Apply oitnb and mypy 0.620, then make everything work again0.15.48

84 files changed, 4821 insertions, 2840 deletions

diff --git a/CHANGES b/CHANGES
index 082da98..3fc9b84 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+[0, 15, 48]: 2018-08-03
+  - housekeeping: ``oitnb`` for formatting, mypy 0.620 upgrade and conformity
+
 [0, 15, 47]: 2018-07-31
   - fix broken 3.6 manylinux1 (result of an unclean ``build`` (reported by 
     `Roman Sichnyi <https://bitbucket.org/rsichnyi-gl/>`__)
diff --git a/README.rst b/README.rst
index 78971a4..2f91868 100644
--- a/README.rst
+++ b/README.rst
@@ -4,8 +4,8 @@ ruamel.yaml
 
 ``ruamel.yaml`` is a YAML 1.2 loader/dumper package for Python.
 
-:version:       0.15.47
-:updated:       2018-07-31
+:version:       0.15.48
+:updated:       2018-08-03
 :documentation: http://yaml.readthedocs.io
 :repository:    https://bitbucket.org/ruamel/
 :pypi:          https://pypi.org/project/ruamel.yaml/
@@ -46,12 +46,17 @@ when the status of the API is stable enough to make the transition.
 .. image:: https://bitbucket.org/ruamel/oitnb/raw/default/_doc/_static/oitnb.svg
    :target: https://pypi.org/project/oitnb/
 
+.. image:: http://www.mypy-lang.org/static/mypy_badge.svg
+   :target: http://mypy-lang.org/
 
 ChangeLog
 =========
 
 .. should insert NEXT: at the beginning of line for next key (with empty line)
 
+0.15.48 (2018-08-03):
+  - housekeeping: ``oitnb`` for formatting, mypy 0.620 upgrade and conformity
+
 0.15.47 (2018-07-31):
   - fix broken 3.6 manylinux1, the result of an unclean ``build`` (reported by 
     `Roman Sichnyi <https://bitbucket.org/rsichnyi-gl/>`__)
diff --git a/__init__.py b/__init__.py
index e5363cc..c675a8e 100644
--- a/__init__.py
+++ b/__init__.py
@@ -7,24 +7,33 @@ if False:  # MYPY
 
 _package_data = dict(
     full_package_name='ruamel.yaml',
-    version_info=(0, 15, 47),
-    __version__='0.15.47',
+    version_info=(0, 15, 48),
+    __version__='0.15.48',
     author='Anthon van der Neut',
     author_email='a.van.der.neut@ruamel.eu',
     description='ruamel.yaml is a YAML parser/emitter that supports roundtrip preservation of comments, seq/map flow style, and map key order',  # NOQA
     entry_points=None,
     since=2014,
-    extras_require={':platform_python_implementation=="CPython" and python_version<="2.7"': [
-            'ruamel.ordereddict',
-        ], 'jinja2': ['ruamel.yaml.jinja2>=0.2'], 'docs': ['ryd']},
-    ext_modules=[dict(
+    extras_require={
+        ':platform_python_implementation=="CPython" and python_version<="2.7"': [
+            'ruamel.ordereddict'
+        ],
+        'jinja2': ['ruamel.yaml.jinja2>=0.2'],
+        'docs': ['ryd'],
+    },
+    ext_modules=[
+        dict(
             name='_ruamel_yaml',
-            src=['ext/_ruamel_yaml.c', 'ext/api.c', 'ext/writer.c', 'ext/dumper.c',
-                    'ext/loader.c',
-                    'ext/reader.c',
-                    'ext/scanner.c',
-                    'ext/parser.c',
-                    'ext/emitter.c',
+            src=[
+                'ext/_ruamel_yaml.c',
+                'ext/api.c',
+                'ext/writer.c',
+                'ext/dumper.c',
+                'ext/loader.c',
+                'ext/reader.c',
+                'ext/scanner.c',
+                'ext/parser.c',
+                'ext/emitter.c',
             ],
             lib=[],
             test="""
@@ -34,20 +43,21 @@ _package_data = dict(
               return 0;
             }
             """,
-        )],
-                  # NOQA
-            # test='#include "ext/yaml.h"\n\nint main(int argc, char* argv[])\n{\nyaml_parser_t parser;\nparser = parser;  /* prevent warning */\nreturn 0;\n}\n',  # NOQA
+        )
+    ],
+    # NOQA
+    # test='#include "ext/yaml.h"\n\nint main(int argc, char* argv[])\n{\nyaml_parser_t parser;\nparser = parser;  /* prevent warning */\nreturn 0;\n}\n',  # NOQA
     classifiers=[
-            'Programming Language :: Python :: 2.7',
-            'Programming Language :: Python :: 3.4',
-            'Programming Language :: Python :: 3.5',
-            'Programming Language :: Python :: 3.6',
-            'Programming Language :: Python :: 3.7',
-            'Programming Language :: Python :: Implementation :: CPython',
-            'Programming Language :: Python :: Implementation :: PyPy',
-            'Programming Language :: Python :: Implementation :: Jython',
-            'Topic :: Software Development :: Libraries :: Python Modules',
-            'Topic :: Text Processing :: Markup',
+        'Programming Language :: Python :: 2.7',
+        'Programming Language :: Python :: 3.4',
+        'Programming Language :: Python :: 3.5',
+        'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.7',
+        'Programming Language :: Python :: Implementation :: CPython',
+        'Programming Language :: Python :: Implementation :: PyPy',
+        'Programming Language :: Python :: Implementation :: Jython',
+        'Topic :: Software Development :: Libraries :: Python Modules',
+        'Topic :: Text Processing :: Markup',
     ],
     keywords='yaml 1.2 parser round-trip preserve quotes order config',
     windows_wheels=True,
@@ -55,12 +65,9 @@ _package_data = dict(
     many_linux='libyaml-devel',
     supported=[(2, 7), (3, 4)],  # minimum
     tox=dict(
-        flake8=dict(
-            version='==2.5.5',
-        ),
-        env='*pn',   # also test narrow 2.7.15
-        deps='ruamel.std.pathlib',
-        fl8excl='_test/lib',
+        env=u'*pn',  # also test narrow 2.7.15
+        deps=u'ruamel.std.pathlib',
+        fl8excl=u'_test/lib',
     ),
     rtfd=47359,
 )  # type: Dict[Any, Any]
@@ -71,6 +78,7 @@ __version__ = _package_data['__version__']
 
 try:
     from .cyaml import *  # NOQA
+
     __with_libyaml__ = True
 except (ImportError, ValueError):  # for Jython
     __with_libyaml__ = False
diff --git a/_doc/_static/pypi.svg b/_doc/_static/pypi.svg
index 42d5a40..45c5650 100644
--- a/_doc/_static/pypi.svg
+++ b/_doc/_static/pypi.svg
@@ -1 +1 @@
-<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="86" height="20"><linearGradient id="b" x2="0" y2="100%"><stop offset="0" stop-color="#bbb" stop-opacity=".1"/><stop offset="1" stop-opacity=".1"/></linearGradient><clipPath id="a"><rect width="86" height="20" rx="3" fill="#fff"/></clipPath><g clip-path="url(#a)"><path fill="#555" d="M0 0h33v20H0z"/><path fill="#007ec6" d="M33 0h53v20H33z"/><path fill="url(#b)" d="M0 0h86v20H0z"/></g><g fill="#fff" text-anchor="middle" font-family="DejaVu Sans,Verdana,Geneva,sans-serif" font-size="110"> <text x="175" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="230">pypi</text><text x="175" y="140" transform="scale(.1)" textLength="230">pypi</text><text x="585" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="430">0.15.47</text><text x="585" y="140" transform="scale(.1)" textLength="430">0.15.47</text></g> </svg>
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="86" height="20"><linearGradient id="b" x2="0" y2="100%"><stop offset="0" stop-color="#bbb" stop-opacity=".1"/><stop offset="1" stop-opacity=".1"/></linearGradient><clipPath id="a"><rect width="86" height="20" rx="3" fill="#fff"/></clipPath><g clip-path="url(#a)"><path fill="#555" d="M0 0h33v20H0z"/><path fill="#007ec6" d="M33 0h53v20H33z"/><path fill="url(#b)" d="M0 0h86v20H0z"/></g><g fill="#fff" text-anchor="middle" font-family="DejaVu Sans,Verdana,Geneva,sans-serif" font-size="110"> <text x="175" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="230">pypi</text><text x="175" y="140" transform="scale(.1)" textLength="230">pypi</text><text x="585" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="430">0.15.48</text><text x="585" y="140" transform="scale(.1)" textLength="430">0.15.48</text></g> </svg>
diff --git a/_doc/conf.py b/_doc/conf.py
index 19a19a3..632b117 100644
--- a/_doc/conf.py
+++ b/_doc/conf.py
@@ -13,7 +13,7 @@
 # serve to show the default.
 
 import sys  # NOQA
-import os   # NOQA
+import os  # NOQA
 
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
@@ -55,6 +55,7 @@ author = u'Anthon van der Neut'
 #
 try:
     from ruamel.yaml import __version__, version_info  # NOQA
+
     # The short X.Y version.
     version = '.'.join([str(l) for l in version_info[:3]])
     # The full version, including alpha/beta/rc tags.
@@ -69,6 +70,7 @@ print('ruamel.yaml version', version)
 try:
     from ryd.__main__ import RYDCmd
     from ruamel.std.pathlib import Path
+
     oldargv = sys.argv
     for fn in Path('.').glob('*.ryd'):
         sys.argv = ['ryd', 'convert', '--no-pdf', str(fn)]
@@ -141,7 +143,7 @@ html_theme = 'default'
 
 # The name for this set of Sphinx documents.  If None, it defaults to
 # "<project> v<release> documentation".
-html_title = "Python YAML package documentation"
+html_title = 'Python YAML package documentation'
 
 # A shorter title for the navigation bar.  Default is the same as html_title.
 # html_short_title = None
@@ -228,13 +230,10 @@ htmlhelp_basename = 'yamldoc'
 latex_elements = {
     # The paper size ('letterpaper' or 'a4paper').
     'papersize': 'a4paper',
-
     # The font size ('10pt', '11pt' or '12pt').
     # 'pointsize': '10pt',
-
     # Additional stuff for the LaTeX preamble.
     # 'preamble': '',
-
     # Latex figure (float) alignment
     # 'figure_align': 'htbp',
 }
@@ -243,8 +242,13 @@ latex_elements = {
 # (source start file, target name, title,
 #  author, documentclass [howto, manual, or own class]).
 latex_documents = [
-    (master_doc, 'yaml.tex', u'Python YAML package documentation',
-     u'Anthon van der Neut', 'manual'),
+    (
+        master_doc,
+        'yaml.tex',
+        u'Python YAML package documentation',
+        u'Anthon van der Neut',
+        'manual',
+    )
 ]
 
 # The name of an image file (relative to this directory) to place at the top of
@@ -272,10 +276,7 @@ latex_documents = [
 
 # One entry per manual page. List of tuples
 # (source start file, name, description, authors, manual section).
-man_pages = [
-    (master_doc, 'yaml', u'yaml Documentation',
-     [author], 1)
-]
+man_pages = [(master_doc, 'yaml', u'yaml Documentation', [author], 1)]
 
 # If true, show URL addresses after external links.
 # man_show_urls = False
@@ -287,9 +288,15 @@ man_pages = [
 # (source start file, target name, title, author,
 #  dir menu entry, description, category)
 texinfo_documents = [
-    (master_doc, 'yaml', u'yaml Documentation',
-     author, 'yaml', 'One line description of project.',
-     'Miscellaneous'),
+    (
+        master_doc,
+        'yaml',
+        u'yaml Documentation',
+        author,
+        'yaml',
+        'One line description of project.',
+        'Miscellaneous',
+    )
 ]
 
 # Documents to append as an appendix to all manuals.
diff --git a/_test/lib/canonical.py b/_test/lib/canonical.py
index 64f3153..af2c3cf 100644
--- a/_test/lib/canonical.py
+++ b/_test/lib/canonical.py
@@ -11,7 +11,6 @@ class CanonicalError(ruamel.yaml.YAMLError):
 
 
 class CanonicalScanner:
-
     def __init__(self, data):
         try:
             if PY3:
@@ -20,7 +19,7 @@ class CanonicalScanner:
             else:
                 data = unicode(data, 'utf-8')  # NOQA
         except UnicodeDecodeError:
-            raise CanonicalError("utf-8 stream is expected")
+            raise CanonicalError('utf-8 stream is expected')
         self.data = data + u'\0'
         self.index = 0
         self.tokens = []
@@ -48,7 +47,7 @@ class CanonicalScanner:
             self.scan()
         token = self.tokens.pop(0)
         if choice and not isinstance(token, choice):
-            raise CanonicalError("unexpected token " + repr(token))
+            raise CanonicalError('unexpected token ' + repr(token))
         return token
 
     def get_token_value(self):
@@ -65,7 +64,7 @@ class CanonicalScanner:
                 break
             elif ch == u'%':
                 self.tokens.append(self.scan_directive())
-            elif ch == u'-' and self.data[self.index:self.index + 3] == u'---':
+            elif ch == u'-' and self.data[self.index : self.index + 3] == u'---':
                 self.index += 3
                 self.tokens.append(ruamel.yaml.DocumentStartToken(None, None))
             elif ch == u'[':
@@ -96,18 +95,20 @@ class CanonicalScanner:
             elif ch == u'"':
                 self.tokens.append(self.scan_scalar())
             else:
-                raise CanonicalError("invalid token")
+                raise CanonicalError('invalid token')
         self.scanned = True
 
     DIRECTIVE = u'%YAML 1.1'
 
     def scan_directive(self):
-        if self.data[self.index:self.index + len(self.DIRECTIVE)] == self.DIRECTIVE and \
-                self.data[self.index + len(self.DIRECTIVE)] in u' \n\0':
+        if (
+            self.data[self.index : self.index + len(self.DIRECTIVE)] == self.DIRECTIVE
+            and self.data[self.index + len(self.DIRECTIVE)] in u' \n\0'
+        ):
             self.index += len(self.DIRECTIVE)
             return ruamel.yaml.DirectiveToken('YAML', (1, 1), None, None)
         else:
-            raise CanonicalError("invalid directive")
+            raise CanonicalError('invalid directive')
 
     def scan_alias(self):
         if self.data[self.index] == u'*':
@@ -118,7 +119,7 @@ class CanonicalScanner:
         start = self.index
         while self.data[self.index] not in u', \n\0':
             self.index += 1
-        value = self.data[start:self.index]
+        value = self.data[start : self.index]
         return TokenClass(value, None, None)
 
     def scan_tag(self):
@@ -126,7 +127,7 @@ class CanonicalScanner:
         start = self.index
         while self.data[self.index] not in u' \n\0':
             self.index += 1
-        value = self.data[start:self.index]
+        value = self.data[start : self.index]
         if not value:
             value = u'!'
         elif value[0] == u'!':
@@ -137,15 +138,11 @@ class CanonicalScanner:
             value = u'!' + value
         return ruamel.yaml.TagToken(value, None, None)
 
-    QUOTE_CODES = {
-        'x': 2,
-        'u': 4,
-        'U': 8,
-    }
+    QUOTE_CODES = {'x': 2, 'u': 4, 'U': 8}
 
     QUOTE_REPLACES = {
         u'\\': u'\\',
-        u'\"': u'\"',
+        u'"': u'"',
         u' ': u' ',
         u'a': u'\x07',
         u'b': u'\x08',
@@ -160,7 +157,6 @@ class CanonicalScanner:
         u'P': u'\u2029',
         u'_': u'_',
         u'0': u'\x00',
-
     }
 
     def scan_scalar(self):
@@ -171,7 +167,7 @@ class CanonicalScanner:
         while self.data[self.index] != u'"':
             if self.data[self.index] == u'\\':
                 ignore_spaces = False
-                chunks.append(self.data[start:self.index])
+                chunks.append(self.data[start : self.index])
                 self.index += 1
                 ch = self.data[self.index]
                 self.index += 1
@@ -179,16 +175,16 @@ class CanonicalScanner:
                     ignore_spaces = True
                 elif ch in self.QUOTE_CODES:
                     length = self.QUOTE_CODES[ch]
-                    code = int(self.data[self.index:self.index + length], 16)
+                    code = int(self.data[self.index : self.index + length], 16)
                     chunks.append(unichr(code))
                     self.index += length
                 else:
                     if ch not in self.QUOTE_REPLACES:
-                        raise CanonicalError("invalid escape code")
+                        raise CanonicalError('invalid escape code')
                     chunks.append(self.QUOTE_REPLACES[ch])
                 start = self.index
             elif self.data[self.index] == u'\n':
-                chunks.append(self.data[start:self.index])
+                chunks.append(self.data[start : self.index])
                 chunks.append(u' ')
                 self.index += 1
                 start = self.index
@@ -199,9 +195,9 @@ class CanonicalScanner:
             else:
                 ignore_spaces = False
                 self.index += 1
-        chunks.append(self.data[start:self.index])
+        chunks.append(self.data[start : self.index])
         self.index += 1
-        return ruamel.yaml.ScalarToken(u''.join(chunks), False, None, None)
+        return ruamel.yaml.ScalarToken("".join(chunks), False, None, None)
 
     def find_token(self):
         found = False
@@ -233,7 +229,7 @@ class CanonicalParser:
             if self.check_token(ruamel.yaml.DirectiveToken, ruamel.yaml.DocumentStartToken):
                 self.parse_document()
             else:
-                raise CanonicalError("document is expected, got " + repr(self.tokens[0]))
+                raise CanonicalError('document is expected, got ' + repr(self.tokens[0]))
         self.get_token(ruamel.yaml.StreamEndToken)
         self.events.append(ruamel.yaml.StreamEndEvent(None, None))
 
@@ -259,8 +255,11 @@ class CanonicalParser:
             if self.check_token(ruamel.yaml.TagToken):
                 tag = self.get_token_value()
             if self.check_token(ruamel.yaml.ScalarToken):
-                self.events.append(ruamel.yaml.ScalarEvent(anchor, tag, (False, False),
-                                                           self.get_token_value(), None, None))
+                self.events.append(
+                    ruamel.yaml.ScalarEvent(
+                        anchor, tag, (False, False), self.get_token_value(), None, None
+                    )
+                )
             elif self.check_token(ruamel.yaml.FlowSequenceStartToken):
                 self.events.append(ruamel.yaml.SequenceStartEvent(anchor, tag, None, None))
                 self.parse_sequence()
@@ -268,8 +267,9 @@ class CanonicalParser:
                 self.events.append(ruamel.yaml.MappingStartEvent(anchor, tag, None, None))
                 self.parse_mapping()
             else:
-                raise CanonicalError("SCALAR, '[', or '{' is expected, got " +
-                                     repr(self.tokens[0]))
+                raise CanonicalError(
+                    "SCALAR, '[', or '{' is expected, got " + repr(self.tokens[0])
+                )
 
     # sequence: SEQUENCE-START (node (ENTRY node)*)? ENTRY? SEQUENCE-END
     def parse_sequence(self):
@@ -328,9 +328,7 @@ class CanonicalParser:
         return self.events[0]
 
 
-class CanonicalLoader(CanonicalScanner, CanonicalParser,
-                      Composer, Constructor, Resolver):
-
+class CanonicalLoader(CanonicalScanner, CanonicalParser, Composer, Constructor, Resolver):
     def __init__(self, stream):
         if hasattr(stream, 'read'):
             stream = stream.read()
diff --git a/_test/lib/test_all.py b/_test/lib/test_all.py
index 9e951eb..8099ec8 100644
--- a/_test/lib/test_all.py
+++ b/_test/lib/test_all.py
@@ -7,9 +7,11 @@ import test_appliance
 def main(args=None):
     collections = []
     import test_yaml
+
     collections.append(test_yaml)
     if ruamel.yaml.__with_libyaml__:
         import test_yaml_ext
+
         collections.append(test_yaml_ext)
     test_appliance.run(collections, args)
 
diff --git a/_test/lib/test_appliance.py b/_test/lib/test_appliance.py
index a96052d..137c271 100644
--- a/_test/lib/test_appliance.py
+++ b/_test/lib/test_appliance.py
@@ -44,31 +44,34 @@ def find_test_filenames(directory):
 
 def parse_arguments(args):
     """"""
-    parser = argparse.ArgumentParser(usage=""" run the yaml tests. By default
+    parser = argparse.ArgumentParser(
+        usage=""" run the yaml tests. By default
     all functions on all appropriate test_files are run. Functions have
     unittest attributes that determine the required extensions to filenames
     that need to be available in order to run that test. E.g.\n\n
     python test_yaml.py test_constructor_types\n
     python test_yaml.py --verbose test_tokens spec-02-05\n\n
     The presence of an extension in the .skip attribute of a function
-    disables the test for that function.""")
+    disables the test for that function."""
+    )
     # ToDo: make into int and test > 0 in functions
     parser.add_argument(
-        '--verbose', '-v', action="store_true",
+        '--verbose',
+        '-v',
+        action='store_true',
         default='YAML_TEST_VERBOSE' in os.environ,
-        help="set verbosity output",
+        help='set verbosity output',
     )
     parser.add_argument(
-        '--list-functions', action="store_true",
+        '--list-functions',
+        action='store_true',
         help="""list all functions with required file extensions for test files
-        """
-    )
-    parser.add_argument(
-        'function', nargs='?',
-        help="""restrict function to run""",
+        """,
     )
+    parser.add_argument('function', nargs='?', help="""restrict function to run""")
     parser.add_argument(
-        'filenames', nargs='*',
+        'filenames',
+        nargs='*',
         help="""basename of filename set, extensions (.code, .data) have to
         be a superset of those in the unittest attribute of the selected
         function""",
@@ -194,7 +197,7 @@ def run(collections, args=None):
     results = []
     for function in test_functions:
         if include_functions and function.__name__ not in include_functions:
-                continue
+            continue
         if function.unittest:
             for base, exts in test_filenames:
                 if include_filenames and base not in include_filenames:
diff --git a/_test/lib/test_build.py b/_test/lib/test_build.py
index 5d19e3a..f7837eb 100644
--- a/_test/lib/test_build.py
+++ b/_test/lib/test_build.py
@@ -3,11 +3,14 @@ if __name__ == '__main__':
     import sys
     import os
     import distutils.util
+
     build_lib = 'build/lib'
-    build_lib_ext = os.path.join('build', 'lib.%s-%s' % (distutils.util.get_platform(),
-                                                         sys.version[0:3]))
+    build_lib_ext = os.path.join(
+        'build', 'lib.%s-%s' % (distutils.util.get_platform(), sys.version[0:3])
+    )
     sys.path.insert(0, build_lib)
     sys.path.insert(0, build_lib_ext)
     import test_yaml
     import test_appliance
+
     test_appliance.run(test_yaml)
diff --git a/_test/lib/test_build_ext.py b/_test/lib/test_build_ext.py
index 92d927e..1a58fd2 100644
--- a/_test/lib/test_build_ext.py
+++ b/_test/lib/test_build_ext.py
@@ -4,11 +4,14 @@ if __name__ == '__main__':
     import sys
     import os
     import distutils.util
+
     build_lib = 'build/lib'
-    build_lib_ext = os.path.join('build', 'lib.%s-%s' % (distutils.util.get_platform(),
-                                                         sys.version[0:3]))
+    build_lib_ext = os.path.join(
+        'build', 'lib.%s-%s' % (distutils.util.get_platform(), sys.version[0:3])
+    )
     sys.path.insert(0, build_lib)
     sys.path.insert(0, build_lib_ext)
     import test_yaml_ext
     import test_appliance
+
     test_appliance.run(test_yaml_ext)
diff --git a/_test/lib/test_canonical.py b/_test/lib/test_canonical.py
index 682f6ab..48a1764 100644
--- a/_test/lib/test_canonical.py
+++ b/_test/lib/test_canonical.py
@@ -40,7 +40,7 @@ def test_canonical_error(data_filename, canonical_filename, verbose=False):
         if verbose:
             print(exc)
     else:
-        raise AssertionError("expected an exception")
+        raise AssertionError('expected an exception')
 
 
 test_canonical_error.unittest = ['.data', '.canonical']
@@ -48,4 +48,5 @@ test_canonical_error.skip = ['.empty']
 
 if __name__ == '__main__':
     import test_appliance
+
     test_appliance.run(globals())
diff --git a/_test/lib/test_constructor.py b/_test/lib/test_constructor.py
index d10ea4d..a66ff1a 100644
--- a/_test/lib/test_constructor.py
+++ b/_test/lib/test_constructor.py
@@ -6,6 +6,7 @@ import pprint
 from ruamel.yaml.compat import PY2
 
 import datetime
+
 try:
     set
 except NameError:
@@ -20,10 +21,7 @@ def execute(code):
 
 
 def _make_objects():
-    global MyLoader, MyDumper, MyTestClass1, MyTestClass2, MyTestClass3, YAMLobject1, \
-        YAMLobject2, AnObject, AnInstance, AState, ACustomState, InitArgs, InitArgsWithState, \
-        NewArgs, NewArgsWithState, Reduce, ReduceWithState, MyInt, MyList, MyDict,  \
-        FixedOffset, today, execute
+    global MyLoader, MyDumper, MyTestClass1, MyTestClass2, MyTestClass3, YAMLobject1, YAMLobject2, AnObject, AnInstance, AState, ACustomState, InitArgs, InitArgsWithState, NewArgs, NewArgsWithState, Reduce, ReduceWithState, MyInt, MyList, MyDict, FixedOffset, today, execute
 
     class MyLoader(ruamel.yaml.Loader):
         pass
@@ -48,27 +46,29 @@ def _make_objects():
         return MyTestClass1(**mapping)
 
     def represent1(representer, native):
-        return representer.represent_mapping("!tag1", native.__dict__)
+        return representer.represent_mapping('!tag1', native.__dict__)
 
-    ruamel.yaml.add_constructor("!tag1", construct1, Loader=MyLoader)
+    ruamel.yaml.add_constructor('!tag1', construct1, Loader=MyLoader)
     ruamel.yaml.add_representer(MyTestClass1, represent1, Dumper=MyDumper)
 
     class MyTestClass2(MyTestClass1, ruamel.yaml.YAMLObject):
         ruamel.yaml.loader = MyLoader
         ruamel.yaml.dumper = MyDumper
-        ruamel.yaml.tag = "!tag2"
+        ruamel.yaml.tag = '!tag2'
 
         def from_yaml(cls, constructor, node):
             x = constructor.construct_yaml_int(node)
             return cls(x=x)
+
         from_yaml = classmethod(from_yaml)
 
         def to_yaml(cls, representer, native):
             return representer.represent_scalar(cls.yaml_tag, str(native.x))
+
         to_yaml = classmethod(to_yaml)
 
     class MyTestClass3(MyTestClass2):
-        ruamel.yaml.tag = "!tag3"
+        ruamel.yaml.tag = '!tag3'
 
         def from_yaml(cls, constructor, node):
             mapping = constructor.construct_mapping(node)
@@ -77,10 +77,12 @@ def _make_objects():
                 del mapping['=']
                 mapping['x'] = x
             return cls(**mapping)
+
         from_yaml = classmethod(from_yaml)
 
         def to_yaml(cls, representer, native):
             return representer.represent_mapping(cls.yaml_tag, native.__dict__)
+
         to_yaml = classmethod(to_yaml)
 
     class YAMLobject1(ruamel.yaml.YAMLObject):
@@ -131,12 +133,17 @@ def _make_objects():
             return self
 
         def __cmp__(self, other):
-            return cmp((type(self), self.foo, self.bar, self.baz),  # NOQA
-                       (type(other), other.foo, other.bar, other.baz))
+            return cmp(
+                (type(self), self.foo, self.bar, self.baz),  # NOQA
+                (type(other), other.foo, other.bar, other.baz),
+            )
 
         def __eq__(self, other):
-            return type(self) is type(other) and    \
-                (self.foo, self.bar, self.baz) == (other.foo, other.bar, other.baz)
+            return type(self) is type(other) and (self.foo, self.bar, self.baz) == (
+                other.foo,
+                other.bar,
+                other.baz,
+            )
 
     class AnInstance:
         def __init__(self, foo=None, bar=None, baz=None):
@@ -145,20 +152,21 @@ def _make_objects():
             self.baz = baz
 
         def __cmp__(self, other):
-            return cmp((type(self), self.foo, self.bar, self.baz),  # NOQA
-                       (type(other), other.foo, other.bar, other.baz))
+            return cmp(
+                (type(self), self.foo, self.bar, self.baz),  # NOQA
+                (type(other), other.foo, other.bar, other.baz),
+            )
 
         def __eq__(self, other):
-            return type(self) is type(other) and    \
-                (self.foo, self.bar, self.baz) == (other.foo, other.bar, other.baz)
+            return type(self) is type(other) and (self.foo, self.bar, self.baz) == (
+                other.foo,
+                other.bar,
+                other.baz,
+            )
 
     class AState(AnInstance):
         def __getstate__(self):
-            return {
-                '_foo': self.foo,
-                '_bar': self.bar,
-                '_baz': self.baz,
-            }
+            return {'_foo': self.foo, '_bar': self.bar, '_baz': self.baz}
 
         def __setstate__(self, state):
             self.foo = state['_foo']
@@ -259,6 +267,7 @@ try:
     from ruamel.ordereddict import ordereddict
 except ImportError:
     from collections import OrderedDict
+
     # to get the right name import ... as ordereddict doesn't do that
 
     class ordereddict(OrderedDict):
@@ -277,7 +286,7 @@ def _serialize_value(data):
         for key, value in data.items():
             key = _serialize_value(key)
             value = _serialize_value(value)
-            items.append("%s: %s" % (key, value))
+            items.append('%s: %s' % (key, value))
         items.sort()
         return '{%s}' % ', '.join(items)
     elif isinstance(data, datetime.datetime):
@@ -308,16 +317,16 @@ def test_constructor_types(data_filename, code_filename, verbose=False):
             pass
         # print('native1', native1)
         if verbose:
-            print("SERIALIZED NATIVE1:")
+            print('SERIALIZED NATIVE1:')
             print(_serialize_value(native1))
-            print("SERIALIZED NATIVE2:")
+            print('SERIALIZED NATIVE2:')
             print(_serialize_value(native2))
         assert _serialize_value(native1) == _serialize_value(native2), (native1, native2)
     finally:
         if verbose:
-            print("NATIVE1:")
+            print('NATIVE1:')
             pprint.pprint(native1)
-            print("NATIVE2:")
+            print('NATIVE2:')
             pprint.pprint(native2)
 
 
@@ -327,23 +336,28 @@ test_constructor_types.unittest = ['.data', '.code']
 def test_roundtrip_data(code_filename, roundtrip_filename, verbose=False):
     _make_objects()
     with open(code_filename, 'rb') as fp0:
-        value1 = fp0 .read()
+        value1 = fp0.read()
     native2 = list(ruamel.yaml.load_all(value1, Loader=MyLoader))
     if len(native2) == 1:
         native2 = native2[0]
     try:
-        value2 = ruamel.yaml.dump(native2, Dumper=MyDumper, default_flow_style=False,
-                                  allow_unicode=True, encoding='utf-8')
+        value2 = ruamel.yaml.dump(
+            native2,
+            Dumper=MyDumper,
+            default_flow_style=False,
+            allow_unicode=True,
+            encoding='utf-8',
+        )
         # value2 += x
         if verbose:
-            print("SERIALIZED NATIVE1:")
+            print('SERIALIZED NATIVE1:')
             print(value1)
-            print("SERIALIZED NATIVE2:")
+            print('SERIALIZED NATIVE2:')
             print(value2)
         assert value1 == value2, (value1, value2)
     finally:
         if verbose:
-            print("NATIVE2:")
+            print('NATIVE2:')
             pprint.pprint(native2)
 
 
@@ -353,6 +367,8 @@ test_roundtrip_data.unittest = ['.data', '.roundtrip']
 if __name__ == '__main__':
     import sys
     import test_constructor  # NOQA
+
     sys.modules['test_constructor'] = sys.modules['__main__']
     import test_appliance
+
     test_appliance.run(globals())
diff --git a/_test/lib/test_emitter.py b/_test/lib/test_emitter.py
index 4b6fb76..fbdbb79 100644
--- a/_test/lib/test_emitter.py
+++ b/_test/lib/test_emitter.py
@@ -23,7 +23,7 @@ def test_emitter_on_data(data_filename, canonical_filename, verbose=False):
         events = list(yaml.parse(fp0))
     output = yaml.emit(events)
     if verbose:
-        print("OUTPUT:")
+        print('OUTPUT:')
         print(output)
     new_events = list(yaml.parse(output))
     _compare_events(events, new_events)
@@ -38,7 +38,7 @@ def test_emitter_on_canonical(canonical_filename, verbose=False):
     for canonical in [False, True]:
         output = yaml.emit(events, canonical=canonical)
         if verbose:
-            print("OUTPUT (canonical=%s):" % canonical)
+            print('OUTPUT (canonical=%s):' % canonical)
             print(output)
         new_events = list(yaml.parse(output))
         _compare_events(events, new_events)
@@ -52,23 +52,28 @@ def test_emitter_styles(data_filename, canonical_filename, verbose=False):
         with open(filename, 'rb') as fp0:
             events = list(yaml.parse(fp0))
         for flow_style in [False, True]:
-            for style in ['|', '>', '"', '\'', '']:
+            for style in ['|', '>', '"', "'", ""]:
                 styled_events = []
                 for event in events:
                     if isinstance(event, yaml.ScalarEvent):
-                        event = yaml.ScalarEvent(event.anchor, event.tag,
-                                                 event.implicit, event.value, style=style)
+                        event = yaml.ScalarEvent(
+                            event.anchor, event.tag, event.implicit, event.value, style=style
+                        )
                     elif isinstance(event, yaml.SequenceStartEvent):
-                        event = yaml.SequenceStartEvent(event.anchor, event.tag,
-                                                        event.implicit, flow_style=flow_style)
+                        event = yaml.SequenceStartEvent(
+                            event.anchor, event.tag, event.implicit, flow_style=flow_style
+                        )
                     elif isinstance(event, yaml.MappingStartEvent):
-                        event = yaml.MappingStartEvent(event.anchor, event.tag,
-                                                       event.implicit, flow_style=flow_style)
+                        event = yaml.MappingStartEvent(
+                            event.anchor, event.tag, event.implicit, flow_style=flow_style
+                        )
                     styled_events.append(event)
                 output = yaml.emit(styled_events)
                 if verbose:
-                    print("OUTPUT (filename=%r, flow_style=%r, style=%r)" %
-                          (filename, flow_style, style))
+                    print(
+                        'OUTPUT (filename=%r, flow_style=%r, style=%r)'
+                        % (filename, flow_style, style)
+                    )
                     print(output)
                 new_events = list(yaml.parse(output))
                 _compare_events(events, new_events)
@@ -78,15 +83,18 @@ test_emitter_styles.unittest = ['.data', '.canonical']
 
 
 class EventsLoader(yaml.Loader):
-
     def construct_event(self, node):
         if isinstance(node, yaml.ScalarNode):
             mapping = {}
         else:
             mapping = self.construct_mapping(node)
         class_name = str(node.tag[1:]) + 'Event'
-        if class_name in ['AliasEvent', 'ScalarEvent', 'SequenceStartEvent',
-                          'MappingStartEvent']:
+        if class_name in [
+            'AliasEvent',
+            'ScalarEvent',
+            'SequenceStartEvent',
+            'MappingStartEvent',
+        ]:
             mapping.setdefault('anchor', None)
         if class_name in ['ScalarEvent', 'SequenceStartEvent', 'MappingStartEvent']:
             mapping.setdefault('tag', None)
@@ -94,10 +102,11 @@ class EventsLoader(yaml.Loader):
             mapping.setdefault('implicit', True)
         if class_name == 'ScalarEvent':
             mapping.setdefault('implicit', (False, True))
-            mapping.setdefault('value', '')
+            mapping.setdefault('value', "")
         value = getattr(yaml, class_name)(**mapping)
         return value
 
+
 # if Loader is not a composite, add this function
 # EventsLoader.add_constructor = yaml.constructor.Constructor.add_constructor
 
@@ -110,7 +119,7 @@ def test_emitter_events(events_filename, verbose=False):
         events = list(yaml.load(fp0, Loader=EventsLoader))
     output = yaml.emit(events)
     if verbose:
-        print("OUTPUT:")
+        print('OUTPUT:')
         print(output)
     new_events = list(yaml.parse(output))
     _compare_events(events, new_events)
@@ -118,4 +127,5 @@ def test_emitter_events(events_filename, verbose=False):
 
 if __name__ == '__main__':
     import test_appliance
+
     test_appliance.run(globals())
diff --git a/_test/lib/test_errors.py b/_test/lib/test_errors.py
index cfaa000..b43540c 100644
--- a/_test/lib/test_errors.py
+++ b/_test/lib/test_errors.py
@@ -4,6 +4,7 @@ from __future__ import print_function
 import ruamel.yaml as yaml
 import test_emitter
 import warnings
+
 warnings.simplefilter('ignore', yaml.error.UnsafeLoaderWarning)
 
 
@@ -13,9 +14,9 @@ def test_loader_error(error_filename, verbose=False):
             list(yaml.load_all(fp0))
     except yaml.YAMLError as exc:
         if verbose:
-            print("%s:" % exc.__class__.__name__, exc)
+            print('%s:' % exc.__class__.__name__, exc)
     else:
-        raise AssertionError("expected an exception")
+        raise AssertionError('expected an exception')
 
 
 test_loader_error.unittest = ['.loader-error']
@@ -27,9 +28,9 @@ def test_loader_error_string(error_filename, verbose=False):
             list(yaml.load_all(fp0.read()))
     except yaml.YAMLError as exc:
         if verbose:
-            print("%s:" % exc.__class__.__name__, exc)
+            print('%s:' % exc.__class__.__name__, exc)
     else:
-        raise AssertionError("expected an exception")
+        raise AssertionError('expected an exception')
 
 
 test_loader_error_string.unittest = ['.loader-error']
@@ -41,9 +42,9 @@ def test_loader_error_single(error_filename, verbose=False):
             yaml.load(fp0.read())
     except yaml.YAMLError as exc:
         if verbose:
-            print("%s:" % exc.__class__.__name__, exc)
+            print('%s:' % exc.__class__.__name__, exc)
     else:
-        raise AssertionError("expected an exception")
+        raise AssertionError('expected an exception')
 
 
 test_loader_error_single.unittest = ['.single-loader-error']
@@ -51,15 +52,14 @@ test_loader_error_single.unittest = ['.single-loader-error']
 
 def test_emitter_error(error_filename, verbose=False):
     with open(error_filename, 'rb') as fp0:
-        events = list(yaml.load(fp0,
-                                Loader=test_emitter.EventsLoader))
+        events = list(yaml.load(fp0, Loader=test_emitter.EventsLoader))
     try:
         yaml.emit(events)
     except yaml.YAMLError as exc:
         if verbose:
-            print("%s:" % exc.__class__.__name__, exc)
+            print('%s:' % exc.__class__.__name__, exc)
     else:
-        raise AssertionError("expected an exception")
+        raise AssertionError('expected an exception')
 
 
 test_emitter_error.unittest = ['.emitter-error']
@@ -70,16 +70,18 @@ def test_dumper_error(error_filename, verbose=False):
         code = fp0.read()
     try:
         import yaml
+
         exec(code)
     except yaml.YAMLError as exc:
         if verbose:
-            print("%s:" % exc.__class__.__name__, exc)
+            print('%s:' % exc.__class__.__name__, exc)
     else:
-        raise AssertionError("expected an exception")
+        raise AssertionError('expected an exception')
 
 
 test_dumper_error.unittest = ['.dumper-error']
 
 if __name__ == '__main__':
     import test_appliance
+
     test_appliance.run(globals())
diff --git a/_test/lib/test_input_output.py b/_test/lib/test_input_output.py
index 27f7aed..c36477f 100644
--- a/_test/lib/test_input_output.py
+++ b/_test/lib/test_input_output.py
@@ -9,6 +9,7 @@ import os.path
 from ruamel.yaml.compat import PY2, PY3, StringIO, BytesIO
 
 if PY2:
+
     def _unicode_open(file, encoding, errors='strict'):
         info = codecs.lookup(encoding)
         if isinstance(info, tuple):
@@ -21,7 +22,9 @@ if PY2:
         srw.encoding = encoding
         return srw
 
+
 if PY3:
+
     def test_unicode_input(unicode_filename, verbose=False):
         with open(unicode_filename, 'rb') as fp:
             data = fp.read().decode('utf-8')
@@ -30,64 +33,77 @@ if PY3:
         assert output == value, (output, value)
         output = yaml.load(StringIO(data))
         assert output == value, (output, value)
-        for input in [data.encode('utf-8'),
-                      codecs.BOM_UTF8 + data.encode('utf-8'),
-                      codecs.BOM_UTF16_BE + data.encode('utf-16-be'),
-                      codecs.BOM_UTF16_LE + data.encode('utf-16-le')]:
+        for input in [
+            data.encode('utf-8'),
+            codecs.BOM_UTF8 + data.encode('utf-8'),
+            codecs.BOM_UTF16_BE + data.encode('utf-16-be'),
+            codecs.BOM_UTF16_LE + data.encode('utf-16-le'),
+        ]:
             if verbose:
-                print("INPUT:", repr(input[:10]), "...")
+                print('INPUT:', repr(input[:10]), '...')
             output = yaml.load(input)
             assert output == value, (output, value)
             output = yaml.load(BytesIO(input))
             assert output == value, (output, value)
+
+
 else:
+
     def test_unicode_input(unicode_filename, verbose=False):
         with open(unicode_filename, 'rb') as fp:
             data = fp.read().decode('utf-8')
         value = ' '.join(data.split())
         output = yaml.load(_unicode_open(StringIO(data.encode('utf-8')), 'utf-8'))
         assert output == value, (output, value)
-        for input in [data, data.encode('utf-8'),
-                      codecs.BOM_UTF8 + data.encode('utf-8'),
-                      codecs.BOM_UTF16_BE + data.encode('utf-16-be'),
-                      codecs.BOM_UTF16_LE + data.encode('utf-16-le')]:
+        for input in [
+            data,
+            data.encode('utf-8'),
+            codecs.BOM_UTF8 + data.encode('utf-8'),
+            codecs.BOM_UTF16_BE + data.encode('utf-16-be'),
+            codecs.BOM_UTF16_LE + data.encode('utf-16-le'),
+        ]:
             if verbose:
-                print("INPUT:", repr(input[:10]), "...")
+                print('INPUT:', repr(input[:10]), '...')
             output = yaml.load(input)
             assert output == value, (output, value)
             output = yaml.load(StringIO(input))
             assert output == value, (output, value)
 
+
 test_unicode_input.unittest = ['.unicode']
 
 
 def test_unicode_input_errors(unicode_filename, verbose=False):
     with open(unicode_filename, 'rb') as fp:
         data = fp.read().decode('utf-8')
-    for input in [data.encode('latin1', 'ignore'),
-                  data.encode('utf-16-be'), data.encode('utf-16-le'),
-                  codecs.BOM_UTF8 + data.encode('utf-16-be'),
-                  codecs.BOM_UTF16_BE + data.encode('utf-16-le'),
-                  codecs.BOM_UTF16_LE + data.encode('utf-8') + b'!']:
+    for input in [
+        data.encode('latin1', 'ignore'),
+        data.encode('utf-16-be'),
+        data.encode('utf-16-le'),
+        codecs.BOM_UTF8 + data.encode('utf-16-be'),
+        codecs.BOM_UTF16_BE + data.encode('utf-16-le'),
+        codecs.BOM_UTF16_LE + data.encode('utf-8') + b'!',
+    ]:
         try:
             yaml.load(input)
         except yaml.YAMLError as exc:
             if verbose:
                 print(exc)
         else:
-            raise AssertionError("expected an exception")
+            raise AssertionError('expected an exception')
         try:
             yaml.load(BytesIO(input) if PY3 else StringIO(input))
         except yaml.YAMLError as exc:
             if verbose:
                 print(exc)
         else:
-            raise AssertionError("expected an exception")
+            raise AssertionError('expected an exception')
 
 
 test_unicode_input_errors.unittest = ['.unicode']
 
 if PY3:
+
     def test_unicode_output(unicode_filename, verbose=False):
         with open(unicode_filename, 'rb') as fp:
             data = fp.read().decode('utf-8')
@@ -105,19 +121,20 @@ if PY3:
                 stream = BytesIO()
                 if encoding is None:
                     try:
-                        yaml.dump(value, stream, encoding=encoding,
-                                  allow_unicode=allow_unicode)
+                        yaml.dump(
+                            value, stream, encoding=encoding, allow_unicode=allow_unicode
+                        )
                     except TypeError as exc:
                         if verbose:
                             print(exc)
                         data4 = None
                     else:
-                        raise AssertionError("expected an exception")
+                        raise AssertionError('expected an exception')
                 else:
                     yaml.dump(value, stream, encoding=encoding, allow_unicode=allow_unicode)
                     data4 = stream.getvalue()
                     if verbose:
-                        print("BYTES:", data4[:50])
+                        print('BYTES:', data4[:50])
                     data4 = data4.decode(encoding)
                 for copy in [data1, data2, data3, data4]:
                     if copy is None:
@@ -130,12 +147,15 @@ if PY3:
                             if verbose:
                                 print(exc)
                         else:
-                            raise AssertionError("expected an exception")
+                            raise AssertionError('expected an exception')
                     else:
                         copy[4:].encode('ascii')
                 assert isinstance(data1, str), (type(data1), encoding)
                 assert isinstance(data2, str), (type(data2), encoding)
+
+
 else:
+
     def test_unicode_output(unicode_filename, verbose=False):
         with open(unicode_filename, 'rb') as fp:
             data = fp.read().decode('utf-8')
@@ -144,8 +164,12 @@ else:
             data1 = yaml.dump(value, allow_unicode=allow_unicode)
             for encoding in [None, 'utf-8', 'utf-16-be', 'utf-16-le']:
                 stream = StringIO()
-                yaml.dump(value, _unicode_open(stream, 'utf-8'), encoding=encoding,
-                          allow_unicode=allow_unicode)
+                yaml.dump(
+                    value,
+                    _unicode_open(stream, 'utf-8'),
+                    encoding=encoding,
+                    allow_unicode=allow_unicode,
+                )
                 data2 = stream.getvalue()
                 data3 = yaml.dump(value, encoding=encoding, allow_unicode=allow_unicode)
                 stream = StringIO()
@@ -159,7 +183,7 @@ else:
                             if verbose:
                                 print(exc)
                         else:
-                            raise AssertionError("expected an exception")
+                            raise AssertionError('expected an exception')
                     else:
                         copy[4:].encode('ascii')
                 assert isinstance(data1, str), (type(data1), encoding)
@@ -206,8 +230,7 @@ def test_file_output(unicode_filename, verbose=False):
             with open(filename, 'rb') as fp0:
                 data2 = fp0.read()
             with open(filename, 'wb') as stream:
-                yaml.dump(data, stream, encoding='utf-16-le',
-                          allow_unicode=True)
+                yaml.dump(data, stream, encoding='utf-16-le', allow_unicode=True)
             with open(filename, 'rb') as fp0:
                 data3 = fp0.read().decode('utf-16-le')[1:].encode('utf-8')
             stream = _unicode_open(open(filename, 'wb'), 'utf-8')
@@ -267,4 +290,5 @@ test_unicode_transfer.unittest = ['.unicode']
 
 if __name__ == '__main__':
     import test_appliance
+
     test_appliance.run(globals())
diff --git a/_test/lib/test_mark.py b/_test/lib/test_mark.py
index 4e0728f..0ff2789 100644
--- a/_test/lib/test_mark.py
+++ b/_test/lib/test_mark.py
@@ -19,8 +19,7 @@ def test_marks(marks_filename, verbose=False):
             else:
                 column += 1
             index += 1
-        mark = yaml.Mark(marks_filename, index, line, column, text_type(input),
-                         index)
+        mark = yaml.Mark(marks_filename, index, line, column, text_type(input), index)
         snippet = mark.get_snippet(indent=2, max_length=79)
         if verbose:
             print(snippet)
@@ -35,4 +34,5 @@ test_marks.unittest = ['.marks']
 
 if __name__ == '__main__':
     import test_appliance
+
     test_appliance.run(globals())
diff --git a/_test/lib/test_reader.py b/_test/lib/test_reader.py
index 7ce0dc9..6604f24 100644
--- a/_test/lib/test_reader.py
+++ b/_test/lib/test_reader.py
@@ -1,7 +1,7 @@
 from __future__ import absolute_import
 from __future__ import print_function
 
-import codecs   # NOQA
+import codecs  # NOQA
 import io
 
 from ruamel.yaml.compat import PY2
@@ -17,7 +17,7 @@ def _run_reader(data, verbose):
         if verbose:
             print(exc)
     else:
-        raise AssertionError("expected an exception")
+        raise AssertionError('expected an exception')
 
 
 def test_stream_error(error_filename, verbose=False):
@@ -47,4 +47,5 @@ test_stream_error.unittest = ['.stream-error']
 
 if __name__ == '__main__':
     import test_appliance
+
     test_appliance.run(globals())
diff --git a/_test/lib/test_recursive.py b/_test/lib/test_recursive.py
index e7084e7..c87f879 100644
--- a/_test/lib/test_recursive.py
+++ b/_test/lib/test_recursive.py
@@ -11,14 +11,12 @@ class AnInstance:
 
     def __repr__(self):
         try:
-            return "%s(foo=%r, bar=%r)" % (self.__class__.__name__,
-                                           self.foo, self.bar)
+            return '%s(foo=%r, bar=%r)' % (self.__class__.__name__, self.foo, self.bar)
         except RuntimeError:
-            return "%s(foo=..., bar=...)" % self.__class__.__name__
+            return '%s(foo=..., bar=...)' % self.__class__.__name__
 
 
 class AnInstanceWithState(AnInstance):
-
     def __getstate__(self):
         return {'attributes': [self.foo, self.bar]}
 
@@ -41,11 +39,11 @@ def test_recursive(recursive_filename, verbose=False):
         assert output1 == output2, (output1, output2)
     finally:
         if verbose:
-            print("VALUE1:", value1)
-            print("VALUE2:", value2)
-            print("OUTPUT1:")
+            print('VALUE1:', value1)
+            print('VALUE2:', value2)
+            print('OUTPUT1:')
             print(output1)
-            print("OUTPUT2:")
+            print('OUTPUT2:')
             print(output2)
 
 
@@ -53,4 +51,5 @@ test_recursive.unittest = ['.recursive']
 
 if __name__ == '__main__':
     import test_appliance
+
     test_appliance.run(globals())
diff --git a/_test/lib/test_representer.py b/_test/lib/test_representer.py
index 2c7e2c8..a83d2b2 100644
--- a/_test/lib/test_representer.py
+++ b/_test/lib/test_representer.py
@@ -14,8 +14,12 @@ def test_representer_types(code_filename, verbose=False):
                 native1 = test_constructor._load_code(fp0.read())
             native2 = None
             try:
-                output = yaml.dump(native1, Dumper=test_constructor.MyDumper,
-                                   allow_unicode=allow_unicode, encoding=encoding)
+                output = yaml.dump(
+                    native1,
+                    Dumper=test_constructor.MyDumper,
+                    allow_unicode=allow_unicode,
+                    encoding=encoding,
+                )
                 native2 = yaml.load(output, Loader=test_constructor.MyLoader)
                 try:
                     if native1 == native2:
@@ -25,18 +29,18 @@ def test_representer_types(code_filename, verbose=False):
                 value1 = test_constructor._serialize_value(native1)
                 value2 = test_constructor._serialize_value(native2)
                 if verbose:
-                    print("SERIALIZED NATIVE1:")
+                    print('SERIALIZED NATIVE1:')
                     print(value1)
-                    print("SERIALIZED NATIVE2:")
+                    print('SERIALIZED NATIVE2:')
                     print(value2)
                 assert value1 == value2, (native1, native2)
             finally:
                 if verbose:
-                    print("NATIVE1:")
+                    print('NATIVE1:')
                     pprint.pprint(native1)
-                    print("NATIVE2:")
+                    print('NATIVE2:')
                     pprint.pprint(native2)
-                    print("OUTPUT:")
+                    print('OUTPUT:')
                     print(output)
 
 
@@ -44,4 +48,5 @@ test_representer_types.unittest = ['.code']
 
 if __name__ == '__main__':
     import test_appliance
+
     test_appliance.run(globals())
diff --git a/_test/lib/test_resolver.py b/_test/lib/test_resolver.py
index 4d1e6a4..0a04e7a 100644
--- a/_test/lib/test_resolver.py
+++ b/_test/lib/test_resolver.py
@@ -20,9 +20,9 @@ def test_implicit_resolver(data_filename, detect_filename, verbose=False):
             assert scalar.tag == correct_tag, (scalar.tag, correct_tag)
     finally:
         if verbose:
-            print("CORRECT TAG:", correct_tag)
+            print('CORRECT TAG:', correct_tag)
             if hasattr(node, 'value'):
-                print("CHILDREN:")
+                print('CHILDREN:')
                 pprint.pprint(node.value)
 
 
@@ -38,16 +38,19 @@ def _make_path_loader_and_dumper():
     class MyDumper(yaml.Dumper):
         pass
 
-    yaml.add_path_resolver(u'!root', [],
-                           Loader=MyLoader, Dumper=MyDumper)
-    yaml.add_path_resolver(u'!root/scalar', [], str,
-                           Loader=MyLoader, Dumper=MyDumper)
-    yaml.add_path_resolver(u'!root/key11/key12/*', ['key11', 'key12'],
-                           Loader=MyLoader, Dumper=MyDumper)
-    yaml.add_path_resolver(u'!root/key21/1/*', ['key21', 1],
-                           Loader=MyLoader, Dumper=MyDumper)
-    yaml.add_path_resolver(u'!root/key31/*/*/key14/map', ['key31', None, None, 'key14'], dict,
-                           Loader=MyLoader, Dumper=MyDumper)
+    yaml.add_path_resolver(u'!root', [], Loader=MyLoader, Dumper=MyDumper)
+    yaml.add_path_resolver(u'!root/scalar', [], str, Loader=MyLoader, Dumper=MyDumper)
+    yaml.add_path_resolver(
+        u'!root/key11/key12/*', ['key11', 'key12'], Loader=MyLoader, Dumper=MyDumper
+    )
+    yaml.add_path_resolver(u'!root/key21/1/*', ['key21', 1], Loader=MyLoader, Dumper=MyDumper)
+    yaml.add_path_resolver(
+        u'!root/key31/*/*/key14/map',
+        ['key31', None, None, 'key14'],
+        dict,
+        Loader=MyLoader,
+        Dumper=MyDumper,
+    )
 
     return MyLoader, MyDumper
 
@@ -106,4 +109,5 @@ test_path_resolver_dumper.unittest = ['.data', '.path']
 
 if __name__ == '__main__':
     import test_appliance
+
     test_appliance.run(globals())
diff --git a/_test/lib/test_structure.py b/_test/lib/test_structure.py
index 4d04b11..2656bbb 100644
--- a/_test/lib/test_structure.py
+++ b/_test/lib/test_structure.py
@@ -2,7 +2,7 @@ from __future__ import absolute_import
 from __future__ import print_function
 
 import ruamel.yaml as yaml
-import canonical   # NOQA
+import canonical  # NOQA
 import pprint
 from ruamel.yaml.compat import text_type, PY3
 
@@ -46,8 +46,12 @@ def test_structure(data_filename, structure_filename, verbose=False):
         with open(data_filename, 'rb') as fp:
             loader = yaml.Loader(fp)
         while loader.check_event():
-            if loader.check_event(yaml.StreamStartEvent, yaml.StreamEndEvent,
-                                  yaml.DocumentStartEvent, yaml.DocumentEndEvent):
+            if loader.check_event(
+                yaml.StreamStartEvent,
+                yaml.StreamEndEvent,
+                yaml.DocumentStartEvent,
+                yaml.DocumentEndEvent,
+            ):
                 loader.get_event()
                 continue
             nodes1.append(_convert_structure(loader))
@@ -56,9 +60,9 @@ def test_structure(data_filename, structure_filename, verbose=False):
         assert nodes1 == nodes2, (nodes1, nodes2)
     finally:
         if verbose:
-            print("NODES1:")
+            print('NODES1:')
             pprint.pprint(nodes1)
-            print("NODES2:")
+            print('NODES2:')
             pprint.pprint(nodes2)
 
 
@@ -89,9 +93,9 @@ def test_parser(data_filename, canonical_filename, verbose=False):
         _compare_events(events1, events2)
     finally:
         if verbose:
-            print("EVENTS1:")
+            print('EVENTS1:')
             pprint.pprint(events1)
-            print("EVENTS2:")
+            print('EVENTS2:')
             pprint.pprint(events2)
 
 
@@ -109,9 +113,9 @@ def test_parser_on_canonical(canonical_filename, verbose=False):
         _compare_events(events1, events2, full=True)
     finally:
         if verbose:
-            print("EVENTS1:")
+            print('EVENTS1:')
             pprint.pprint(events1)
-            print("EVENTS2:")
+            print('EVENTS2:')
             pprint.pprint(events2)
 
 
@@ -146,9 +150,9 @@ def test_composer(data_filename, canonical_filename, verbose=False):
             _compare_nodes(node1, node2)
     finally:
         if verbose:
-            print("NODES1:")
+            print('NODES1:')
             pprint.pprint(nodes1)
-            print("NODES2:")
+            print('NODES2:')
             pprint.pprint(nodes2)
 
 
@@ -189,8 +193,9 @@ def _make_canonical_loader():
         def construct_undefined(self, node):
             return self.construct_scalar(node)
 
-    MyCanonicalLoader.add_constructor(u'tag:yaml.org,2002:map',
-                                      MyCanonicalLoader.construct_mapping)
+    MyCanonicalLoader.add_constructor(
+        u'tag:yaml.org,2002:map', MyCanonicalLoader.construct_mapping
+    )
     MyCanonicalLoader.add_constructor(None, MyCanonicalLoader.construct_undefined)
 
 
@@ -207,9 +212,9 @@ def test_constructor(data_filename, canonical_filename, verbose=False):
         assert native1 == native2, (native1, native2)
     finally:
         if verbose:
-            print("NATIVE1:")
+            print('NATIVE1:')
             pprint.pprint(native1)
-            print("NATIVE2:")
+            print('NATIVE2:')
             pprint.pprint(native2)
 
 
@@ -217,4 +222,5 @@ test_constructor.unittest = ['.data', '.canonical']
 
 if __name__ == '__main__':
     import test_appliance
+
     test_appliance.run(globals())
diff --git a/_test/lib/test_tokens.py b/_test/lib/test_tokens.py
index e240efe..cdb41ba 100644
--- a/_test/lib/test_tokens.py
+++ b/_test/lib/test_tokens.py
@@ -53,13 +53,12 @@ def test_tokens(data_filename, tokens_filename, verbose=False):
     try:
         with open(data_filename, 'rb') as fp1:
             for token in yaml.scan(fp1):
-                if not isinstance(
-                        token, (yaml.StreamStartToken, yaml.StreamEndToken)):
+                if not isinstance(token, (yaml.StreamStartToken, yaml.StreamEndToken)):
                     tokens1.append(_replaces[token.__class__])
     finally:
         if verbose:
-            print("TOKENS1:", ' '.join(tokens1))
-            print("TOKENS2:", ' '.join(tokens2))
+            print('TOKENS1:', ' '.join(tokens1))
+            print('TOKENS2:', ' '.join(tokens2))
     assert len(tokens1) == len(tokens2), (tokens1, tokens2)
     for token1, token2 in zip(tokens1, tokens2):
         assert token1 == token2, (token1, token2)
@@ -84,4 +83,5 @@ test_scanner.unittest = ['.data', '.canonical']
 
 if __name__ == '__main__':
     import test_appliance
+
     test_appliance.run(globals())
diff --git a/_test/lib/test_yaml.py b/_test/lib/test_yaml.py
index c650762..cf64a73 100644
--- a/_test/lib/test_yaml.py
+++ b/_test/lib/test_yaml.py
@@ -1,19 +1,20 @@
 # coding: utf-8
 
-from test_mark import *          # NOQA
-from test_reader import *        # NOQA
-from test_canonical import *     # NOQA
-from test_tokens import *        # NOQA
-from test_structure import *     # NOQA
-from test_errors import *        # NOQA
-from test_resolver import *      # NOQA
-from test_constructor import *   # NOQA
-from test_emitter import *       # NOQA
-from test_representer import *   # NOQA
-from test_recursive import *     # NOQA
+from test_mark import *  # NOQA
+from test_reader import *  # NOQA
+from test_canonical import *  # NOQA
+from test_tokens import *  # NOQA
+from test_structure import *  # NOQA
+from test_errors import *  # NOQA
+from test_resolver import *  # NOQA
+from test_constructor import *  # NOQA
+from test_emitter import *  # NOQA
+from test_representer import *  # NOQA
+from test_recursive import *  # NOQA
 from test_input_output import *  # NOQA
 
 if __name__ == '__main__':
     import sys
     import test_appliance
+
     sys.exit(test_appliance.run(globals()))
diff --git a/_test/lib/test_yaml_ext.py b/_test/lib/test_yaml_ext.py
index c4a1493..e36ddd0 100644
--- a/_test/lib/test_yaml_ext.py
+++ b/_test/lib/test_yaml_ext.py
@@ -173,8 +173,10 @@ def test_c_version(verbose=False):
     if verbose:
         print(_ruamel_yaml.get_version())
         print(_ruamel_yaml.get_version_string())
-    assert ("%s.%s.%s" % _ruamel_yaml.get_version()) == _ruamel_yaml.get_version_string(), \
-           (_ruamel_yaml.get_version(), _ruamel_yaml.get_version_string())
+    assert ('%s.%s.%s' % _ruamel_yaml.get_version()) == _ruamel_yaml.get_version_string(), (
+        _ruamel_yaml.get_version(),
+        _ruamel_yaml.get_version_string(),
+    )
 
 
 def _compare_scanners(py_data, c_data, verbose):
@@ -190,20 +192,29 @@ def _compare_scanners(py_data, c_data, verbose):
                 assert py_token.value == c_token.value, (py_token, c_token)
             if isinstance(py_token, ruamel.yaml.StreamEndToken):
                 continue
-            py_start = (py_token.start_mark.index, py_token.start_mark.line,
-                        py_token.start_mark.column)
-            py_end = (py_token.end_mark.index, py_token.end_mark.line,
-                      py_token.end_mark.column)
-            c_start = (c_token.start_mark.index, c_token.start_mark.line,
-                       c_token.start_mark.column)
+            py_start = (
+                py_token.start_mark.index,
+                py_token.start_mark.line,
+                py_token.start_mark.column,
+            )
+            py_end = (
+                py_token.end_mark.index,
+                py_token.end_mark.line,
+                py_token.end_mark.column,
+            )
+            c_start = (
+                c_token.start_mark.index,
+                c_token.start_mark.line,
+                c_token.start_mark.column,
+            )
             c_end = (c_token.end_mark.index, c_token.end_mark.line, c_token.end_mark.column)
             assert py_start == c_start, (py_start, c_start)
             assert py_end == c_end, (py_end, c_end)
     finally:
         if verbose:
-            print("PY_TOKENS:")
+            print('PY_TOKENS:')
             pprint.pprint(py_tokens)
-            print("C_TOKENS:")
+            print('C_TOKENS:')
             pprint.pprint(c_tokens)
 
 
@@ -234,16 +245,24 @@ def _compare_parsers(py_data, c_data, verbose):
             c_events.append(event)
         assert len(py_events) == len(c_events), (len(py_events), len(c_events))
         for py_event, c_event in zip(py_events, c_events):
-            for attribute in ['__class__', 'anchor', 'tag', 'implicit',
-                              'value', 'explicit', 'version', 'tags']:
+            for attribute in [
+                '__class__',
+                'anchor',
+                'tag',
+                'implicit',
+                'value',
+                'explicit',
+                'version',
+                'tags',
+            ]:
                 py_value = getattr(py_event, attribute, None)
                 c_value = getattr(c_event, attribute, None)
                 assert py_value == c_value, (py_event, c_event, attribute)
     finally:
         if verbose:
-            print("PY_EVENTS:")
+            print('PY_EVENTS:')
             pprint.pprint(py_events)
-            print("C_EVENTS:")
+            print('C_EVENTS:')
             pprint.pprint(c_events)
 
 
@@ -277,13 +296,25 @@ def _compare_emitters(data, verbose):
         assert len(events) == len(py_events), (len(events), len(py_events))
         assert len(events) == len(c_events), (len(events), len(c_events))
         for event, py_event, c_event in zip(events, py_events, c_events):
-            for attribute in ['__class__', 'anchor', 'tag', 'implicit',
-                              'value', 'explicit', 'version', 'tags']:
+            for attribute in [
+                '__class__',
+                'anchor',
+                'tag',
+                'implicit',
+                'value',
+                'explicit',
+                'version',
+                'tags',
+            ]:
                 value = getattr(event, attribute, None)
                 py_value = getattr(py_event, attribute, None)
                 c_value = getattr(c_event, attribute, None)
-                if attribute == 'tag' and value in [None, u'!'] \
-                        and py_value in [None, u'!'] and c_value in [None, u'!']:
+                if (
+                    attribute == 'tag'
+                    and value in [None, u'!']
+                    and py_value in [None, u'!']
+                    and c_value in [None, u'!']
+                ):
                     continue
                 if attribute == 'explicit' and (py_value or c_value):
                     continue
@@ -291,11 +322,11 @@ def _compare_emitters(data, verbose):
                 assert value == c_value, (event, c_event, attribute)
     finally:
         if verbose:
-            print("EVENTS:")
+            print('EVENTS:')
             pprint.pprint(events)
-            print("PY_EVENTS:")
+            print('PY_EVENTS:')
             pprint.pprint(py_events)
-            print("C_EVENTS:")
+            print('C_EVENTS:')
             pprint.pprint(c_events)
 
 
@@ -317,6 +348,7 @@ def wrap_ext_function(function):
             function(*args, **kwds)
         finally:
             _tear_down()
+
     if PY3:
         wrapper.__name__ = '%s_ext' % function.__name__
     else:
@@ -349,19 +381,33 @@ def wrap_ext(collections):
             assert function.unittest_name not in globals()
             globals()[function.unittest_name] = function
 
-import test_tokens         # NOQA
-import test_structure      # NOQA
-import test_errors         # NOQA
-import test_resolver       # NOQA
-import test_constructor    # NOQA
-import test_emitter        # NOQA
-import test_representer    # NOQA
-import test_recursive      # NOQA
-import test_input_output   # NOQA
-wrap_ext([test_tokens, test_structure, test_errors, test_resolver, test_constructor,
-          test_emitter, test_representer, test_recursive, test_input_output])
+
+import test_tokens  # NOQA
+import test_structure  # NOQA
+import test_errors  # NOQA
+import test_resolver  # NOQA
+import test_constructor  # NOQA
+import test_emitter  # NOQA
+import test_representer  # NOQA
+import test_recursive  # NOQA
+import test_input_output  # NOQA
+
+wrap_ext(
+    [
+        test_tokens,
+        test_structure,
+        test_errors,
+        test_resolver,
+        test_constructor,
+        test_emitter,
+        test_representer,
+        test_recursive,
+        test_input_output,
+    ]
+)
 
 if __name__ == '__main__':
     import sys
     import test_appliance
+
     sys.exit(test_appliance.run(globals()))
diff --git a/_test/roundtrip.py b/_test/roundtrip.py
index 8548969..86e4862 100644
--- a/_test/roundtrip.py
+++ b/_test/roundtrip.py
@@ -21,12 +21,13 @@ def dedent(data):
     except ValueError:
         pass
     else:
-        data = data[position_of_first_newline + 1:]
+        data = data[position_of_first_newline + 1 :]
     return textwrap.dedent(data)
 
 
 def round_trip_load(inp, preserve_quotes=None, version=None):
     import ruamel.yaml  # NOQA
+
     dinp = dedent(inp)
     return ruamel.yaml.load(
         dinp,
@@ -38,6 +39,7 @@ def round_trip_load(inp, preserve_quotes=None, version=None):
 
 def round_trip_load_all(inp, preserve_quotes=None, version=None):
     import ruamel.yaml  # NOQA
+
     dinp = dedent(inp)
     return ruamel.yaml.load_all(
         dinp,
@@ -47,21 +49,35 @@ def round_trip_load_all(inp, preserve_quotes=None, version=None):
     )
 
 
-def round_trip_dump(data, stream=None,
-                    indent=None, block_seq_indent=None, top_level_colon_align=None,
-                    prefix_colon=None, explicit_start=None, explicit_end=None, version=None):
+def round_trip_dump(
+    data,
+    stream=None,
+    indent=None,
+    block_seq_indent=None,
+    top_level_colon_align=None,
+    prefix_colon=None,
+    explicit_start=None,
+    explicit_end=None,
+    version=None,
+):
     import ruamel.yaml  # NOQA
-    return ruamel.yaml.round_trip_dump(data, stream=stream,
-                                       indent=indent, block_seq_indent=block_seq_indent,
-                                       top_level_colon_align=top_level_colon_align,
-                                       prefix_colon=prefix_colon,
-                                       explicit_start=explicit_start,
-                                       explicit_end=explicit_end,
-                                       version=version)
+
+    return ruamel.yaml.round_trip_dump(
+        data,
+        stream=stream,
+        indent=indent,
+        block_seq_indent=block_seq_indent,
+        top_level_colon_align=top_level_colon_align,
+        prefix_colon=prefix_colon,
+        explicit_start=explicit_start,
+        explicit_end=explicit_end,
+        version=version,
+    )
 
 
 def diff(inp, outp, file_name='stdin'):
     import difflib
+
     inl = inp.splitlines(True)  # True for keepends
     outl = outp.splitlines(True)
     diff = difflib.unified_diff(inl, outl, file_name, 'round trip YAML')
@@ -73,11 +89,20 @@ def diff(inp, outp, file_name='stdin'):
         sys.stdout.write(line)
 
 
-def round_trip(inp, outp=None, extra=None, intermediate=None, indent=None,
-               block_seq_indent=None, top_level_colon_align=None, prefix_colon=None,
-               preserve_quotes=None,
-               explicit_start=None, explicit_end=None,
-               version=None):
+def round_trip(
+    inp,
+    outp=None,
+    extra=None,
+    intermediate=None,
+    indent=None,
+    block_seq_indent=None,
+    top_level_colon_align=None,
+    prefix_colon=None,
+    preserve_quotes=None,
+    explicit_start=None,
+    explicit_end=None,
+    version=None,
+):
     """
     inp:    input string to parse
     outp:   expected output (equals input if not specified)
@@ -94,23 +119,31 @@ def round_trip(inp, outp=None, extra=None, intermediate=None, indent=None,
                 if data[k] != v:
                     print('{0!r} <> {1!r}'.format(data[k], v))
                     raise ValueError
-    res = round_trip_dump(data, indent=indent, block_seq_indent=block_seq_indent,
-                          top_level_colon_align=top_level_colon_align,
-                          prefix_colon=prefix_colon,
-                          explicit_start=explicit_start,
-                          explicit_end=explicit_end,
-                          version=version)
+    res = round_trip_dump(
+        data,
+        indent=indent,
+        block_seq_indent=block_seq_indent,
+        top_level_colon_align=top_level_colon_align,
+        prefix_colon=prefix_colon,
+        explicit_start=explicit_start,
+        explicit_end=explicit_end,
+        version=version,
+    )
     if res != doutp:
-        diff(doutp, res, "input string")
-    print('\nroundtrip data:\n', res, sep='')
+        diff(doutp, res, 'input string')
+    print('\nroundtrip data:\n', res, sep="")
     assert res == doutp
-    res = round_trip_dump(data, indent=indent, block_seq_indent=block_seq_indent,
-                          top_level_colon_align=top_level_colon_align,
-                          prefix_colon=prefix_colon,
-                          explicit_start=explicit_start,
-                          explicit_end=explicit_end,
-                          version=version)
-    print('roundtrip second round data:\n', res, sep='')
+    res = round_trip_dump(
+        data,
+        indent=indent,
+        block_seq_indent=block_seq_indent,
+        top_level_colon_align=top_level_colon_align,
+        prefix_colon=prefix_colon,
+        explicit_start=explicit_start,
+        explicit_end=explicit_end,
+        version=version,
+    )
+    print('roundtrip second round data:\n', res, sep="")
     assert res == doutp
     return data
 
@@ -120,6 +153,7 @@ def YAML(**kw):
 
     class MyYAML(ruamel.yaml.YAML):
         """auto dedent string parameters on load"""
+
         def load(self, stream):
             if isinstance(stream, str):
                 if stream and stream[0] == '\n':
@@ -137,6 +171,7 @@ def YAML(**kw):
 
         def dump(self, data, **kw):
             from ruamel.yaml.compat import StringIO, BytesIO  # NOQA
+
             assert ('stream' in kw) ^ ('compare' in kw)
             if 'stream' in kw:
                 return ruamel.yaml.YAML.dump(data, **kw)
@@ -156,6 +191,7 @@ def YAML(**kw):
 
         def round_trip(self, stream, **kw):
             from ruamel.yaml.compat import StringIO, BytesIO  # NOQA
+
             assert isinstance(stream, ruamel.yaml.compat.text_type)
             lkw = kw.copy()
             if stream and stream[0] == '\n':
@@ -167,7 +203,7 @@ def YAML(**kw):
             ruamel.yaml.YAML.dump(self, data, **lkw)
             res = st.getvalue()
             if res != outp:
-                diff(outp, res, "input string")
+                diff(outp, res, 'input string')
             assert res == outp
 
     return MyYAML(**kw)
diff --git a/_test/test_a_dedent.py b/_test/test_a_dedent.py
index 1362deb..984e1a2 100644
--- a/_test/test_a_dedent.py
+++ b/_test/test_a_dedent.py
@@ -4,39 +4,54 @@ from roundtrip import dedent
 
 class TestDedent:
     def test_start_newline(self):
-        x = dedent("""
+        x = dedent(
+            """
         123
           456
-        """)
-        assert x == "123\n  456\n"
+        """
+        )
+        assert x == '123\n  456\n'
 
     def test_start_space_newline(self):
         # special construct to prevent stripping of following whitespac
-        x = dedent("   " """
+        x = dedent(
+            '   '
+            """
         123
-        """)
-        assert x == "123\n"
+        """
+        )
+        assert x == '123\n'
 
     def test_start_no_newline(self):
         # special construct to prevent stripping of following whitespac
-        x = dedent("""\
+        x = dedent(
+            """\
         123
           456
-        """)
-        assert x == "123\n  456\n"
+        """
+        )
+        assert x == '123\n  456\n'
 
     def test_preserve_no_newline_at_end(self):
-        x = dedent("""
-        123""")
-        assert x == "123"
+        x = dedent(
+            """
+        123"""
+        )
+        assert x == '123'
 
     def test_preserve_no_newline_at_all(self):
-        x = dedent("""\
-        123""")
-        assert x == "123"
+        x = dedent(
+            """\
+        123"""
+        )
+        assert x == '123'
 
     def test_multiple_dedent(self):
-        x = dedent(dedent("""
+        x = dedent(
+            dedent(
+                """
         123
-        """))
-        assert x == "123\n"
+        """
+            )
+        )
+        assert x == '123\n'
diff --git a/_test/test_add_xxx.py b/_test/test_add_xxx.py
index f2e976f..031b89f 100644
--- a/_test/test_add_xxx.py
+++ b/_test/test_add_xxx.py
@@ -1,7 +1,7 @@
 # coding: utf-8
 
 import re
-import pytest   # NOQA
+import pytest  # NOQA
 
 from roundtrip import dedent
 
@@ -12,7 +12,7 @@ class Dice(tuple):
         return tuple.__new__(cls, [a, b])
 
     def __repr__(self):
-        return "Dice(%s,%s)" % self
+        return 'Dice(%s,%s)' % self
 
 
 def dice_constructor(loader, node):
@@ -27,6 +27,7 @@ def dice_representer(dumper, data):
 
 def test_dice_constructor():
     import ruamel.yaml  # NOQA
+
     ruamel.yaml.add_constructor(u'!dice', dice_constructor)
     data = ruamel.yaml.load('initial hit points: !dice 8d4', Loader=ruamel.yaml.Loader)
     assert str(data) == "{'initial hit points': Dice(8,4)}"
@@ -34,6 +35,7 @@ def test_dice_constructor():
 
 def test_dice_constructor_with_loader():
     import ruamel.yaml  # NOQA
+
     ruamel.yaml.add_constructor(u'!dice', dice_constructor, Loader=ruamel.yaml.Loader)
     data = ruamel.yaml.load('initial hit points: !dice 8d4', Loader=ruamel.yaml.Loader)
     assert str(data) == "{'initial hit points': Dice(8,4)}"
@@ -41,20 +43,27 @@ def test_dice_constructor_with_loader():
 
 def test_dice_representer():
     import ruamel.yaml  # NOQA
+
     ruamel.yaml.add_representer(Dice, dice_representer)
     # ruamel.yaml 0.15.8+ no longer forces quotes tagged scalars
-    assert ruamel.yaml.dump(dict(gold=Dice(10, 6)), default_flow_style=False) == \
-        "gold: !dice 10d6\n"
+    assert (
+        ruamel.yaml.dump(dict(gold=Dice(10, 6)), default_flow_style=False)
+        == 'gold: !dice 10d6\n'
+    )
 
 
 def test_dice_implicit_resolver():
     import ruamel.yaml  # NOQA
+
     pattern = re.compile(r'^\d+d\d+$')
     ruamel.yaml.add_implicit_resolver(u'!dice', pattern)
-    assert ruamel.yaml.dump(dict(treasure=Dice(10, 20)), default_flow_style=False) == \
-        'treasure: 10d20\n'
-    assert ruamel.yaml.load('damage: 5d10', Loader=ruamel.yaml.Loader) == \
-        dict(damage=Dice(5, 10))
+    assert (
+        ruamel.yaml.dump(dict(treasure=Dice(10, 20)), default_flow_style=False)
+        == 'treasure: 10d20\n'
+    )
+    assert ruamel.yaml.load('damage: 5d10', Loader=ruamel.yaml.Loader) == dict(
+        damage=Dice(5, 10)
+    )
 
 
 class Obj1(dict):
@@ -78,6 +87,7 @@ class YAMLObj1(object):
     @classmethod
     def from_yaml(cls, loader, suffix, node):
         import ruamel.yaml  # NOQA
+
         obj1 = Obj1(suffix)
         if isinstance(node, ruamel.yaml.MappingNode):
             obj1.add_node(loader.construct_mapping(node))
@@ -92,22 +102,25 @@ class YAMLObj1(object):
 
 def test_yaml_obj():
     import ruamel.yaml  # NOQA
+
     ruamel.yaml.add_representer(Obj1, YAMLObj1.to_yaml)
     ruamel.yaml.add_multi_constructor(YAMLObj1.yaml_tag, YAMLObj1.from_yaml)
     x = ruamel.yaml.load('!obj:x.2\na: 1', Loader=ruamel.yaml.Loader)
     print(x)
-    assert ruamel.yaml.dump(x) == '''!obj:x.2 "{'a': 1}"\n'''
+    assert ruamel.yaml.dump(x) == """!obj:x.2 "{'a': 1}"\n"""
 
 
 def test_yaml_obj_with_loader_and_dumper():
     import ruamel.yaml  # NOQA
+
     ruamel.yaml.add_representer(Obj1, YAMLObj1.to_yaml, Dumper=ruamel.yaml.Dumper)
-    ruamel.yaml.add_multi_constructor(YAMLObj1.yaml_tag, YAMLObj1.from_yaml,
-                                      Loader=ruamel.yaml.Loader)
+    ruamel.yaml.add_multi_constructor(
+        YAMLObj1.yaml_tag, YAMLObj1.from_yaml, Loader=ruamel.yaml.Loader
+    )
     x = ruamel.yaml.load('!obj:x.2\na: 1', Loader=ruamel.yaml.Loader)
     # x = ruamel.yaml.load('!obj:x.2\na: 1')
     print(x)
-    assert ruamel.yaml.dump(x) == '''!obj:x.2 "{'a': 1}"\n'''
+    assert ruamel.yaml.dump(x) == """!obj:x.2 "{'a': 1}"\n"""
 
 
 # ToDo use nullege to search add_multi_representer and add_path_resolver
@@ -134,12 +147,13 @@ def test_issue_127():
         @classmethod
         def to_yaml(cls, dumper, data):
             if isinstance(data.logical_id, ruamel.yaml.scalarstring.ScalarString):
-                style = data.logical_id.style   # ruamel.yaml>0.15.8
+                style = data.logical_id.style  # ruamel.yaml>0.15.8
             else:
                 style = None
             return dumper.represent_scalar(cls.yaml_tag, data.logical_id, style=style)
 
-    document = dedent('''\
+    document = dedent(
+        """\
     AList:
       - !Ref One
       - !Ref 'Two'
@@ -149,7 +163,9 @@ def test_issue_127():
     CList:
       - Five Six
       - 'Seven Eight'
-    ''')
+    """
+    )
     data = ruamel.yaml.round_trip_load(document, preserve_quotes=True)
-    assert ruamel.yaml.round_trip_dump(data, indent=4, block_seq_indent=2) == \
-        document.replace('\n    Two and', ' Two and')
+    assert ruamel.yaml.round_trip_dump(data, indent=4, block_seq_indent=2) == document.replace(
+        '\n    Two and', ' Two and'
+    )
diff --git a/_test/test_anchor.py b/_test/test_anchor.py
index ae6469a..cb632d8 100644
--- a/_test/test_anchor.py
+++ b/_test/test_anchor.py
@@ -22,23 +22,30 @@ def compare(d, s):
 class TestAnchorsAliases:
     def test_anchor_id_renumber(self):
         from ruamel.yaml.serializer import Serializer
+
         assert Serializer.ANCHOR_TEMPLATE == 'id%03d'
-        data = load("""
+        data = load(
+            """
         a: &id002
           b: 1
           c: 2
         d: *id002
-        """)
-        compare(data, """
+        """
+        )
+        compare(
+            data,
+            """
         a: &id001
           b: 1
           c: 2
         d: *id001
-        """)
+        """,
+        )
 
     def test_template_matcher(self):
         """test if id matches the anchor template"""
         from ruamel.yaml.serializer import templated_id
+
         assert templated_id(u'id001')
         assert templated_id(u'id999')
         assert templated_id(u'id1000')
@@ -56,7 +63,9 @@ class TestAnchorsAliases:
 
     def test_anchor_assigned(self):
         from ruamel.yaml.comments import CommentedMap
-        data = load("""
+
+        data = load(
+            """
         a: &id002
           b: 1
           c: 2
@@ -65,7 +74,8 @@ class TestAnchorsAliases:
           b: 1
           c: 2
         f: *etemplate
-        """)
+        """
+        )
         d = data['d']
         assert isinstance(d, CommentedMap)
         assert d.yaml_anchor() is None  # got dropped as it matches pattern
@@ -75,7 +85,8 @@ class TestAnchorsAliases:
         assert e.yaml_anchor().always_dump is False
 
     def test_anchor_id_retained(self):
-        data = load("""
+        data = load(
+            """
         a: &id002
           b: 1
           c: 2
@@ -84,8 +95,11 @@ class TestAnchorsAliases:
           b: 1
           c: 2
         f: *etemplate
-        """)
-        compare(data, """
+        """
+        )
+        compare(
+            data,
+            """
         a: &id001
           b: 1
           c: 2
@@ -94,26 +108,33 @@ class TestAnchorsAliases:
           b: 1
           c: 2
         f: *etemplate
-        """)
+        """,
+        )
 
-    @pytest.mark.skipif(platform.python_implementation() == 'Jython',
-                        reason="Jython throws RepresenterError")
+    @pytest.mark.skipif(
+        platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
+    )
     def test_alias_before_anchor(self):
         from ruamel.yaml.composer import ComposerError
+
         with pytest.raises(ComposerError):
-            data = load("""
+            data = load(
+                """
             d: *id002
             a: &id002
               b: 1
               c: 2
-            """)
+            """
+            )
             data = data
 
     def test_anchor_on_sequence(self):
         # as reported by Bjorn Stabell
         # https://bitbucket.org/ruamel/yaml/issue/7/anchor-names-not-preserved
         from ruamel.yaml.comments import CommentedSeq
-        data = load("""
+
+        data = load(
+            """
         nut1: &alice
          - 1
          - 2
@@ -123,13 +144,15 @@ class TestAnchorsAliases:
         nut3:
          - *blake
          - *alice
-        """)
+        """
+        )
         r = data['nut1']
         assert isinstance(r, CommentedSeq)
         assert r.yaml_anchor() is not None
         assert r.yaml_anchor().value == 'alice'
 
-    merge_yaml = dedent("""
+    merge_yaml = dedent(
+        """
         - &CENTER {x: 1, y: 2}
         - &LEFT {x: 0, y: 2}
         - &BIG {r: 10}
@@ -151,7 +174,8 @@ class TestAnchorsAliases:
         - <<: [*BIG, *LEFT, *SMALL]
           x: 1
           label: center/huge
-        """)
+        """
+    )
 
     def test_merge_00(self):
         data = load(self.merge_yaml)
@@ -171,14 +195,17 @@ class TestAnchorsAliases:
 
     def test_merge_accessible(self):
         from ruamel.yaml.comments import CommentedMap, merge_attrib
-        data = load("""
+
+        data = load(
+            """
         k: &level_2 { a: 1, b2 }
         l: &level_1 { a: 10, c: 3 }
         m:
           <<: *level_1
           c: 30
           d: 40
-        """)
+        """
+        )
         d = data['m']
         assert isinstance(d, CommentedMap)
         assert hasattr(d, merge_attrib)
@@ -188,7 +215,7 @@ class TestAnchorsAliases:
         compare(data, self.merge_yaml)
 
     def test_merge_nested(self):
-        yaml = '''
+        yaml = """
         a:
           <<: &content
             1: plugh
@@ -196,11 +223,11 @@ class TestAnchorsAliases:
           0: xyzzy
         b:
           <<: *content
-        '''
+        """
         data = round_trip(yaml)  # NOQA
 
     def test_merge_nested_with_sequence(self):
-        yaml = '''
+        yaml = """
         a:
           <<: &content
             <<: &y2
@@ -209,11 +236,12 @@ class TestAnchorsAliases:
           0: xyzzy
         b:
           <<: [*content, *y2]
-        '''
+        """
         data = round_trip(yaml)  # NOQA
 
     def test_add_anchor(self):
         from ruamel.yaml.comments import CommentedMap
+
         data = CommentedMap()
         data_a = CommentedMap()
         data['a'] = data_a
@@ -221,31 +249,37 @@ class TestAnchorsAliases:
         data['b'] = 2
         data.yaml_set_anchor('klm', always_dump=True)
         data['a'].yaml_set_anchor('xyz', always_dump=True)
-        compare(data, """
+        compare(
+            data,
+            """
         &klm
         a: &xyz
           c: 3
         b: 2
-        """)
+        """,
+        )
 
     # this is an error in PyYAML
     def test_reused_anchor(self):
         from ruamel.yaml.error import ReusedAnchorWarning
-        yaml = '''
+
+        yaml = """
         - &a
           x: 1
         - <<: *a
         - &a
           x: 2
         - <<: *a
-        '''
+        """
         with pytest.warns(ReusedAnchorWarning):
             data = round_trip(yaml)  # NOQA
 
     def test_issue_130(self):
         # issue 130 reported by Devid Fee
         import ruamel.yaml
-        ys = dedent("""\
+
+        ys = dedent(
+            """\
         components:
           server: &server_component
             type: spark.server:ServerComponent
@@ -261,14 +295,17 @@ class TestAnchorsAliases:
             <<: *shell_component
             components:
               server: {<<: *server_service}
-        """)
+        """
+        )
         data = ruamel.yaml.safe_load(ys)
         assert data['services']['shell']['components']['server']['port'] == 8000
 
     def test_issue_130a(self):
         # issue 130 reported by Devid Fee
         import ruamel.yaml
-        ys = dedent("""\
+
+        ys = dedent(
+            """\
         components:
           server: &server_component
             type: spark.server:ServerComponent
@@ -285,14 +322,16 @@ class TestAnchorsAliases:
             <<: *shell_component
             components:
               server: {<<: *server_service}
-        """)
+        """
+        )
         data = ruamel.yaml.safe_load(ys)
         assert data['services']['shell']['components']['server']['port'] == 4000
 
 
 class TestMergeKeysValues:
 
-    yaml_str = dedent("""\
+    yaml_str = dedent(
+        """\
     - &mx
       a: x1
       b: x2
@@ -306,12 +345,14 @@ class TestMergeKeysValues:
       <<: *mx
       m: 6
       <<: *my
-        """)
+        """
+    )
 
     # in the following d always has "expanded" the merges
 
     def test_merge_for(self):
         from ruamel.yaml import safe_load
+
         d = safe_load(self.yaml_str)
         data = round_trip_load(self.yaml_str)
         count = 0
@@ -322,6 +363,7 @@ class TestMergeKeysValues:
 
     def test_merge_keys(self):
         from ruamel.yaml import safe_load
+
         d = safe_load(self.yaml_str)
         data = round_trip_load(self.yaml_str)
         count = 0
@@ -332,6 +374,7 @@ class TestMergeKeysValues:
 
     def test_merge_values(self):
         from ruamel.yaml import safe_load
+
         d = safe_load(self.yaml_str)
         data = round_trip_load(self.yaml_str)
         count = 0
@@ -342,6 +385,7 @@ class TestMergeKeysValues:
 
     def test_merge_items(self):
         from ruamel.yaml import safe_load
+
         d = safe_load(self.yaml_str)
         data = round_trip_load(self.yaml_str)
         count = 0
@@ -353,6 +397,7 @@ class TestMergeKeysValues:
     def test_len_items_delete(self):
         from ruamel.yaml import safe_load
         from ruamel.yaml.compat import PY3
+
         d = safe_load(self.yaml_str)
         data = round_trip_load(self.yaml_str)
         x = data[2].items()
@@ -377,13 +422,16 @@ class TestDuplicateKeyThroughAnchor:
         from ruamel.yaml import version_info
         from ruamel.yaml import safe_load, round_trip_load
         from ruamel.yaml.constructor import DuplicateKeyFutureWarning, DuplicateKeyError
-        s = dedent("""\
+
+        s = dedent(
+            """\
         &anchor foo:
             foo: bar
             *anchor : duplicate key
             baz: bat
             *anchor : duplicate key
-        """)
+        """
+        )
         if version_info < (0, 15, 1):
             pass
         elif version_info < (0, 16, 0):
@@ -402,27 +450,27 @@ class TestFullCharSetAnchors:
     def test_master_of_orion(self):
         # https://bitbucket.org/ruamel/yaml/issues/72/not-allowed-in-anchor-names
         # submitted by Shalon Wood
-        yaml_str = '''
+        yaml_str = """
         - collection: &Backend.Civilizations.RacialPerk
             items:
                   - key: perk_population_growth_modifier
         - *Backend.Civilizations.RacialPerk
-        '''
+        """
         data = load(yaml_str)  # NOQA
 
     def test_roundtrip_00(self):
-        yaml_str = '''
+        yaml_str = """
         - &dotted.words.here
           a: 1
           b: 2
         - *dotted.words.here
-        '''
+        """
         data = round_trip(yaml_str)  # NOQA
 
     def test_roundtrip_01(self):
-        yaml_str = '''
+        yaml_str = """
         - &dotted.words.here[a, b]
         - *dotted.words.here
-        '''
+        """
         data = load(yaml_str)  # NOQA
         compare(data, yaml_str.replace('[', ' ['))  # an extra space is inserted
diff --git a/_test/test_api_change.py b/_test/test_api_change.py
index 59473fe..f191c56 100644
--- a/_test/test_api_change.py
+++ b/_test/test_api_change.py
@@ -16,6 +16,7 @@ class TestNewAPI:
     def test_duplicate_keys_00(self):
         from ruamel.yaml import YAML
         from ruamel.yaml.constructor import DuplicateKeyError
+
         yaml = YAML()
         with pytest.raises(DuplicateKeyError):
             yaml.load('{a: 1, a: 2}')
@@ -23,6 +24,7 @@ class TestNewAPI:
     def test_duplicate_keys_01(self):
         from ruamel.yaml import YAML
         from ruamel.yaml.constructor import DuplicateKeyError
+
         yaml = YAML(typ='safe', pure=True)
         with pytest.raises(DuplicateKeyError):
             yaml.load('{a: 1, a: 2}')
@@ -31,6 +33,7 @@ class TestNewAPI:
     def test_duplicate_keys_02(self):
         from ruamel.yaml import YAML
         from ruamel.yaml.constructor import DuplicateKeyError
+
         yaml = YAML(typ='safe')
         with pytest.raises(DuplicateKeyError):
             yaml.load('{a: 1, a: 2}')
@@ -38,6 +41,7 @@ class TestNewAPI:
     def test_issue_135(self):
         # reported by Andrzej Ostrowski
         from ruamel.yaml import YAML
+
         data = {'a': 1, 'b': 2}
         yaml = YAML(typ='safe')
         # originally on 2.7: with pytest.raises(TypeError):
@@ -46,6 +50,7 @@ class TestNewAPI:
     def test_issue_135_temporary_workaround(self):
         # never raised error
         from ruamel.yaml import YAML
+
         data = {'a': 1, 'b': 2}
         yaml = YAML(typ='safe', pure=True)
         yaml.dump(data, sys.stdout)
@@ -54,16 +59,18 @@ class TestNewAPI:
 class TestWrite:
     def test_dump_path(self, tmpdir):
         from ruamel.yaml import YAML
+
         fn = Path(str(tmpdir)) / 'test.yaml'
         yaml = YAML()
         data = yaml.map()
         data['a'] = 1
         data['b'] = 2
         yaml.dump(data, fn)
-        assert fn.read_text() == "a: 1\nb: 2\n"
+        assert fn.read_text() == 'a: 1\nb: 2\n'
 
     def test_dump_file(self, tmpdir):
         from ruamel.yaml import YAML
+
         fn = Path(str(tmpdir)) / 'test.yaml'
         yaml = YAML()
         data = yaml.map()
@@ -71,10 +78,11 @@ class TestWrite:
         data['b'] = 2
         with open(str(fn), 'w') as fp:
             yaml.dump(data, fp)
-        assert fn.read_text() == "a: 1\nb: 2\n"
+        assert fn.read_text() == 'a: 1\nb: 2\n'
 
     def test_dump_missing_stream(self):
         from ruamel.yaml import YAML
+
         yaml = YAML()
         data = yaml.map()
         data['a'] = 1
@@ -84,6 +92,7 @@ class TestWrite:
 
     def test_dump_too_many_args(self, tmpdir):
         from ruamel.yaml import YAML
+
         fn = Path(str(tmpdir)) / 'test.yaml'
         yaml = YAML()
         data = yaml.map()
@@ -104,23 +113,25 @@ class TestWrite:
         data['a'] = 1
         data['b'] = 2
         yaml.dump(data, fn, transform=tr)
-        assert fn.read_text() == "a:  1\nb:  2\n"
+        assert fn.read_text() == 'a:  1\nb:  2\n'
 
     def test_print(self, capsys):
         from ruamel.yaml import YAML
+
         yaml = YAML()
         data = yaml.map()
         data['a'] = 1
         data['b'] = 2
         yaml.dump(data, sys.stdout)
         out, err = capsys.readouterr()
-        assert out == "a: 1\nb: 2\n"
+        assert out == 'a: 1\nb: 2\n'
 
 
 class TestRead:
     def test_multi_load(self):
         # make sure reader, scanner, parser get reset
         from ruamel.yaml import YAML
+
         yaml = YAML()
         yaml.load('a: 1')
         yaml.load('a: 1')  # did not work in 0.15.4
@@ -130,14 +141,19 @@ class TestLoadAll:
     def test_multi_document_load(self, tmpdir):
         """this went wrong on 3.7 because of StopIteration, PR 37 and Issue 211"""
         from ruamel.yaml import YAML
+
         fn = Path(str(tmpdir)) / 'test.yaml'
-        fn.write_text(textwrap.dedent(u"""\
+        fn.write_text(
+            textwrap.dedent(
+                u"""\
         ---
         - a
         ---
         - b
         ...
-        """))
+        """
+            )
+        )
         yaml = YAML()
         assert list(yaml.load_all(fn)) == [['a'], ['b']]
 
@@ -147,15 +163,20 @@ class TestDuplSet:
         # round-trip-loader should except
         from ruamel.yaml import YAML
         from ruamel.yaml.constructor import DuplicateKeyError
+
         yaml = YAML()
         with pytest.raises(DuplicateKeyError):
-            yaml.load(textwrap.dedent("""\
+            yaml.load(
+                textwrap.dedent(
+                    """\
             !!set
             ? a
             ? b
             ? c
             ? a
-            """))
+            """
+                )
+            )
 
 
 class TestDumpLoadUnicode:
@@ -163,26 +184,29 @@ class TestDumpLoadUnicode:
     # and answer by randomir (https://stackoverflow.com/a/45281922/1307905)
     def test_write_unicode(self, tmpdir):
         from ruamel.yaml import YAML
+
         yaml = YAML()
-        text_dict = {"text": u"HELLO_WORLD©"}
+        text_dict = {'text': u'HELLO_WORLD©'}
         file_name = str(tmpdir) + '/tstFile.yaml'
         yaml.dump(text_dict, open(file_name, 'w'))
         assert open(file_name, 'rb').read().decode('utf-8') == u'text: HELLO_WORLD©\n'
 
     def test_read_unicode(self, tmpdir):
         from ruamel.yaml import YAML
+
         yaml = YAML()
         file_name = str(tmpdir) + '/tstFile.yaml'
         with open(file_name, 'wb') as fp:
             fp.write(u'text: HELLO_WORLD©\n'.encode('utf-8'))
         text_dict = yaml.load(open(file_name, 'r'))
-        assert text_dict["text"] == u"HELLO_WORLD©"
+        assert text_dict['text'] == u'HELLO_WORLD©'
 
 
 class TestFlowStyle:
     def test_flow_style(self, capsys):
         # https://stackoverflow.com/questions/45791712/
         from ruamel.yaml import YAML
+
         yaml = YAML()
         yaml.default_flow_style = None
         data = yaml.map()
@@ -190,15 +214,16 @@ class TestFlowStyle:
         data['a'] = [[1, 2], [3, 4]]
         yaml.dump(data, sys.stdout)
         out, err = capsys.readouterr()
-        assert out == "b: 1\na:\n- [1, 2]\n- [3, 4]\n"
+        assert out == 'b: 1\na:\n- [1, 2]\n- [3, 4]\n'
 
 
 class TestOldAPI:
-    @pytest.mark.skipif(sys.version_info >= (3, 0), reason="ok on Py3")
+    @pytest.mark.skipif(sys.version_info >= (3, 0), reason='ok on Py3')
     @pytest.mark.xfail(strict=True)
     def test_duplicate_keys_02(self):
         # Issue 165 unicode keys in error/warning
         from ruamel.yaml import safe_load
         from ruamel.yaml.constructor import DuplicateKeyFutureWarning
+
         with pytest.warns(DuplicateKeyFutureWarning):
             safe_load('type: Doméstica\ntype: International')
diff --git a/_test/test_class_register.py b/_test/test_class_register.py
index 3da9fb7..126d93f 100644
--- a/_test/test_class_register.py
+++ b/_test/test_class_register.py
@@ -22,8 +22,7 @@ class User1(object):
 
     @classmethod
     def to_yaml(cls, representer, node):
-        return representer.represent_scalar(cls.yaml_tag,
-                                            u'{.name}-{.age}'.format(node, node))
+        return representer.represent_scalar(cls.yaml_tag, u'{.name}-{.age}'.format(node, node))
 
     @classmethod
     def from_yaml(cls, constructor, node):
@@ -34,66 +33,66 @@ class TestRegisterClass(object):
     def test_register_0_rt(self):
         yaml = YAML()
         yaml.register_class(User0)
-        ys = '''
+        ys = """
         - !User0
           name: Anthon
           age: 18
-        '''
+        """
         d = yaml.load(ys)
         yaml.dump(d, compare=ys, unordered_lines=True)
 
     def test_register_0_safe(self):
         # default_flow_style = None
-        yaml = YAML(typ="safe")
+        yaml = YAML(typ='safe')
         yaml.register_class(User0)
-        ys = '''
+        ys = """
         - !User0 {age: 18, name: Anthon}
-        '''
+        """
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
     def test_register_0_unsafe(self):
         # default_flow_style = None
-        yaml = YAML(typ="unsafe")
+        yaml = YAML(typ='unsafe')
         yaml.register_class(User0)
-        ys = '''
+        ys = """
         - !User0 {age: 18, name: Anthon}
-        '''
+        """
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
     def test_register_1_rt(self):
         yaml = YAML()
         yaml.register_class(User1)
-        ys = '''
+        ys = """
         - !user Anthon-18
-        '''
+        """
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
     def test_register_1_safe(self):
-        yaml = YAML(typ="safe")
+        yaml = YAML(typ='safe')
         yaml.register_class(User1)
-        ys = '''
+        ys = """
         [!user Anthon-18]
-        '''
+        """
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
     def test_register_1_unsafe(self):
-        yaml = YAML(typ="unsafe")
+        yaml = YAML(typ='unsafe')
         yaml.register_class(User1)
-        ys = '''
+        ys = """
         [!user Anthon-18]
-        '''
+        """
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
 
 class TestDecorator(object):
-
     def test_decorator_implicit(self):
         from ruamel.yaml import yaml_object
+
         yml = YAML()
 
         @yaml_object(yml)
@@ -102,16 +101,17 @@ class TestDecorator(object):
                 self.name = name
                 self.age = age
 
-        ys = '''
+        ys = """
         - !User2
           name: Anthon
           age: 18
-        '''
+        """
         d = yml.load(ys)
         yml.dump(d, compare=ys, unordered_lines=True)
 
     def test_decorator_explicit(self):
         from ruamel.yaml import yaml_object
+
         yml = YAML()
 
         @yaml_object(yml)
@@ -124,15 +124,16 @@ class TestDecorator(object):
 
             @classmethod
             def to_yaml(cls, representer, node):
-                return representer.represent_scalar(cls.yaml_tag,
-                                                    u'{.name}-{.age}'.format(node, node))
+                return representer.represent_scalar(
+                    cls.yaml_tag, u'{.name}-{.age}'.format(node, node)
+                )
 
             @classmethod
             def from_yaml(cls, constructor, node):
                 return cls(*node.value.split('-'))
 
-        ys = '''
+        ys = """
         - !USER Anthon-18
-        '''
+        """
         d = yml.load(ys)
         yml.dump(d, compare=ys)
diff --git a/_test/test_collections.py b/_test/test_collections.py
index e70dbd2..e6033bb 100644
--- a/_test/test_collections.py
+++ b/_test/test_collections.py
@@ -7,7 +7,7 @@ This is now so integrated in Python that it can be mapped to !!omap
 
 """
 
-import pytest    # NOQA
+import pytest  # NOQA
 
 
 from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump  # NOQA
@@ -16,5 +16,6 @@ from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump  # NO
 class TestOrderedDict:
     def test_ordereddict(self):
         from collections import OrderedDict
-        import ruamel.yaml   # NOQA
+        import ruamel.yaml  # NOQA
+
         assert ruamel.yaml.dump(OrderedDict()) == '!!omap []\n'
diff --git a/_test/test_comment_manipulation.py b/_test/test_comment_manipulation.py
index 7586954..92810da 100644
--- a/_test/test_comment_manipulation.py
+++ b/_test/test_comment_manipulation.py
@@ -16,8 +16,11 @@ def compare(data, s, **kw):
 
 
 def compare_eol(data, s):
-    assert round_trip_dump(data).replace('\n', '|\n') == \
-        dedent(s).replace('EOL', '').replace('\n', '|\n')
+    assert round_trip_dump(data).replace('\n', '|\n') == dedent(s).replace('EOL', "").replace(
+        '\n', '|\n'
+    )
+
+
 # @pytest.mark.xfail
 
 
@@ -25,336 +28,451 @@ class TestCommentsManipulation:
 
     # list
     def test_seq_set_comment_on_existing_explicit_column(self):
-        data = load("""
+        data = load(
+            """
         - a   # comment 1
         - b
         - c
-        """)
+        """
+        )
         data.yaml_add_eol_comment('comment 2', key=1, column=6)
-        compare(data, """
+        compare(
+            data,
+            """
         - a   # comment 1
         - b   # comment 2
         - c
-        """)
+        """,
+        )
 
     def test_seq_overwrite_comment_on_existing_explicit_column(self):
-        data = load("""
+        data = load(
+            """
         - a   # comment 1
         - b
         - c
-        """)
+        """
+        )
         data.yaml_add_eol_comment('comment 2', key=0, column=6)
-        compare(data, """
+        compare(
+            data,
+            """
         - a   # comment 2
         - b
         - c
-        """)
+        """,
+        )
 
     def test_seq_first_comment_explicit_column(self):
-        data = load("""
+        data = load(
+            """
         - a
         - b
         - c
-        """)
+        """
+        )
         data.yaml_add_eol_comment('comment 1', key=1, column=6)
-        compare(data, """
+        compare(
+            data,
+            """
         - a
         - b   # comment 1
         - c
-        """)
+        """,
+        )
 
     def test_seq_set_comment_on_existing_column_prev(self):
-        data = load("""
+        data = load(
+            """
         - a   # comment 1
         - b
         - c
         - d     # comment 3
-        """)
+        """
+        )
         data.yaml_add_eol_comment('comment 2', key=1)
-        compare(data, """
+        compare(
+            data,
+            """
         - a   # comment 1
         - b   # comment 2
         - c
         - d     # comment 3
-        """)
+        """,
+        )
 
     def test_seq_set_comment_on_existing_column_next(self):
-        data = load("""
+        data = load(
+            """
         - a   # comment 1
         - b
         - c
         - d     # comment 3
-        """)
+        """
+        )
         print(data._yaml_comment)
         # print(type(data._yaml_comment._items[0][0].start_mark))
         # ruamel.yaml.error.Mark
         # print(type(data._yaml_comment._items[0][0].start_mark))
         data.yaml_add_eol_comment('comment 2', key=2)
-        compare(data, """
+        compare(
+            data,
+            """
         - a   # comment 1
         - b
         - c     # comment 2
         - d     # comment 3
-        """)
+        """,
+        )
 
     def test_seq_set_comment_on_existing_column_further_away(self):
         """
         no comment line before or after, take the latest before
         the new position
         """
-        data = load("""
+        data = load(
+            """
         - a   # comment 1
         - b
         - c
         - d
         - e
         - f     # comment 3
-        """)
+        """
+        )
         print(data._yaml_comment)
         # print(type(data._yaml_comment._items[0][0].start_mark))
         # ruamel.yaml.error.Mark
         # print(type(data._yaml_comment._items[0][0].start_mark))
         data.yaml_add_eol_comment('comment 2', key=3)
-        compare(data, """
+        compare(
+            data,
+            """
         - a   # comment 1
         - b
         - c
         - d   # comment 2
         - e
         - f     # comment 3
-        """)
+        """,
+        )
 
     def test_seq_set_comment_on_existing_explicit_column_with_hash(self):
-        data = load("""
+        data = load(
+            """
         - a   # comment 1
         - b
         - c
-        """)
+        """
+        )
         data.yaml_add_eol_comment('#  comment 2', key=1, column=6)
-        compare(data, """
+        compare(
+            data,
+            """
         - a   # comment 1
         - b   #  comment 2
         - c
-        """)
+        """,
+        )
 
     # dict
 
     def test_dict_set_comment_on_existing_explicit_column(self):
-        data = load("""
+        data = load(
+            """
         a: 1   # comment 1
         b: 2
         c: 3
         d: 4
         e: 5
-        """)
+        """
+        )
         data.yaml_add_eol_comment('comment 2', key='c', column=7)
-        compare(data, """
+        compare(
+            data,
+            """
         a: 1   # comment 1
         b: 2
         c: 3   # comment 2
         d: 4
         e: 5
-        """)
+        """,
+        )
 
     def test_dict_overwrite_comment_on_existing_explicit_column(self):
-        data = load("""
+        data = load(
+            """
         a: 1   # comment 1
         b: 2
         c: 3
         d: 4
         e: 5
-        """)
+        """
+        )
         data.yaml_add_eol_comment('comment 2', key='a', column=7)
-        compare(data, """
+        compare(
+            data,
+            """
         a: 1   # comment 2
         b: 2
         c: 3
         d: 4
         e: 5
-        """)
+        """,
+        )
 
     def test_map_set_comment_on_existing_column_prev(self):
-        data = load("""
+        data = load(
+            """
             a: 1   # comment 1
             b: 2
             c: 3
             d: 4
             e: 5     # comment 3
-            """)
+            """
+        )
         data.yaml_add_eol_comment('comment 2', key='b')
-        compare(data, """
+        compare(
+            data,
+            """
             a: 1   # comment 1
             b: 2   # comment 2
             c: 3
             d: 4
             e: 5     # comment 3
-            """)
+            """,
+        )
 
     def test_map_set_comment_on_existing_column_next(self):
-        data = load("""
+        data = load(
+            """
             a: 1   # comment 1
             b: 2
             c: 3
             d: 4
             e: 5     # comment 3
-            """)
+            """
+        )
         data.yaml_add_eol_comment('comment 2', key='d')
-        compare(data, """
+        compare(
+            data,
+            """
             a: 1   # comment 1
             b: 2
             c: 3
             d: 4     # comment 2
             e: 5     # comment 3
-            """)
+            """,
+        )
 
     def test_map_set_comment_on_existing_column_further_away(self):
         """
         no comment line before or after, take the latest before
         the new position
         """
-        data = load("""
+        data = load(
+            """
             a: 1   # comment 1
             b: 2
             c: 3
             d: 4
             e: 5     # comment 3
-            """)
+            """
+        )
         data.yaml_add_eol_comment('comment 2', key='c')
         print(round_trip_dump(data))
-        compare(data, """
+        compare(
+            data,
+            """
             a: 1   # comment 1
             b: 2
             c: 3   # comment 2
             d: 4
             e: 5     # comment 3
-            """)
+            """,
+        )
 
     # @pytest.mark.xfail
     def test_before_top_map_rt(self):
-        data = load("""
+        data = load(
+            """
         a: 1
         b: 2
-        """)
+        """
+        )
         data.yaml_set_start_comment('Hello\nWorld\n')
-        compare(data, """
+        compare(
+            data,
+            """
         # Hello
         # World
         a: 1
         b: 2
-        """.format(comment='#'))
+        """.format(
+                comment='#'
+            ),
+        )
 
     def test_before_top_map_replace(self):
-        data = load("""
+        data = load(
+            """
         # abc
         # def
         a: 1 # 1
         b: 2
-        """)
+        """
+        )
         data.yaml_set_start_comment('Hello\nWorld\n')
-        compare(data, """
+        compare(
+            data,
+            """
         # Hello
         # World
         a: 1 # 1
         b: 2
-        """.format(comment='#'))
+        """.format(
+                comment='#'
+            ),
+        )
 
     def test_before_top_map_from_scratch(self):
         from ruamel.yaml.comments import CommentedMap
+
         data = CommentedMap()
         data['a'] = 1
         data['b'] = 2
         data.yaml_set_start_comment('Hello\nWorld\n')
         # print(data.ca)
         # print(data.ca._items)
-        compare(data, """
+        compare(
+            data,
+            """
             # Hello
             # World
             a: 1
             b: 2
-            """.format(comment='#'))
+            """.format(
+                comment='#'
+            ),
+        )
 
     def test_before_top_seq_rt(self):
-        data = load("""
+        data = load(
+            """
         - a
         - b
-        """)
+        """
+        )
         data.yaml_set_start_comment('Hello\nWorld\n')
         print(round_trip_dump(data))
-        compare(data, """
+        compare(
+            data,
+            """
         # Hello
         # World
         - a
         - b
-        """)
+        """,
+        )
 
     def test_before_top_seq_rt_replace(self):
-        data = load("""
+        data = load(
+            """
         # this
         # that
         - a
         - b
-        """.format(comment='#'))
+        """.format(
+                comment='#'
+            )
+        )
         data.yaml_set_start_comment('Hello\nWorld\n')
         print(round_trip_dump(data))
-        compare(data, """
+        compare(
+            data,
+            """
         # Hello
         # World
         - a
         - b
-        """.format(comment='#'))
+        """.format(
+                comment='#'
+            ),
+        )
 
     def test_before_top_seq_from_scratch(self):
         from ruamel.yaml.comments import CommentedSeq
+
         data = CommentedSeq()
         data.append('a')
         data.append('b')
         data.yaml_set_start_comment('Hello\nWorld\n')
         print(round_trip_dump(data))
-        compare(data, """
+        compare(
+            data,
+            """
         # Hello
         # World
         - a
         - b
-        """.format(comment='#'))
+        """.format(
+                comment='#'
+            ),
+        )
 
     # nested variants
     def test_before_nested_map_rt(self):
-        data = load("""
+        data = load(
+            """
         a: 1
         b:
           c: 2
           d: 3
-        """)
+        """
+        )
         data['b'].yaml_set_start_comment('Hello\nWorld\n')
-        compare(data, """
+        compare(
+            data,
+            """
         a: 1
         b:
         # Hello
         # World
           c: 2
           d: 3
-        """.format(comment='#'))
+        """.format(
+                comment='#'
+            ),
+        )
 
     def test_before_nested_map_rt_indent(self):
-        data = load("""
+        data = load(
+            """
         a: 1
         b:
           c: 2
           d: 3
-        """)
+        """
+        )
         data['b'].yaml_set_start_comment('Hello\nWorld\n', indent=2)
-        compare(data, """
+        compare(
+            data,
+            """
         a: 1
         b:
           # Hello
           # World
           c: 2
           d: 3
-        """.format(comment='#'))
+        """.format(
+                comment='#'
+            ),
+        )
         print(data['b'].ca)
 
     def test_before_nested_map_from_scratch(self):
         from ruamel.yaml.comments import CommentedMap
+
         data = CommentedMap()
         datab = CommentedMap()
         data['a'] = 1
@@ -362,17 +480,23 @@ class TestCommentsManipulation:
         datab['c'] = 2
         datab['d'] = 3
         data['b'].yaml_set_start_comment('Hello\nWorld\n')
-        compare(data, """
+        compare(
+            data,
+            """
         a: 1
         b:
         # Hello
         # World
           c: 2
           d: 3
-        """.format(comment='#'))
+        """.format(
+                comment='#'
+            ),
+        )
 
     def test_before_nested_seq_from_scratch(self):
         from ruamel.yaml.comments import CommentedMap, CommentedSeq
+
         data = CommentedMap()
         datab = CommentedSeq()
         data['a'] = 1
@@ -380,17 +504,23 @@ class TestCommentsManipulation:
         datab.append('c')
         datab.append('d')
         data['b'].yaml_set_start_comment('Hello\nWorld\n', indent=2)
-        compare(data, """
+        compare(
+            data,
+            """
         a: 1
         b:
           # Hello
           # World
         - c
         - d
-        """.format(comment='#'))
+        """.format(
+                comment='#'
+            ),
+        )
 
     def test_before_nested_seq_from_scratch_block_seq_indent(self):
         from ruamel.yaml.comments import CommentedMap, CommentedSeq
+
         data = CommentedMap()
         datab = CommentedSeq()
         data['a'] = 1
@@ -398,18 +528,26 @@ class TestCommentsManipulation:
         datab.append('c')
         datab.append('d')
         data['b'].yaml_set_start_comment('Hello\nWorld\n', indent=2)
-        compare(data, """
+        compare(
+            data,
+            """
         a: 1
         b:
           # Hello
           # World
           - c
           - d
-        """.format(comment='#'), indent=4, block_seq_indent=2)
+        """.format(
+                comment='#'
+            ),
+            indent=4,
+            block_seq_indent=2,
+        )
 
     def test_map_set_comment_before_and_after_non_first_key_00(self):
         # http://stackoverflow.com/a/40705671/1307905
-        data = load("""
+        data = load(
+            """
         xyz:
           a: 1    # comment 1
           b: 2
@@ -417,11 +555,15 @@ class TestCommentsManipulation:
         test1:
           test2:
             test3: 3
-                """)
-        data.yaml_set_comment_before_after_key('test1', 'before test1 (top level)',
-                                               after='before test2')
+                """
+        )
+        data.yaml_set_comment_before_after_key(
+            'test1', 'before test1 (top level)', after='before test2'
+        )
         data['test1']['test2'].yaml_set_start_comment('after test2', indent=4)
-        compare(data, """
+        compare(
+            data,
+            """
         xyz:
           a: 1    # comment 1
           b: 2
@@ -432,10 +574,12 @@ class TestCommentsManipulation:
           test2:
             # after test2
             test3: 3
-        """)
+        """,
+        )
 
     def test_map_set_comment_before_and_after_non_first_key_01(self):
-        data = load("""
+        data = load(
+            """
         xyz:
           a: 1    # comment 1
           b: 2
@@ -443,12 +587,16 @@ class TestCommentsManipulation:
         test1:
           test2:
             test3: 3
-        """)
-        data.yaml_set_comment_before_after_key('test1', 'before test1 (top level)',
-                                               after='before test2\n\n')
+        """
+        )
+        data.yaml_set_comment_before_after_key(
+            'test1', 'before test1 (top level)', after='before test2\n\n'
+        )
         data['test1']['test2'].yaml_set_start_comment('after test2', indent=4)
         # EOL is needed here as dedenting gets rid of spaces (as well as does Emacs
-        compare_eol(data, """
+        compare_eol(
+            data,
+            """
         xyz:
           a: 1    # comment 1
           b: 2
@@ -460,10 +608,12 @@ class TestCommentsManipulation:
           test2:
             # after test2
             test3: 3
-        """)
+        """,
+        )
 
     def test_map_set_comment_before_and_after_non_first_key_02(self):
-        data = load("""
+        data = load(
+            """
         xyz:
           a: 1    # comment 1
           b: 2
@@ -471,12 +621,16 @@ class TestCommentsManipulation:
         test1:
           test2:
             test3: 3
-        """)
-        data.yaml_set_comment_before_after_key('test1', 'xyz\n\nbefore test1 (top level)',
-                                               after='\nbefore test2', after_indent=4)
+        """
+        )
+        data.yaml_set_comment_before_after_key(
+            'test1', 'xyz\n\nbefore test1 (top level)', after='\nbefore test2', after_indent=4
+        )
         data['test1']['test2'].yaml_set_start_comment('after test2', indent=4)
         # EOL is needed here as dedenting gets rid of spaces (as well as does Emacs
-        compare_eol(data, """
+        compare_eol(
+            data,
+            """
         xyz:
           a: 1    # comment 1
           b: 2
@@ -490,4 +644,5 @@ class TestCommentsManipulation:
           test2:
             # after test2
             test3: 3
-        """)
+        """,
+        )
diff --git a/_test/test_comments.py b/_test/test_comments.py
index 921b193..7a43a97 100644
--- a/_test/test_comments.py
+++ b/_test/test_comments.py
@@ -27,15 +27,18 @@ class TestComments:
             round_trip(x, extra='a\n')
 
     def test_no_comments(self):
-        round_trip("""
+        round_trip(
+            """
         - europe: 10
         - usa:
           - ohio: 2
           - california: 9
-        """)
+        """
+        )
 
     def test_round_trip_ordering(self):
-        round_trip("""
+        round_trip(
+            """
         a: 1
         b: 2
         c: 3
@@ -44,25 +47,32 @@ class TestComments:
         d: 4
         e: 5
         f: 6
-        """)
+        """
+        )
 
     def test_complex(self):
-        round_trip("""
+        round_trip(
+            """
         - europe: 10 # top
         - usa:
           - ohio: 2
           - california: 9 # o
-        """)
+        """
+        )
 
     def test_dropped(self):
-        round_trip("""
+        round_trip(
+            """
         # comment
         scalar
         ...
-        """, "scalar\n...\n")
+        """,
+            'scalar\n...\n',
+        )
 
     def test_main_mapping_begin_end(self):
-        round_trip("""
+        round_trip(
+            """
         # C start a
         # C start b
         abc: 1
@@ -70,7 +80,8 @@ class TestComments:
         klm: 3
         # C end a
         # C end b
-        """)
+        """
+        )
 
     def test_reindent(self):
         x = """\
@@ -80,14 +91,17 @@ class TestComments:
         """
         d = round_trip_load(x)
         y = round_trip_dump(d, indent=4)
-        assert y == dedent("""\
+        assert y == dedent(
+            """\
         a:
             b:   # comment 1
                 c: 1 # comment 2
-        """)
+        """
+        )
 
     def test_main_mapping_begin_end_items_post(self):
-        round_trip("""
+        round_trip(
+            """
         # C start a
         # C start b
         abc: 1      # abc comment
@@ -95,10 +109,12 @@ class TestComments:
         klm: 3      # klm comment
         # C end a
         # C end b
-        """)
+        """
+        )
 
     def test_main_sequence_begin_end(self):
-        round_trip("""
+        round_trip(
+            """
         # C start a
         # C start b
         - abc
@@ -106,10 +122,12 @@ class TestComments:
         - klm
         # C end a
         # C end b
-        """)
+        """
+        )
 
     def test_main_sequence_begin_end_items_post(self):
-        round_trip("""
+        round_trip(
+            """
         # C start a
         # C start b
         - abc      # abc comment
@@ -117,10 +135,12 @@ class TestComments:
         - klm      # klm comment
         # C end a
         # C end b
-        """)
+        """
+        )
 
     def test_main_mapping_begin_end_complex(self):
-        round_trip("""
+        round_trip(
+            """
         # C start a
         # C start b
         abc: 1
@@ -130,10 +150,12 @@ class TestComments:
           3b: beta   # it is all greek to me
         # C end a
         # C end b
-        """)
+        """
+        )
 
-    def test_09(self):   # 2.9 from the examples in the spec
-        round_trip("""
+    def test_09(self):  # 2.9 from the examples in the spec
+        round_trip(
+            """
         hr: # 1998 hr ranking
           - Mark McGwire
           - Sammy Sosa
@@ -141,10 +163,14 @@ class TestComments:
           # 1998 rbi ranking
           - Sammy Sosa
           - Ken Griffey
-        """, indent=4, block_seq_indent=2)
+        """,
+            indent=4,
+            block_seq_indent=2,
+        )
 
     def test_09a(self):
-        round_trip("""
+        round_trip(
+            """
         hr: # 1998 hr ranking
         - Mark McGwire
         - Sammy Sosa
@@ -152,36 +178,44 @@ class TestComments:
           # 1998 rbi ranking
         - Sammy Sosa
         - Ken Griffey
-        """)
+        """
+        )
 
     def test_simple_map_middle_comment(self):
-        round_trip("""
+        round_trip(
+            """
         abc: 1
         # C 3a
         # C 3b
         ghi: 2
-        """)
+        """
+        )
 
     def test_map_in_map_0(self):
-        round_trip("""
+        round_trip(
+            """
         map1: # comment 1
           # comment 2
           map2:
             key1: val1
-        """)
+        """
+        )
 
     def test_map_in_map_1(self):
         # comment is moved from value to key
-        round_trip("""
+        round_trip(
+            """
         map1:
           # comment 1
           map2:
             key1: val1
-        """)
+        """
+        )
 
     def test_application_arguments(self):
         # application configur
-        round_trip("""
+        round_trip(
+            """
         args:
           username: anthon
           passwd: secret
@@ -190,7 +224,8 @@ class TestComments:
             session-name: test
           loop:
             wait: 10
-        """)
+        """
+        )
 
     def test_substitute(self):
         x = """
@@ -210,7 +245,8 @@ class TestComments:
         assert round_trip_dump(data) == dedent(x)
 
     def test_set_comment(self):
-        round_trip("""
+        round_trip(
+            """
         !!set
         # the beginning
         ? a
@@ -218,29 +254,35 @@ class TestComments:
         ? b  #  You see? Promised you.
         ? c
         # this is the end
-        """)
+        """
+        )
 
     def test_omap_comment_roundtrip(self):
-        round_trip("""
+        round_trip(
+            """
         !!omap
         - a: 1
         - b: 2  # two
         - c: 3  # three
         - d: 4
-        """)
+        """
+        )
 
     def test_omap_comment_roundtrip_pre_comment(self):
-        round_trip("""
+        round_trip(
+            """
         !!omap
         - a: 1
         - b: 2  # two
         - c: 3  # three
         # last one
         - d: 4
-        """)
+        """
+        )
 
     def test_non_ascii(self):
-        round_trip("""
+        round_trip(
+            """
         verbosity: 1                  # 0 is minimal output, -1 none
         base_url: http://gopher.net
         special_indices: [1, 5, 8]
@@ -259,34 +301,43 @@ class TestComments:
             <<: *asia_europe
             Spain: Madrid
             Italy: Rome
-        """)
+        """
+        )
 
     def test_dump_utf8(self):
         import ruamel.yaml  # NOQA
-        x = dedent("""\
+
+        x = dedent(
+            """\
         ab:
         - x  # comment
         - y  # more comment
-        """)
+        """
+        )
         data = round_trip_load(x)
         dumper = ruamel.yaml.RoundTripDumper
         for utf in [True, False]:
-            y = ruamel.yaml.dump(data, default_flow_style=False, Dumper=dumper,
-                                 allow_unicode=utf)
+            y = ruamel.yaml.dump(
+                data, default_flow_style=False, Dumper=dumper, allow_unicode=utf
+            )
             assert y == x
 
     def test_dump_unicode_utf8(self):
         import ruamel.yaml  # NOQA
-        x = dedent(u"""\
+
+        x = dedent(
+            u"""\
         ab:
         - x  # comment
         - y  # more comment
-        """)
+        """
+        )
         data = round_trip_load(x)
         dumper = ruamel.yaml.RoundTripDumper
         for utf in [True, False]:
-            y = ruamel.yaml.dump(data, default_flow_style=False, Dumper=dumper,
-                                 allow_unicode=utf)
+            y = ruamel.yaml.dump(
+                data, default_flow_style=False, Dumper=dumper, allow_unicode=utf
+            )
             assert y == x
 
     def test_mlget_00(self):
@@ -327,7 +378,8 @@ class TestInsertPopList:
         d = round_trip_load(self.ins)
         d['ab'].insert(0, 'xyz')
         y = round_trip_dump(d, indent=2)
-        assert y == dedent("""\
+        assert y == dedent(
+            """\
         ab:
         - xyz
         - a      # a
@@ -338,13 +390,15 @@ class TestInsertPopList:
         de:
         - 1
         - 2
-        """)
+        """
+        )
 
     def test_insert_1(self):
         d = round_trip_load(self.ins)
         d['ab'].insert(4, 'xyz')
         y = round_trip_dump(d, indent=2)
-        assert y == dedent("""\
+        assert y == dedent(
+            """\
         ab:
         - a      # a
         - b      # b
@@ -355,13 +409,15 @@ class TestInsertPopList:
         de:
         - 1
         - 2
-        """)
+        """
+        )
 
     def test_insert_2(self):
         d = round_trip_load(self.ins)
         d['ab'].insert(1, 'xyz')
         y = round_trip_dump(d, indent=2)
-        assert y == dedent("""\
+        assert y == dedent(
+            """\
         ab:
         - a      # a
         - xyz
@@ -372,14 +428,16 @@ class TestInsertPopList:
         de:
         - 1
         - 2
-        """)
+        """
+        )
 
     def test_pop_0(self):
         d = round_trip_load(self.ins)
         d['ab'].pop(0)
         y = round_trip_dump(d, indent=2)
         print(y)
-        assert y == dedent("""\
+        assert y == dedent(
+            """\
         ab:
         - b      # b
         - c
@@ -388,14 +446,16 @@ class TestInsertPopList:
         de:
         - 1
         - 2
-        """)
+        """
+        )
 
     def test_pop_1(self):
         d = round_trip_load(self.ins)
         d['ab'].pop(1)
         y = round_trip_dump(d, indent=2)
         print(y)
-        assert y == dedent("""\
+        assert y == dedent(
+            """\
         ab:
         - a      # a
         - c
@@ -404,14 +464,16 @@ class TestInsertPopList:
         de:
         - 1
         - 2
-        """)
+        """
+        )
 
     def test_pop_2(self):
         d = round_trip_load(self.ins)
         d['ab'].pop(2)
         y = round_trip_dump(d, indent=2)
         print(y)
-        assert y == dedent("""\
+        assert y == dedent(
+            """\
         ab:
         - a      # a
         - b      # b
@@ -420,14 +482,16 @@ class TestInsertPopList:
         de:
         - 1
         - 2
-        """)
+        """
+        )
 
     def test_pop_3(self):
         d = round_trip_load(self.ins)
         d['ab'].pop(3)
         y = round_trip_dump(d, indent=2)
         print(y)
-        assert y == dedent("""\
+        assert y == dedent(
+            """\
         ab:
         - a      # a
         - b      # b
@@ -435,7 +499,8 @@ class TestInsertPopList:
         de:
         - 1
         - 2
-        """)
+        """
+        )
 
 
 # inspired by demux' question on stackoverflow
@@ -451,45 +516,52 @@ class TestInsertInMapping:
 
     def test_insert_at_pos_1(self):
         d = round_trip_load(self.ins)
-        d.insert(1, 'last name', 'Vandelay', comment="new key")
+        d.insert(1, 'last name', 'Vandelay', comment='new key')
         y = round_trip_dump(d)
         print(y)
-        assert y == dedent("""\
+        assert y == dedent(
+            """\
         first_name: Art
         last name: Vandelay    # new key
         occupation: Architect  # This is an occupation comment
         about: Art Vandelay is a fictional character that George invents...
-        """)
+        """
+        )
 
     def test_insert_at_pos_0(self):
         d = round_trip_load(self.ins)
-        d.insert(0, 'last name', 'Vandelay', comment="new key")
+        d.insert(0, 'last name', 'Vandelay', comment='new key')
         y = round_trip_dump(d)
         print(y)
-        assert y == dedent("""\
+        assert y == dedent(
+            """\
         last name: Vandelay  # new key
         first_name: Art
         occupation: Architect  # This is an occupation comment
         about: Art Vandelay is a fictional character that George invents...
-        """)
+        """
+        )
 
     def test_insert_at_pos_3(self):
         # much more simple if done with appending.
         d = round_trip_load(self.ins)
-        d.insert(3, 'last name', 'Vandelay', comment="new key")
+        d.insert(3, 'last name', 'Vandelay', comment='new key')
         y = round_trip_dump(d)
         print(y)
-        assert y == dedent("""\
+        assert y == dedent(
+            """\
         first_name: Art
         occupation: Architect  # This is an occupation comment
         about: Art Vandelay is a fictional character that George invents...
         last name: Vandelay  # new key
-        """)
+        """
+        )
 
 
 class TestCommentedMapMerge:
     def test_in_operator(self):
-        data = round_trip_load("""
+        data = round_trip_load(
+            """
         x: &base
           a: 1
           b: 2
@@ -498,31 +570,36 @@ class TestCommentedMapMerge:
           <<: *base
           k: 4
           l: 5
-        """)
+        """
+        )
         assert data['x']['a'] == 1
         assert 'a' in data['x']
         assert data['y']['a'] == 1
         assert 'a' in data['y']
 
     def test_issue_60(self):
-        data = round_trip_load("""
+        data = round_trip_load(
+            """
         x: &base
           a: 1
         y:
           <<: *base
-        """)
+        """
+        )
         assert data['x']['a'] == 1
         assert data['y']['a'] == 1
         assert str(data['y']) == """ordereddict([('a', 1)])"""
 
     def test_issue_60_1(self):
-        data = round_trip_load("""
+        data = round_trip_load(
+            """
         x: &base
           a: 1
         y:
           <<: *base
           b: 2
-        """)
+        """
+        )
         assert data['x']['a'] == 1
         assert data['y']['a'] == 1
         assert str(data['y']) == """ordereddict([('b', 2), ('a', 1)])"""
@@ -531,7 +608,8 @@ class TestCommentedMapMerge:
 class TestEmptyLines:
     # prompted by issue 46 from Alex Harvey
     def test_issue_46(self):
-        yaml_str = dedent("""\
+        yaml_str = dedent(
+            """\
         ---
         # Please add key/value pairs in alphabetical order
 
@@ -540,13 +618,15 @@ class TestEmptyLines:
         jenkins_ad_credentials:
           bind_name: 'CN=svc-AAA-BBB-T,OU=Example,DC=COM,DC=EXAMPLE,DC=Local'
           bind_pass: 'xxxxyyyy{'
-        """)
+        """
+        )
         d = round_trip_load(yaml_str, preserve_quotes=True)
         y = round_trip_dump(d, explicit_start=True)
         assert yaml_str == y
 
     def test_multispace_map(self):
-        round_trip("""
+        round_trip(
+            """
         a: 1x
 
         b: 2x
@@ -558,11 +638,13 @@ class TestEmptyLines:
 
         d: 4x
 
-        """)
+        """
+        )
 
     @pytest.mark.xfail(strict=True)
     def test_multispace_map_initial(self):
-        round_trip("""
+        round_trip(
+            """
 
         a: 1x
 
@@ -575,27 +657,33 @@ class TestEmptyLines:
 
         d: 4x
 
-        """)
+        """
+        )
 
     def test_embedded_map(self):
-        round_trip("""
+        round_trip(
+            """
         - a: 1y
           b: 2y
 
           c: 3y
-        """)
+        """
+        )
 
     def test_toplevel_seq(self):
-        round_trip("""\
+        round_trip(
+            """\
         - 1
 
         - 2
 
         - 3
-        """)
+        """
+        )
 
     def test_embedded_seq(self):
-        round_trip("""
+        round_trip(
+            """
         a:
           b:
           - 1
@@ -604,7 +692,8 @@ class TestEmptyLines:
 
 
           - 3
-        """)
+        """
+        )
 
     def test_line_with_only_spaces(self):
         # issue 54
@@ -629,12 +718,14 @@ class TestEmptyLines:
         assert stripped == y
 
     def test_issue_54_not_ok(self):
-        yaml_str = dedent("""\
+        yaml_str = dedent(
+            """\
         toplevel:
 
             # some comment
             sublevel: 300
-        """)
+        """
+        )
         d = round_trip_load(yaml_str)
         print(d.ca)
         y = round_trip_dump(d, indent=4)
@@ -642,50 +733,61 @@ class TestEmptyLines:
         assert yaml_str == y
 
     def test_issue_54_ok(self):
-        yaml_str = dedent("""\
+        yaml_str = dedent(
+            """\
         toplevel:
             # some comment
             sublevel: 300
-        """)
+        """
+        )
         d = round_trip_load(yaml_str)
         y = round_trip_dump(d, indent=4)
         assert yaml_str == y
 
     def test_issue_93(self):
-        round_trip("""\
+        round_trip(
+            """\
         a:
           b:
           - c1: cat  # a1
           # my comment on catfish
           - c2: catfish  # a2
-        """)
+        """
+        )
 
     def test_issue_93_00(self):
-        round_trip("""\
+        round_trip(
+            """\
         a:
         - - c1: cat   # a1
           # my comment on catfish
           - c2: catfish  # a2
-        """)
+        """
+        )
 
     def test_issue_93_01(self):
-        round_trip("""\
+        round_trip(
+            """\
         - - c1: cat   # a1
           # my comment on catfish
           - c2: catfish  # a2
-        """)
+        """
+        )
 
     def test_issue_93_02(self):
         # never failed as there is no indent
-        round_trip("""\
+        round_trip(
+            """\
         - c1: cat
         # my comment on catfish
         - c2: catfish
-        """)
+        """
+        )
 
     def test_issue_96(self):
         # inserted extra line on trailing spaces
-        round_trip("""\
+        round_trip(
+            """\
         a:
           b:
             c: c_val
@@ -693,14 +795,15 @@ class TestEmptyLines:
 
           e:
             g: g_val
-        """)
+        """
+        )
 
 
 class TestUnicodeComments:
-
-    @pytest.mark.skipif(sys.version_info < (2, 7), reason="wide unicode")
+    @pytest.mark.skipif(sys.version_info < (2, 7), reason='wide unicode')
     def test_issue_55(self):  # reported by Haraguroicha Hsu
-        round_trip("""\
+        round_trip(
+            """\
         name: TEST
         description: test using
         author: Harguroicha
@@ -715,87 +818,111 @@ class TestUnicodeComments:
           - :no: 05338777 # 〇〇啓
           - :no: 05273867 # 〇
           - :no: 05205786 # 〇𤦌
-        """)
+        """
+        )
 
 
 class TestEmptyValueBeforeComments:
     def test_issue_25a(self):
-        round_trip("""\
+        round_trip(
+            """\
         - a: b
           c: d
           d:  # foo
           - e: f
-        """)
+        """
+        )
 
     def test_issue_25a1(self):
-        round_trip("""\
+        round_trip(
+            """\
         - a: b
           c: d
           d:  # foo
             e: f
-        """)
+        """
+        )
 
     def test_issue_25b(self):
-        round_trip("""\
+        round_trip(
+            """\
         var1: #empty
         var2: something #notempty
-        """)
+        """
+        )
 
     def test_issue_25c(self):
-        round_trip("""\
+        round_trip(
+            """\
         params:
           a: 1 # comment a
           b:   # comment b
           c: 3 # comment c
-        """)
+        """
+        )
 
     def test_issue_25c1(self):
-        round_trip("""\
+        round_trip(
+            """\
         params:
           a: 1 # comment a
           b:   # comment b
           # extra
           c: 3 # comment c
-        """)
+        """
+        )
 
     def test_issue_25_00(self):
-        round_trip("""\
+        round_trip(
+            """\
         params:
           a: 1 # comment a
           b:   # comment b
-        """)
+        """
+        )
 
     def test_issue_25_01(self):
-        round_trip("""\
+        round_trip(
+            """\
         a:        # comment 1
                   #  comment 2
         - b:      #   comment 3
             c: 1  #    comment 4
-        """)
+        """
+        )
 
     def test_issue_25_02(self):
-        round_trip("""\
+        round_trip(
+            """\
         a:        # comment 1
                   #  comment 2
         - b: 2    #   comment 3
-        """)
+        """
+        )
 
     def test_issue_25_03(self):
-        round_trip("""\
+        round_trip(
+            """\
         a:        # comment 1
                   #  comment 2
           - b: 2  #   comment 3
-        """, indent=4, block_seq_indent=2)
+        """,
+            indent=4,
+            block_seq_indent=2,
+        )
 
     def test_issue_25_04(self):
-        round_trip("""\
+        round_trip(
+            """\
         a:        # comment 1
                   #  comment 2
           b: 1    #   comment 3
-        """)
+        """
+        )
 
     def test_flow_seq_within_seq(self):
-        round_trip("""\
+        round_trip(
+            """\
         # comment 1
         - a
         - b
@@ -807,7 +934,8 @@ class TestEmptyValueBeforeComments:
         - f
         # comment 4
         - []
-        """)
+        """
+        )
 
 
 test_block_scalar_commented_line_template = """\
@@ -824,8 +952,17 @@ class TestBlockScalarWithComments:
     # issue 99 reported by Colm O'Connor
     def test_scalar_with_comments(self):
         import ruamel.yaml  # NOQA
-        for x in ['', '\n', '\n# Another comment\n', '\n\n', '\n\n# abc\n#xyz\n',
-                  '\n\n# abc\n#xyz\n', '# abc\n\n#xyz\n', '\n\n  # abc\n  #xyz\n']:
+
+        for x in [
+            "",
+            '\n',
+            '\n# Another comment\n',
+            '\n\n',
+            '\n\n# abc\n#xyz\n',
+            '\n\n# abc\n#xyz\n',
+            '# abc\n\n#xyz\n',
+            '\n\n  # abc\n  #xyz\n',
+        ]:
 
             commented_line = test_block_scalar_commented_line_template.format(x)
             data = ruamel.yaml.round_trip_load(commented_line)
diff --git a/_test/test_copy.py b/_test/test_copy.py
index 9a6deb0..a912259 100644
--- a/_test/test_copy.py
+++ b/_test/test_copy.py
@@ -6,16 +6,18 @@ Testing copy and deepcopy, instigated by Issue 84 (Peter Amstutz)
 
 import copy
 
-import pytest            # NOQA
+import pytest  # NOQA
 
 from roundtrip import dedent, round_trip_load, round_trip_dump
 
 
 class TestDeepCopy:
     def test_preserve_flow_style_simple(self):
-        x = dedent("""\
+        x = dedent(
+            """\
         {foo: bar, baz: quux}
-        """)
+        """
+        )
         data = round_trip_load(x)
         data_copy = copy.deepcopy(data)
         y = round_trip_dump(data_copy)
@@ -25,9 +27,11 @@ class TestDeepCopy:
         assert data.fa.flow_style() == data_copy.fa.flow_style()
 
     def test_deepcopy_flow_style_nested_dict(self):
-        x = dedent("""\
+        x = dedent(
+            """\
         a: {foo: bar, baz: quux}
-        """)
+        """
+        )
         data = round_trip_load(x)
         assert data['a'].fa.flow_style() is True
         data_copy = copy.deepcopy(data)
@@ -40,16 +44,20 @@ class TestDeepCopy:
 
         print('x [{}]'.format(x))
         print('y [{}]'.format(y))
-        assert y == dedent("""\
+        assert y == dedent(
+            """\
         a:
           foo: bar
           baz: quux
-        """)
+        """
+        )
 
     def test_deepcopy_flow_style_nested_list(self):
-        x = dedent("""\
+        x = dedent(
+            """\
         a: [1, 2, 3]
-        """)
+        """
+        )
         data = round_trip_load(x)
         assert data['a'].fa.flow_style() is True
         data_copy = copy.deepcopy(data)
@@ -62,19 +70,23 @@ class TestDeepCopy:
 
         print('x [{}]'.format(x))
         print('y [{}]'.format(y))
-        assert y == dedent("""\
+        assert y == dedent(
+            """\
         a:
         - 1
         - 2
         - 3
-        """)
+        """
+        )
 
 
 class TestCopy:
     def test_copy_flow_style_nested_dict(self):
-        x = dedent("""\
+        x = dedent(
+            """\
         a: {foo: bar, baz: quux}
-        """)
+        """
+        )
         data = round_trip_load(x)
         assert data['a'].fa.flow_style() is True
         data_copy = copy.copy(data)
@@ -87,16 +99,20 @@ class TestCopy:
         z = round_trip_dump(data)
         assert y == z
 
-        assert y == dedent("""\
+        assert y == dedent(
+            """\
         a:
           foo: bar
           baz: quux
-        """)
+        """
+        )
 
     def test_copy_flow_style_nested_list(self):
-        x = dedent("""\
+        x = dedent(
+            """\
         a: [1, 2, 3]
-        """)
+        """
+        )
         data = round_trip_load(x)
         assert data['a'].fa.flow_style() is True
         data_copy = copy.copy(data)
@@ -109,9 +125,11 @@ class TestCopy:
 
         print('x [{}]'.format(x))
         print('y [{}]'.format(y))
-        assert y == dedent("""\
+        assert y == dedent(
+            """\
         a:
         - 1
         - 2
         - 3
-        """)
+        """
+        )
diff --git a/_test/test_cyaml.py b/_test/test_cyaml.py
index 4c5c5db..2d67509 100644
--- a/_test/test_cyaml.py
+++ b/_test/test_cyaml.py
@@ -4,18 +4,26 @@ import platform
 import pytest
 
