuntimeError(
+                "Can't write to ZIP archive while an open writing handle exists."
+            )
+
+        if compress_type is not None:
+            zinfo.compress_type = compress_type
 
         zinfo.file_size = len(data)            # Uncompressed size
         with self._lock:
-            if self._seekable:
-                self.fp.seek(self.start_dir)
-            zinfo.header_offset = self.fp.tell()    # Start of header data
-            if compress_type is not None:
-                zinfo.compress_type = compress_type
-            zinfo.header_offset = self.fp.tell()    # Start of header data
-            if compress_type is not None:
-                zinfo.compress_type = compress_type
-            if zinfo.compress_type == ZIP_LZMA:
-                # Compressed data includes an end-of-stream (EOS) marker
-                zinfo.flag_bits |= 0x02
-
-            self._writecheck(zinfo)
-            self._didModify = True
-            zinfo.CRC = crc32(data)       # CRC-32 checksum
-            co = _get_compressor(zinfo.compress_type)
-            if co:
-                data = co.compress(data) + co.flush()
-                zinfo.compress_size = len(data)    # Compressed size
-            else:
-                zinfo.compress_size = zinfo.file_size
-            zip64 = zinfo.file_size > ZIP64_LIMIT or \
-                zinfo.compress_size > ZIP64_LIMIT
-            if zip64 and not self._allowZip64:
-                raise LargeZipFile("Filesize would require ZIP64 extensions")
-            self.fp.write(zinfo.FileHeader(zip64))
-            self.fp.write(data)
-            if zinfo.flag_bits & 0x08:
-                # Write CRC and file sizes after the file data
-                fmt = '<LQQ' if zip64 else '<LLL'
-                self.fp.write(struct.pack(fmt, zinfo.CRC, zinfo.compress_size,
-                                          zinfo.file_size))
-            self.fp.flush()
-            self.start_dir = self.fp.tell()
-            self.filelist.append(zinfo)
-            self.NameToInfo[zinfo.filename] = zinfo
+            with self.open(zinfo, mode='w') as dest:
+                dest.write(data)
 
     def __del__(self):
         """Call the "close()" method in case the user forgot."""
@@ -1600,6 +1695,11 @@ class ZipFile:
         if self.fp is None:
             return
 
+        if self._writing:
+            raise RuntimeError("Can't close the ZIP file while there is "
+                               "an open writing handle on it. "
+                               "Close the writing handle before closing the zip.")
+
         try:
             if self.mode in ('w', 'x', 'a') and self._didModify: # write ending records
                 with self._lock: