Run black -l 79 against all source files

This is a straight reformat run using black as is, with no edits
applied at all.

The black run will format code consistently, however in
some cases that are prevalent in SQLAlchemy code it produces
too-long lines.   The too-long lines will be resolved in the
following commit that will resolve all remaining flake8 issues
including shadowed builtins, long lines, import order, unused
imports, duplicate imports, and docstring issues.

Change-Id: I7eda77fed3d8e73df84b3651fd6cfcfe858d4dc9

1 files changed, 466 insertions, 334 deletions

diff --git a/lib/sqlalchemy/sql/elements.py b/lib/sqlalchemy/sql/elements.py
index de3b7992a..e857f2da8 100644
--- a/lib/sqlalchemy/sql/elements.py
+++ b/lib/sqlalchemy/sql/elements.py
@@ -51,9 +51,8 @@ def collate(expression, collation):
 
     expr = _literal_as_binds(expression)
     return BinaryExpression(
-        expr,
-        CollationClause(collation),
-        operators.collate, type_=expr.type)
+        expr, CollationClause(collation), operators.collate, type_=expr.type
+    )
 
 
 def between(expr, lower_bound, upper_bound, symmetric=False):
@@ -130,8 +129,6 @@ def literal(value, type_=None):
     return BindParameter(None, value, type_=type_, unique=True)
 
 
-
-
 def outparam(key, type_=None):
     """Create an 'OUT' parameter for usage in functions (stored procedures),
     for databases which support them.
@@ -142,8 +139,7 @@ def outparam(key, type_=None):
     attribute, which returns a dictionary containing the values.
 
     """
-    return BindParameter(
-        key, None, type_=type_, unique=False, isoutparam=True)
+    return BindParameter(key, None, type_=type_, unique=False, isoutparam=True)
 
 
 def not_(clause):
@@ -163,7 +159,8 @@ class ClauseElement(Visitable):
     expression.
 
     """
-    __visit_name__ = 'clause'
+
+    __visit_name__ = "clause"
 
     _annotations = {}
     supports_execution = False
@@ -230,7 +227,7 @@ class ClauseElement(Visitable):
 
     def __getstate__(self):
         d = self.__dict__.copy()
-        d.pop('_is_clone_of', None)
+        d.pop("_is_clone_of", None)
         return d
 
     def _annotate(self, values):
@@ -300,7 +297,8 @@ class ClauseElement(Visitable):
             kwargs.update(optionaldict[0])
         elif len(optionaldict) > 1:
             raise exc.ArgumentError(
-                "params() takes zero or one positional dictionary argument")
+                "params() takes zero or one positional dictionary argument"
+            )
 
         def visit_bindparam(bind):
             if bind.key in kwargs:
@@ -308,7 +306,8 @@ class ClauseElement(Visitable):
                 bind.required = False
             if unique:
                 bind._convert_to_unique()
-        return cloned_traverse(self, {}, {'bindparam': visit_bindparam})
+
+        return cloned_traverse(self, {}, {"bindparam": visit_bindparam})
 
     def compare(self, other, **kw):
         r"""Compare this ClauseElement to the given ClauseElement.
@@ -451,7 +450,7 @@ class ClauseElement(Visitable):
         if util.py3k:
             return str(self.compile())
         else:
-            return unicode(self.compile()).encode('ascii', 'backslashreplace')
+            return unicode(self.compile()).encode("ascii", "backslashreplace")
 
     def __and__(self, other):
         """'and' at the ClauseElement level.
@@ -472,7 +471,7 @@ class ClauseElement(Visitable):
         return or_(self, other)
 
     def __invert__(self):
-        if hasattr(self, 'negation_clause'):
+        if hasattr(self, "negation_clause"):
             return self.negation_clause
         else:
             return self._negate()
@@ -481,7 +480,8 @@ class ClauseElement(Visitable):
         return UnaryExpression(
             self.self_group(against=operators.inv),
             operator=operators.inv,
-            negate=None)
+            negate=None,
+        )
 
     def __bool__(self):
         raise TypeError("Boolean value of this clause is not defined")
@@ -493,8 +493,12 @@ class ClauseElement(Visitable):
         if friendly is None:
             return object.__repr__(self)
         else:
-            return '<%s.%s at 0x%x; %s>' % (
-                self.__module__, self.__class__.__name__, id(self), friendly)
+            return "<%s.%s at 0x%x; %s>" % (
+                self.__module__,
+                self.__class__.__name__,
+                id(self),
+                friendly,
+            )
 
 
 class ColumnElement(operators.ColumnOperators, ClauseElement):
@@ -571,7 +575,7 @@ class ColumnElement(operators.ColumnOperators, ClauseElement):
 
     """
 
-    __visit_name__ = 'column_element'
+    __visit_name__ = "column_element"
     primary_key = False
     foreign_keys = []
 
@@ -646,11 +650,12 @@ class ColumnElement(operators.ColumnOperators, ClauseElement):
     _alt_names = ()
 
     def self_group(self, against=None):
-        if (against in (operators.and_, operators.or_, operators._asbool) and
-                self.type._type_affinity
-                is type_api.BOOLEANTYPE._type_affinity):
+        if (
+            against in (operators.and_, operators.or_, operators._asbool)
+            and self.type._type_affinity is type_api.BOOLEANTYPE._type_affinity
+        ):
             return AsBoolean(self, operators.istrue, operators.isfalse)
-        elif (against in (operators.any_op, operators.all_op)):
+        elif against in (operators.any_op, operators.all_op):
             return Grouping(self)
         else:
             return self
@@ -675,7 +680,8 @@ class ColumnElement(operators.ColumnOperators, ClauseElement):
         except AttributeError:
             raise TypeError(
                 "Object %r associated with '.type' attribute "
-                "is not a TypeEngine class or object" % self.type)
+                "is not a TypeEngine class or object" % self.type
+            )
         else:
             return comparator_factory(self)
 
@@ -684,10 +690,8 @@ class ColumnElement(operators.ColumnOperators, ClauseElement):
             return getattr(self.comparator, key)
         except AttributeError:
             raise AttributeError(
-                'Neither %r object nor %r object has an attribute %r' % (
-                    type(self).__name__,
-                    type(self.comparator).__name__,
-                    key)
+                "Neither %r object nor %r object has an attribute %r"
+                % (type(self).__name__, type(self.comparator).__name__, key)
             )
 
     def operate(self, op, *other, **kwargs):
@@ -697,10 +701,14 @@ class ColumnElement(operators.ColumnOperators, ClauseElement):
         return op(other, self.comparator, **kwargs)
 
     def _bind_param(self, operator, obj, type_=None):
-        return BindParameter(None, obj,
-                             _compared_to_operator=operator,
-                             type_=type_,
-                             _compared_to_type=self.type, unique=True)
+        return BindParameter(
+            None,
+            obj,
+            _compared_to_operator=operator,
+            type_=type_,
+            _compared_to_type=self.type,
+            unique=True,
+        )
 
     @property
     def expression(self):
@@ -713,17 +721,18 @@ class ColumnElement(operators.ColumnOperators, ClauseElement):
 
     @property
     def _select_iterable(self):
-        return (self, )
+        return (self,)
 
     @util.memoized_property
     def base_columns(self):
-        return util.column_set(c for c in self.proxy_set
-                               if not hasattr(c, '_proxies'))
+        return util.column_set(
+            c for c in self.proxy_set if not hasattr(c, "_proxies")
+        )
 
     @util.memoized_property
     def proxy_set(self):
         s = util.column_set([self])
-        if hasattr(self, '_proxies'):
+        if hasattr(self, "_proxies"):
             for c in self._proxies:
                 s.update(c.proxy_set)
         return s
@@ -738,11 +747,15 @@ class ColumnElement(operators.ColumnOperators, ClauseElement):
         """Return True if the given column element compares to this one
         when targeting within a result row."""
 
-        return hasattr(other, 'name') and hasattr(self, 'name') and \
-            other.name == self.name
+        return (
+            hasattr(other, "name")
+            and hasattr(self, "name")
+            and other.name == self.name
+        )
 
     def _make_proxy(
-            self, selectable, name=None, name_is_truncatable=False, **kw):
+        self, selectable, name=None, name_is_truncatable=False, **kw
+    ):
         """Create a new :class:`.ColumnElement` representing this
         :class:`.ColumnElement` as it appears in the select list of a
         descending selectable.
@@ -762,13 +775,12 @@ class ColumnElement(operators.ColumnOperators, ClauseElement):
             key = name
         co = ColumnClause(
             _as_truncated(name) if name_is_truncatable else name,
-            type_=getattr(self, 'type', None),
-            _selectable=selectable
+            type_=getattr(self, "type", None),
+            _selectable=selectable,
         )
         co._proxies = [self]
         if selectable._is_clone_of is not None:
-            co._is_clone_of = \
-                selectable._is_clone_of.columns.get(key)
+            co._is_clone_of = selectable._is_clone_of.columns.get(key)
         selectable._columns[key] = co
         return co
 
@@ -788,7 +800,7 @@ class ColumnElement(operators.ColumnOperators, ClauseElement):
           this one via foreign key or other criterion.
 
         """
-        to_compare = (other, )
+        to_compare = (other,)
         if equivalents and other in equivalents:
             to_compare = equivalents[other].union(to_compare)
 
@@ -838,7 +850,7 @@ class ColumnElement(operators.ColumnOperators, ClauseElement):
             self = self._is_clone_of
 
         return _anonymous_label(
-            '%%(%d %s)s' % (id(self), getattr(self, 'name', 'anon'))
+            "%%(%d %s)s" % (id(self), getattr(self, "name", "anon"))
         )
 
 
@@ -862,18 +874,25 @@ class BindParameter(ColumnElement):
 
     """
 
-    __visit_name__ = 'bindparam'
+    __visit_name__ = "bindparam"
 
     _is_crud = False
     _expanding_in_types = ()
 
-    def __init__(self, key, value=NO_ARG, type_=None,
-                 unique=False, required=NO_ARG,
-                 quote=None, callable_=None,
-                 expanding=False,
-                 isoutparam=False,
-                 _compared_to_operator=None,
-                 _compared_to_type=None):
+    def __init__(
+        self,
+        key,
+        value=NO_ARG,
+        type_=None,
+        unique=False,
+        required=NO_ARG,
+        quote=None,
+        callable_=None,
+        expanding=False,
+        isoutparam=False,
+        _compared_to_operator=None,
+        _compared_to_type=None,
+    ):
         r"""Produce a "bound expression".
 
         The return value is an instance of :class:`.BindParameter`; this
@@ -1093,7 +1112,7 @@ class BindParameter(ColumnElement):
             type_ = key.type
             key = key.key
         if required is NO_ARG:
-            required = (value is NO_ARG and callable_ is None)
+            required = value is NO_ARG and callable_ is None
         if value is NO_ARG:
             value = None
 
@@ -1101,11 +1120,11 @@ class BindParameter(ColumnElement):
             key = quoted_name(key, quote)
 
         if unique:
-            self.key = _anonymous_label('%%(%d %s)s' % (id(self), key
-                                                        or 'param'))
+            self.key = _anonymous_label(
+                "%%(%d %s)s" % (id(self), key or "param")
+            )
         else:
-            self.key = key or _anonymous_label('%%(%d param)s'
-                                               % id(self))
+            self.key = key or _anonymous_label("%%(%d param)s" % id(self))
 
         # identifying key that won't change across
         # clones, used to identify the bind's logical
@@ -1114,7 +1133,7 @@ class BindParameter(ColumnElement):
 
         # key that was passed in the first place, used to
         # generate new keys
-        self._orig_key = key or 'param'
+        self._orig_key = key or "param"
 
         self.unique = unique
         self.value = value
@@ -1125,9 +1144,9 @@ class BindParameter(ColumnElement):
 
         if type_ is None:
             if _compared_to_type is not None:
-                self.type = \
-                    _compared_to_type.coerce_compared_value(
-                        _compared_to_operator, value)
+                self.type = _compared_to_type.coerce_compared_value(
+                    _compared_to_operator, value
+                )
             else:
                 self.type = type_api._resolve_value_to_type(value)
         elif isinstance(type_, type):
@@ -1174,24 +1193,28 @@ class BindParameter(ColumnElement):
     def _clone(self):
         c = ClauseElement._clone(self)
         if self.unique:
-            c.key = _anonymous_label('%%(%d %s)s' % (id(c), c._orig_key
-                                                     or 'param'))
+            c.key = _anonymous_label(
+                "%%(%d %s)s" % (id(c), c._orig_key or "param")
+            )
         return c
 
     def _convert_to_unique(self):
         if not self.unique:
             self.unique = True
             self.key = _anonymous_label(
-                '%%(%d %s)s' % (id(self), self._orig_key or 'param'))
+                "%%(%d %s)s" % (id(self), self._orig_key or "param")
+            )
 
     def compare(self, other, **kw):
         """Compare this :class:`BindParameter` to the given
         clause."""
 
-        return isinstance(other, BindParameter) \
-            and self.type._compare_type_affinity(other.type) \
-            and self.value == other.value \
+        return (
+            isinstance(other, BindParameter)
+            and self.type._compare_type_affinity(other.type)
+            and self.value == other.value
             and self.callable == other.callable
+        )
 
     def __getstate__(self):
         """execute a deferred value for serialization purposes."""
@@ -1200,13 +1223,16 @@ class BindParameter(ColumnElement):
         v = self.value
         if self.callable:
             v = self.callable()
-            d['callable'] = None
-        d['value'] = v
+            d["callable"] = None
+        d["value"] = v
         return d
 
     def __repr__(self):
-        return 'BindParameter(%r, %r, type_=%r)' % (self.key,
-                                                    self.value, self.type)
+        return "BindParameter(%r, %r, type_=%r)" % (
+            self.key,
+            self.value,
+            self.type,
+        )
 
 
 class TypeClause(ClauseElement):
@@ -1216,7 +1242,7 @@ class TypeClause(ClauseElement):
 
     """
 
-    __visit_name__ = 'typeclause'
+    __visit_name__ = "typeclause"
 
     def __init__(self, type):
         self.type = type
@@ -1242,12 +1268,12 @@ class TextClause(Executable, ClauseElement):
 
     """
 
-    __visit_name__ = 'textclause'
+    __visit_name__ = "textclause"
 
-    _bind_params_regex = re.compile(r'(?<![:\w\x5c]):(\w+)(?!:)', re.UNICODE)
-    _execution_options = \
-        Executable._execution_options.union(
-            {'autocommit': PARSE_AUTOCOMMIT})
+    _bind_params_regex = re.compile(r"(?<![:\w\x5c]):(\w+)(?!:)", re.UNICODE)
+    _execution_options = Executable._execution_options.union(
+        {"autocommit": PARSE_AUTOCOMMIT}
+    )
     _is_implicitly_boolean = False
 
     @property
@@ -1268,24 +1294,22 @@ class TextClause(Executable, ClauseElement):
 
     _allow_label_resolve = False
 
-    def __init__(
-            self,
-            text,
-            bind=None):
+    def __init__(self, text, bind=None):
         self._bind = bind
         self._bindparams = {}
 
         def repl(m):
             self._bindparams[m.group(1)] = BindParameter(m.group(1))
-            return ':%s' % m.group(1)
+            return ":%s" % m.group(1)
 
         # scan the string and search for bind parameter names, add them
         # to the list of bindparams
         self.text = self._bind_params_regex.sub(repl, text)
 
     @classmethod
-    def _create_text(self, text, bind=None, bindparams=None,
-                     typemap=None, autocommit=None):
+    def _create_text(
+        self, text, bind=None, bindparams=None, typemap=None, autocommit=None
+    ):
         r"""Construct a new :class:`.TextClause` clause, representing
         a textual SQL string directly.
 
@@ -1428,8 +1452,10 @@ class TextClause(Executable, ClauseElement):
         if typemap:
             stmt = stmt.columns(**typemap)
         if autocommit is not None:
-            util.warn_deprecated('autocommit on text() is deprecated.  '
-                                 'Use .execution_options(autocommit=True)')
+            util.warn_deprecated(
+                "autocommit on text() is deprecated.  "
+                "Use .execution_options(autocommit=True)"
+            )
             stmt = stmt.execution_options(autocommit=autocommit)
 
         return stmt
@@ -1513,7 +1539,8 @@ class TextClause(Executable, ClauseElement):
             except KeyError:
                 raise exc.ArgumentError(
                     "This text() construct doesn't define a "
-                    "bound parameter named %r" % bind.key)
+                    "bound parameter named %r" % bind.key
+                )
             else:
                 new_params[existing.key] = bind
 
@@ -1523,11 +1550,12 @@ class TextClause(Executable, ClauseElement):
             except KeyError:
                 raise exc.ArgumentError(
                     "This text() construct doesn't define a "
-                    "bound parameter named %r" % key)
+                    "bound parameter named %r" % key
+                )
             else:
                 new_params[key] = existing._with_value(value)
 
-    @util.dependencies('sqlalchemy.sql.selectable')
+    @util.dependencies("sqlalchemy.sql.selectable")
     def columns(self, selectable, *cols, **types):
         """Turn this :class:`.TextClause` object into a :class:`.TextAsFrom`
         object that can be embedded into another statement.
@@ -1629,12 +1657,14 @@ class TextClause(Executable, ClauseElement):
             for col in cols
         ]
         keyed_input_cols = [
-            ColumnClause(key, type_) for key, type_ in types.items()]
+            ColumnClause(key, type_) for key, type_ in types.items()
+        ]
 
         return selectable.TextAsFrom(
             self,
             positional_input_cols + keyed_input_cols,
-            positional=bool(positional_input_cols) and not keyed_input_cols)
+            positional=bool(positional_input_cols) and not keyed_input_cols,
+        )
 
     @property
     def type(self):
@@ -1651,8 +1681,9 @@ class TextClause(Executable, ClauseElement):
             return self
 
     def _copy_internals(self, clone=_clone, **kw):
-        self._bindparams = dict((b.key, clone(b, **kw))
-                                for b in self._bindparams.values())
+        self._bindparams = dict(
+            (b.key, clone(b, **kw)) for b in self._bindparams.values()
+        )
 
     def get_children(self, **kwargs):
         return list(self._bindparams.values())
@@ -1669,7 +1700,7 @@ class Null(ColumnElement):
 
     """
 
-    __visit_name__ = 'null'
+    __visit_name__ = "null"
 
     @util.memoized_property
     def type(self):
@@ -1693,7 +1724,7 @@ class False_(ColumnElement):
 
     """
 
-    __visit_name__ = 'false'
+    __visit_name__ = "false"
 
     @util.memoized_property
     def type(self):
@@ -1752,7 +1783,7 @@ class True_(ColumnElement):
 
     """
 
-    __visit_name__ = 'true'
+    __visit_name__ = "true"
 
     @util.memoized_property
     def type(self):
@@ -1816,23 +1847,23 @@ class ClauseList(ClauseElement):
     By default, is comma-separated, such as a column listing.
 
     """
-    __visit_name__ = 'clauselist'
+
+    __visit_name__ = "clauselist"
 
     def __init__(self, *clauses, **kwargs):
-        self.operator = kwargs.pop('operator', operators.comma_op)
-        self.group = kwargs.pop('group', True)
-        self.group_contents = kwargs.pop('group_contents', True)
+        self.operator = kwargs.pop("operator", operators.comma_op)
+        self.group = kwargs.pop("group", True)
+        self.group_contents = kwargs.pop("group_contents", True)
         text_converter = kwargs.pop(
-            '_literal_as_text',
-            _expression_literal_as_text)
+            "_literal_as_text", _expression_literal_as_text
+        )
         if self.group_contents:
             self.clauses = [
                 text_converter(clause).self_group(against=self.operator)
-                for clause in clauses]
+                for clause in clauses
+            ]
         else:
-            self.clauses = [
-                text_converter(clause)
-                for clause in clauses]
+            self.clauses = [text_converter(clause) for clause in clauses]
         self._is_implicitly_boolean = operators.is_boolean(self.operator)
 
     def __iter__(self):
@@ -1847,8 +1878,9 @@ class ClauseList(ClauseElement):
 
     def append(self, clause):
         if self.group_contents:
-            self.clauses.append(_literal_as_text(clause).
-                                self_group(against=self.operator))
+            self.clauses.append(
+                _literal_as_text(clause).self_group(against=self.operator)
+            )
         else:
             self.clauses.append(_literal_as_text(clause))
 
@@ -1875,14 +1907,18 @@ class ClauseList(ClauseElement):
         """
         if not isinstance(other, ClauseList) and len(self.clauses) == 1:
             return self.clauses[0].compare(other, **kw)
-        elif isinstance(other, ClauseList) and \
-                len(self.clauses) == len(other.clauses) and \
-                self.operator is other.operator:
+        elif (
+            isinstance(other, ClauseList)
+            and len(self.clauses) == len(other.clauses)
+            and self.operator is other.operator
+        ):
 
             if self.operator in (operators.and_, operators.or_):
                 completed = set()
                 for clause in self.clauses:
-                    for other_clause in set(other.clauses).difference(completed):
+                    for other_clause in set(other.clauses).difference(
+                        completed
+                    ):
                         if clause.compare(other_clause, **kw):
                             completed.add(other_clause)
                             break
@@ -1898,11 +1934,12 @@ class ClauseList(ClauseElement):
 
 
 class BooleanClauseList(ClauseList, ColumnElement):
-    __visit_name__ = 'clauselist'
+    __visit_name__ = "clauselist"
 
     def __init__(self, *arg, **kw):
         raise NotImplementedError(
-            "BooleanClauseList has a private constructor")
+            "BooleanClauseList has a private constructor"
+        )
 
     @classmethod
     def _construct(cls, operator, continue_on, skip_on, *clauses, **kw):
@@ -1910,8 +1947,7 @@ class BooleanClauseList(ClauseList, ColumnElement):
 
         clauses = [
             _expression_literal_as_text(clause)
-            for clause in
-            util.coerce_generator_arg(clauses)
+            for clause in util.coerce_generator_arg(clauses)
         ]
         for clause in clauses:
 
@@ -1927,8 +1963,9 @@ class BooleanClauseList(ClauseList, ColumnElement):
         elif not convert_clauses and clauses:
             return clauses[0].self_group(against=operators._asbool)
 
-        convert_clauses = [c.self_group(against=operator)
-                           for c in convert_clauses]
+        convert_clauses = [
+            c.self_group(against=operator) for c in convert_clauses
+        ]
 
         self = cls.__new__(cls)
         self.clauses = convert_clauses
@@ -2014,7 +2051,7 @@ class BooleanClauseList(ClauseList, ColumnElement):
 
     @property
     def _select_iterable(self):
-        return (self, )
+        return (self,)
 
     def self_group(self, against=None):
         if not self.clauses:
@@ -2056,22 +2093,31 @@ class Tuple(ClauseList, ColumnElement):
 
         clauses = [_literal_as_binds(c) for c in clauses]
         self._type_tuple = [arg.type for arg in clauses]
-        self.type = kw.pop('type_', self._type_tuple[0]
-                           if self._type_tuple else type_api.NULLTYPE)
+        self.type = kw.pop(
+            "type_",
+            self._type_tuple[0] if self._type_tuple else type_api.NULLTYPE,
+        )
 
         super(Tuple, self).__init__(*clauses, **kw)
 
     @property
     def _select_iterable(self):
-        return (self, )
+        return (self,)
 
     def _bind_param(self, operator, obj, type_=None):
-        return Tuple(*[
-            BindParameter(None, o, _compared_to_operator=operator,
-                          _compared_to_type=compared_to_type, unique=True,
-                          type_=type_)
-            for o, compared_to_type in zip(obj, self._type_tuple)
-        ]).self_group()
+        return Tuple(
+            *[
+                BindParameter(
+                    None,
+                    o,
+                    _compared_to_operator=operator,
+                    _compared_to_type=compared_to_type,
+                    unique=True,
+                    type_=type_,
+                )
+                for o, compared_to_type in zip(obj, self._type_tuple)
+            ]
+        ).self_group()
 
 
 class Case(ColumnElement):
@@ -2101,7 +2147,7 @@ class Case(ColumnElement):
 
     """
 
-    __visit_name__ = 'case'
+    __visit_name__ = "case"
 
     def __init__(self, whens, value=None, else_=None):
         r"""Produce a ``CASE`` expression.
@@ -2231,13 +2277,13 @@ class Case(ColumnElement):
 
         if value is not None:
             whenlist = [
-                (_literal_as_binds(c).self_group(),
-                 _literal_as_binds(r)) for (c, r) in whens
+                (_literal_as_binds(c).self_group(), _literal_as_binds(r))
+                for (c, r) in whens
             ]
         else:
             whenlist = [
-                (_no_literals(c).self_group(),
-                 _literal_as_binds(r)) for (c, r) in whens
+                (_no_literals(c).self_group(), _literal_as_binds(r))
+                for (c, r) in whens
             ]
 
         if whenlist:
@@ -2260,8 +2306,7 @@ class Case(ColumnElement):
     def _copy_internals(self, clone=_clone, **kw):
         if self.value is not None:
             self.value = clone(self.value, **kw)
-        self.whens = [(clone(x, **kw), clone(y, **kw))
-                      for x, y in self.whens]
+        self.whens = [(clone(x, **kw), clone(y, **kw)) for x, y in self.whens]
         if self.else_ is not None:
             self.else_ = clone(self.else_, **kw)
 
@@ -2276,8 +2321,9 @@ class Case(ColumnElement):
 
     @property
     def _from_objects(self):
-        return list(itertools.chain(*[x._from_objects for x in
-                                      self.get_children()]))
+        return list(
+            itertools.chain(*[x._from_objects for x in self.get_children()])
+        )
 
 
 def literal_column(text, type_=None):
@@ -2333,7 +2379,7 @@ class Cast(ColumnElement):
 
     """
 
-    __visit_name__ = 'cast'
+    __visit_name__ = "cast"
 
     def __init__(self, expression, type_):
         """Produce a ``CAST`` expression.
@@ -2416,7 +2462,7 @@ class TypeCoerce(ColumnElement):
 
     """
 
-    __visit_name__ = 'type_coerce'
+    __visit_name__ = "type_coerce"
 
     def __init__(self, expression, type_):
         """Associate a SQL expression with a particular type, without rendering
@@ -2484,10 +2530,10 @@ class TypeCoerce(ColumnElement):
 
     def _copy_internals(self, clone=_clone, **kw):
         self.clause = clone(self.clause, **kw)
-        self.__dict__.pop('typed_expression', None)
+        self.__dict__.pop("typed_expression", None)
 
     def get_children(self, **kwargs):
-        return self.clause,
+        return (self.clause,)
 
     @property
     def _from_objects(self):
@@ -2506,7 +2552,7 @@ class TypeCoerce(ColumnElement):
 class Extract(ColumnElement):
     """Represent a SQL EXTRACT clause, ``extract(field FROM expr)``."""
 
-    __visit_name__ = 'extract'
+    __visit_name__ = "extract"
 
     def __init__(self, field, expr, **kwargs):
         """Return a :class:`.Extract` construct.
@@ -2524,7 +2570,7 @@ class Extract(ColumnElement):
         self.expr = clone(self.expr, **kw)
 
     def get_children(self, **kwargs):
-        return self.expr,
+        return (self.expr,)
 
     @property
     def _from_objects(self):
@@ -2543,7 +2589,8 @@ class _label_reference(ColumnElement):
     within an OVER clause.
 
     """
-    __visit_name__ = 'label_reference'
+
+    __visit_name__ = "label_reference"
 
     def __init__(self, element):
         self.element = element
@@ -2557,7 +2604,7 @@ class _label_reference(ColumnElement):
 
 
 class _textual_label_reference(ColumnElement):
-    __visit_name__ = 'textual_label_reference'
+    __visit_name__ = "textual_label_reference"
 
     def __init__(self, element):
         self.element = element
@@ -2580,14 +2627,23 @@ class UnaryExpression(ColumnElement):
     :func:`.nullsfirst` and :func:`.nullslast`.
 
     """
-    __visit_name__ = 'unary'
 
-    def __init__(self, element, operator=None, modifier=None,
-                 type_=None, negate=None, wraps_column_expression=False):
+    __visit_name__ = "unary"
+
+    def __init__(
+        self,
+        element,
+        operator=None,
+        modifier=None,
+        type_=None,
+        negate=None,
+        wraps_column_expression=False,
+    ):
         self.operator = operator
         self.modifier = modifier
         self.element = element.self_group(
-            against=self.operator or self.modifier)
+            against=self.operator or self.modifier
+        )
         self.type = type_api.to_instance(type_)
         self.negate = negate
         self.wraps_column_expression = wraps_column_expression
@@ -2633,7 +2689,8 @@ class UnaryExpression(ColumnElement):
         return UnaryExpression(
             _literal_as_label_reference(column),
             modifier=operators.nullsfirst_op,
-            wraps_column_expression=False)
+            wraps_column_expression=False,
+        )
 
     @classmethod
     def _create_nullslast(cls, column):
@@ -2675,7 +2732,8 @@ class UnaryExpression(ColumnElement):
         return UnaryExpression(
             _literal_as_label_reference(column),
             modifier=operators.nullslast_op,
-            wraps_column_expression=False)
+            wraps_column_expression=False,
+        )
 
     @classmethod
     def _create_desc(cls, column):
@@ -2715,7 +2773,8 @@ class UnaryExpression(ColumnElement):
         return UnaryExpression(
             _literal_as_label_reference(column),
             modifier=operators.desc_op,
-            wraps_column_expression=False)
+            wraps_column_expression=False,
+        )
 
     @classmethod
     def _create_asc(cls, column):
@@ -2754,7 +2813,8 @@ class UnaryExpression(ColumnElement):
         return UnaryExpression(
             _literal_as_label_reference(column),
             modifier=operators.asc_op,
-            wraps_column_expression=False)
+            wraps_column_expression=False,
+        )
 
     @classmethod
     def _create_distinct(cls, expr):
@@ -2794,8 +2854,11 @@ class UnaryExpression(ColumnElement):
         """
         expr = _literal_as_binds(expr)
         return UnaryExpression(
-            expr, operator=operators.distinct_op,
-            type_=expr.type, wraps_column_expression=False)
+            expr,
+            operator=operators.distinct_op,
+            type_=expr.type,
+            wraps_column_expression=False,
+        )
 
     @property
     def _order_by_label_element(self):
@@ -2812,17 +2875,17 @@ class UnaryExpression(ColumnElement):
         self.element = clone(self.element, **kw)
 
     def get_children(self, **kwargs):
-        return self.element,
+        return (self.element,)
 
     def compare(self, other, **kw):
         """Compare this :class:`UnaryExpression` against the given
         :class:`.ClauseElement`."""
 
         return (
-            isinstance(other, UnaryExpression) and
-            self.operator == other.operator and
-            self.modifier == other.modifier and
-            self.element.compare(other.element, **kw)
+            isinstance(other, UnaryExpression)
+            and self.operator == other.operator
+            and self.modifier == other.modifier
+            and self.element.compare(other.element, **kw)
         )
 
     def _negate(self):
@@ -2833,14 +2896,16 @@ class UnaryExpression(ColumnElement):
                 negate=self.operator,
                 modifier=self.modifier,
                 type_=self.type,
-                wraps_column_expression=self.wraps_column_expression)
+                wraps_column_expression=self.wraps_column_expression,
+            )
         elif self.type._type_affinity is type_api.BOOLEANTYPE._type_affinity:
             return UnaryExpression(
                 self.self_group(against=operators.inv),
                 operator=operators.inv,
                 type_=type_api.BOOLEANTYPE,
                 wraps_column_expression=self.wraps_column_expression,
-                negate=None)
+                negate=None,
+            )
         else:
             return ClauseElement._negate(self)
 
@@ -2860,6 +2925,7 @@ class CollectionAggregate(UnaryExpression):
     MySQL, they only work for subqueries.
 
     """
+
     @classmethod
     def _create_any(cls, expr):
         """Produce an ANY expression.
@@ -2883,12 +2949,15 @@ class CollectionAggregate(UnaryExpression):
 
         expr = _literal_as_binds(expr)
 
-        if expr.is_selectable and hasattr(expr, 'as_scalar'):
+        if expr.is_selectable and hasattr(expr, "as_scalar"):
             expr = expr.as_scalar()
         expr = expr.self_group()
         return CollectionAggregate(
-            expr, operator=operators.any_op,
-            type_=type_api.NULLTYPE, wraps_column_expression=False)
+            expr,
+            operator=operators.any_op,
+            type_=type_api.NULLTYPE,
+            wraps_column_expression=False,
+        )
 
     @classmethod
     def _create_all(cls, expr):
@@ -2912,12 +2981,15 @@ class CollectionAggregate(UnaryExpression):
         """
 
         expr = _literal_as_binds(expr)
-        if expr.is_selectable and hasattr(expr, 'as_scalar'):
+        if expr.is_selectable and hasattr(expr, "as_scalar"):
             expr = expr.as_scalar()
         expr = expr.self_group()
         return CollectionAggregate(
-            expr, operator=operators.all_op,
-            type_=type_api.NULLTYPE, wraps_column_expression=False)
+            expr,
+            operator=operators.all_op,
+            type_=type_api.NULLTYPE,
+            wraps_column_expression=False,
+        )
 
     # operate and reverse_operate are hardwired to
     # dispatch onto the type comparator directly, so that we can
@@ -2925,19 +2997,20 @@ class CollectionAggregate(UnaryExpression):
     def operate(self, op, *other, **kwargs):
         if not operators.is_comparison(op):
             raise exc.ArgumentError(
-                "Only comparison operators may be used with ANY/ALL")
-        kwargs['reverse'] = True
+                "Only comparison operators may be used with ANY/ALL"
+            )
+        kwargs["reverse"] = True
         return self.comparator.operate(operators.mirror(op), *other, **kwargs)
 
     def reverse_operate(self, op, other, **kwargs):
         # comparison operators should never call reverse_operate
         assert not operators.is_comparison(op)
         raise exc.ArgumentError(
-            "Only comparison operators may be used with ANY/ALL")
+            "Only comparison operators may be used with ANY/ALL"
+        )
 
 
 class AsBoolean(UnaryExpression):
-
     def __init__(self, element, operator, negate):
         self.element = element
         self.type = type_api.BOOLEANTYPE
@@ -2971,7 +3044,7 @@ class BinaryExpression(ColumnElement):
 
     """
 
-    __visit_name__ = 'binary'
+    __visit_name__ = "binary"
 
     _is_implicitly_boolean = True
     """Indicates that any database will know this is a boolean expression
@@ -2979,8 +3052,9 @@ class BinaryExpression(ColumnElement):
 
     """
 
-    def __init__(self, left, right, operator, type_=None,
-                 negate=None, modifiers=None):
+    def __init__(
+        self, left, right, operator, type_=None, negate=None, modifiers=None
+    ):
         # allow compatibility with libraries that
         # refer to BinaryExpression directly and pass strings
         if isinstance(operator, util.string_types):
@@ -3026,15 +3100,15 @@ class BinaryExpression(ColumnElement):
         given :class:`BinaryExpression`."""
 
         return (
-            isinstance(other, BinaryExpression) and
-            self.operator == other.operator and
-            (
-                self.left.compare(other.left, **kw) and
-                self.right.compare(other.right, **kw) or
-                (
-                    operators.is_commutative(self.operator) and
-                    self.left.compare(other.right, **kw) and
-                    self.right.compare(other.left, **kw)
+            isinstance(other, BinaryExpression)
+            and self.operator == other.operator
+            and (
+                self.left.compare(other.left, **kw)
+                and self.right.compare(other.right, **kw)
+                or (
+                    operators.is_commutative(self.operator)
+                    and self.left.compare(other.right, **kw)
+                    and self.right.compare(other.left, **kw)
                 )
             )
         )
@@ -3053,7 +3127,8 @@ class BinaryExpression(ColumnElement):
                 self.negate,
                 negate=self.operator,
                 type_=self.type,
-                modifiers=self.modifiers)
+                modifiers=self.modifiers,
+            )
         else:
             return super(BinaryExpression, self)._negate()
 
@@ -3065,7 +3140,8 @@ class Slice(ColumnElement):
     may be interpreted by specific dialects, e.g. PostgreSQL.
 
     """
-    __visit_name__ = 'slice'
+
+    __visit_name__ = "slice"
 
     def __init__(self, start, stop, step):
         self.start = start
@@ -3081,17 +3157,18 @@ class Slice(ColumnElement):
 class IndexExpression(BinaryExpression):
     """Represent the class of expressions that are like an "index" operation.
     """
+
     pass
 
 
 class Grouping(ColumnElement):
     """Represent a grouping within a column expression"""
 
-    __visit_name__ = 'grouping'
+    __visit_name__ = "grouping"
 
     def __init__(self, element):
         self.element = element
-        self.type = getattr(element, 'type', type_api.NULLTYPE)
+        self.type = getattr(element, "type", type_api.NULLTYPE)
 
     def self_group(self, against=None):
         return self
@@ -3106,13 +3183,13 @@ class Grouping(ColumnElement):
 
     @property
     def _label(self):
-        return getattr(self.element, '_label', None) or self.anon_label
+        return getattr(self.element, "_label", None) or self.anon_label
 
     def _copy_internals(self, clone=_clone, **kw):
         self.element = clone(self.element, **kw)
 
     def get_children(self, **kwargs):
-        return self.element,
+        return (self.element,)
 
     @property
     def _from_objects(self):
@@ -3122,15 +3199,16 @@ class Grouping(ColumnElement):
         return getattr(self.element, attr)
 
     def __getstate__(self):
-        return {'element': self.element, 'type': self.type}
+        return {"element": self.element, "type": self.type}
 
     def __setstate__(self, state):
-        self.element = state['element']
-        self.type = state['type']
+        self.element = state["element"]
+        self.type = state["type"]
 
     def compare(self, other, **kw):
-        return isinstance(other, Grouping) and \
-            self.element.compare(other.element)
+        return isinstance(other, Grouping) and self.element.compare(
+            other.element
+        )
 
 
 RANGE_UNBOUNDED = util.symbol("RANGE_UNBOUNDED")
@@ -3147,14 +3225,15 @@ class Over(ColumnElement):
     backends.
 
     """
-    __visit_name__ = 'over'
+
+    __visit_name__ = "over"
 
     order_by = None
     partition_by = None
 
     def __init__(
-            self, element, partition_by=None,
-            order_by=None, range_=None, rows=None):
+        self, element, partition_by=None, order_by=None, range_=None, rows=None
+    ):
         """Produce an :class:`.Over` object against a function.
 