 
-@pytest.mark.skipif(platform.python_implementation() == 'Jython',
-                    reason="Jython throws RepresenterError")
+@pytest.mark.skipif(
+    platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
+)
 def test_load_cyaml():
     import ruamel.yaml
+
     assert ruamel.yaml.__with_libyaml__
     from ruamel.yaml.cyaml import CLoader
-    ruamel.yaml.load("abc: 1", Loader=CLoader)
+
+    ruamel.yaml.load('abc: 1', Loader=CLoader)
 
 
 def test_dump_cyaml():
     import ruamel.yaml
+
     data = {'a': 1, 'b': 2}
-    res = ruamel.yaml.dump(data, Dumper=ruamel.yaml.cyaml.CSafeDumper,
-                           default_flow_style=False, allow_unicode=True)
-    assert res == "a: 1\nb: 2\n"
+    res = ruamel.yaml.dump(
+        data,
+        Dumper=ruamel.yaml.cyaml.CSafeDumper,
+        default_flow_style=False,
+        allow_unicode=True,
+    )
+    assert res == 'a: 1\nb: 2\n'
diff --git a/_test/test_datetime.py b/_test/test_datetime.py
index b48d529..fe94c02 100644
--- a/_test/test_datetime.py
+++ b/_test/test_datetime.py
@@ -20,110 +20,147 @@ Please note that a fraction can only be included if not equal to 0
 """
 
 import copy
-import pytest    # NOQA
+import pytest  # NOQA
 
 from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump  # NOQA
 
 
 class TestDateTime:
     def test_date_only(self):
-        round_trip("""
+        round_trip(
+            """
         - 2011-10-02
-        """, """
+        """,
+            """
         - 2011-10-02
-        """)
+        """,
+        )
 
     def test_zero_fraction(self):
-        round_trip("""
+        round_trip(
+            """
         - 2011-10-02 16:45:00.0
-        """, """
+        """,
+            """
         - 2011-10-02 16:45:00
-        """)
+        """,
+        )
 
     def test_long_fraction(self):
-        round_trip("""
+        round_trip(
+            """
         - 2011-10-02 16:45:00.1234      # expand with zeros
         - 2011-10-02 16:45:00.123456
         - 2011-10-02 16:45:00.12345612  # round to microseconds
         - 2011-10-02 16:45:00.1234565   # round up
         - 2011-10-02 16:45:00.12345678  # round up
-        """, """
+        """,
+            """
         - 2011-10-02 16:45:00.123400    # expand with zeros
         - 2011-10-02 16:45:00.123456
         - 2011-10-02 16:45:00.123456    # round to microseconds
         - 2011-10-02 16:45:00.123457    # round up
         - 2011-10-02 16:45:00.123457    # round up
-        """)
+        """,
+        )
 
     def test_canonical(self):
-        round_trip("""
+        round_trip(
+            """
         - 2011-10-02T16:45:00.1Z
-        """, """
+        """,
+            """
         - 2011-10-02T16:45:00.100000Z
-        """)
+        """,
+        )
 
     def test_spaced_timezone(self):
-        round_trip("""
+        round_trip(
+            """
         - 2011-10-02T11:45:00 -5
-        """, """
+        """,
+            """
         - 2011-10-02T11:45:00-5
-        """)
+        """,
+        )
 
     def test_normal_timezone(self):
-        round_trip("""
+        round_trip(
+            """
         - 2011-10-02T11:45:00-5
         - 2011-10-02 11:45:00-5
         - 2011-10-02T11:45:00-05:00
         - 2011-10-02 11:45:00-05:00
-        """)
+        """
+        )
 
     def test_no_timezone(self):
-        round_trip("""
+        round_trip(
+            """
         - 2011-10-02 6:45:00
-        """, """
+        """,
+            """
         - 2011-10-02 06:45:00
-        """)
+        """,
+        )
 
     def test_explicit_T(self):
-        round_trip("""
+        round_trip(
+            """
         - 2011-10-02T16:45:00
-        """, """
+        """,
+            """
         - 2011-10-02T16:45:00
-        """)
+        """,
+        )
 
     def test_explicit_t(self):  # to upper
-        round_trip("""
+        round_trip(
+            """
         - 2011-10-02t16:45:00
-        """, """
+        """,
+            """
         - 2011-10-02T16:45:00
-        """)
+        """,
+        )
 
     def test_no_T_multi_space(self):
-        round_trip("""
+        round_trip(
+            """
         - 2011-10-02   16:45:00
-        """, """
+        """,
+            """
         - 2011-10-02 16:45:00
-        """)
+        """,
+        )
 
     def test_iso(self):
-        round_trip("""
+        round_trip(
+            """
         - 2011-10-02T15:45:00+01:00
-        """)
+        """
+        )
 
     def test_zero_tz(self):
-        round_trip("""
+        round_trip(
+            """
         - 2011-10-02T15:45:00+0
-        """)
+        """
+        )
 
     def test_issue_45(self):
-        round_trip("""
+        round_trip(
+            """
         dt: 2016-08-19T22:45:47Z
-        """)
+        """
+        )
 
     def test_deepcopy_datestring(self):
         # reported by Quuxplusone, http://stackoverflow.com/a/41577841/1307905
-        x = dedent("""\
+        x = dedent(
+            """\
         foo: 2016-10-12T12:34:56
-        """)
+        """
+        )
         data = copy.deepcopy(round_trip_load(x))
         assert round_trip_dump(data) == x
diff --git a/_test/test_deprecation.py b/_test/test_deprecation.py
index f1a5419..35cb095 100644
--- a/_test/test_deprecation.py
+++ b/_test/test_deprecation.py
@@ -6,7 +6,7 @@ import sys
 import pytest  # NOQA
 
 
-@pytest.mark.skipif(sys.version_info < (3, 7), reason="collections not available?")
+@pytest.mark.skipif(sys.version_info < (3, 7), reason='collections not available?')
 def test_collections_deprecation():
     with pytest.warns(DeprecationWarning):
         from collections import Hashable  # NOQA
diff --git a/_test/test_documents.py b/_test/test_documents.py
index 6da293a..476f70c 100644
--- a/_test/test_documents.py
+++ b/_test/test_documents.py
@@ -1,70 +1,99 @@
 # coding: utf-8
 
-import pytest   # NOQA
+import pytest  # NOQA
 
 from roundtrip import round_trip, round_trip_load_all
 
 
 class TestDocument:
     def test_single_doc_begin_end(self):
-        round_trip("""\
+        round_trip(
+            """\
         ---
         - a
         - b
         ...
-        """, explicit_start=True, explicit_end=True)
+        """,
+            explicit_start=True,
+            explicit_end=True,
+        )
 
     def test_multi_doc_begin_end(self):
         from ruamel import yaml
-        docs = list(round_trip_load_all("""\
+
+        docs = list(
+            round_trip_load_all(
+                """\
         ---
         - a
         ...
         ---
         - b
         ...
-        """))
+        """
+            )
+        )
         assert docs == [['a'], ['b']]
-        out = yaml.dump_all(docs, Dumper=yaml.RoundTripDumper, explicit_start=True,
-                            explicit_end=True)
-        assert out == "---\n- a\n...\n---\n- b\n...\n"
+        out = yaml.dump_all(
+            docs, Dumper=yaml.RoundTripDumper, explicit_start=True, explicit_end=True
+        )
+        assert out == '---\n- a\n...\n---\n- b\n...\n'
 
     def test_multi_doc_no_start(self):
-        docs = list(round_trip_load_all("""\
+        docs = list(
+            round_trip_load_all(
+                """\
         - a
         ...
         ---
         - b
         ...
-        """))
+        """
+            )
+        )
         assert docs == [['a'], ['b']]
 
     def test_multi_doc_no_end(self):
-        docs = list(round_trip_load_all("""\
+        docs = list(
+            round_trip_load_all(
+                """\
         - a
         ---
         - b
-        """))
+        """
+            )
+        )
         assert docs == [['a'], ['b']]
 
     def test_multi_doc_ends_only(self):
         # this is ok in 1.2
-        docs = list(round_trip_load_all("""\
+        docs = list(
+            round_trip_load_all(
+                """\
         - a
         ...
         - b
         ...
-        """, version=(1, 2)))
+        """,
+                version=(1, 2),
+            )
+        )
         assert docs == [['a'], ['b']]
 
     def test_multi_doc_ends_only_1_1(self):
         from ruamel import yaml
+
         # this is not ok in 1.1
         with pytest.raises(yaml.parser.ParserError):
-            docs = list(round_trip_load_all("""\
+            docs = list(
+                round_trip_load_all(
+                    """\
             - a
             ...
             - b
             ...
-            """, version=(1, 1)))
+            """,
+                    version=(1, 1),
+                )
+            )
             assert docs == [['a'], ['b']]  # not True, but not reached
diff --git a/_test/test_fail.py b/_test/test_fail.py
index fb85e5f..9c318a0 100644
--- a/_test/test_fail.py
+++ b/_test/test_fail.py
@@ -15,7 +15,8 @@ class TestCommentFailures:
     @pytest.mark.xfail(strict=True)
     def test_set_comment_before_tag(self):
         # no comments before tags
-        round_trip("""
+        round_trip(
+            """
         # the beginning
         !!set
         # or this one?
@@ -24,11 +25,15 @@ class TestCommentFailures:
         ? b  #  You see? Promised you.
         ? c
         # this is the end
-        """)
+        """
+        )
 
     def test_set_comment_before_tag_no_fail(self):
         # no comments before tags
-        assert round_trip_dump(round_trip_load("""
+        assert (
+            round_trip_dump(
+                round_trip_load(
+                    """
         # the beginning
         !!set
         # or this one?
@@ -37,7 +42,11 @@ class TestCommentFailures:
         ? b  #  You see? Promised you.
         ? c
         # this is the end
-        """)) == dedent("""
+        """
+                )
+            )
+            == dedent(
+                """
         !!set
         # or this one?
         ? a
@@ -45,15 +54,19 @@ class TestCommentFailures:
         ? b  #  You see? Promised you.
         ? c
         # this is the end
-        """)
+        """
+            )
+        )
 
     @pytest.mark.xfail(strict=True)
     def test_comment_dash_line(self):
-        round_trip("""
+        round_trip(
+            """
         - # abc
            a: 1
            b: 2
-        """)
+        """
+        )
 
     def test_comment_dash_line_fail(self):
         x = """
@@ -63,18 +76,20 @@ class TestCommentFailures:
         """
         data = round_trip_load(x)
         # this is not nice
-        assert round_trip_dump(data) == dedent("""
+        assert round_trip_dump(data) == dedent(
+            """
           # abc
         - a: 1
           b: 2
-        """)
+        """
+        )
 
 
 class TestIndentFailures:
-
     @pytest.mark.xfail(strict=True)
     def test_indent_not_retained(self):
-        round_trip("""
+        round_trip(
+            """
         verbosity: 1                  # 0 is minimal output, -1 none
         base_url: http://gopher.net
         special_indices: [1, 5, 8]
@@ -95,10 +110,14 @@ class TestIndentFailures:
                 Italy: Rome
             Antarctica:
             -   too cold
-        """)
+        """
+        )
 
     def test_indent_not_retained_no_fail(self):
-        assert round_trip_dump(round_trip_load("""
+        assert (
+            round_trip_dump(
+                round_trip_load(
+                    """
         verbosity: 1                  # 0 is minimal output, -1 none
         base_url: http://gopher.net
         special_indices: [1, 5, 8]
@@ -119,7 +138,12 @@ class TestIndentFailures:
                 Italy: Rome
             Antarctica:
             -   too cold
-        """), indent=4) == dedent("""
+        """
+                ),
+                indent=4,
+            )
+            == dedent(
+                """
         verbosity: 1                  # 0 is minimal output, -1 none
         base_url: http://gopher.net
         special_indices: [1, 5, 8]
@@ -140,46 +164,67 @@ class TestIndentFailures:
                 Italy: Rome
             Antarctica:
             -   too cold
-        """)
+        """
+            )
+        )
 
     def Xtest_indent_top_level_no_fail(self):
-        round_trip("""
+        round_trip(
+            """
         -   a:
             - b
-        """, indent=4)
+        """,
+            indent=4,
+        )
 
 
 class TestTagFailures:
     @pytest.mark.xfail(strict=True)
     def test_standard_short_tag(self):
-        round_trip("""\
+        round_trip(
+            """\
         !!map
         name: Anthon
         location: Germany
         language: python
-        """)
+        """
+        )
 
     def test_standard_short_tag_no_fail(self):
-        assert round_trip_dump(round_trip_load("""
+        assert (
+            round_trip_dump(
+                round_trip_load(
+                    """
         !!map
         name: Anthon
         location: Germany
         language: python
-        """)) == dedent("""
+        """
+                )
+            )
+            == dedent(
+                """
         name: Anthon
         location: Germany
         language: python
-        """)
+        """
+            )
+        )
 
 
 class TestFlowValues:
     def test_flow_value_with_colon(self):
-        round_trip("""\
+        round_trip(
+            """\
         {a: bcd:efg}
-        """)
+        """
+        )
 
     # @pytest.mark.xfail(strict=True)
     def test_flow_value_with_colon_quoted(self):
-        round_trip("""\
+        round_trip(
+            """\
         {a: 'bcd:efg'}
-        """, preserve_quotes=True)
+        """,
+            preserve_quotes=True,
+        )
diff --git a/_test/test_float.py b/_test/test_float.py
index 2bfe098..b115eb3 100644
--- a/_test/test_float.py
+++ b/_test/test_float.py
@@ -11,7 +11,8 @@ from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump  # NO
 
 class TestFloat:
     def test_round_trip_non_exp(self):
-        data = round_trip("""\
+        data = round_trip(
+            """\
         - 1.0
         - 1.00
         - 23.100
@@ -21,7 +22,8 @@ class TestFloat:
         - 42.
         - -42.
         - +42.
-        """)
+        """
+        )
         print(data)
         assert 0.999 < data[0] < 1.001
         assert 0.999 < data[1] < 1.001
@@ -34,7 +36,8 @@ class TestFloat:
         assert 41.999 < data[8] < 42.001
 
     def test_round_trip_zeros_0(self):
-        data = round_trip("""\
+        data = round_trip(
+            """\
         - 0.
         - +0.
         - -0.
@@ -44,7 +47,8 @@ class TestFloat:
         - 0.00
         - +0.00
         - -0.00
-        """)
+        """
+        )
         print(data)
         for d in data:
             assert -0.00001 < d < 0.00001
@@ -52,114 +56,137 @@ class TestFloat:
     # @pytest.mark.xfail(strict=True)
     def test_round_trip_zeros_1(self):
         # not sure if this should be supported, but it is
-        data = round_trip("""\
+        data = round_trip(
+            """\
         - 00.0
         - +00.0
         - -00.0
-        """)
+        """
+        )
         print(data)
         for d in data:
             assert -0.00001 < d < 0.00001
 
     def Xtest_round_trip_non_exp_trailing_dot(self):
-        data = round_trip("""\
-        """)
+        data = round_trip(
+            """\
+        """
+        )
         print(data)
 
     def test_round_trip_exp_00(self):
-        data = round_trip("""\
+        data = round_trip(
+            """\
         - 42e56
         - 42E56
         - 42.0E56
         - +42.0e56
         - 42.0E+056
         - +42.00e+056
-        """)
+        """
+        )
         print(data)
         for d in data:
             assert 41.99e56 < d < 42.01e56
 
     # @pytest.mark.xfail(strict=True)
     def test_round_trip_exp_00f(self):
-        data = round_trip("""\
+        data = round_trip(
+            """\
         - 42.E56
-        """)
+        """
+        )
         print(data)
         for d in data:
             assert 41.99e56 < d < 42.01e56
 
     def test_round_trip_exp_01(self):
-        data = round_trip("""\
+        data = round_trip(
+            """\
         - -42e56
         - -42E56
         - -42.0e56
         - -42.0E+056
-        """)
+        """
+        )
         print(data)
         for d in data:
             assert -41.99e56 > d > -42.01e56
 
     def test_round_trip_exp_02(self):
-        data = round_trip("""\
+        data = round_trip(
+            """\
         - 42e-56
         - 42E-56
         - 42.0E-56
         - +42.0e-56
         - 42.0E-056
         - +42.0e-056
-        """)
+        """
+        )
         print(data)
         for d in data:
             assert 41.99e-56 < d < 42.01e-56
 
     def test_round_trip_exp_03(self):
-        data = round_trip("""\
+        data = round_trip(
+            """\
         - -42e-56
         - -42E-56
         - -42.0e-56
         - -42.0E-056
-        """)
+        """
+        )
         print(data)
         for d in data:
             assert -41.99e-56 > d > -42.01e-56
 
     def test_round_trip_exp_04(self):
-        round_trip("""\
+        round_trip(
+            """\
         - 1.2e+34
         - 1.23e+034
         - 1.230e+34
         - 1.023e+34
         - -1.023e+34
         - 250e6
-        """)
+        """
+        )
 
     def test_round_trip_exp_05(self):
-        data = round_trip("""\
+        data = round_trip(
+            """\
         - 3.0517578123e-56
         - 3.0517578123E-56
         - 3.0517578123e-056
         - 3.0517578123E-056
-        """)
+        """
+        )
         print(data)
         for d in data:
             assert 3.0517578122e-56 < d < 3.0517578124e-56
 
     def test_yaml_1_1_no_dot(self):
         from ruamel.yaml.error import MantissaNoDotYAML1_1Warning
+
         with pytest.warns(MantissaNoDotYAML1_1Warning):
-            round_trip_load("""\
+            round_trip_load(
+                """\
             %YAML 1.1
             ---
             - 1e6
-            """)
+            """
+            )
 
 
 class TestCalculations(object):
     def test_mul_00(self):
         # issue 149 reported by jan.brezina@tul.cz
-        d = round_trip_load("""\
+        d = round_trip_load(
+            """\
         - 0.1
-        """)
+        """
+        )
         d[0] *= -1
         x = round_trip_dump(d)
         assert x == '- -0.1\n'
diff --git a/_test/test_flowsequencekey.py b/_test/test_flowsequencekey.py
index 8490430..f8f122e 100644
--- a/_test/test_flowsequencekey.py
+++ b/_test/test_flowsequencekey.py
@@ -12,7 +12,8 @@ from roundtrip import round_trip  # , dedent, round_trip_load, round_trip_dump
 
 class TestFlowStyleSequenceKey:
     def test_so_39595807(self):
-        round_trip("""
+        round_trip(
+            """
         %YAML 1.2
         ---
         [2, 3, 4]:
@@ -21,4 +22,8 @@ class TestFlowStyleSequenceKey:
           - 2
           b: Hello World!
           c: 'Voilà!'
-        """, preserve_quotes=True, explicit_start=True, version=(1, 2))
+        """,
+            preserve_quotes=True,
+            explicit_start=True,
+            version=(1, 2),
+        )
diff --git a/_test/test_indentation.py b/_test/test_indentation.py
index 528e3b6..dcac772 100644
--- a/_test/test_indentation.py
+++ b/_test/test_indentation.py
@@ -12,10 +12,14 @@ from roundtrip import round_trip, round_trip_load, round_trip_dump, dedent, YAML
 
 def rt(s):
     import ruamel.yaml
-    return ruamel.yaml.dump(
-        ruamel.yaml.load(s, Loader=ruamel.yaml.RoundTripLoader),
-        Dumper=ruamel.yaml.RoundTripDumper,
-    ).strip() + '\n'
+
+    return (
+        ruamel.yaml.dump(
+            ruamel.yaml.load(s, Loader=ruamel.yaml.RoundTripLoader),
+            Dumper=ruamel.yaml.RoundTripDumper,
+        ).strip()
+        + '\n'
+    )
 
 
 class TestIndent:
@@ -25,41 +29,50 @@ class TestIndent:
         assert s == output
 
     def test_roundtrip_mapping_of_inline_lists(self):
-        s = dedent("""\
+        s = dedent(
+            """\
         a: [a, b, c]
         j: [k, l, m]
-        """)
+        """
+        )
         output = rt(s)
         assert s == output
 
     def test_roundtrip_mapping_of_inline_lists_comments(self):
-        s = dedent("""\
+        s = dedent(
+            """\
         # comment A
         a: [a, b, c]
         # comment B
         j: [k, l, m]
-        """)
+        """
+        )
         output = rt(s)
         assert s == output
 
     def test_roundtrip_mapping_of_inline_sequence_eol_comments(self):
-        s = dedent("""\
+        s = dedent(
+            """\
         # comment A
         a: [a, b, c]  # comment B
         j: [k, l, m]  # comment C
-        """)
+        """
+        )
         output = rt(s)
         assert s == output
 
     # first test by explicitly setting flow style
     def test_added_inline_list(self):
         import ruamel.yaml
-        s1 = dedent("""
+
+        s1 = dedent(
+            """
         a:
         - b
         - c
         - d
-        """)
+        """
+        )
         s = 'a: [b, c, d]\n'
         data = ruamel.yaml.load(s1, Loader=ruamel.yaml.RoundTripLoader)
         val = data['a']
@@ -72,58 +85,79 @@ class TestIndent:
 
     def test_roundtrip_flow_mapping(self):
         import ruamel.yaml
-        s = dedent("""\
+
+        s = dedent(
+            """\
         - {a: 1, b: hallo}
         - {j: fka, k: 42}
-        """)
+        """
+        )
         data = ruamel.yaml.load(s, Loader=ruamel.yaml.RoundTripLoader)
         output = ruamel.yaml.dump(data, Dumper=ruamel.yaml.RoundTripDumper)
         assert s == output
 
     def test_roundtrip_sequence_of_inline_mappings_eol_comments(self):
-        s = dedent("""\
+        s = dedent(
+            """\
         # comment A
         - {a: 1, b: hallo}  # comment B
         - {j: fka, k: 42}  # comment C
-        """)
+        """
+        )
         output = rt(s)
         assert s == output
 
     def test_indent_top_level(self):
-        round_trip("""
+        round_trip(
+            """
         -   a:
             -   b
-        """, indent=4)
+        """,
+            indent=4,
+        )
 
     def test_set_indent_5_block_list_indent_1(self):
-        round_trip("""
+        round_trip(
+            """
         a:
          -   b: c
          -   1
          -   d:
               -   2
-        """, indent=5, block_seq_indent=1)
+        """,
+            indent=5,
+            block_seq_indent=1,
+        )
 
     def test_set_indent_4_block_list_indent_2(self):
-        round_trip("""
+        round_trip(
+            """
         a:
           - b: c
           - 1
           - d:
               - 2
-        """, indent=4, block_seq_indent=2)
+        """,
+            indent=4,
+            block_seq_indent=2,
+        )
 
     def test_set_indent_3_block_list_indent_0(self):
-        round_trip("""
+        round_trip(
+            """
         a:
         -  b: c
         -  1
         -  d:
            -  2
-        """, indent=3, block_seq_indent=0)
+        """,
+            indent=3,
+            block_seq_indent=0,
+        )
 
     def Xtest_set_indent_3_block_list_indent_2(self):
-        round_trip("""
+        round_trip(
+            """
         a:
           -
            b: c
@@ -133,19 +167,27 @@ class TestIndent:
            d:
              -
               2
-        """, indent=3, block_seq_indent=2)
+        """,
+            indent=3,
+            block_seq_indent=2,
+        )
 
     def test_set_indent_3_block_list_indent_2(self):
-        round_trip("""
+        round_trip(
+            """
         a:
           - b: c
           - 1
           - d:
              - 2
-        """, indent=3, block_seq_indent=2)
+        """,
+            indent=3,
+            block_seq_indent=2,
+        )
 
     def Xtest_set_indent_2_block_list_indent_2(self):
-        round_trip("""
+        round_trip(
+            """
         a:
           -
            b: c
@@ -155,42 +197,55 @@ class TestIndent:
            d:
              -
               2
-        """, indent=2, block_seq_indent=2)
+        """,
+            indent=2,
+            block_seq_indent=2,
+        )
 
     # this is how it should be: block_seq_indent stretches the indent
     def test_set_indent_2_block_list_indent_2(self):
-        round_trip("""
+        round_trip(
+            """
         a:
           - b: c
           - 1
           - d:
             - 2
-        """, indent=2, block_seq_indent=2)
+        """,
+            indent=2,
+            block_seq_indent=2,
+        )
 
     # have to set indent!
     def test_roundtrip_four_space_indents(self):
-        s = (
-            'a:\n'
-            '-   foo\n'
-            '-   bar\n'
-        )
+        s = 'a:\n' '-   foo\n' '-   bar\n'
         round_trip(s, indent=4)
 
     def test_roundtrip_four_space_indents_no_fail(self):
-        assert round_trip_dump(round_trip_load("""
+        assert (
+            round_trip_dump(
+                round_trip_load(
+                    """
         a:
         -   foo
         -   bar
-        """)) == dedent("""
+        """
+                )
+            )
+            == dedent(
+                """
         a:
         - foo
         - bar
-        """)
+        """
+            )
+        )
 
 
 class TestYpkgIndent:
     def test_00(self):
-        round_trip("""
+        round_trip(
+            """
         name       : nano
         version    : 2.3.2
         release    : 1
@@ -205,41 +260,67 @@ class TestYpkgIndent:
             GNU nano is an easy-to-use text editor originally designed
             as a replacement for Pico, the ncurses-based editor from the non-free mailer
             package Pine (itself now available under the Apache License as Alpine).
-        """, indent=4, block_seq_indent=2, top_level_colon_align=True, prefix_colon=' ')
+        """,
+            indent=4,
+            block_seq_indent=2,
+            top_level_colon_align=True,
+            prefix_colon=' ',
+        )
 
 
 def guess(s):
     from ruamel.yaml.util import load_yaml_guess_indent
+
     x, y, z = load_yaml_guess_indent(dedent(s))
     return y, z
 
 
 class TestGuessIndent:
     def test_guess_20(self):
-        assert guess("""\
+        assert (
+            guess(
+                """\
         a:
         - 1
-        """) == (2, 0)
+        """
+            )
+            == (2, 0)
+        )
 
     def test_guess_42(self):
-        assert guess("""\
+        assert (
+            guess(
+                """\
         a:
           - 1
-        """) == (4, 2)
+        """
+            )
+            == (4, 2)
+        )
 
     def test_guess_42a(self):
         # block seq indent prevails over nested key indent level
-        assert guess("""\
+        assert (
+            guess(
+                """\
         b:
               a:
                 - 1
-        """) == (4, 2)
+        """
+            )
+            == (4, 2)
+        )
 
     def test_guess_3None(self):
-        assert guess("""\
+        assert (
+            guess(
+                """\
         b:
            a: 1
-        """) == (3, None)
+        """
+            )
+            == (3, None)
+        )
 
 
 class TestSeparateMapSeqIndents:
@@ -250,58 +331,70 @@ class TestSeparateMapSeqIndents:
         yaml = YAML()
         yaml.indent = 6
         yaml.block_seq_indent = 3
-        yaml.round_trip("""
+        yaml.round_trip(
+            """
         a:
            -  1
            -  [1, 2]
-        """)
+        """
+        )
 
     def test_01(self):
         yaml = YAML()
         yaml.indent(sequence=6)
         yaml.indent(offset=3)
-        yaml.round_trip("""
+        yaml.round_trip(
+            """
         a:
            -  1
            -  {b: 3}
-        """)
+        """
+        )
 
     def test_02(self):
         yaml = YAML()
         yaml.indent(mapping=5, sequence=6, offset=3)
-        yaml.round_trip("""
+        yaml.round_trip(
+            """
         a:
              b:
                 -  1
                 -  [1, 2]
-        """)
+        """
+        )
 
     def test_03(self):
-        round_trip("""
+        round_trip(
+            """
         a:
             b:
                 c:
                 -   1
                 -   [1, 2]
-        """, indent=4)
+        """,
+            indent=4,
+        )
 
     def test_04(self):
         yaml = YAML()
         yaml.indent(mapping=5, sequence=6)
-        yaml.round_trip("""
+        yaml.round_trip(
+            """
         a:
              b:
              -     1
              -     [1, 2]
              -     {d: 3.14}
-        """)
+        """
+        )
 
     def test_issue_51(self):
         yaml = YAML()
         # yaml.map_indent = 2 # the default
         yaml.indent(sequence=4, offset=2)
         yaml.preserve_quotes = True
-        yaml.round_trip("""
+        yaml.round_trip(
+            """
         role::startup::author::rsyslog_inputs:
           imfile:
             - ruleset: 'AEM-slinglog'
@@ -312,6 +405,8 @@ class TestSeparateMapSeqIndents:
               File: '/opt/aem/author/crx-quickstart/logs/stdout.log'
               startmsg.regex: '^[-+T.:[:digit:]]*'
               tag: 'stdout'
-        """)
+        """
+        )
+
 
 # ############ indentation
diff --git a/_test/test_int.py b/_test/test_int.py
index 080eb54..daf4fda 100644
--- a/_test/test_int.py
+++ b/_test/test_int.py
@@ -12,23 +12,27 @@ from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump
 class TestBinHexOct:
     # @pytest.mark.xfail(strict=True)
     def test_round_trip_hex_oct(self):
-        round_trip("""\
+        round_trip(
+            """\
         - 42
         - 0b101010
         - 0x2a
         - 0x2A
         - 0o52
-        """)
+        """
+        )
 
     def test_calculate(self):
         # make sure type, leading zero(s) and underscore are preserved
-        s = dedent("""\
+        s = dedent(
+            """\
         - 42
         - 0b101010
         - 0x_2a
         - 0x2A
         - 0o00_52
-        """)
+        """
+        )
         x = round_trip_load(s)
         for idx, elem in enumerate(x):
             # x[idx] = type(elem)(elem - 21)
@@ -51,7 +55,8 @@ class TestBinHexOct:
     # the old octal representation.
 
     def test_leading_zero_hex_oct_bin(self):
-        round_trip("""\
+        round_trip(
+            """\
         - 0b0101010
         - 0b00101010
         - 0x02a
@@ -60,26 +65,32 @@ class TestBinHexOct:
         - 0x002A
         - 0o052
         - 0o0052
-        """)
+        """
+        )
 
     def test_leading_zero_int(self):
-        round_trip("""\
+        round_trip(
+            """\
         - 042
         - 0042
-        """)
+        """
+        )
 
     def test_leading_zero_YAML_1_1(self):
-        d = round_trip_load("""\
+        d = round_trip_load(
+            """\
         %YAML 1.1
         ---
         - 042
         - 0o42
-        """)
+        """
+        )
         assert d[0] == 0o42
         assert d[1] == '0o42'
 
     def test_underscore(self):
-        round_trip("""\
+        round_trip(
+            """\
         - 0b10000_10010010
         - 0b0_0000_1001_0010
         - 0x2_87_57_b2_
@@ -87,23 +98,28 @@ class TestBinHexOct:
         - 0x_0_2_8_7_5_7_B_2
         - 0o2416_53662
         - 42_42_
-        """)
+        """
+        )
 
     def test_leading_underscore(self):
-        d = round_trip_load("""\
+        d = round_trip_load(
+            """\
         - 0x_2_8_7_5_7_B_2
         - _42_42_
         - 42_42_
-        """)
+        """
+        )
         assert d[0] == 42424242
         assert d[1] == '_42_42_'
         assert d[2] == 4242
 
     def test_big(self):
         # bitbucket issue 144 reported by ccatterina
-        d = round_trip_load("""\
+        d = round_trip_load(
+            """\
         - 2_147_483_647
         - 9_223_372_036_854_775_808
-        """)
+        """
+        )
         assert d[0] == 2147483647
         assert d[1] == 9223372036854775808
diff --git a/_test/test_issues.py b/_test/test_issues.py
index 0e01875..559dcba 100644
--- a/_test/test_issues.py
+++ b/_test/test_issues.py
@@ -12,7 +12,9 @@ from roundtrip import round_trip, round_trip_load, round_trip_dump, dedent  # NO
 class TestIssue61:
     def test_issue_61(self):
         import ruamel.yaml
-        s = dedent("""
+
+        s = dedent(
+            """
         def1: &ANCHOR1
             key1: value1
         def: &ANCHOR
@@ -20,7 +22,8 @@ class TestIssue61:
             key: value
         comb:
             <<: *ANCHOR
-        """)
+        """
+        )
         data = ruamel.yaml.round_trip_load(s)
         assert str(data['comb']) == str(data['def'])
         assert str(data['comb']) == "ordereddict([('key', 'value'), ('key1', 'value1')])"
diff --git a/_test/test_json_numbers.py b/_test/test_json_numbers.py
index a580277..56b7b6f 100644
--- a/_test/test_json_numbers.py
+++ b/_test/test_json_numbers.py
@@ -9,6 +9,7 @@ import json
 
 def load(s, typ=float):
     import ruamel.yaml
+
     x = '{"low": %s }' % (s)
     print('input: [%s]' % (s), repr(x))
     # just to check it is loadable json
@@ -27,23 +28,29 @@ class TestJSONNumbers:
     #
     # which is not a superset of the JSON numbers
     def test_json_number_float(self):
-        for x in (y.split('#')[0].strip() for y in """
+        for x in (
+            y.split('#')[0].strip()
+            for y in """
         1.0  # should fail on YAML spec on 1-9 allowed as single digit
         -1.0
         1e-06
         3.1e-5
         3.1e+5
         3.1e5  # should fail on YAML spec: no +- after e
-        """.splitlines()):
+        """.splitlines()
+        ):
             if not x:
                 continue
             res = load(x)
             assert isinstance(res, float)
 
     def test_json_number_int(self):
-        for x in (y.split('#')[0].strip() for y in """
+        for x in (
+            y.split('#')[0].strip()
+            for y in """
         42
-        """.splitlines()):
+        """.splitlines()
+        ):
             if not x:
                 continue
             res = load(x, int)
diff --git a/_test/test_line_col.py b/_test/test_line_col.py
index febe9c2..4f7ad5d 100644
--- a/_test/test_line_col.py
+++ b/_test/test_line_col.py
@@ -11,80 +11,94 @@ def load(s):
 
 class TestLineCol:
     def test_item_00(self):
-        data = load("""
+        data = load(
+            """
             - a
             - e
             - [b, d]
             - c
-            """)
+            """
+        )
         assert data[2].lc.line == 2
         assert data[2].lc.col == 2
 
     def test_item_01(self):
-        data = load("""
+        data = load(
+            """
             - a
             - e
             - {x: 3}
             - c
-            """)
+            """
+        )
         assert data[2].lc.line == 2
         assert data[2].lc.col == 2
 
     def test_item_02(self):
-        data = load("""
+        data = load(
+            """
             - a
             - e
             - !!set {x, y}
             - c
-            """)
+            """
+        )
         assert data[2].lc.line == 2
         assert data[2].lc.col == 2
 
     def test_item_03(self):
-        data = load("""
+        data = load(
+            """
             - a
             - e
             - !!omap
               - x: 1
               - y: 3
             - c
-            """)
+            """
+        )
         assert data[2].lc.line == 2
         assert data[2].lc.col == 2
 
     def test_item_04(self):
-        data = load("""
+        data = load(
+            """
          # testing line and column based on SO
          # http://stackoverflow.com/questions/13319067/
          - key1: item 1
            key2: item 2
          - key3: another item 1
            key4: another item 2
-            """)
+            """
+        )
         assert data[0].lc.line == 2
         assert data[0].lc.col == 2
         assert data[1].lc.line == 4
         assert data[1].lc.col == 2
 
     def test_pos_mapping(self):
-        data = load("""
+        data = load(
+            """
         a: 1
         b: 2
         c: 3
         # comment
         klm: 42
         d: 4
-        """)
+        """
+        )
         assert data.lc.key('klm') == (4, 0)
         assert data.lc.value('klm') == (4, 5)
 
     def test_pos_sequence(self):
-        data = load("""
+        data = load(
+            """
         - a
         - b
         - c
         # next one!
         - klm
         - d
-        """)
+        """
+        )
         assert data.lc.item(3) == (4, 2)
diff --git a/_test/test_literal.py b/_test/test_literal.py
index 0499a16..74dca3d 100644
--- a/_test/test_literal.py
+++ b/_test/test_literal.py
@@ -31,126 +31,178 @@ class TestNoIndent:
     def test_top_literal_scalar_indent_example_9_5(self):
         yaml = YAML()
         s = '%!PS-Adobe-2.0'
-        d = yaml.load("""
+        d = yaml.load(
+            """
         --- |
           {}
-        """.format(s))
+        """.format(
+                s
+            )
+        )
         print(d)
         assert d == s + '\n'
 
     def test_top_literal_scalar_no_indent(self):
         yaml = YAML()
         s = 'testing123'
-        d = yaml.load("""
+        d = yaml.load(
+            """
         --- |
         {}
-        """.format(s))
+        """.format(
+                s
+            )
+        )
         print(d)
         assert d == s + '\n'
 
     def test_top_literal_scalar_no_indent_1_1(self):
         yaml = YAML()
         s = 'testing123'
-        d = yaml.load("""
+        d = yaml.load(
+            """
         %YAML 1.1
         --- |
         {}
-        """.format(s))
+        """.format(
+                s
+            )
+        )
         print(d)
         assert d == s + '\n'
 
     def test_top_literal_scalar_no_indent_1_1_old_style(self):
         from textwrap import dedent
         from ruamel.yaml import safe_load
+
         s = 'testing123'
-        d = safe_load(dedent("""
+        d = safe_load(
+            dedent(
+                """
         %YAML 1.1
         --- |
           {}
-        """.format(s)))
+        """.format(
+                    s
+                )
+            )
+        )
         print(d)
         assert d == s + '\n'
 
     def test_top_literal_scalar_no_indent_1_1_raise(self):
         from ruamel.yaml.parser import ParserError
+
         yaml = YAML()
         yaml.top_level_block_style_scalar_no_indent_error_1_1 = True
         s = 'testing123'
         with pytest.raises(ParserError):
-            yaml.load("""
+            yaml.load(
+                """
             %YAML 1.1
             --- |
             {}
-            """.format(s))
+            """.format(
+                    s
+                )
+            )
 
     def test_top_literal_scalar_indent_offset_one(self):
         yaml = YAML()
         s = 'testing123'
-        d = yaml.load("""
+        d = yaml.load(
+            """
         --- |1
          {}
-        """.format(s))
+        """.format(
+                s
+            )
+        )
         print(d)
         assert d == s + '\n'
 
     def test_top_literal_scalar_indent_offset_four(self):
         yaml = YAML()
         s = 'testing123'
-        d = yaml.load("""
+        d = yaml.load(
+            """
         --- |4
             {}
-        """.format(s))
+        """.format(
+                s
+            )
+        )
         print(d)
         assert d == s + '\n'
 
     def test_top_literal_scalar_indent_offset_two_leading_space(self):
         yaml = YAML()
         s = ' testing123'
-        d = yaml.load("""
+        d = yaml.load(
+            """
         --- |4
             {s}
             {s}
-        """.format(s=s))
+        """.format(
+                s=s
+            )
+        )
         print(d)
         assert d == (s + '\n') * 2
 
     def test_top_literal_scalar_no_indent_special(self):
         yaml = YAML()
         s = '%!PS-Adobe-2.0'
-        d = yaml.load("""
+        d = yaml.load(
+            """
         --- |
         {}
-        """.format(s))
+        """.format(
+                s
+            )
+        )
         print(d)
         assert d == s + '\n'
 
     def test_top_folding_scalar_indent(self):
         yaml = YAML()
         s = '%!PS-Adobe-2.0'
-        d = yaml.load("""
+        d = yaml.load(
+            """
         --- >
           {}
-        """.format(s))
+        """.format(
+                s
+            )
+        )
         print(d)
         assert d == s + '\n'
 
     def test_top_folding_scalar_no_indent(self):
         yaml = YAML()
         s = 'testing123'
-        d = yaml.load("""
+        d = yaml.load(
+            """
         --- >
         {}
-        """.format(s))
+        """.format(
+                s
+            )
+        )
         print(d)
         assert d == s + '\n'
 
     def test_top_folding_scalar_no_indent_special(self):
         yaml = YAML()
         s = '%!PS-Adobe-2.0'
-        d = yaml.load("""
+        d = yaml.load(
+            """
         --- >
         {}
-        """.format(s))
+        """.format(
+                s
+            )
+        )
         print(d)
         assert d == s + '\n'
 
@@ -158,12 +210,18 @@ class TestNoIndent:
         yaml = YAML(typ='safe', pure=True)
         s1 = 'abc'
         s2 = 'klm'
-        for idx, d1 in enumerate(yaml.load_all("""
+        for idx, d1 in enumerate(
+            yaml.load_all(
+                """
         --- |-
         {}
         --- |
         {}
-        """.format(s1, s2))):
+        """.format(
+                    s1, s2
+                )
+            )
+        ):
             print('d1:', d1)
             assert ['abc', 'klm\n'][idx] == d1
 
@@ -176,7 +234,9 @@ class Test_RoundTripLiteral:
         ys = """
         --- |
         {}
-        """.format(s)
+        """.format(
+            s
+        )
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
@@ -188,7 +248,9 @@ class Test_RoundTripLiteral:
         ys = """
         --- |
             {}
-        """.format(s)
+        """.format(
+            s
+        )
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
@@ -200,7 +262,9 @@ class Test_RoundTripLiteral:
         ys = """
         ---
         {}
-        """.format(s)
+        """.format(
+            s
+        )
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
@@ -212,7 +276,9 @@ class Test_RoundTripLiteral:
         ys = """
         ---
             {}
-        """.format(s)
+        """.format(
+            s
+        )
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
@@ -224,7 +290,9 @@ class Test_RoundTripLiteral:
         ys = """
         ---
             {}
-        """.format(s)
+        """.format(
+            s
+        )
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
@@ -238,7 +306,9 @@ class Test_RoundTripLiteral:
         ys = """
         ---
         {}
-        """.format(s)
+        """.format(
+            s
+        )
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
@@ -249,7 +319,9 @@ class Test_RoundTripLiteral:
         ys = """
         --- |-
         {}
-        """.format(s)
+        """.format(
+            s
+        )
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
 
@@ -259,6 +331,8 @@ class Test_RoundTripLiteral:
         ys = """
         - |
           {}
-        """.format(s)
+        """.format(
+            s
+        )
         d = yaml.load(ys)
         yaml.dump(d, compare=ys)
diff --git a/_test/test_none.py b/_test/test_none.py
index 681f1e0..e313edc 100644
--- a/_test/test_none.py
+++ b/_test/test_none.py
@@ -1,12 +1,13 @@
 # coding: utf-8
 
 
-import pytest    # NOQA
+import pytest  # NOQA
 
 
 class TestNone:
     def test_dump00(self):
-        import ruamel.yaml   # NOQA
+        import ruamel.yaml  # NOQA
+
         data = None
         s = ruamel.yaml.round_trip_dump(data)
         assert s == 'null\n...\n'
@@ -14,7 +15,8 @@ class TestNone:
         assert d == data
 
     def test_dump01(self):
-        import ruamel.yaml   # NOQA
+        import ruamel.yaml  # NOQA
+
         data = None
         s = ruamel.yaml.round_trip_dump(data, explicit_end=True)
         assert s == 'null\n...\n'
@@ -22,7 +24,8 @@ class TestNone:
         assert d == data
 
     def test_dump02(self):
-        import ruamel.yaml   # NOQA
+        import ruamel.yaml  # NOQA
+
         data = None
         s = ruamel.yaml.round_trip_dump(data, explicit_end=False)
         assert s == 'null\n...\n'
@@ -30,7 +33,8 @@ class TestNone:
         assert d == data
 
     def test_dump03(self):
-        import ruamel.yaml   # NOQA
+        import ruamel.yaml  # NOQA
+
         data = None
         s = ruamel.yaml.round_trip_dump(data, explicit_start=True)
         assert s == '---\n...\n'
@@ -38,7 +42,8 @@ class TestNone:
         assert d == data
 
     def test_dump04(self):
-        import ruamel.yaml   # NOQA
+        import ruamel.yaml  # NOQA
+
         data = None
         s = ruamel.yaml.round_trip_dump(data, explicit_start=True, explicit_end=False)
         assert s == '---\n...\n'
diff --git a/_test/test_numpy.py b/_test/test_numpy.py
index e3a7718..2747fc4 100644
--- a/_test/test_numpy.py
+++ b/_test/test_numpy.py
@@ -10,6 +10,7 @@ except:  # NOQA
 
 def Xtest_numpy():
     import ruamel.yaml
+
     if numpy is None:
         return
     data = numpy.arange(10)
diff --git a/_test/test_program_config.py b/_test/test_program_config.py
index dcd8351..4d7cbd5 100644
--- a/_test/test_program_config.py
+++ b/_test/test_program_config.py
@@ -8,7 +8,8 @@ from roundtrip import round_trip
 class TestProgramConfig:
     def test_application_arguments(self):
         # application configur
-        round_trip("""
+        round_trip(
+            """
         args:
           username: anthon
           passwd: secret
@@ -17,11 +18,13 @@ class TestProgramConfig:
             session-name: test
           loop:
             wait: 10
-        """)
+        """
+        )
 
     def test_single(self):
         # application configuration
-        round_trip("""
+        round_trip(
+            """
         # default arguments for the program
         args:  # needed to prevent comment wrapping
         # this should be your username
@@ -36,11 +39,13 @@ class TestProgramConfig:
             # experiment with the following
             wait: 10
           # no more argument info to pass
-        """)
+        """
+        )
 
     def test_multi(self):
         # application configuration
-        round_trip("""
+        round_trip(
+            """
         # default arguments for the program
         args:  # needed to prevent comment wrapping
         # this should be your username
@@ -55,4 +60,5 @@ class TestProgramConfig:
             # experiment with the following
             wait: 10
           # no more argument info to pass
-        """)
+        """
+        )
diff --git a/_test/test_string.py b/_test/test_string.py
index f095095..351ca0e 100644
--- a/_test/test_string.py
+++ b/_test/test_string.py
@@ -24,26 +24,35 @@ from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump  # NO
 
 class TestPreservedScalarString:
     def test_basic_string(self):
-        round_trip("""
+        round_trip(
+            """
         a: abcdefg
-        """, )
+        """
+        )
 
     def test_quoted_integer_string(self):
-        round_trip("""
+        round_trip(
+            """
         a: '12345'
-        """)
+        """
+        )
 
-    @pytest.mark.skipif(platform.python_implementation() == 'Jython',
-                        reason="Jython throws RepresenterError")
+    @pytest.mark.skipif(
+        platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
+    )
     def test_preserve_string(self):
-        round_trip("""
+        round_trip(
+            """
             a: |
               abc
               def
-            """, intermediate=dict(a='abc\ndef\n'))
+            """,
+            intermediate=dict(a='abc\ndef\n'),
+        )
 
-    @pytest.mark.skipif(platform.python_implementation() == 'Jython',
-                        reason="Jython throws RepresenterError")
+    @pytest.mark.skipif(
+        platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
+    )
     def test_preserve_string_strip(self):
         s = """
             a: |-
@@ -53,105 +62,140 @@ class TestPreservedScalarString:
             """
         round_trip(s, intermediate=dict(a='abc\ndef'))
 
-    @pytest.mark.skipif(platform.python_implementation() == 'Jython',
-                        reason="Jython throws RepresenterError")
+    @pytest.mark.skipif(
+        platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
+    )
     def test_preserve_string_keep(self):
-            # with pytest.raises(AssertionError) as excinfo:
-            round_trip("""
+        # with pytest.raises(AssertionError) as excinfo:
+        round_trip(
+            """
             a: |+
               ghi
               jkl
 
 
             b: x
-            """, intermediate=dict(a='ghi\njkl\n\n\n', b='x'))
+            """,
+            intermediate=dict(a='ghi\njkl\n\n\n', b='x'),
+        )
 
-    @pytest.mark.skipif(platform.python_implementation() == 'Jython',
-                        reason="Jython throws RepresenterError")
+    @pytest.mark.skipif(
+        platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
+    )
     def test_preserve_string_keep_at_end(self):
         # at EOF you have to specify the ... to get proper "closure"
         # of the multiline scalar
-        round_trip("""
+        round_trip(
+            """
             a: |+
               ghi
               jkl
 
             ...
-            """, intermediate=dict(a='ghi\njkl\n\n'))
+            """,
+            intermediate=dict(a='ghi\njkl\n\n'),
+        )
 
     def test_fold_string(self):
         with pytest.raises(AssertionError) as excinfo:  # NOQA
-            round_trip("""
+            round_trip(
+                """
             a: >
               abc
               def
 
-            """, intermediate=dict(a='abc def\n'))
+            """,
+                intermediate=dict(a='abc def\n'),
+            )
 
     def test_fold_string_strip(self):
         with pytest.raises(AssertionError) as excinfo:  # NOQA
-            round_trip("""
+            round_trip(
+                """
             a: >-
               abc
               def
 
-            """, intermediate=dict(a='abc def'))
+            """,
+                intermediate=dict(a='abc def'),
+            )
 
     def test_fold_string_keep(self):
         with pytest.raises(AssertionError) as excinfo:  # NOQA
-            round_trip("""
+            round_trip(
+                """
             a: >+
               abc
               def
 
-            """, intermediate=dict(a='abc def\n\n'))
+            """,
+                intermediate=dict(a='abc def\n\n'),
+            )
 
 
 class TestQuotedScalarString:
     def test_single_quoted_string(self):
-        round_trip("""
+        round_trip(
+            """
         a: 'abc'
-        """, preserve_quotes=True)
+        """,
+            preserve_quotes=True,
+        )
 
     def test_double_quoted_string(self):
-        round_trip("""
+        round_trip(
+            """
         a: "abc"
-        """, preserve_quotes=True)
+        """,
+            preserve_quotes=True,
+        )
 
     def test_non_preserved_double_quoted_string(self):
-        round_trip("""
+        round_trip(
+            """
         a: "abc"
-        """, outp="""
+        """,
+            outp="""
         a: abc
-        """)
+        """,
+        )
 
 
 class TestReplace:
     """inspired by issue 110 from sandres23"""
+
     def test_replace_preserved_scalar_string(self):
         import ruamel
-        s = dedent("""\
+
+        s = dedent(
+            """\
         foo: |
           foo
           foo
           bar
           foo
-        """)
+        """
+        )
         data = round_trip_load(s, preserve_quotes=True)
         so = data['foo'].replace('foo', 'bar', 2)
         assert isinstance(so, ruamel.yaml.scalarstring.PreservedScalarString)
-        assert so == dedent("""
+        assert so == dedent(
+            """
         bar
         bar
         bar
         foo
-        """)
+        """
+        )
 
     def test_replace_double_quoted_scalar_string(self):
         import ruamel
-        s = dedent("""\
+
+        s = dedent(
+            """\
         foo: "foo foo bar foo"
-        """)
+        """
+        )
         data = round_trip_load(s, preserve_quotes=True)
         so = data['foo'].replace('foo', 'bar', 2)
         assert isinstance(so, ruamel.yaml.scalarstring.DoubleQuotedScalarString)
diff --git a/_test/test_tag.py b/_test/test_tag.py
index c4fabc0..824a0c3 100644
--- a/_test/test_tag.py
+++ b/_test/test_tag.py
@@ -1,6 +1,6 @@
 # coding: utf-8
 
-import pytest   # NOQA
+import pytest  # NOQA
 
 from roundtrip import round_trip, round_trip_load
 
@@ -25,92 +25,112 @@ def register_xxx(**kw):
 
 class TestIndentFailures:
     def test_tag(self):
-        round_trip("""\
+        round_trip(
+            """\
         !!python/object:__main__.Developer
         name: Anthon
         location: Germany
         language: python
-        """)
+        """
+        )
 
     def test_full_tag(self):
-        round_trip("""\
+        round_trip(
+            """\
         !!tag:yaml.org,2002:python/object:__main__.Developer
         name: Anthon
         location: Germany
         language: python
-        """)
+        """
+        )
 
     def test_standard_tag(self):
-        round_trip("""\
+        round_trip(
+            """\
         !!tag:yaml.org,2002:python/object:map
         name: Anthon
         location: Germany
         language: python
-        """)
+        """
+        )
 
     def test_Y1(self):
-        round_trip("""\
+        round_trip(
+            """\
         !yyy
         name: Anthon
         location: Germany
         language: python
-        """)
+        """
+        )
 
     def test_Y2(self):
-        round_trip("""\
+        round_trip(
+            """\
         !!yyy
         name: Anthon
         location: Germany
         language: python
-        """)
+        """
+        )
 
 
 class TestRoundTripCustom:
     def test_X1(self):
         register_xxx()
-        round_trip("""\
+        round_trip(
+            """\
         !xxx
         name: Anthon
         location: Germany
         language: python
-        """)
+        """
+        )
 
     @pytest.mark.xfail(strict=True)
     def test_X_pre_tag_comment(self):
         register_xxx()
-        round_trip("""\
+        round_trip(
+            """\
         -
           # hello
           !xxx
           name: Anthon
           location: Germany
           language: python
-        """)
+        """
+        )
 
     @pytest.mark.xfail(strict=True)
     def test_X_post_tag_comment(self):
         register_xxx()
-        round_trip("""\
+        round_trip(
+            """\
         - !xxx
           # hello
           name: Anthon
           location: Germany
           language: python
-        """)
+        """
+        )
 
     def test_scalar_00(self):
         # https://stackoverflow.com/a/45967047/1307905
-        round_trip("""\
+        round_trip(
+            """\
         Outputs:
           Vpc:
             Value: !Ref: vpc    # first tag
             Export:
               Name: !Sub "${AWS::StackName}-Vpc"  # second tag
-        """)
+        """
+        )
 
 
 class TestIssue201:
     def test_encoded_unicode_tag(self):
-        round_trip_load("""
+        round_trip_load(
+            """
         s: !!python/%75nicode 'abc'
-        """)
+        """
+        )
diff --git a/_test/test_version.py b/_test/test_version.py
index 0855a5c..9aa4133 100644
--- a/_test/test_version.py
+++ b/_test/test_version.py
@@ -1,18 +1,20 @@
 # coding: utf-8
 
-import pytest                        # NOQA
+import pytest  # NOQA
 
 from roundtrip import dedent, round_trip, round_trip_load
 
 
 def load(s, version=None):
     import ruamel.yaml  # NOQA
+
     return ruamel.yaml.round_trip_load(dedent(s), version)
 
 
 class TestVersions:
     def test_explicit_1_2(self):
-        r = load("""\
+        r = load(
+            """\
         %YAML 1.2
         ---
         - 12:34:56
@@ -24,7 +26,8 @@ class TestVersions:
         - yes
         - no
         - true
-        """)
+        """
+        )
         assert r[0] == '12:34:56'
         assert r[1] == 12
         assert r[2] == 12345678
@@ -36,7 +39,8 @@ class TestVersions:
         assert r[8] is True
 
     def test_explicit_1_1(self):
-        r = load("""\
+        r = load(
+            """\
         %YAML 1.1
         ---
         - 12:34:56
@@ -48,7 +52,8 @@ class TestVersions:
         - yes
         - no
         - true
-        """)
+        """
+        )
         assert r[0] == 45296
         assert r[1] == 10
         assert r[2] == '012345678'
@@ -60,7 +65,8 @@ class TestVersions:
         assert r[8] is True
 
     def test_implicit_1_2(self):
-        r = load("""\
+        r = load(
+            """\
         - 12:34:56
         - 12:34:56.78
         - 012
@@ -71,7 +77,8 @@ class TestVersions:
         - yes
         - no
         - true
-        """)
+        """
+        )
         assert r[0] == '12:34:56'
         assert r[1] == '12:34:56.78'
         assert r[2] == 12
@@ -84,7 +91,8 @@ class TestVersions:
         assert r[9] is True
 
     def test_load_version_1_1(self):
-        r = load("""\
+        r = load(
+            """\
         - 12:34:56
         - 12:34:56.78
         - 012
@@ -95,7 +103,9 @@ class TestVersions:
         - yes
         - no
         - true
-        """, version="1.1")
+        """,
+            version='1.1',
+        )
         assert r[0] == 45296
         assert r[1] == 45296.78
         assert r[2] == 10
@@ -112,7 +122,9 @@ class TestIssue62:
     # bitbucket issue 62, issue_62
     def test_00(self):
         import ruamel.yaml  # NOQA
-        s = dedent("""\
+
+        s = dedent(
+            """\
         {}# Outside flow collection:
         - ::vector
         - ": - ()"
@@ -121,14 +133,17 @@ class TestIssue62:
         - http://example.com/foo#bar
         # Inside flow collection:
         - [::vector, ": - ()", "Down, down and away!", -456, http://example.com/foo#bar]
-        """)
+        """
+        )
         with pytest.raises(ruamel.yaml.parser.ParserError):
             round_trip(s.format('%YAML 1.1\n---\n'), preserve_quotes=True)
-        round_trip(s.format(''), preserve_quotes=True)
+        round_trip(s.format(""), preserve_quotes=True)
 
     def test_00_single_comment(self):
         import ruamel.yaml  # NOQA
-        s = dedent("""\
+
+        s = dedent(
+            """\
         {}# Outside flow collection:
         - ::vector
         - ": - ()"
@@ -136,22 +151,26 @@ class TestIssue62:
         - -123
         - http://example.com/foo#bar
         - [::vector, ": - ()", "Down, down and away!", -456, http://example.com/foo#bar]
-        """)
+        """
+        )
         with pytest.raises(ruamel.yaml.parser.ParserError):
             round_trip(s.format('%YAML 1.1\n---\n'), preserve_quotes=True)
-        round_trip(s.format(''), preserve_quotes=True)
+        round_trip(s.format(""), preserve_quotes=True)
         # round_trip(s.format('%YAML 1.2\n---\n'), preserve_quotes=True, version=(1, 2))
 
     def test_01(self):
         import ruamel.yaml  # NOQA
-        s = dedent("""\
+
+        s = dedent(
+            """\
         {}[random plain value that contains a ? character]
-        """)
+        """
+        )
         with pytest.raises(ruamel.yaml.parser.ParserError):
             round_trip(s.format('%YAML 1.1\n---\n'), preserve_quotes=True)
-        round_trip(s.format(''), preserve_quotes=True)
+        round_trip(s.format(""), preserve_quotes=True)
         # note the flow seq on the --- line!
-        round_trip(s.format('%YAML 1.2\n--- '), preserve_quotes=True, version="1.2")
+        round_trip(s.format('%YAML 1.2\n--- '), preserve_quotes=True, version='1.2')
 
     def test_so_45681626(self):
         # was not properly parsing
diff --git a/_test/test_yamlfile.py b/_test/test_yamlfile.py
index d1ba63c..b5897f0 100644
--- a/_test/test_yamlfile.py
+++ b/_test/test_yamlfile.py
@@ -6,7 +6,7 @@ various test cases for YAML files
 """
 
 import sys
-import pytest      # NOQA
+import pytest  # NOQA
 import platform
 
 from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump  # NOQA
@@ -14,66 +14,77 @@ from roundtrip import round_trip, dedent, round_trip_load, round_trip_dump  # NO
 
 class TestYAML:
     def test_backslash(self):
-        round_trip("""
+        round_trip(
+            """
         handlers:
           static_files: applications/\\1/static/\\2
-        """)
+        """
+        )
 
     def test_omap_out(self):
         # ordereddict mapped to !!omap
         from ruamel.yaml.compat import ordereddict
         import ruamel.yaml  # NOQA
+
         x = ordereddict([('a', 1), ('b', 2)])
         res = ruamel.yaml.dump(x, default_flow_style=False)
-        assert res == dedent("""
+        assert res == dedent(
+            """
         !!omap
         - a: 1
         - b: 2
-        """)
+        """
+        )
 
     def test_omap_roundtrip(self):
-        round_trip("""
+        round_trip(
+            """
         !!omap
         - a: 1
         - b: 2
         - c: 3
         - d: 4
-        """)
+        """
+        )
 
-    @pytest.mark.skipif(sys.version_info < (2, 7), reason="collections not available")
+    @pytest.mark.skipif(sys.version_info < (2, 7), reason='collections not available')
     def test_dump_collections_ordereddict(self):
         from collections import OrderedDict
         import ruamel.yaml  # NOQA
+
         # OrderedDict mapped to !!omap
         x = OrderedDict([('a', 1), ('b', 2)])
-        res = ruamel.yaml.dump(x,
-                               Dumper=ruamel.yaml.RoundTripDumper,
-                               default_flow_style=False)
-        assert res == dedent("""
+        res = ruamel.yaml.dump(x, Dumper=ruamel.yaml.RoundTripDumper, default_flow_style=False)
+        assert res == dedent(
+            """
         !!omap
         - a: 1
         - b: 2
-        """)
+        """
+        )
 
-    @pytest.mark.skipif(sys.version_info >= (3, 0) or
-                        platform.python_implementation() != "CPython",
-                        reason="ruamel.yaml not available")
+    @pytest.mark.skipif(
+        sys.version_info >= (3, 0) or platform.python_implementation() != 'CPython',
+        reason='ruamel.yaml not available',
+    )
     def test_dump_ruamel_ordereddict(self):
         from ruamel.ordereddict import ordereddict
         import ruamel.yaml  # NOQA
+
         # OrderedDict mapped to !!omap
         x = ordereddict([('a', 1), ('b', 2)])
-        res = ruamel.yaml.dump(x,
-                               Dumper=ruamel.yaml.RoundTripDumper,
-                               default_flow_style=False)
-        assert res == dedent("""
+        res = ruamel.yaml.dump(x, Dumper=ruamel.yaml.RoundTripDumper, default_flow_style=False)
+        assert res == dedent(
+            """
         !!omap
         - a: 1
         - b: 2
-        """)
+        """
+        )
 
     def test_CommentedSet(self):
         from ruamel.yaml.constructor import CommentedSet
+
         s = CommentedSet(['a', 'b', 'c'])
         s.remove('b')
         s.add('d')
@@ -86,46 +97,56 @@ class TestYAML:
     def test_set_out(self):
         # preferable would be the shorter format without the ': null'
         import ruamel.yaml  # NOQA
+
         x = set(['a', 'b', 'c'])
         res = ruamel.yaml.dump(x, default_flow_style=False)
-        assert res == dedent("""
+        assert res == dedent(
+            """
         !!set
         a: null
         b: null
         c: null
-        """)
+        """
+        )
 
     # @pytest.mark.xfail
     # ordering is not preserved in a set
     def test_set_compact(self):
         # this format is read and also should be written by default
-        round_trip("""
+        round_trip(
+            """
         !!set
         ? a
         ? b
         ? c
-        """)
+        """
+        )
 
     def test_blank_line_after_comment(self):
-        round_trip("""
+        round_trip(
+            """
         # Comment with spaces after it.
 
 
         a: 1
-        """)
+        """
+        )
 
     def test_blank_line_between_seq_items(self):
-        round_trip("""
+        round_trip(
+            """
         # Seq with spaces in between items.
         b:
         - bar
 
 
         - baz
-        """)
+        """
+        )
 
-    @pytest.mark.skipif(platform.python_implementation() == 'Jython',
-                        reason="Jython throws RepresenterError")
+    @pytest.mark.skipif(
+        platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
+    )
     def test_blank_line_after_literal_chip(self):
         s = """
         c:
@@ -147,8 +168,9 @@ class TestYAML:
         assert d['c'][0].split('it.')[1] == '\n'
         assert d['c'][1].split('line.')[1] == '\n'
 
-    @pytest.mark.skipif(platform.python_implementation() == 'Jython',
-                        reason="Jython throws RepresenterError")
+    @pytest.mark.skipif(
+        platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
+    )
     def test_blank_line_after_literal_keep(self):
         """ have to insert an eof marker in YAML to test this"""
         s = """
@@ -172,8 +194,9 @@ class TestYAML:
         assert d['c'][0].split('it.')[1] == '\n\n'
         assert d['c'][1].split('line.')[1] == '\n\n\n'
 
-    @pytest.mark.skipif(platform.python_implementation() == 'Jython',
-                        reason="Jython throws RepresenterError")
+    @pytest.mark.skipif(
+        platform.python_implementation() == 'Jython', reason='Jython throws RepresenterError'
+    )
     def test_blank_line_after_literal_strip(self):
         s = """
         c:
@@ -192,16 +215,19 @@ class TestYAML:
         d = round_trip_load(dedent(s))
         print(d)
         round_trip(s)
-        assert d['c'][0].split('it.')[1] == ''
-        assert d['c'][1].split('line.')[1] == ''
+        assert d['c'][0].split('it.')[1] == ""
+        assert d['c'][1].split('line.')[1] == ""
 
     def test_load_all_perserve_quotes(self):
         import ruamel.yaml  # NOQA
-        s = dedent("""\
+
+        s = dedent(
+            """\
         a: 'hello'
         ---
         b: "goodbye"
-        """)
+        """
+        )
         data = []
         for x in ruamel.yaml.round_trip_load_all(s, preserve_quotes=True):
             data.append(x)
diff --git a/_test/test_yamlobject.py b/_test/test_yamlobject.py
index 4147bc3..1d730b5 100644
--- a/_test/test_yamlobject.py
+++ b/_test/test_yamlobject.py
@@ -2,7 +2,7 @@
 
 from __future__ import print_function
 
-import pytest   # NOQA
+import pytest  # NOQA
 
 from roundtrip import save_and_run  # NOQA
 
diff --git a/_test/test_z_check_debug_leftovers.py b/_test/test_z_check_debug_leftovers.py
index f5be5df..37d6970 100644
--- a/_test/test_z_check_debug_leftovers.py
+++ b/_test/test_z_check_debug_leftovers.py
@@ -10,25 +10,29 @@ class TestLeftOverDebug:
     # idea here is to capture round_trip_output via pytest stdout capture
     # if there is are any leftover debug statements they should show up
     def test_00(self, capsys):
-        s = dedent("""
+        s = dedent(
+            """
         a: 1
         b: []
         c: [a, 1]
         d: {f: 3.14, g: 42}
-        """)
+        """
+        )
         d = round_trip_load(s)
         round_trip_dump(d, sys.stdout)
         out, err = capsys.readouterr()
         assert out == s
 
     def test_01(self, capsys):
-        s = dedent("""
+        s = dedent(
+            """
         - 1
         - []
         - [a, 1]
         - {f: 3.14, g: 42}
         - - 123
-        """)
+        """
+        )
         d = round_trip_load(s)
         round_trip_dump(d, sys.stdout)
         out, err = capsys.readouterr()
diff --git a/_test/test_z_data.py b/_test/test_z_data.py
index 9ea921b..5a142cf 100644
--- a/_test/test_z_data.py
+++ b/_test/test_z_data.py
@@ -4,12 +4,12 @@ from __future__ import print_function
 
 import sys
 import os
-import pytest    # NOQA
+import pytest  # NOQA
 import platform  # NOQA
 
 sys.path.insert(0, os.path.dirname(__file__) + '/lib')
 
-import warnings        # NOQA
+import warnings  # NOQA
 
 
 args = []
@@ -17,8 +17,10 @@ args = []
 
 def test_data():
     import test_appliance  # NOQA
+
     collections = []
     import test_yaml
+
     collections.append(test_yaml)
     test_appliance.run(collections, args)
 
@@ -26,12 +28,15 @@ def test_data():
 # @pytest.mark.skipif(not ruamel.yaml.__with_libyaml__,
 #                     reason="no libyaml")
 
+
 def test_data_ext():
     collections = []
-    import ruamel.yaml     # NOQA
+    import ruamel.yaml  # NOQA
     import test_appliance  # NOQA
+
     warnings.simplefilter('ignore', ruamel.yaml.error.UnsafeLoaderWarning)
     if ruamel.yaml.__with_libyaml__:
         import test_yaml_ext
+
         collections.append(test_yaml_ext)
         test_appliance.run(collections, args)
diff --git a/comments.py b/comments.py
index 16fbbb8..32ce8ce 100644
--- a/comments.py
+++ b/comments.py
@@ -23,9 +23,11 @@ else:
 if False:  # MYPY
     from typing import Any, Dict, Optional, List, Union  # NOQA
 
+# fmt: off
 __all__ = ["CommentedSeq", "CommentedKeySeq",
            "CommentedMap", "CommentedOrderedMap",
            "CommentedSet", 'comment_attrib', 'merge_attrib']
+# fmt: on
 
 comment_attrib = '_yaml_comment'
 format_attrib = '_yaml_format'
@@ -38,7 +40,7 @@ tag_attrib = '_yaml_tag'
 class Comment(object):
     # sys.getsize tested the Comment objects, __slots__ makes them bigger
     # and adding self.end did not matter
-    __slots__ = 'comment', '_items', '_end', '_start',
+    __slots__ = 'comment', '_items', '_end', '_start'
     attrib = comment_attrib
 
     def __init__(self):
@@ -56,9 +58,8 @@ class Comment(object):
         if bool(self._end):
             end = ',\n  end=' + str(self._end)
         else:
-            end = ''
-        return "Comment(comment={0},\n  items={1}{2})".format(
-            self.comment, self._items, end)
+            end = ""
+        return 'Comment(comment={0},\n  items={1}{2})'.format(self.comment, self._items, end)
 
     @property
     def items(self):
@@ -93,7 +94,7 @@ def NoComment():
 
 
 class Format(object):
-    __slots__ = '_flow_style',
+    __slots__ = ('_flow_style',)
     attrib = format_attrib
 
     def __init__(self):
@@ -163,7 +164,7 @@ class LineCol(object):
 
 
 class Anchor(object):
-    __slots__ = 'value', 'always_dump',
+    __slots__ = 'value', 'always_dump'
     attrib = anchor_attrib
 
     def __init__(self):
@@ -174,7 +175,8 @@ class Anchor(object):
 
 class Tag(object):
     """store tag information for roundtripping"""
-    __slots__ = 'value',
+
+    __slots__ = ('value',)
     attrib = tag_attrib
 
     def __init__(self):
@@ -231,6 +233,7 @@ class CommentedBase(object):
         """
         from .error import CommentMark
         from .tokens import CommentToken
+
         pre_comments = self._yaml_get_pre_comment()
         if comment[-1] == '\n':
             comment = comment[:-1]  # strip final newline if there
@@ -238,8 +241,9 @@ class CommentedBase(object):
         for com in comment.split('\n'):
             pre_comments.append(CommentToken('# ' + com + '\n', start_mark, None))
 
-    def yaml_set_comment_before_after_key(self, key, before=None, indent=0,
-                                          after=None, after_indent=None):
+    def yaml_set_comment_before_after_key(
+        self, key, before=None, indent=0, after=None, after_indent=None
+    ):
         # type: (Any, Any, Any, Any, Any) -> None
         """
         expects comment (before/after) to be without `#` and possible have multiple lines
@@ -250,7 +254,7 @@ class CommentedBase(object):
         def comment_token(s, mark):
             # type: (Any, Any) -> Any
             # handle empty lines as having no comment
-            return CommentToken(('# ' if s else '') + s + '\n', mark, None)
+            return CommentToken(('# ' if s else "") + s + '\n', mark, None)
 
         if after_indent is None:
             after_indent = indent + 2
@@ -261,7 +265,7 @@ class CommentedBase(object):
         start_mark = CommentMark(indent)
         c = self.ca.items.setdefault(key, [None, [], None, None])
         if before == '\n':
-            c[1].append(comment_token('', start_mark))
+            c[1].append(comment_token("", start_mark))
         elif before:
             for com in before.split('\n'):
                 c[1].append(comment_token(com, start_mark))
@@ -291,6 +295,7 @@ class CommentedBase(object):
         """
         from .tokens import CommentToken
         from .error import CommentMark
+
         if column is None:
             column = self._yaml_get_column(key)
         if comment[0] != '#':
@@ -354,6 +359,7 @@ class CommentedBase(object):
 
     def copy_attributes(self, t, deep=False):
         # type: (Any, bool) -> None
+        # fmt: off
         for a in [Comment.attrib, Format.attrib, LineCol.attrib, Anchor.attrib,
                   Tag.attrib, merge_attrib]:
             if hasattr(self, a):
@@ -361,6 +367,7 @@ class CommentedBase(object):
                     setattr(t, a, copy.deepcopy(getattr(self, a)))
                 else:
                     setattr(t, a, getattr(self, a))
+        # fmt: on
 
     def _yaml_add_eol_comment(self, comment, key):
         # type: (Any, Any) -> None
@@ -376,7 +383,7 @@ class CommentedBase(object):
 
 
 class CommentedSeq(list, CommentedBase):
-    __slots__ = Comment.attrib,
+    __slots__ = (Comment.attrib,)
 
     def _yaml_add_comment(self, comment, key=NoComment):
         # type: (Any, Optional[Any]) -> None
@@ -404,7 +411,7 @@ class CommentedSeq(list, CommentedBase):
 
     def pop(self, idx=None):
         # type: (Any) -> Any
-        res = list.pop(self, idx)  # type: ignore
+        res = list.pop(self, idx)
         self.ca.items.pop(idx, None)  # might not be there -> default value
         for list_index in sorted(self.ca.items):
             if list_index < idx:
@@ -455,15 +462,18 @@ class CommentedSeq(list, CommentedBase):
         # type: (Any, Any) -> None
         # try to preserve the scalarstring type if setting an existing key to a new value
         if idx < len(self):
-            if isinstance(value, string_types) and \
-               not isinstance(value, ScalarString) and \
-               isinstance(self[idx], ScalarString):
+            if (
+                isinstance(value, string_types)
+                and not isinstance(value, ScalarString)
+                and isinstance(self[idx], ScalarString)
+            ):
                 value = type(self[idx])(value)
         list.__setitem__(self, idx, value)
 
 
 class CommentedKeySeq(tuple, CommentedBase):
     """This primarily exists to be able to roundtrip keys that are sequences"""
+
     def _yaml_add_comment(self, comment, key=NoComment):
         # type: (Any, Optional[Any]) -> None
         if key is not NoComment:
@@ -511,7 +521,7 @@ class CommentedKeySeq(tuple, CommentedBase):
 
 
 class CommentedMapView(Sized):
-    __slots__ = '_mapping',
+    __slots__ = ('_mapping',)
 
     def __init__(self, mapping):
         # type: (Any) -> None
@@ -597,7 +607,7 @@ class CommentedMapValuesView(CommentedMapView):
 
 
 class CommentedMap(ordereddict, CommentedBase):
-    __slots__ = Comment.attrib,
+    __slots__ = (Comment.attrib,)
 
     def _yaml_add_comment(self, comment, key=NoComment, value=NoComment):
         # type: (Any, Optional[Any], Optional[Any]) -> None
@@ -714,9 +724,11 @@ class CommentedMap(ordereddict, CommentedBase):
         # type: (Any, Any) -> None
         # try to preserve the scalarstring type if setting an existing key to a new value
         if key in self:
-            if isinstance(value, string_types) and \
-               not isinstance(value, ScalarString) and \
-               isinstance(self[key], ScalarString):
+            if (
+                isinstance(value, string_types)
+                and not isinstance(value, ScalarString)
+                and isinstance(self[key], ScalarString)
+            ):
                 value = type(self[key])(value)
         ordereddict.__setitem__(self, key, value)
 