         Used against aggregate or so-called "window" functions,
@@ -3237,17 +3316,20 @@ class Over(ColumnElement):
         if order_by is not None:
             self.order_by = ClauseList(
                 *util.to_list(order_by),
-                _literal_as_text=_literal_as_label_reference)
+                _literal_as_text=_literal_as_label_reference
+            )
         if partition_by is not None:
             self.partition_by = ClauseList(
                 *util.to_list(partition_by),
-                _literal_as_text=_literal_as_label_reference)
+                _literal_as_text=_literal_as_label_reference
+            )
 
         if range_:
             self.range_ = self._interpret_range(range_)
             if rows:
                 raise exc.ArgumentError(
-                    "'range_' and 'rows' are mutually exclusive")
+                    "'range_' and 'rows' are mutually exclusive"
+                )
             else:
                 self.rows = None
         elif rows:
@@ -3267,7 +3349,8 @@ class Over(ColumnElement):
                 lower = int(range_[0])
             except ValueError:
                 raise exc.ArgumentError(
-                    "Integer or None expected for range value")
+                    "Integer or None expected for range value"
+                )
             else:
                 if lower == 0:
                     lower = RANGE_CURRENT
@@ -3279,7 +3362,8 @@ class Over(ColumnElement):
                 upper = int(range_[1])
             except ValueError:
                 raise exc.ArgumentError(
-                    "Integer or None expected for range value")
+                    "Integer or None expected for range value"
+                )
             else:
                 if upper == 0:
                     upper = RANGE_CURRENT
@@ -3303,9 +3387,11 @@ class Over(ColumnElement):
         return self.element.type
 
     def get_children(self, **kwargs):
-        return [c for c in
-                (self.element, self.partition_by, self.order_by)
-                if c is not None]
+        return [
+            c
+            for c in (self.element, self.partition_by, self.order_by)
+            if c is not None
+        ]
 
     def _copy_internals(self, clone=_clone, **kw):
         self.element = clone(self.element, **kw)
@@ -3316,11 +3402,15 @@ class Over(ColumnElement):
 
     @property
     def _from_objects(self):
-        return list(itertools.chain(
-            *[c._from_objects for c in
-                (self.element, self.partition_by, self.order_by)
-              if c is not None]
-        ))
+        return list(
+            itertools.chain(
+                *[
+                    c._from_objects
+                    for c in (self.element, self.partition_by, self.order_by)
+                    if c is not None
+                ]
+            )
+        )
 
 
 class WithinGroup(ColumnElement):
@@ -3339,7 +3429,8 @@ class WithinGroup(ColumnElement):
     ``None``, the function's ``.type`` is used.
 
     """
-    __visit_name__ = 'withingroup'
+
+    __visit_name__ = "withingroup"
 
     order_by = None
 
@@ -3383,7 +3474,8 @@ class WithinGroup(ColumnElement):
         if order_by is not None:
             self.order_by = ClauseList(
                 *util.to_list(order_by),
-                _literal_as_text=_literal_as_label_reference)
+                _literal_as_text=_literal_as_label_reference
+            )
 
     def over(self, partition_by=None, order_by=None, range_=None, rows=None):
         """Produce an OVER clause against this :class:`.WithinGroup`
@@ -3394,8 +3486,12 @@ class WithinGroup(ColumnElement):
 
         """
         return Over(
-            self, partition_by=partition_by, order_by=order_by,
-            range_=range_, rows=rows)
+            self,
+            partition_by=partition_by,
+            order_by=order_by,
+            range_=range_,
+            rows=rows,
+        )
 
     @util.memoized_property
     def type(self):
@@ -3406,9 +3502,7 @@ class WithinGroup(ColumnElement):
             return self.element.type
 
     def get_children(self, **kwargs):
-        return [c for c in
-                (self.element, self.order_by)
-                if c is not None]
+        return [c for c in (self.element, self.order_by) if c is not None]
 
     def _copy_internals(self, clone=_clone, **kw):
         self.element = clone(self.element, **kw)
@@ -3417,11 +3511,15 @@ class WithinGroup(ColumnElement):
 
     @property
     def _from_objects(self):
-        return list(itertools.chain(
-            *[c._from_objects for c in
-                (self.element, self.order_by)
-              if c is not None]
-        ))
+        return list(
+            itertools.chain(
+                *[
+                    c._from_objects
+                    for c in (self.element, self.order_by)
+                    if c is not None
+                ]
+            )
+        )
 
 
 class FunctionFilter(ColumnElement):
@@ -3443,7 +3541,8 @@ class FunctionFilter(ColumnElement):
         :meth:`.FunctionElement.filter`
 
     """
-    __visit_name__ = 'funcfilter'
+
+    __visit_name__ = "funcfilter"
 
     criterion = None
 
@@ -3515,17 +3614,19 @@ class FunctionFilter(ColumnElement):
 
         """
         return Over(
-            self, partition_by=partition_by, order_by=order_by,
-            range_=range_, rows=rows)
+            self,
+            partition_by=partition_by,
+            order_by=order_by,
+            range_=range_,
+            rows=rows,
+        )
 
     @util.memoized_property
     def type(self):
         return self.func.type
 
     def get_children(self, **kwargs):
-        return [c for c in
-                (self.func, self.criterion)
-                if c is not None]
+        return [c for c in (self.func, self.criterion) if c is not None]
 
     def _copy_internals(self, clone=_clone, **kw):
         self.func = clone(self.func, **kw)
@@ -3534,10 +3635,15 @@ class FunctionFilter(ColumnElement):
 
     @property
     def _from_objects(self):
-        return list(itertools.chain(
-            *[c._from_objects for c in (self.func, self.criterion)
-              if c is not None]
-        ))
+        return list(
+            itertools.chain(
+                *[
+                    c._from_objects
+                    for c in (self.func, self.criterion)
+                    if c is not None
+                ]
+            )
+        )
 
 
 class Label(ColumnElement):
@@ -3548,7 +3654,7 @@ class Label(ColumnElement):
 
     """
 
-    __visit_name__ = 'label'
+    __visit_name__ = "label"
 
     def __init__(self, name, element, type_=None):
         """Return a :class:`Label` object for the
@@ -3577,7 +3683,7 @@ class Label(ColumnElement):
             self._resolve_label = self.name
         else:
             self.name = _anonymous_label(
-                '%%(%d %s)s' % (id(self), getattr(element, 'name', 'anon'))
+                "%%(%d %s)s" % (id(self), getattr(element, "name", "anon"))
             )
 
         self.key = self._label = self._key_label = self.name
@@ -3603,7 +3709,7 @@ class Label(ColumnElement):
     @util.memoized_property
     def type(self):
         return type_api.to_instance(
-            self._type or getattr(self._element, 'type', None)
+            self._type or getattr(self._element, "type", None)
         )
 
     @util.memoized_property
@@ -3619,9 +3725,7 @@ class Label(ColumnElement):
     def _apply_to_inner(self, fn, *arg, **kw):
         sub_element = fn(*arg, **kw)
         if sub_element is not self._element:
-            return Label(self.name,
-                         sub_element,
-                         type_=self._type)
+            return Label(self.name, sub_element, type_=self._type)
         else:
             return self
 
@@ -3634,16 +3738,16 @@ class Label(ColumnElement):
         return self.element.foreign_keys
 
     def get_children(self, **kwargs):
-        return self.element,
+        return (self.element,)
 
     def _copy_internals(self, clone=_clone, anonymize_labels=False, **kw):
         self._element = clone(self._element, **kw)
-        self.__dict__.pop('element', None)
-        self.__dict__.pop('_allow_label_resolve', None)
+        self.__dict__.pop("element", None)
+        self.__dict__.pop("_allow_label_resolve", None)
         if anonymize_labels:
             self.name = self._resolve_label = _anonymous_label(
-                '%%(%d %s)s' % (
-                    id(self), getattr(self.element, 'name', 'anon'))
+                "%%(%d %s)s"
+                % (id(self), getattr(self.element, "name", "anon"))
             )
             self.key = self._label = self._key_label = self.name
 