@@ -802,6 +814,7 @@ class CommentedMap(ordereddict, CommentedBase):
             done.append(merged[1])
 
     if PY2:
+
         def keys(self):
             # type: () -> Any
             return list(self._keys())
@@ -813,7 +826,9 @@ class CommentedMap(ordereddict, CommentedBase):
         def viewkeys(self):
             # type: () -> Any
             return CommentedMapKeysView(self)
+
     else:
+
         def keys(self):
             # type: () -> Any
             return CommentedMapKeysView(self)
@@ -835,6 +850,7 @@ class CommentedMap(ordereddict, CommentedBase):
             done.append(merged[1])
 
     if PY2:
+
         def values(self):
             # type: () -> Any
             return list(self._values())
@@ -846,7 +862,9 @@ class CommentedMap(ordereddict, CommentedBase):
         def viewvalues(self):
             # type: () -> Any
             return CommentedMapValuesView(self)
+
     else:
+
         def values(self):
             # type: () -> Any
             return CommentedMapValuesView(self)
@@ -868,6 +886,7 @@ class CommentedMap(ordereddict, CommentedBase):
             done.append(merged[1])
 
     if PY2:
+
         def items(self):
             # type: () -> Any
             return list(self._items())
@@ -879,7 +898,9 @@ class CommentedMap(ordereddict, CommentedBase):
         def viewitems(self):
             # type: () -> Any
             return CommentedMapItemsView(self)
+
     else:
+
         def items(self):
             # type: () -> Any
             return CommentedMapItemsView(self)
@@ -906,11 +927,11 @@ class CommentedMap(ordereddict, CommentedBase):
 
 
 class CommentedOrderedMap(CommentedMap):
-    __slots__ = Comment.attrib,
+    __slots__ = (Comment.attrib,)
 
 
 class CommentedSet(MutableSet, CommentedMap):
-    __slots__ = Comment.attrib, 'odict',
+    __slots__ = Comment.attrib, 'odict'
 
     def __init__(self, values=None):
         # type: (Any) -> None
@@ -949,11 +970,17 @@ class CommentedSet(MutableSet, CommentedMap):
 
 class TaggedScalar(CommentedBase):
     # the value and style attributes are set during roundtrip construction
+    def __init__(self):
+        # type: () -> None
+        self.value = None
+        self.style = None
+
     def __str__(self):
+        # type: () -> Any
         return self.value
 
 
-def dump_comments(d, name='', sep='.', out=sys.stdout):
+def dump_comments(d, name="", sep='.', out=sys.stdout):
     # type: (Any, str, str, Any) -> None
     """
     recursively dump comments, all but the toplevel preceded by the path
@@ -970,5 +997,6 @@ def dump_comments(d, name='', sep='.', out=sys.stdout):
             print(name)
         print(d.ca, file=out)  # type: ignore
         for idx, k in enumerate(d):
-            dump_comments(k, name=(name + sep + str(idx)) if name else str(idx),
-                          sep=sep, out=out)
+            dump_comments(
+                k, name=(name + sep + str(idx)) if name else str(idx), sep=sep, out=out
+            )
diff --git a/compat.py b/compat.py
index e7ad8db..a962103 100644
--- a/compat.py
+++ b/compat.py
@@ -9,7 +9,7 @@ import os
 import types
 
 if False:  # MYPY
-    from typing import Any, Dict, Optional, List, Union, BinaryIO, IO, Text, Tuple   # NOQA
+    from typing import Any, Dict, Optional, List, Union, BinaryIO, IO, Text, Tuple  # NOQA
 
 _DEFAULT_YAML_VERSION = (1, 2)
 
@@ -22,8 +22,9 @@ except:  # NOQA
         from ordereddict import OrderedDict  # type: ignore
     # to get the right name import ... as ordereddict doesn't do that
 
-    class ordereddict(OrderedDict):   # type: ignore
+    class ordereddict(OrderedDict):  # type: ignore
         if not hasattr(OrderedDict, 'insert'):
+
             def insert(self, pos, key, value):
                 # type: (int, Any, Any) -> None
                 if pos >= len(self):
@@ -44,6 +45,7 @@ PY3 = sys.version_info[0] == 3
 
 
 if PY3:
+
     def utf8(s):
         # type: (str) -> str
         return s
@@ -56,7 +58,9 @@ if PY3:
         # type: (str) -> str
         return s
 
+
 else:
+
     def utf8(s):
         # type: (unicode) -> str
         return s.encode('utf-8')
@@ -67,7 +71,8 @@ else:
 
     def to_unicode(s):
         # type: (str) -> unicode
-        return unicode(s)    # NOQA
+        return unicode(s)  # NOQA
+
 
 if PY3:
     string_types = str
@@ -79,6 +84,7 @@ if PY3:
     MAXSIZE = sys.maxsize
     unichr = chr
     import io
+
     StringIO = io.StringIO
     BytesIO = io.BytesIO
     # have unlimited precision
@@ -86,17 +92,19 @@ if PY3:
     from collections.abc import Hashable  # NOQA
 
 else:
-    string_types = basestring    # NOQA
+    string_types = basestring  # NOQA
     integer_types = (int, long)  # NOQA
     class_types = (type, types.ClassType)
-    text_type = unicode          # NOQA
+    text_type = unicode  # NOQA
     binary_type = str
 
     # to allow importing
     unichr = unichr  # type: ignore
     from StringIO import StringIO as _StringIO
+
     StringIO = _StringIO
     import cStringIO
+
     BytesIO = cStringIO.StringIO
     # have unlimited precision
     no_limit_int = long  # NOQA not available on Python 3
@@ -120,7 +128,7 @@ UNICODE_SIZE = 4 if sys.maxunicode > 65535 else 2
 def with_metaclass(meta, *bases):
     # type: (Any, Any) -> Any
     """Create a base class with a metaclass."""
-    return meta("NewBase", bases, {})
+    return meta('NewBase', bases, {})
 
 
 DBG_TOKEN = 1
@@ -138,6 +146,7 @@ if 'RUAMELDEBUG' in os.environ:
 
 
 if bool(_debug):
+
     class ObjectCounter(object):
         def __init__(self):
             # type: () -> None
@@ -176,6 +185,7 @@ def nprint(*args, **kw):
     if bool(dbg):
         print(*args, **kw)
 
+
 # char checkers following production rules
 
 
@@ -202,6 +212,7 @@ def check_anchorname_char(ch):
 def version_tnf(t1, t2=None):
     # type: (Any, Any) -> Any
     from ruamel.yaml import version_info  # NOQA
+
     if version_info < t1:
         return True
     if t2 is not None and version_info < t2:
diff --git a/composer.py b/composer.py
index 516a3ae..80adb68 100644
--- a/composer.py
+++ b/composer.py
@@ -9,12 +9,16 @@ from ruamel.yaml.error import MarkedYAMLError, ReusedAnchorWarning
 from ruamel.yaml.compat import utf8
 
 from ruamel.yaml.events import (
-    StreamStartEvent, StreamEndEvent, MappingStartEvent, MappingEndEvent,
-    SequenceStartEvent, SequenceEndEvent, AliasEvent, ScalarEvent,
-)
-from ruamel.yaml.nodes import (
-    MappingNode, ScalarNode, SequenceNode,
+    StreamStartEvent,
+    StreamEndEvent,
+    MappingStartEvent,
+    MappingEndEvent,
+    SequenceStartEvent,
+    SequenceEndEvent,
+    AliasEvent,
+    ScalarEvent,
 )
+from ruamel.yaml.nodes import MappingNode, ScalarNode, SequenceNode
 
 if False:  # MYPY
     from typing import Any, Dict, Optional, List  # NOQA
@@ -38,16 +42,16 @@ class Composer(object):
     def parser(self):
         # type: () -> Any
         if hasattr(self.loader, 'typ'):
-            self.loader.parser  # type: ignore
-        return self.loader._parser  # type: ignore
+            self.loader.parser
+        return self.loader._parser
 
     @property
     def resolver(self):
         # type: () -> Any
         # assert self.loader._resolver is not None
         if hasattr(self.loader, 'typ'):
-            self.loader.resolver  # type: ignore
-        return self.loader._resolver  # type: ignore
+            self.loader.resolver
+        return self.loader._resolver
 
     def check_node(self):
         # type: () -> Any
@@ -78,9 +82,11 @@ class Composer(object):
         if not self.parser.check_event(StreamEndEvent):
             event = self.parser.get_event()
             raise ComposerError(
-                "expected a single document in the stream",
-                document.start_mark, "but found another document",
-                event.start_mark)
+                'expected a single document in the stream',
+                document.start_mark,
+                'but found another document',
+                event.start_mark,
+            )
 
         # Drop the STREAM-END event.
         self.parser.get_event()
@@ -108,8 +114,8 @@ class Composer(object):
             alias = event.anchor
             if alias not in self.anchors:
                 raise ComposerError(
-                    None, None, "found undefined alias %r"
-                    % utf8(alias), event.start_mark)
+                    None, None, 'found undefined alias %r' % utf8(alias), event.start_mark
+                )
             return self.anchors[alias]
         event = self.parser.peek_event()
         anchor = event.anchor
@@ -119,9 +125,10 @@ class Composer(object):
                 #     "found duplicate anchor %r; first occurrence"
                 #     % utf8(anchor), self.anchors[anchor].start_mark,
                 #     "second occurrence", event.start_mark)
-                ws = "\nfound duplicate anchor {!r}\nfirst occurrence {}\nsecond occurrence "\
-                     "{}".format(
-                         (anchor), self.anchors[anchor].start_mark, event.start_mark)
+                ws = (
+                    '\nfound duplicate anchor {!r}\nfirst occurrence {}\nsecond occurrence '
+                    '{}'.format((anchor), self.anchors[anchor].start_mark, event.start_mark)
+                )
                 warnings.warn(ws, ReusedAnchorWarning)
         self.resolver.descend_resolver(parent, index)
         if self.parser.check_event(ScalarEvent):
@@ -139,9 +146,14 @@ class Composer(object):
         tag = event.tag
         if tag is None or tag == u'!':
             tag = self.resolver.resolve(ScalarNode, event.value, event.implicit)
-        node = ScalarNode(tag, event.value,
-                          event.start_mark, event.end_mark, style=event.style,
-                          comment=event.comment)
+        node = ScalarNode(
+            tag,
+            event.value,
+            event.start_mark,
+            event.end_mark,
+            style=event.style,
+            comment=event.comment,
+        )
         if anchor is not None:
             self.anchors[anchor] = node
         return node
@@ -152,10 +164,15 @@ class Composer(object):
         tag = start_event.tag
         if tag is None or tag == u'!':
             tag = self.resolver.resolve(SequenceNode, None, start_event.implicit)
-        node = SequenceNode(tag, [],
-                            start_event.start_mark, None,
-                            flow_style=start_event.flow_style,
-                            comment=start_event.comment, anchor=anchor)
+        node = SequenceNode(
+            tag,
+            [],
+            start_event.start_mark,
+            None,
+            flow_style=start_event.flow_style,
+            comment=start_event.comment,
+            anchor=anchor,
+        )
         if anchor is not None:
             self.anchors[anchor] = node
         index = 0
@@ -165,8 +182,10 @@ class Composer(object):
         end_event = self.parser.get_event()
         if node.flow_style is True and end_event.comment is not None:
             if node.comment is not None:
-                print('Warning: unexpected end_event commment in sequence '
-                      'node {}'.format(node.flow_style))
+                print(
+                    'Warning: unexpected end_event commment in sequence '
+                    'node {}'.format(node.flow_style)
+                )
             node.comment = end_event.comment
         node.end_mark = end_event.end_mark
         self.check_end_doc_comment(end_event, node)
@@ -178,10 +197,15 @@ class Composer(object):
         tag = start_event.tag
         if tag is None or tag == u'!':
             tag = self.resolver.resolve(MappingNode, None, start_event.implicit)
-        node = MappingNode(tag, [],
-                           start_event.start_mark, None,
-                           flow_style=start_event.flow_style,
-                           comment=start_event.comment, anchor=anchor)
+        node = MappingNode(
+            tag,
+            [],
+            start_event.start_mark,
+            None,
+            flow_style=start_event.flow_style,
+            comment=start_event.comment,
+            anchor=anchor,
+        )
         if anchor is not None:
             self.anchors[anchor] = node
         while not self.parser.check_event(MappingEndEvent):
diff --git a/configobjwalker.py b/configobjwalker.py
index c0ab608..cbc6148 100644
--- a/configobjwalker.py
+++ b/configobjwalker.py
@@ -10,5 +10,5 @@ if False:  # MYPY
 
 def configobj_walker(cfg):
     # type: (Any) -> Any
-    warnings.warn("configobj_walker has moved to ruamel.yaml.util, please update your code")
+    warnings.warn('configobj_walker has moved to ruamel.yaml.util, please update your code')
     return new_configobj_walker(cfg)
diff --git a/constructor.py b/constructor.py
index a99f682..6a26da3 100644
--- a/constructor.py
+++ b/constructor.py
@@ -10,6 +10,7 @@ import sys
 import types
 import warnings
 
+# fmt: off
 from ruamel.yaml.error import (MarkedYAMLError, MarkedYAMLFutureWarning,
                                MantissaNoDotYAML1_1Warning)
 from ruamel.yaml.nodes import *                               # NOQA
@@ -28,11 +29,12 @@ from ruamel.yaml.timestamp import TimeStamp
 from ruamel.yaml.util import RegExp
 
 if False:  # MYPY
-    from typing import Any, Dict, List, Set, Generator  # NOQA
+    from typing import Any, Dict, List, Set, Generator, Union  # NOQA
 
 
 __all__ = ['BaseConstructor', 'SafeConstructor', 'Constructor',
            'ConstructorError', 'RoundTripConstructor']
+# fmt: on
 
 
 class ConstructorError(MarkedYAMLError):
@@ -49,11 +51,11 @@ class DuplicateKeyError(MarkedYAMLFutureWarning):
 
 class BaseConstructor(object):
 
-    yaml_constructors = {}   # type: Dict[Any, Any]
-    yaml_multi_constructors = {}   # type: Dict[Any, Any]
+    yaml_constructors = {}  # type: Dict[Any, Any]
+    yaml_multi_constructors = {}  # type: Dict[Any, Any]
 
     def __init__(self, preserve_quotes=None, loader=None):
-        # type: (bool, Any) -> None
+        # type: (Union[None, bool], Any) -> None
         self.loader = loader
         if self.loader is not None and getattr(self.loader, '_constructor', None) is None:
             self.loader._constructor = self
@@ -69,12 +71,12 @@ class BaseConstructor(object):
     def composer(self):
         # type: () -> Any
         if hasattr(self.loader, 'typ'):
-            return self.loader.composer  # type: ignore
+            return self.loader.composer
         try:
-            return self.loader._composer  # type: ignore
+            return self.loader._composer
         except AttributeError:
             print('slt', type(self))
-            print('slc', self.loader._composer)  # type: ignore
+            print('slc', self.loader._composer)
             print(dir(self))
             raise
 
@@ -82,8 +84,8 @@ class BaseConstructor(object):
     def resolver(self):
         # type: () -> Any
         if hasattr(self.loader, 'typ'):
-            return self.loader.resolver  # type: ignore
-        return self.loader._resolver  # type: ignore
+            return self.loader.resolver
+        return self.loader._resolver
 
     def check_data(self):
         # type: () -> Any
@@ -130,8 +132,8 @@ class BaseConstructor(object):
             self.deep_construct = True
         if node in self.recursive_objects:
             raise ConstructorError(
-                None, None,
-                "found unconstructable recursive node", node.start_mark)
+                None, None, 'found unconstructable recursive node', node.start_mark
+            )
         self.recursive_objects[node] = None
         constructor = None  # type: Any
         tag_suffix = None
@@ -140,7 +142,7 @@ class BaseConstructor(object):
         else:
             for tag_prefix in self.yaml_multi_constructors:
                 if node.tag.startswith(tag_prefix):
-                    tag_suffix = node.tag[len(tag_prefix):]
+                    tag_suffix = node.tag[len(tag_prefix) :]
                     constructor = self.yaml_multi_constructors[tag_prefix]
                     break
             else:
@@ -154,16 +156,16 @@ class BaseConstructor(object):
                 elif isinstance(node, SequenceNode):
                     constructor = self.__class__.construct_sequence  # type: ignore
                 elif isinstance(node, MappingNode):
-                    constructor = self.__class__.construct_mapping   # type: ignore
+                    constructor = self.__class__.construct_mapping  # type: ignore
         if tag_suffix is None:
             data = constructor(self, node)
         else:
             data = constructor(self, tag_suffix, node)
         if isinstance(data, types.GeneratorType):
             generator = data
-            data = next(generator)  # type: ignore
+            data = next(generator)
             if self.deep_construct:
-                for _dummy in generator:  # type: ignore
+                for _dummy in generator:
                     pass
             else:
                 self.state_generators.append(generator)
@@ -177,9 +179,8 @@ class BaseConstructor(object):
         # type: (Any) -> Any
         if not isinstance(node, ScalarNode):
             raise ConstructorError(
-                None, None,
-                "expected a scalar node, but found %s" % node.id,
-                node.start_mark)
+                None, None, 'expected a scalar node, but found %s' % node.id, node.start_mark
+            )
         return node.value
 
     def construct_sequence(self, node, deep=False):
@@ -189,11 +190,9 @@ class BaseConstructor(object):
         """
         if not isinstance(node, SequenceNode):
             raise ConstructorError(
-                None, None,
-                "expected a sequence node, but found %s" % node.id,
-                node.start_mark)
-        return [self.construct_object(child, deep=deep)
-                for child in node.value]
+                None, None, 'expected a sequence node, but found %s' % node.id, node.start_mark
+            )
+        return [self.construct_object(child, deep=deep) for child in node.value]
 
     def construct_mapping(self, node, deep=False):
         # type: (Any, bool) -> Any
@@ -202,9 +201,8 @@ class BaseConstructor(object):
         """
         if not isinstance(node, MappingNode):
             raise ConstructorError(
-                None, None,
-                "expected a mapping node, but found %s" % node.id,
-                node.start_mark)
+                None, None, 'expected a mapping node, but found %s' % node.id, node.start_mark
+            )
         total_mapping = {}
         if getattr(node, 'merge', None) is not None:
             todo = [(node.merge, False), (node.value, False)]
@@ -224,14 +222,19 @@ class BaseConstructor(object):
                         hash(key)
                     except TypeError as exc:
                         raise ConstructorError(
-                            "while constructing a mapping", node.start_mark,
-                            "found unacceptable key (%s)" %
-                            exc, key_node.start_mark)
+                            'while constructing a mapping',
+                            node.start_mark,
+                            'found unacceptable key (%s)' % exc,
+                            key_node.start_mark,
+                        )
                 else:
                     if not isinstance(key, Hashable):
                         raise ConstructorError(
-                            "while constructing a mapping", node.start_mark,
-                            "found unhashable key", key_node.start_mark)
+                            'while constructing a mapping',
+                            node.start_mark,
+                            'found unhashable key',
+                            key_node.start_mark,
+                        )
 
                 value = self.construct_object(value_node, deep=deep)
                 if check:
@@ -245,10 +248,11 @@ class BaseConstructor(object):
         if key in mapping:
             if not self.allow_duplicate_keys:
                 args = [
-                    "while constructing a mapping", node.start_mark,
+                    'while constructing a mapping',
+                    node.start_mark,
                     'found duplicate key "{}" with value "{}" '
-                    '(original value: "{}")'.format(
-                        key, value, mapping.get(key)), key_node.start_mark,
+                    '(original value: "{}")'.format(key, value, mapping.get(key)),
+                    key_node.start_mark,
                     """
                     To suppress this check see:
                         http://yaml.readthedocs.io/en/latest/api.html#duplicate-keys
@@ -267,9 +271,8 @@ class BaseConstructor(object):
         # type: (Any, bool) -> Any
         if not isinstance(node, MappingNode):
             raise ConstructorError(
-                None, None,
-                "expected a mapping node, but found %s" % node.id,
-                node.start_mark)
+                None, None, 'expected a mapping node, but found %s' % node.id, node.start_mark
+            )
         pairs = []
         for key_node, value_node in node.value:
             key = self.construct_object(key_node, deep=deep)
@@ -322,10 +325,11 @@ class SafeConstructor(BaseConstructor):
                     for subnode in value_node.value:
                         if not isinstance(subnode, MappingNode):
                             raise ConstructorError(
-                                "while constructing a mapping",
+                                'while constructing a mapping',
                                 node.start_mark,
-                                "expected a mapping for merging, but found %s"
-                                % subnode.id, subnode.start_mark)
+                                'expected a mapping for merging, but found %s' % subnode.id,
+                                subnode.start_mark,
+                            )
                         self.flatten_mapping(subnode)
                         submerge.append(subnode.value)
                     submerge.reverse()
@@ -333,10 +337,12 @@ class SafeConstructor(BaseConstructor):
                         merge.extend(value)
                 else:
                     raise ConstructorError(
-                        "while constructing a mapping", node.start_mark,
-                        "expected a mapping or list of mappings for merging, "
-                        "but found %s"
-                        % value_node.id, value_node.start_mark)
+                        'while constructing a mapping',
+                        node.start_mark,
+                        'expected a mapping or list of mappings for merging, '
+                        'but found %s' % value_node.id,
+                        value_node.start_mark,
+                    )
             elif key_node.tag == u'tag:yaml.org,2002:value':
                 key_node.tag = u'tag:yaml.org,2002:str'
                 index += 1
@@ -378,7 +384,7 @@ class SafeConstructor(BaseConstructor):
     def construct_yaml_int(self, node):
         # type: (Any) -> int
         value_s = to_str(self.construct_scalar(node))
-        value_s = value_s.replace('_', '')
+        value_s = value_s.replace('_', "")
         sign = +1
         if value_s[0] == '-':
             sign = -1
@@ -409,12 +415,12 @@ class SafeConstructor(BaseConstructor):
     inf_value = 1e300
     while inf_value != inf_value * inf_value:
         inf_value *= inf_value
-    nan_value = -inf_value / inf_value   # Trying to make a quiet NaN (like C99).
+    nan_value = -inf_value / inf_value  # Trying to make a quiet NaN (like C99).
 
     def construct_yaml_float(self, node):
         # type: (Any) -> float
         value_so = to_str(self.construct_scalar(node))
-        value_s = value_so.replace('_', '').lower()
+        value_s = value_so.replace('_', "").lower()
         sign = +1
         if value_s[0] == '-':
             sign = -1
@@ -442,15 +448,18 @@ class SafeConstructor(BaseConstructor):
             return sign * float(value_s)
 
     if PY3:
+
         def construct_yaml_binary(self, node):
             # type: (Any) -> Any
             try:
                 value = self.construct_scalar(node).encode('ascii')
             except UnicodeEncodeError as exc:
                 raise ConstructorError(
-                    None, None,
-                    "failed to convert base64 data into ascii: %s" % exc,
-                    node.start_mark)
+                    None,
+                    None,
+                    'failed to convert base64 data into ascii: %s' % exc,
+                    node.start_mark,
+                )
             try:
                 if hasattr(base64, 'decodebytes'):
                     return base64.decodebytes(value)
@@ -458,9 +467,11 @@ class SafeConstructor(BaseConstructor):
                     return base64.decodestring(value)
             except binascii.Error as exc:
                 raise ConstructorError(
-                    None, None,
-                    "failed to decode base64 data: %s" % exc, node.start_mark)
+                    None, None, 'failed to decode base64 data: %s' % exc, node.start_mark
+                )
+
     else:
+
         def construct_yaml_binary(self, node):
             # type: (Any) -> Any
             value = self.construct_scalar(node)
@@ -468,11 +479,11 @@ class SafeConstructor(BaseConstructor):
                 return to_str(value).decode('base64')
             except (binascii.Error, UnicodeEncodeError) as exc:
                 raise ConstructorError(
-                    None, None,
-                    "failed to decode base64 data: %s" % exc, node.start_mark)
+                    None, None, 'failed to decode base64 data: %s' % exc, node.start_mark
+                )
 
     timestamp_regexp = RegExp(
-        u'''^(?P<year>[0-9][0-9][0-9][0-9])
+        u"""^(?P<year>[0-9][0-9][0-9][0-9])
           -(?P<month>[0-9][0-9]?)
           -(?P<day>[0-9][0-9]?)
           (?:((?P<t>[Tt])|[ \\t]+)   # explictly not retaining extra spaces
@@ -481,7 +492,9 @@ class SafeConstructor(BaseConstructor):
           :(?P<second>[0-9][0-9])
           (?:\\.(?P<fraction>[0-9]*))?
           (?:[ \\t]*(?P<tz>Z|(?P<tz_sign>[-+])(?P<tz_hour>[0-9][0-9]?)
-          (?::(?P<tz_minute>[0-9][0-9]))?))?)?$''', re.X)
+          (?::(?P<tz_minute>[0-9][0-9]))?))?)?$""",
+        re.X,
+    )
 
     def construct_yaml_timestamp(self, node, values=None):
         # type: (Any, Any) -> Any
@@ -492,9 +505,11 @@ class SafeConstructor(BaseConstructor):
                 match = None
             if match is None:
                 raise ConstructorError(
-                    None, None,
+                    None,
+                    None,
                     'failed to construct timestamp from "{}"'.format(node.value),
-                    node.start_mark)
+                    node.start_mark,
+                )
             values = match.groupdict()
         year = int(values['year'])
         month = int(values['month'])
@@ -520,8 +535,7 @@ class SafeConstructor(BaseConstructor):
             delta = datetime.timedelta(hours=tz_hour, minutes=tz_minute)
             if values['tz_sign'] == '-':
                 delta = -delta
-        data = datetime.datetime(year, month, day, hour, minute, second,
-                                 fraction)
+        data = datetime.datetime(year, month, day, hour, minute, second, fraction)
         if delta:
             data -= delta
         return data
@@ -533,21 +547,26 @@ class SafeConstructor(BaseConstructor):
         yield omap
         if not isinstance(node, SequenceNode):
             raise ConstructorError(
-                "while constructing an ordered map", node.start_mark,
-                "expected a sequence, but found %s" % node.id, node.start_mark)
+                'while constructing an ordered map',
+                node.start_mark,
+                'expected a sequence, but found %s' % node.id,
+                node.start_mark,
+            )
         for subnode in node.value:
             if not isinstance(subnode, MappingNode):
                 raise ConstructorError(
-                    "while constructing an ordered map", node.start_mark,
-                    "expected a mapping of length 1, but found %s" %
-                    subnode.id,
-                    subnode.start_mark)
+                    'while constructing an ordered map',
+                    node.start_mark,
+                    'expected a mapping of length 1, but found %s' % subnode.id,
+                    subnode.start_mark,
+                )
             if len(subnode.value) != 1:
                 raise ConstructorError(
-                    "while constructing an ordered map", node.start_mark,
-                    "expected a single mapping item, but found %d items" %
-                    len(subnode.value),
-                    subnode.start_mark)
+                    'while constructing an ordered map',
+                    node.start_mark,
+                    'expected a single mapping item, but found %d items' % len(subnode.value),
+                    subnode.start_mark,
+                )
             key_node, value_node = subnode.value[0]
             key = self.construct_object(key_node)
             assert key not in omap
@@ -561,21 +580,26 @@ class SafeConstructor(BaseConstructor):
         yield pairs
         if not isinstance(node, SequenceNode):
             raise ConstructorError(
-                "while constructing pairs", node.start_mark,
-                "expected a sequence, but found %s" % node.id, node.start_mark)
+                'while constructing pairs',
+                node.start_mark,
+                'expected a sequence, but found %s' % node.id,
+                node.start_mark,
+            )
         for subnode in node.value:
             if not isinstance(subnode, MappingNode):
                 raise ConstructorError(
-                    "while constructing pairs", node.start_mark,
-                    "expected a mapping of length 1, but found %s" %
-                    subnode.id,
-                    subnode.start_mark)
+                    'while constructing pairs',
+                    node.start_mark,
+                    'expected a mapping of length 1, but found %s' % subnode.id,
+                    subnode.start_mark,
+                )
             if len(subnode.value) != 1:
                 raise ConstructorError(
-                    "while constructing pairs", node.start_mark,
-                    "expected a single mapping item, but found %d items" %
-                    len(subnode.value),
-                    subnode.start_mark)
+                    'while constructing pairs',
+                    node.start_mark,
+                    'expected a single mapping item, but found %d items' % len(subnode.value),
+                    subnode.start_mark,
+                )
             key_node, value_node = subnode.value[0]
             key = self.construct_object(key_node)
             value = self.construct_object(value_node)
@@ -583,7 +607,7 @@ class SafeConstructor(BaseConstructor):
 
     def construct_yaml_set(self, node):
         # type: (Any) -> Any
-        data = set()    # type: Set[Any]
+        data = set()  # type: Set[Any]
         yield data
         value = self.construct_mapping(node)
         data.update(value)
@@ -625,70 +649,54 @@ class SafeConstructor(BaseConstructor):
     def construct_undefined(self, node):
         # type: (Any) -> None
         raise ConstructorError(
-            None, None,
-            "could not determine a constructor for the tag %r" %
-            utf8(node.tag),
-            node.start_mark)
+            None,
+            None,
+            'could not determine a constructor for the tag %r' % utf8(node.tag),
+            node.start_mark,
+        )
 
 
-SafeConstructor.add_constructor(
-    u'tag:yaml.org,2002:null',
-    SafeConstructor.construct_yaml_null)
+SafeConstructor.add_constructor(u'tag:yaml.org,2002:null', SafeConstructor.construct_yaml_null)
 
-SafeConstructor.add_constructor(
-    u'tag:yaml.org,2002:bool',
-    SafeConstructor.construct_yaml_bool)
+SafeConstructor.add_constructor(u'tag:yaml.org,2002:bool', SafeConstructor.construct_yaml_bool)
 
-SafeConstructor.add_constructor(
-    u'tag:yaml.org,2002:int',
-    SafeConstructor.construct_yaml_int)
+SafeConstructor.add_constructor(u'tag:yaml.org,2002:int', SafeConstructor.construct_yaml_int)
 
 SafeConstructor.add_constructor(
-    u'tag:yaml.org,2002:float',
-    SafeConstructor.construct_yaml_float)
+    u'tag:yaml.org,2002:float', SafeConstructor.construct_yaml_float
+)
 
 SafeConstructor.add_constructor(
-    u'tag:yaml.org,2002:binary',
-    SafeConstructor.construct_yaml_binary)
+    u'tag:yaml.org,2002:binary', SafeConstructor.construct_yaml_binary
+)
 
 SafeConstructor.add_constructor(
-    u'tag:yaml.org,2002:timestamp',
-    SafeConstructor.construct_yaml_timestamp)
+    u'tag:yaml.org,2002:timestamp', SafeConstructor.construct_yaml_timestamp
+)
 
-SafeConstructor.add_constructor(
-    u'tag:yaml.org,2002:omap',
-    SafeConstructor.construct_yaml_omap)
+SafeConstructor.add_constructor(u'tag:yaml.org,2002:omap', SafeConstructor.construct_yaml_omap)
 
 SafeConstructor.add_constructor(
-    u'tag:yaml.org,2002:pairs',
-    SafeConstructor.construct_yaml_pairs)
+    u'tag:yaml.org,2002:pairs', SafeConstructor.construct_yaml_pairs
+)
 
-SafeConstructor.add_constructor(
-    u'tag:yaml.org,2002:set',
-    SafeConstructor.construct_yaml_set)
+SafeConstructor.add_constructor(u'tag:yaml.org,2002:set', SafeConstructor.construct_yaml_set)
 
-SafeConstructor.add_constructor(
-    u'tag:yaml.org,2002:str',
-    SafeConstructor.construct_yaml_str)
+SafeConstructor.add_constructor(u'tag:yaml.org,2002:str', SafeConstructor.construct_yaml_str)
 
-SafeConstructor.add_constructor(
-    u'tag:yaml.org,2002:seq',
-    SafeConstructor.construct_yaml_seq)
+SafeConstructor.add_constructor(u'tag:yaml.org,2002:seq', SafeConstructor.construct_yaml_seq)
 
-SafeConstructor.add_constructor(
-    u'tag:yaml.org,2002:map',
-    SafeConstructor.construct_yaml_map)
+SafeConstructor.add_constructor(u'tag:yaml.org,2002:map', SafeConstructor.construct_yaml_map)
 
-SafeConstructor.add_constructor(
-    None, SafeConstructor.construct_undefined)
+SafeConstructor.add_constructor(None, SafeConstructor.construct_undefined)
 
 if PY2:
+
     class classobj:
         pass
 
 
 class Constructor(SafeConstructor):
-
     def construct_python_str(self, node):
         # type: (Any) -> Any
         return utf8(self.construct_scalar(node))
@@ -698,15 +706,18 @@ class Constructor(SafeConstructor):
         return self.construct_scalar(node)
 
     if PY3:
+
         def construct_python_bytes(self, node):
             # type: (Any) -> Any
             try:
                 value = self.construct_scalar(node).encode('ascii')
             except UnicodeEncodeError as exc:
                 raise ConstructorError(
-                    None, None,
-                    "failed to convert base64 data into ascii: %s" % exc,
-                    node.start_mark)
+                    None,
+                    None,
+                    'failed to convert base64 data into ascii: %s' % exc,
+                    node.start_mark,
+                )
             try:
                 if hasattr(base64, 'decodebytes'):
                     return base64.decodebytes(value)
@@ -714,8 +725,8 @@ class Constructor(SafeConstructor):
                     return base64.decodestring(value)
             except binascii.Error as exc:
                 raise ConstructorError(
-                    None, None,
-                    "failed to decode base64 data: %s" % exc, node.start_mark)
+                    None, None, 'failed to decode base64 data: %s' % exc, node.start_mark
+                )
 
     def construct_python_long(self, node):
         # type: (Any) -> int
@@ -736,22 +747,31 @@ class Constructor(SafeConstructor):
         # type: (Any, Any) -> Any
         if not name:
             raise ConstructorError(
-                "while constructing a Python module", mark,
-                "expected non-empty name appended to the tag", mark)
+                'while constructing a Python module',
+                mark,
+                'expected non-empty name appended to the tag',
+                mark,
+            )
         try:
             __import__(name)
         except ImportError as exc:
             raise ConstructorError(
-                "while constructing a Python module", mark,
-                "cannot find module %r (%s)" % (utf8(name), exc), mark)
+                'while constructing a Python module',
+                mark,
+                'cannot find module %r (%s)' % (utf8(name), exc),
+                mark,
+            )
         return sys.modules[name]
 
     def find_python_name(self, name, mark):
         # type: (Any, Any) -> Any
         if not name:
             raise ConstructorError(
-                "while constructing a Python object", mark,
-                "expected non-empty name appended to the tag", mark)
+                'while constructing a Python object',
+                mark,
+                'expected non-empty name appended to the tag',
+                mark,
+            )
         if u'.' in name:
             module_name, object_name = name.rsplit('.', 1)
         else:
@@ -761,14 +781,19 @@ class Constructor(SafeConstructor):
             __import__(module_name)
         except ImportError as exc:
             raise ConstructorError(
-                "while constructing a Python object", mark,
-                "cannot find module %r (%s)" % (utf8(module_name), exc), mark)
+                'while constructing a Python object',
+                mark,
+                'cannot find module %r (%s)' % (utf8(module_name), exc),
+                mark,
+            )
         module = sys.modules[module_name]
         if not hasattr(module, object_name):
             raise ConstructorError(
-                "while constructing a Python object", mark,
-                "cannot find %r in the module %r" % (utf8(object_name),
-                                                     module.__name__), mark)
+                'while constructing a Python object',
+                mark,
+                'cannot find %r in the module %r' % (utf8(object_name), module.__name__),
+                mark,
+            )
         return getattr(module, object_name)
 
     def construct_python_name(self, suffix, node):
@@ -776,9 +801,11 @@ class Constructor(SafeConstructor):
         value = self.construct_scalar(node)
         if value:
             raise ConstructorError(
-                "while constructing a Python name", node.start_mark,
-                "expected the empty value, but found %r" % utf8(value),
-                node.start_mark)
+                'while constructing a Python name',
+                node.start_mark,
+                'expected the empty value, but found %r' % utf8(value),
+                node.start_mark,
+            )
         return self.find_python_name(suffix, node.start_mark)
 
     def construct_python_module(self, suffix, node):
@@ -786,13 +813,14 @@ class Constructor(SafeConstructor):
         value = self.construct_scalar(node)
         if value:
             raise ConstructorError(
-                "while constructing a Python module", node.start_mark,
-                "expected the empty value, but found %r" % utf8(value),
-                node.start_mark)
+                'while constructing a Python module',
+                node.start_mark,
+                'expected the empty value, but found %r' % utf8(value),
+                node.start_mark,
+            )
         return self.find_python_module(suffix, node.start_mark)
 