@@ -3652,8 +3756,9 @@ class Label(ColumnElement):
         return self.element._from_objects
 
     def _make_proxy(self, selectable, name=None, **kw):
-        e = self.element._make_proxy(selectable,
-                                     name=name if name else self.name)
+        e = self.element._make_proxy(
+            selectable, name=name if name else self.name
+        )
         e._proxies.append(self)
         if self._type is not None:
             e.type = self._type
@@ -3694,7 +3799,8 @@ class ColumnClause(Immutable, ColumnElement):
         :class:`.Column`
 
     """
-    __visit_name__ = 'column'
+
+    __visit_name__ = "column"
 
     onupdate = default = server_default = server_onupdate = None
 
@@ -3792,25 +3898,33 @@ class ColumnClause(Immutable, ColumnElement):
         self.is_literal = is_literal
 
     def _compare_name_for_result(self, other):
-        if self.is_literal or \
-                self.table is None or self.table._textual or \
-                not hasattr(other, 'proxy_set') or (
-                    isinstance(other, ColumnClause) and
-                    (other.is_literal or
-                     other.table is None or
-                     other.table._textual)
-                ):
-            return (hasattr(other, 'name') and self.name == other.name) or \
-                (hasattr(other, '_label') and self._label == other._label)
+        if (
+            self.is_literal
+            or self.table is None
+            or self.table._textual
+            or not hasattr(other, "proxy_set")
+            or (
+                isinstance(other, ColumnClause)
+                and (
+                    other.is_literal
+                    or other.table is None
+                    or other.table._textual
+                )
+            )
+        ):
+            return (hasattr(other, "name") and self.name == other.name) or (
+                hasattr(other, "_label") and self._label == other._label
+            )
         else:
             return other.proxy_set.intersection(self.proxy_set)
 
     def _get_table(self):
-        return self.__dict__['table']
+        return self.__dict__["table"]
 
     def _set_table(self, table):
         self._memoized_property.expire_instance(self)
-        self.__dict__['table'] = table
+        self.__dict__["table"] = table
+
     table = property(_get_table, _set_table)
 
     @_memoized_property
@@ -3826,7 +3940,7 @@ class ColumnClause(Immutable, ColumnElement):
         if util.py3k:
             return self.name
         else:
-            return self.name.encode('ascii', 'backslashreplace')
+            return self.name.encode("ascii", "backslashreplace")
 
     @_memoized_property
     def _key_label(self):
@@ -3850,9 +3964,8 @@ class ColumnClause(Immutable, ColumnElement):
             return None
 
         elif t is not None and t.named_with_column:
-            if getattr(t, 'schema', None):
-                label = t.schema.replace('.', '_') + "_" + \
-                    t.name + "_" + name
+            if getattr(t, "schema", None):
+                label = t.schema.replace(".", "_") + "_" + t.name + "_" + name
             else:
                 label = t.name + "_" + name
 
@@ -3884,31 +3997,39 @@ class ColumnClause(Immutable, ColumnElement):
             return name
 
     def _bind_param(self, operator, obj, type_=None):
-        return BindParameter(self.key, obj,
-                             _compared_to_operator=operator,
-                             _compared_to_type=self.type,
-                             type_=type_,
-                             unique=True)
-
-    def _make_proxy(self, selectable, name=None, attach=True,
-                    name_is_truncatable=False, **kw):
+        return BindParameter(
+            self.key,
+            obj,
+            _compared_to_operator=operator,
+            _compared_to_type=self.type,
+            type_=type_,
+            unique=True,
+        )
+
+    def _make_proxy(
+        self,
+        selectable,
+        name=None,
+        attach=True,
+        name_is_truncatable=False,
+        **kw
+    ):
         # propagate the "is_literal" flag only if we are keeping our name,
         # otherwise its considered to be a label
         is_literal = self.is_literal and (name is None or name == self.name)
         c = self._constructor(
-            _as_truncated(name or self.name) if
-            name_is_truncatable else
-            (name or self.name),
+            _as_truncated(name or self.name)
+            if name_is_truncatable
+            else (name or self.name),
             type_=self.type,
             _selectable=selectable,
-            is_literal=is_literal
+            is_literal=is_literal,
         )
         if name is None:
             c.key = self.key
         c._proxies = [self]
         if selectable._is_clone_of is not None:
-            c._is_clone_of = \
-                selectable._is_clone_of.columns.get(c.key)
+            c._is_clone_of = selectable._is_clone_of.columns.get(c.key)
 
         if attach:
             selectable._columns[c.key] = c
@@ -3924,24 +4045,25 @@ class CollationClause(ColumnElement):
 
 class _IdentifiedClause(Executable, ClauseElement):
 
-    __visit_name__ = 'identified'
-    _execution_options = \
-        Executable._execution_options.union({'autocommit': False})
+    __visit_name__ = "identified"
+    _execution_options = Executable._execution_options.union(
+        {"autocommit": False}
+    )
 
     def __init__(self, ident):
         self.ident = ident
 
 
 class SavepointClause(_IdentifiedClause):
-    __visit_name__ = 'savepoint'
+    __visit_name__ = "savepoint"
 
 
 class RollbackToSavepointClause(_IdentifiedClause):
-    __visit_name__ = 'rollback_to_savepoint'
+    __visit_name__ = "rollback_to_savepoint"
 
 
 class ReleaseSavepointClause(_IdentifiedClause):
-    __visit_name__ = 'release_savepoint'
+    __visit_name__ = "release_savepoint"
 
 
 class quoted_name(util.MemoizedSlots, util.text_type):
@@ -3992,7 +4114,7 @@ class quoted_name(util.MemoizedSlots, util.text_type):
 
     """
 
-    __slots__ = 'quote', 'lower', 'upper'
+    __slots__ = "quote", "lower", "upper"
 
     def __new__(cls, value, quote):
         if value is None:
@@ -4026,9 +4148,9 @@ class quoted_name(util.MemoizedSlots, util.text_type):
             return util.text_type(self).upper()
 
     def __repr__(self):
-        backslashed = self.encode('ascii', 'backslashreplace')
+        backslashed = self.encode("ascii", "backslashreplace")
         if not util.py2k:
-            backslashed = backslashed.decode('ascii')
+            backslashed = backslashed.decode("ascii")
         return "'%s'" % backslashed
 
 
@@ -4094,6 +4216,7 @@ class conv(_truncated_label):
         :ref:`constraint_naming_conventions`
 
     """
+
     __slots__ = ()
 
 
@@ -4102,6 +4225,7 @@ class _defer_name(_truncated_label):
     generation.
 
     """
+
     __slots__ = ()
 
     def __new__(cls, value):
@@ -4113,13 +4237,15 @@ class _defer_name(_truncated_label):
             return super(_defer_name, cls).__new__(cls, value)
 
     def __reduce__(self):
-        return self.__class__, (util.text_type(self), )
+        return self.__class__, (util.text_type(self),)
 
 
 class _defer_none_name(_defer_name):
     """indicate a 'deferred' name that was ultimately the value None."""
+
     __slots__ = ()
 
+
 _NONE_NAME = _defer_none_name("_unnamed_")
 
 # for backwards compatibility in case
@@ -4138,15 +4264,15 @@ class _anonymous_label(_truncated_label):
     def __add__(self, other):
         return _anonymous_label(
             quoted_name(
-                util.text_type.__add__(self, util.text_type(other)),
-                self.quote)
+                util.text_type.__add__(self, util.text_type(other)), self.quote
+            )
         )
 
     def __radd__(self, other):
         return _anonymous_label(
             quoted_name(
-                util.text_type.__add__(util.text_type(other), self),
-                self.quote)
+                util.text_type.__add__(util.text_type(other), self), self.quote
+            )
         )
 
     def apply_map(self, map_):
@@ -4206,20 +4332,23 @@ def _cloned_intersection(a, b):
 
     """
     all_overlap = set(_expand_cloned(a)).intersection(_expand_cloned(b))
-    return set(elem for elem in a
-               if all_overlap.intersection(elem._cloned_set))
+    return set(
+        elem for elem in a if all_overlap.intersection(elem._cloned_set)
+    )
 
 
 def _cloned_difference(a, b):
     all_overlap = set(_expand_cloned(a)).intersection(_expand_cloned(b))
-    return set(elem for elem in a
-               if not all_overlap.intersection(elem._cloned_set))
+    return set(
+        elem for elem in a if not all_overlap.intersection(elem._cloned_set)
+    )
 
 
 @util.dependencies("sqlalchemy.sql.functions")
 def _labeled(functions, element):
-    if not hasattr(element, 'name') or \
-            isinstance(element, functions.FunctionElement):
+    if not hasattr(element, "name") or isinstance(
+        element, functions.FunctionElement
+    ):
         return element.label(None)
     else:
         return element
@@ -4235,7 +4364,7 @@ def _find_columns(clause):
     """locate Column objects within the given expression."""
 
     cols = util.column_set()
-    traverse(clause, {}, {'column': cols.add})
+    traverse(clause, {}, {"column": cols.add})
     return cols
 
 
@@ -4253,7 +4382,7 @@ def _find_columns(clause):
 def _column_as_key(element):
     if isinstance(element, util.string_types):
         return element
-    if hasattr(element, '__clause_element__'):
+    if hasattr(element, "__clause_element__"):
         element = element.__clause_element__()
     try:
         return element.key
@@ -4262,7 +4391,7 @@ def _column_as_key(element):
 
 
 def _clause_element_as_expr(element):
-    if hasattr(element, '__clause_element__'):
+    if hasattr(element, "__clause_element__"):
         return element.__clause_element__()
     else:
         return element
@@ -4272,7 +4401,7 @@ def _literal_as_label_reference(element):
     if isinstance(element, util.string_types):
         return _textual_label_reference(element)
 
-    elif hasattr(element, '__clause_element__'):
+    elif hasattr(element, "__clause_element__"):
         element = element.__clause_element__()
 
     return _literal_as_text(element)
@@ -4282,11 +4411,13 @@ def _literal_and_labels_as_label_reference(element):
     if isinstance(element, util.string_types):
         return _textual_label_reference(element)
 
-    elif hasattr(element, '__clause_element__'):
+    elif hasattr(element, "__clause_element__"):
         element = element.__clause_element__()
 
-    if isinstance(element, ColumnElement) and \
-            element._order_by_label_element is not None:
+    if (
+        isinstance(element, ColumnElement)
+        and element._order_by_label_element is not None
+    ):
         return _label_reference(element)
     else:
         return _literal_as_text(element)
@@ -4299,14 +4430,15 @@ def _expression_literal_as_text(element):
 def _literal_as_text(element, warn=False):
     if isinstance(element, Visitable):
         return element
-    elif hasattr(element, '__clause_element__'):
+    elif hasattr(element, "__clause_element__"):
         return element.__clause_element__()
     elif isinstance(element, util.string_types):
         if warn:
             util.warn_limited(
                 "Textual SQL expression %(expr)r should be "
                 "explicitly declared as text(%(expr)r)",
-                {"expr": util.ellipses_string(element)})
+                {"expr": util.ellipses_string(element)},
+            )
 
         return TextClause(util.text_type(element))
     elif isinstance(element, (util.NoneType, bool)):
@@ -4319,20 +4451,23 @@ def _literal_as_text(element, warn=False):
 
 
 def _no_literals(element):
-    if hasattr(element, '__clause_element__'):
+    if hasattr(element, "__clause_element__"):
         return element.__clause_element__()
     elif not isinstance(element, Visitable):
-        raise exc.ArgumentError("Ambiguous literal: %r.  Use the 'text()' "
-                                "function to indicate a SQL expression "
-                                "literal, or 'literal()' to indicate a "
-                                "bound value." % (element, ))
+        raise exc.ArgumentError(
+            "Ambiguous literal: %r.  Use the 'text()' "
+            "function to indicate a SQL expression "
+            "literal, or 'literal()' to indicate a "
+            "bound value." % (element,)
+        )
     else:
         return element
 
 
 def _is_literal(element):
-    return not isinstance(element, Visitable) and \
-        not hasattr(element, '__clause_element__')
+    return not isinstance(element, Visitable) and not hasattr(
+        element, "__clause_element__"
+    )
 
 
 def _only_column_elements_or_none(element, name):
@@ -4343,17 +4478,18 @@ def _only_column_elements_or_none(element, name):
 
 
 def _only_column_elements(element, name):
-    if hasattr(element, '__clause_element__'):
+    if hasattr(element, "__clause_element__"):
         element = element.__clause_element__()
     if not isinstance(element, ColumnElement):
         raise exc.ArgumentError(
             "Column-based expression object expected for argument "
-            "'%s'; got: '%s', type %s" % (name, element, type(element)))
+            "'%s'; got: '%s', type %s" % (name, element, type(element))
+        )
     return element
 
 
 def _literal_as_binds(element, name=None, type_=None):
-    if hasattr(element, '__clause_element__'):
+    if hasattr(element, "__clause_element__"):
         return element.__clause_element__()
     elif not isinstance(element, Visitable):
         if element is None:
@@ -4363,13 +4499,14 @@ def _literal_as_binds(element, name=None, type_=None):
     else:
         return element
 
-_guess_straight_column = re.compile(r'^\w\S*$', re.I)
+
+_guess_straight_column = re.compile(r"^\w\S*$", re.I)
 
 
 def _interpret_as_column_or_from(element):
     if isinstance(element, Visitable):
         return element
-    elif hasattr(element, '__clause_element__'):
+    elif hasattr(element, "__clause_element__"):
         return element.__clause_element__()
 
     insp = inspection.inspect(element, raiseerr=False)
@@ -4399,11 +4536,11 @@ def _interpret_as_column_or_from(element):
             {
                 "column": util.ellipses_string(element),
                 "literal_column": "literal_column"
-                if guess_is_literal else "column"
-            })
-    return ColumnClause(
-        element,
-        is_literal=guess_is_literal)
+                if guess_is_literal
+                else "column",
+            },
+        )
+    return ColumnClause(element, is_literal=guess_is_literal)
 
 
 def _const_expr(element):
@@ -4416,9 +4553,7 @@ def _const_expr(element):
     elif element is True:
         return True_()
     else:
-        raise exc.ArgumentError(
-            "Expected None, False, or True"
-        )
+        raise exc.ArgumentError("Expected None, False, or True")
 
 
 def _type_from_args(args):
@@ -4429,18 +4564,15 @@ def _type_from_args(args):
         return type_api.NULLTYPE
 
 
-def _corresponding_column_or_error(fromclause, column,
-                                   require_embedded=False):
-    c = fromclause.corresponding_column(column,
-                                        require_embedded=require_embedded)
+def _corresponding_column_or_error(fromclause, column, require_embedded=False):
+    c = fromclause.corresponding_column(
+        column, require_embedded=require_embedded
+    )
     if c is None:
         raise exc.InvalidRequestError(
             "Given column '%s', attached to table '%s', "
             "failed to locate a corresponding column from table '%s'"
-            %
-            (column,
-             getattr(column, 'table', None),
-             fromclause.description)
+            % (column, getattr(column, "table", None), fromclause.description)
         )
     return c
 
@@ -4449,7 +4581,7 @@ class AnnotatedColumnElement(Annotated):
     def __init__(self, element, values):
         Annotated.__init__(self, element, values)
         ColumnElement.comparator._reset(self)
-        for attr in ('name', 'key', 'table'):
+        for attr in ("name", "key", "table"):
             if self.__dict__.get(attr, False) is None:
                 self.__dict__.pop(attr)