-    def make_python_instance(self, suffix, node,
-                             args=None, kwds=None, newobj=False):
+    def make_python_instance(self, suffix, node, args=None, kwds=None, newobj=False):
         # type: (Any, Any, Any, Any, bool) -> Any
         if not args:
             args = []
@@ -805,8 +833,7 @@ class Constructor(SafeConstructor):
             else:
                 return cls(*args, **kwds)
         else:
-            if newobj and isinstance(cls, type(classobj))  \
-                    and not args and not kwds:
+            if newobj and isinstance(cls, type(classobj)) and not args and not kwds:
                 instance = classobj()
                 instance.__class__ = cls
                 return instance
@@ -881,74 +908,62 @@ class Constructor(SafeConstructor):
         return self.construct_python_object_apply(suffix, node, newobj=True)
 
 
-Constructor.add_constructor(
-    u'tag:yaml.org,2002:python/none',
-    Constructor.construct_yaml_null)
+Constructor.add_constructor(u'tag:yaml.org,2002:python/none', Constructor.construct_yaml_null)
 
-Constructor.add_constructor(
-    u'tag:yaml.org,2002:python/bool',
-    Constructor.construct_yaml_bool)
+Constructor.add_constructor(u'tag:yaml.org,2002:python/bool', Constructor.construct_yaml_bool)
 
-Constructor.add_constructor(
-    u'tag:yaml.org,2002:python/str',
-    Constructor.construct_python_str)
+Constructor.add_constructor(u'tag:yaml.org,2002:python/str', Constructor.construct_python_str)
 
 Constructor.add_constructor(
-    u'tag:yaml.org,2002:python/unicode',
-    Constructor.construct_python_unicode)
+    u'tag:yaml.org,2002:python/unicode', Constructor.construct_python_unicode
+)
 
 if PY3:
     Constructor.add_constructor(
-        u'tag:yaml.org,2002:python/bytes',
-        Constructor.construct_python_bytes)
+        u'tag:yaml.org,2002:python/bytes', Constructor.construct_python_bytes
+    )
 
-Constructor.add_constructor(
-    u'tag:yaml.org,2002:python/int',
-    Constructor.construct_yaml_int)
+Constructor.add_constructor(u'tag:yaml.org,2002:python/int', Constructor.construct_yaml_int)
 
 Constructor.add_constructor(
-    u'tag:yaml.org,2002:python/long',
-    Constructor.construct_python_long)
+    u'tag:yaml.org,2002:python/long', Constructor.construct_python_long
+)
 
 Constructor.add_constructor(
-    u'tag:yaml.org,2002:python/float',
-    Constructor.construct_yaml_float)
+    u'tag:yaml.org,2002:python/float', Constructor.construct_yaml_float
+)
 
 Constructor.add_constructor(
-    u'tag:yaml.org,2002:python/complex',
-    Constructor.construct_python_complex)
+    u'tag:yaml.org,2002:python/complex', Constructor.construct_python_complex
+)
 
-Constructor.add_constructor(
-    u'tag:yaml.org,2002:python/list',
-    Constructor.construct_yaml_seq)
+Constructor.add_constructor(u'tag:yaml.org,2002:python/list', Constructor.construct_yaml_seq)
 
 Constructor.add_constructor(
-    u'tag:yaml.org,2002:python/tuple',
-    Constructor.construct_python_tuple)
+    u'tag:yaml.org,2002:python/tuple', Constructor.construct_python_tuple
+)
 
-Constructor.add_constructor(
-    u'tag:yaml.org,2002:python/dict',
-    Constructor.construct_yaml_map)
+Constructor.add_constructor(u'tag:yaml.org,2002:python/dict', Constructor.construct_yaml_map)
 
 Constructor.add_multi_constructor(
-    u'tag:yaml.org,2002:python/name:',
-    Constructor.construct_python_name)
+    u'tag:yaml.org,2002:python/name:', Constructor.construct_python_name
+)
 
 Constructor.add_multi_constructor(
-    u'tag:yaml.org,2002:python/module:',
-    Constructor.construct_python_module)
+    u'tag:yaml.org,2002:python/module:', Constructor.construct_python_module
+)
 
 Constructor.add_multi_constructor(
-    u'tag:yaml.org,2002:python/object:',
-    Constructor.construct_python_object)
+    u'tag:yaml.org,2002:python/object:', Constructor.construct_python_object
+)
 
 Constructor.add_multi_constructor(
-    u'tag:yaml.org,2002:python/object/apply:',
-    Constructor.construct_python_object_apply)
+    u'tag:yaml.org,2002:python/object/apply:', Constructor.construct_python_object_apply
+)
 
 Constructor.add_multi_constructor(
-    u'tag:yaml.org,2002:python/object/new:',
-    Constructor.construct_python_object_new)
+    u'tag:yaml.org,2002:python/object/new:', Constructor.construct_python_object_new
+)
 
 
 class RoundTripConstructor(SafeConstructor):
@@ -960,9 +975,8 @@ class RoundTripConstructor(SafeConstructor):
         # type: (Any) -> Any
         if not isinstance(node, ScalarNode):
             raise ConstructorError(
-                None, None,
-                "expected a scalar node, but found %s" % node.id,
-                node.start_mark)
+                None, None, 'expected a scalar node, but found %s' % node.id, node.start_mark
+            )
 
         if node.style == '|' and isinstance(node.value, text_type):
             return PreservedScalarString(node.value)
@@ -984,7 +998,7 @@ class RoundTripConstructor(SafeConstructor):
             underscore = None
         except IndexError:
             underscore = None
-        value_s = value_su.replace('_', '')
+        value_s = value_su.replace('_', "")
         sign = +1
         if value_s[0] == '-':
             sign = -1
@@ -998,8 +1012,9 @@ class RoundTripConstructor(SafeConstructor):
             if underscore is not None:
                 underscore[1] = value_su[2] == '_'
                 underscore[2] = len(value_su[2:]) > 1 and value_su[-1] == '_'
-            return BinaryInt(sign * int(value_s[2:], 2), width=width,   # type: ignore
-                             underscore=underscore)
+            return BinaryInt(  # type: ignore
+                sign * int(value_s[2:], 2), width=width, underscore=underscore
+            )
         elif value_s.startswith('0x'):
             # default to lower-case if no a-fA-F in string
             if self.resolver.processing_version > (1, 1) and value_s[2] == '0':
@@ -1021,8 +1036,9 @@ class RoundTripConstructor(SafeConstructor):
             if underscore is not None:
                 underscore[1] = value_su[2] == '_'
                 underscore[2] = len(value_su[2:]) > 1 and value_su[-1] == '_'
-            return OctalInt(sign * int(value_s[2:], 8), width=width,  # type: ignore
-                            underscore=underscore)
+            return OctalInt(  # type: ignore
+                sign * int(value_s[2:], 8), width=width, underscore=underscore
+            )
         elif self.resolver.processing_version != (1, 2) and value_s[0] == '0':
             return sign * int(value_s, 8)
         elif self.resolver.processing_version != (1, 2) and ':' in value_s:
@@ -1039,13 +1055,15 @@ class RoundTripConstructor(SafeConstructor):
             if underscore is not None:
                 # cannot have a leading underscore
                 underscore[2] = len(value_su) > 1 and value_su[-1] == '_'
-            return ScalarInt(sign * int(value_s), width=len(value_s),  # type: ignore
-                             underscore=underscore)
+            return ScalarInt(  # type: ignore
+                sign * int(value_s), width=len(value_s), underscore=underscore
+            )
         elif underscore:
             # cannot have a leading underscore
             underscore[2] = len(value_su) > 1 and value_su[-1] == '_'
-            return ScalarInt(sign * int(value_s), width=None,  # type: ignore
-                             underscore=underscore)
+            return ScalarInt(  # type: ignore
+                sign * int(value_s), width=None, underscore=underscore
+            )
         else:
             return sign * int(value_s)
 
@@ -1060,10 +1078,11 @@ class RoundTripConstructor(SafeConstructor):
                     lead0 += 1
                 idx += 1
             return lead0
+
         # underscore = None
         m_sign = False  # type: Any
         value_so = to_str(self.construct_scalar(node))
-        value_s = value_so.replace('_', '').lower()
+        value_s = value_so.replace('_', "").lower()
         sign = +1
         if value_s[0] == '-':
             sign = -1
@@ -1102,14 +1121,22 @@ class RoundTripConstructor(SafeConstructor):
             e_width = len(exponent)
             e_sign = exponent[0] in '+-'
             # print('sf', width, prec, m_sign, exp, e_width, e_sign)
-            return ScalarFloat(sign * float(value_s),  # type: ignore
-                               width=width, prec=prec, m_sign=m_sign,
-                               m_lead0=lead0, exp=exp, e_width=e_width, e_sign=e_sign)
+            return ScalarFloat(  # type: ignore
+                sign * float(value_s),
+                width=width,
+                prec=prec,
+                m_sign=m_sign,
+                m_lead0=lead0,
+                exp=exp,
+                e_width=e_width,
+                e_sign=e_sign,
+            )
         width = len(value_so)
         prec = value_so.index('.')  # you can use index, this would not be float without dot
         lead0 = leading_zeros(value_so)
-        return ScalarFloat(sign * float(value_s),  # type: ignore
-                           width=width, prec=prec, m_sign=m_sign, m_lead0=lead0)
+        return ScalarFloat(  # type: ignore
+            sign * float(value_s), width=width, prec=prec, m_sign=m_sign, m_lead0=lead0
+        )
 
     def construct_yaml_str(self, node):
         # type: (Any) -> Any
@@ -1130,9 +1157,8 @@ class RoundTripConstructor(SafeConstructor):
         # type: (Any, Any, bool) -> Any
         if not isinstance(node, SequenceNode):
             raise ConstructorError(
-                None, None,
-                "expected a sequence node, but found %s" % node.id,
-                node.start_mark)
+                None, None, 'expected a sequence node, but found %s' % node.id, node.start_mark
+            )
         ret_val = []
         if node.comment:
             seqtyp._yaml_add_comment(node.comment[:2])
@@ -1140,6 +1166,7 @@ class RoundTripConstructor(SafeConstructor):
                 seqtyp.yaml_end_comment_extend(node.comment[2], clear=True)
         if node.anchor:
             from ruamel.yaml.serializer import templated_id
+
             if not templated_id(node.anchor):
                 seqtyp.yaml_set_anchor(node.anchor)
         for idx, child in enumerate(node.value):
@@ -1147,7 +1174,8 @@ class RoundTripConstructor(SafeConstructor):
             if child.comment:
                 seqtyp._yaml_add_comment(child.comment, key=idx)
             seqtyp._yaml_set_idx_line_col(
-                idx, [child.start_mark.line, child.start_mark.column])
+                idx, [child.start_mark.line, child.start_mark.column]
+            )
         return ret_val
 
     def flatten_mapping(self, node):
@@ -1178,8 +1206,7 @@ class RoundTripConstructor(SafeConstructor):
             if key_node.tag == u'tag:yaml.org,2002:merge':
                 del node.value[index]
                 if isinstance(value_node, MappingNode):
-                    merge_map_list.append(
-                        (index, constructed(value_node)))
+                    merge_map_list.append((index, constructed(value_node)))
                     # self.flatten_mapping(value_node)
                     # merge.extend(value_node.value)
                 elif isinstance(value_node, SequenceNode):
@@ -1187,12 +1214,12 @@ class RoundTripConstructor(SafeConstructor):
                     for subnode in value_node.value:
                         if not isinstance(subnode, MappingNode):
                             raise ConstructorError(
-                                "while constructing a mapping",
+                                'while constructing a mapping',
                                 node.start_mark,
-                                "expected a mapping for merging, but found %s"
-                                % subnode.id, subnode.start_mark)
-                        merge_map_list.append(
-                            (index, constructed(subnode)))
+                                'expected a mapping for merging, but found %s' % subnode.id,
+                                subnode.start_mark,
+                            )
+                        merge_map_list.append((index, constructed(subnode)))
                     #     self.flatten_mapping(subnode)
                     #     submerge.append(subnode.value)
                     # submerge.reverse()
@@ -1200,10 +1227,12 @@ class RoundTripConstructor(SafeConstructor):
                     #     merge.extend(value)
                 else:
                     raise ConstructorError(
-                        "while constructing a mapping", node.start_mark,
-                        "expected a mapping or list of mappings for merging, "
-                        "but found %s"
-                        % value_node.id, value_node.start_mark)
+                        'while constructing a mapping',
+                        node.start_mark,
+                        'expected a mapping or list of mappings for merging, '
+                        'but found %s' % value_node.id,
+                        value_node.start_mark,
+                    )
             elif key_node.tag == u'tag:yaml.org,2002:value':
                 key_node.tag = u'tag:yaml.org,2002:str'
                 index += 1
@@ -1221,17 +1250,17 @@ class RoundTripConstructor(SafeConstructor):
         # type: (Any, Any, bool) -> Any
         if not isinstance(node, MappingNode):
             raise ConstructorError(
-                None, None,
-                "expected a mapping node, but found %s" % node.id,
-                node.start_mark)
+                None, None, 'expected a mapping node, but found %s' % node.id, node.start_mark
+            )
         merge_map = self.flatten_mapping(node)
         # mapping = {}
         if node.comment:
-            maptyp._yaml_add_comment(node.comment[:2])  # type: ignore
+            maptyp._yaml_add_comment(node.comment[:2])
             if len(node.comment) > 2:
-                maptyp.yaml_end_comment_extend(node.comment[2], clear=True)  # type: ignore
+                maptyp.yaml_end_comment_extend(node.comment[2], clear=True)
         if node.anchor:
             from ruamel.yaml.serializer import templated_id
+
             if not templated_id(node.anchor):
                 maptyp.yaml_set_anchor(node.anchor)
         last_key, last_value = None, self._sentinel
@@ -1253,53 +1282,63 @@ class RoundTripConstructor(SafeConstructor):
                     hash(key)
                 except TypeError as exc:
                     raise ConstructorError(
-                        "while constructing a mapping", node.start_mark,
-                        "found unacceptable key (%s)" %
-                        exc, key_node.start_mark)
+                        'while constructing a mapping',
+                        node.start_mark,
+                        'found unacceptable key (%s)' % exc,
+                        key_node.start_mark,
+                    )
             else:
                 if not isinstance(key, Hashable):
                     raise ConstructorError(
-                        "while constructing a mapping", node.start_mark,
-                        "found unhashable key", key_node.start_mark)
+                        'while constructing a mapping',
+                        node.start_mark,
+                        'found unhashable key',
+                        key_node.start_mark,
+                    )
             value = self.construct_object(value_node, deep=deep)
             self.check_mapping_key(node, key_node, maptyp, key, value)
 
-            if key_node.comment and len(key_node.comment) > 4 and \
-               key_node.comment[4]:
+            if key_node.comment and len(key_node.comment) > 4 and key_node.comment[4]:
                 if last_value is None:
                     key_node.comment[0] = key_node.comment.pop(4)
                     maptyp._yaml_add_comment(key_node.comment, value=last_key)
                 else:
                     key_node.comment[2] = key_node.comment.pop(4)
-                    maptyp._yaml_add_comment(key_node.comment, key=key)  # type: ignore
+                    maptyp._yaml_add_comment(key_node.comment, key=key)
                 key_node.comment = None
             if key_node.comment:
-                maptyp._yaml_add_comment(key_node.comment, key=key)  # type: ignore
+                maptyp._yaml_add_comment(key_node.comment, key=key)
             if value_node.comment:
-                maptyp._yaml_add_comment(value_node.comment, value=key)  # type: ignore
-            maptyp._yaml_set_kv_line_col(  # type: ignore
-                key, [key_node.start_mark.line, key_node.start_mark.column,
-                      value_node.start_mark.line, value_node.start_mark.column])
-            maptyp[key] = value  # type: ignore
+                maptyp._yaml_add_comment(value_node.comment, value=key)
+            maptyp._yaml_set_kv_line_col(
+                key,
+                [
+                    key_node.start_mark.line,
+                    key_node.start_mark.column,
+                    value_node.start_mark.line,
+                    value_node.start_mark.column,
+                ],
+            )
+            maptyp[key] = value
             last_key, last_value = key, value  # could use indexing
         # do this last, or <<: before a key will prevent insertion in instances
         # of collections.OrderedDict (as they have no __contains__
         if merge_map:
-            maptyp.add_yaml_merge(merge_map)  # type: ignore
+            maptyp.add_yaml_merge(merge_map)
 
     def construct_setting(self, node, typ, deep=False):
         # type: (Any, Any, bool) -> Any
         if not isinstance(node, MappingNode):
             raise ConstructorError(
-                None, None,
-                "expected a mapping node, but found %s" % node.id,
-                node.start_mark)
+                None, None, 'expected a mapping node, but found %s' % node.id, node.start_mark
+            )
         if node.comment:
             typ._yaml_add_comment(node.comment[:2])
             if len(node.comment) > 2:
                 typ.yaml_end_comment_extend(node.comment[2], clear=True)
         if node.anchor:
             from ruamel.yaml.serializer import templated_id
+
             if not templated_id(node.anchor):
                 typ.yaml_set_anchor(node.anchor)
         for key_node, value_node in node.value:
@@ -1314,14 +1353,19 @@ class RoundTripConstructor(SafeConstructor):
                     hash(key)
                 except TypeError as exc:
                     raise ConstructorError(
-                        "while constructing a mapping", node.start_mark,
-                        "found unacceptable key (%s)" %
-                        exc, key_node.start_mark)
+                        'while constructing a mapping',
+                        node.start_mark,
+                        'found unacceptable key (%s)' % exc,
+                        key_node.start_mark,
+                    )
             else:
                 if not isinstance(key, Hashable):
                     raise ConstructorError(
-                        "while constructing a mapping", node.start_mark,
-                        "found unhashable key", key_node.start_mark)
+                        'while constructing a mapping',
+                        node.start_mark,
+                        'found unhashable key',
+                        key_node.start_mark,
+                    )
             # construct but should be null
             value = self.construct_object(value_node, deep=deep)  # NOQA
             self.check_mapping_key(node, key_node, typ, key, value)
@@ -1382,21 +1426,26 @@ class RoundTripConstructor(SafeConstructor):
                 omap.yaml_end_comment_extend(node.comment[2], clear=True)
         if not isinstance(node, SequenceNode):
             raise ConstructorError(
-                "while constructing an ordered map", node.start_mark,
-                "expected a sequence, but found %s" % node.id, node.start_mark)
+                'while constructing an ordered map',
+                node.start_mark,
+                'expected a sequence, but found %s' % node.id,
+                node.start_mark,
+            )
         for subnode in node.value:
             if not isinstance(subnode, MappingNode):
                 raise ConstructorError(
-                    "while constructing an ordered map", node.start_mark,
-                    "expected a mapping of length 1, but found %s" %
-                    subnode.id,
-                    subnode.start_mark)
+                    'while constructing an ordered map',
+                    node.start_mark,
+                    'expected a mapping of length 1, but found %s' % subnode.id,
+                    subnode.start_mark,
+                )
             if len(subnode.value) != 1:
                 raise ConstructorError(
-                    "while constructing an ordered map", node.start_mark,
-                    "expected a single mapping item, but found %d items" %
-                    len(subnode.value),
-                    subnode.start_mark)
+                    'while constructing an ordered map',
+                    node.start_mark,
+                    'expected a single mapping item, but found %d items' % len(subnode.value),
+                    subnode.start_mark,
+                )
             key_node, value_node = subnode.value[0]
             key = self.construct_object(key_node)
             assert key not in omap
@@ -1431,19 +1480,20 @@ class RoundTripConstructor(SafeConstructor):
                 self.construct_mapping(node, data)
                 return
             elif isinstance(node, ScalarNode):
-                data = TaggedScalar()
-                data.value = self.construct_scalar(node)
-                data.style = node.style
-                data.yaml_set_tag(node.tag)
-                yield data
+                data2 = TaggedScalar()
+                data2.value = self.construct_scalar(node)
+                data2.style = node.style
+                data2.yaml_set_tag(node.tag)
+                yield data2
                 return
         except:  # NOQA
             pass
         raise ConstructorError(
-            None, None,
-            "could not determine a constructor for the tag %r" %
-            utf8(node.tag),
-            node.start_mark)
+            None,
+            None,
+            'could not determine a constructor for the tag %r' % utf8(node.tag),
+            node.start_mark,
+        )
 
     def construct_yaml_timestamp(self, node, values=None):
         # type: (Any, Any) -> Any
@@ -1453,9 +1503,11 @@ class RoundTripConstructor(SafeConstructor):
             match = None
         if match is None:
             raise ConstructorError(
-                None, None,
+                None,
+                None,
                 'failed to construct timestamp from "{}"'.format(node.value),
-                node.start_mark)
+                node.start_mark,
+            )
         values = match.groupdict()
         if not values['hour']:
             return SafeConstructor.construct_yaml_timestamp(self, node, values)
@@ -1489,8 +1541,7 @@ class RoundTripConstructor(SafeConstructor):
         if delta:
             dt = datetime.datetime(year, month, day, hour, minute)
             dt -= delta
-            data = TimeStamp(dt.year, dt.month, dt.day, dt.hour, dt.minute,
-                             second, fraction)
+            data = TimeStamp(dt.year, dt.month, dt.day, dt.hour, dt.minute, second, fraction)
             data._yaml['delta'] = delta
             tz = values['tz_sign'] + values['tz_hour']
             if values['tz_minute']:
@@ -1507,52 +1558,51 @@ class RoundTripConstructor(SafeConstructor):
 
 
 RoundTripConstructor.add_constructor(
-    u'tag:yaml.org,2002:null',
-    RoundTripConstructor.construct_yaml_null)
+    u'tag:yaml.org,2002:null', RoundTripConstructor.construct_yaml_null
+)
 
 RoundTripConstructor.add_constructor(
-    u'tag:yaml.org,2002:bool',
-    RoundTripConstructor.construct_yaml_bool)
+    u'tag:yaml.org,2002:bool', RoundTripConstructor.construct_yaml_bool
+)
 
 RoundTripConstructor.add_constructor(
-    u'tag:yaml.org,2002:int',
-    RoundTripConstructor.construct_yaml_int)
+    u'tag:yaml.org,2002:int', RoundTripConstructor.construct_yaml_int
+)
 
 RoundTripConstructor.add_constructor(
-    u'tag:yaml.org,2002:float',
-    RoundTripConstructor.construct_yaml_float)
+    u'tag:yaml.org,2002:float', RoundTripConstructor.construct_yaml_float
+)
 
 RoundTripConstructor.add_constructor(
-    u'tag:yaml.org,2002:binary',
-    RoundTripConstructor.construct_yaml_binary)
+    u'tag:yaml.org,2002:binary', RoundTripConstructor.construct_yaml_binary
+)
 
 RoundTripConstructor.add_constructor(
-    u'tag:yaml.org,2002:timestamp',
-    RoundTripConstructor.construct_yaml_timestamp)
+    u'tag:yaml.org,2002:timestamp', RoundTripConstructor.construct_yaml_timestamp
+)
 
 RoundTripConstructor.add_constructor(
-    u'tag:yaml.org,2002:omap',
-    RoundTripConstructor.construct_yaml_omap)
+    u'tag:yaml.org,2002:omap', RoundTripConstructor.construct_yaml_omap
+)
 
 RoundTripConstructor.add_constructor(
-    u'tag:yaml.org,2002:pairs',
-    RoundTripConstructor.construct_yaml_pairs)
+    u'tag:yaml.org,2002:pairs', RoundTripConstructor.construct_yaml_pairs
+)
 
 RoundTripConstructor.add_constructor(
-    u'tag:yaml.org,2002:set',
-    RoundTripConstructor.construct_yaml_set)
+    u'tag:yaml.org,2002:set', RoundTripConstructor.construct_yaml_set
+)
 
 RoundTripConstructor.add_constructor(
-    u'tag:yaml.org,2002:str',
-    RoundTripConstructor.construct_yaml_str)
+    u'tag:yaml.org,2002:str', RoundTripConstructor.construct_yaml_str
+)
 
 RoundTripConstructor.add_constructor(
-    u'tag:yaml.org,2002:seq',
-    RoundTripConstructor.construct_yaml_seq)
+    u'tag:yaml.org,2002:seq', RoundTripConstructor.construct_yaml_seq
+)
 
 RoundTripConstructor.add_constructor(
-    u'tag:yaml.org,2002:map',
-    RoundTripConstructor.construct_yaml_map)
+    u'tag:yaml.org,2002:map', RoundTripConstructor.construct_yaml_map
+)
 
-RoundTripConstructor.add_constructor(
-    None, RoundTripConstructor.construct_undefined)
+RoundTripConstructor.add_constructor(None, RoundTripConstructor.construct_undefined)
diff --git a/cyaml.py b/cyaml.py
index 3e5b90a..ed2c1da 100644
--- a/cyaml.py
+++ b/cyaml.py
@@ -2,7 +2,7 @@
 
 from __future__ import absolute_import
 
-from _ruamel_yaml import CParser, CEmitter   # type: ignore
+from _ruamel_yaml import CParser, CEmitter  # type: ignore
 
 from ruamel.yaml.constructor import Constructor, BaseConstructor, SafeConstructor
 from ruamel.yaml.representer import Representer, SafeRepresenter, BaseRepresenter
@@ -12,16 +12,16 @@ if False:  # MYPY
     from typing import Any, Union  # NOQA
     from ruamel.yaml.compat import StreamTextType, StreamType, VersionType  # NOQA
 
-__all__ = ['CBaseLoader', 'CSafeLoader', 'CLoader',
-           'CBaseDumper', 'CSafeDumper', 'CDumper']
+__all__ = ['CBaseLoader', 'CSafeLoader', 'CLoader', 'CBaseDumper', 'CSafeDumper', 'CDumper']
 
 
 # this includes some hacks to solve the  usage of resolver by lower level
 # parts of the parser
 
+
 class CBaseLoader(CParser, BaseConstructor, BaseResolver):  # type: ignore
     def __init__(self, stream, version=None, preserve_quotes=None):
-        # type: (StreamTextType, VersionType, bool) -> None
+        # type: (StreamTextType, Union[None, VersionType], Union[None, bool]) -> None
         CParser.__init__(self, stream)
         self._parser = self._composer = self
         BaseConstructor.__init__(self, loader=self)
@@ -33,7 +33,7 @@ class CBaseLoader(CParser, BaseConstructor, BaseResolver):  # type: ignore
 
 class CSafeLoader(CParser, SafeConstructor, Resolver):  # type: ignore
     def __init__(self, stream, version=None, preserve_quotes=None):
-        # type: (StreamTextType, VersionType, bool) -> None
+        # type: (StreamTextType, Union[None, VersionType], Union[None, bool]) -> None
         CParser.__init__(self, stream)
         self._parser = self._composer = self
         SafeConstructor.__init__(self, loader=self)
@@ -45,7 +45,7 @@ class CSafeLoader(CParser, SafeConstructor, Resolver):  # type: ignore
 
 class CLoader(CParser, Constructor, Resolver):  # type: ignore
     def __init__(self, stream, version=None, preserve_quotes=None):
-        # type: (StreamTextType, VersionType, bool) -> None
+        # type: (StreamTextType, Union[None, VersionType], Union[None, bool]) -> None
         CParser.__init__(self, stream)
         self._parser = self._composer = self
         Constructor.__init__(self, loader=self)
@@ -56,64 +56,130 @@ class CLoader(CParser, Constructor, Resolver):  # type: ignore
 
 
 class CBaseDumper(CEmitter, BaseRepresenter, BaseResolver):  # type: ignore
-    def __init__(self, stream,
-                 default_style=None, default_flow_style=None,
-                 canonical=None, indent=None, width=None,
-                 allow_unicode=None, line_break=None,
-                 encoding=None, explicit_start=None, explicit_end=None,
-                 version=None, tags=None, block_seq_indent=None,
-                 top_level_colon_align=None, prefix_colon=None):
-        # type: (StreamType, Any, Any, Any, bool, Union[None, int], Union[None, int], bool, Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> None   # NOQA
-        CEmitter.__init__(self, stream, canonical=canonical,
-                          indent=indent, width=width, encoding=encoding,
-                          allow_unicode=allow_unicode, line_break=line_break,
-                          explicit_start=explicit_start,
-                          explicit_end=explicit_end,
-                          version=version, tags=tags)
+    def __init__(
+        self,
+        stream,
+        default_style=None,
+        default_flow_style=None,
+        canonical=None,
+        indent=None,
+        width=None,
+        allow_unicode=None,
+        line_break=None,
+        encoding=None,
+        explicit_start=None,
+        explicit_end=None,
+        version=None,
+        tags=None,
+        block_seq_indent=None,
+        top_level_colon_align=None,
+        prefix_colon=None,
+    ):
+        # type: (StreamType, Any, Any, Any, Union[None, bool], Union[None, int], Union[None, int], Union[None, bool], Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> None   # NOQA
+        CEmitter.__init__(
+            self,
+            stream,
+            canonical=canonical,
+            indent=indent,
+            width=width,
+            encoding=encoding,
+            allow_unicode=allow_unicode,
+            line_break=line_break,
+            explicit_start=explicit_start,
+            explicit_end=explicit_end,
+            version=version,
+            tags=tags,
+        )
         self._emitter = self._serializer = self._representer = self
-        BaseRepresenter.__init__(self, default_style=default_style,
-                                 default_flow_style=default_flow_style, dumper=self)
+        BaseRepresenter.__init__(
+            self,
+            default_style=default_style,
+            default_flow_style=default_flow_style,
+            dumper=self,
+        )
         BaseResolver.__init__(self, loadumper=self)
 
 
 class CSafeDumper(CEmitter, SafeRepresenter, Resolver):  # type: ignore
-    def __init__(self, stream,
-                 default_style=None, default_flow_style=None,
-                 canonical=None, indent=None, width=None,
-                 allow_unicode=None, line_break=None,
-                 encoding=None, explicit_start=None, explicit_end=None,
-                 version=None, tags=None, block_seq_indent=None,
-                 top_level_colon_align=None, prefix_colon=None):
-        # type: (StreamType, Any, Any, Any, bool, Union[None, int], Union[None, int], bool, Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> None   # NOQA
+    def __init__(
+        self,
+        stream,
+        default_style=None,
+        default_flow_style=None,
+        canonical=None,
+        indent=None,
+        width=None,
+        allow_unicode=None,
+        line_break=None,
+        encoding=None,
+        explicit_start=None,
+        explicit_end=None,
+        version=None,
+        tags=None,
+        block_seq_indent=None,
+        top_level_colon_align=None,
+        prefix_colon=None,
+    ):
+        # type: (StreamType, Any, Any, Any, Union[None, bool], Union[None, int], Union[None, int], Union[None, bool], Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> None   # NOQA
         self._emitter = self._serializer = self._representer = self
-        CEmitter.__init__(self, stream, canonical=canonical,
-                          indent=indent, width=width, encoding=encoding,
-                          allow_unicode=allow_unicode, line_break=line_break,
-                          explicit_start=explicit_start,
-                          explicit_end=explicit_end,
-                          version=version, tags=tags)
+        CEmitter.__init__(
+            self,
+            stream,
+            canonical=canonical,
+            indent=indent,
+            width=width,
+            encoding=encoding,
+            allow_unicode=allow_unicode,
+            line_break=line_break,
+            explicit_start=explicit_start,
+            explicit_end=explicit_end,
+            version=version,
+            tags=tags,
+        )
         self._emitter = self._serializer = self._representer = self  # type: ignore
-        SafeRepresenter.__init__(self, default_style=default_style,
-                                 default_flow_style=default_flow_style)
+        SafeRepresenter.__init__(
+            self, default_style=default_style, default_flow_style=default_flow_style
+        )
         Resolver.__init__(self)
 
 
 class CDumper(CEmitter, Representer, Resolver):  # type: ignore
-    def __init__(self, stream,
-                 default_style=None, default_flow_style=None,
-                 canonical=None, indent=None, width=None,
-                 allow_unicode=None, line_break=None,
-                 encoding=None, explicit_start=None, explicit_end=None,
-                 version=None, tags=None, block_seq_indent=None,
-                 top_level_colon_align=None, prefix_colon=None):
-        # type: (StreamType, Any, Any, Any, bool, Union[None, int], Union[None, int], bool, Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> None   # NOQA
-        CEmitter.__init__(self, stream, canonical=canonical,
-                          indent=indent, width=width, encoding=encoding,
-                          allow_unicode=allow_unicode, line_break=line_break,
-                          explicit_start=explicit_start,
-                          explicit_end=explicit_end,
-                          version=version, tags=tags)
+    def __init__(
+        self,
+        stream,
+        default_style=None,
+        default_flow_style=None,
+        canonical=None,
+        indent=None,
+        width=None,
+        allow_unicode=None,
+        line_break=None,
+        encoding=None,
+        explicit_start=None,
+        explicit_end=None,
+        version=None,
+        tags=None,
+        block_seq_indent=None,
+        top_level_colon_align=None,
+        prefix_colon=None,
+    ):
+        # type: (StreamType, Any, Any, Any, Union[None, bool], Union[None, int], Union[None, int], Union[None, bool], Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> None   # NOQA
+        CEmitter.__init__(
+            self,
+            stream,
+            canonical=canonical,
+            indent=indent,
+            width=width,
+            encoding=encoding,
+            allow_unicode=allow_unicode,
+            line_break=line_break,
+            explicit_start=explicit_start,
+            explicit_end=explicit_end,
+            version=version,
+            tags=tags,
+        )
         self._emitter = self._serializer = self._representer = self
-        Representer.__init__(self, default_style=default_style,
-                             default_flow_style=default_flow_style)
+        Representer.__init__(
+            self, default_style=default_style, default_flow_style=default_flow_style
+        )
         Resolver.__init__(self)
diff --git a/dumper.py b/dumper.py
index b43260c..5f23c45 100644
--- a/dumper.py
+++ b/dumper.py
@@ -4,114 +4,218 @@ from __future__ import absolute_import
 
 from ruamel.yaml.emitter import Emitter
 from ruamel.yaml.serializer import Serializer
-from ruamel.yaml.representer import Representer, SafeRepresenter, BaseRepresenter, \
-    RoundTripRepresenter
+from ruamel.yaml.representer import (
+    Representer,
+    SafeRepresenter,
+    BaseRepresenter,
+    RoundTripRepresenter,
+)
 from ruamel.yaml.resolver import Resolver, BaseResolver, VersionedResolver
 
 if False:  # MYPY
-    from typing import Any, Dict, List, Union               # NOQA
+    from typing import Any, Dict, List, Union  # NOQA
     from ruamel.yaml.compat import StreamType, VersionType  # NOQA
 
 __all__ = ['BaseDumper', 'SafeDumper', 'Dumper', 'RoundTripDumper']
 
 
 class BaseDumper(Emitter, Serializer, BaseRepresenter, BaseResolver):
-    def __init__(self, stream,
-                 default_style=None, default_flow_style=None,
-                 canonical=None, indent=None, width=None,
-                 allow_unicode=None, line_break=None,
-                 encoding=None, explicit_start=None, explicit_end=None,
-                 version=None, tags=None, block_seq_indent=None,
-                 top_level_colon_align=None, prefix_colon=None):
-        # type: (Any, StreamType, Any, Any, bool, Union[None, int], Union[None, int], bool, Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> None   # NOQA
-        Emitter.__init__(self, stream, canonical=canonical,
-                         indent=indent, width=width,
-                         allow_unicode=allow_unicode, line_break=line_break,
-                         block_seq_indent=block_seq_indent,
-                         dumper=self)
-        Serializer.__init__(self, encoding=encoding,
-                            explicit_start=explicit_start,
-                            explicit_end=explicit_end,
-                            version=version, tags=tags,
-                            dumper=self)
-        BaseRepresenter.__init__(self, default_style=default_style,
-                                 default_flow_style=default_flow_style,
-                                 dumper=self)
+    def __init__(
+        self,
+        stream,
+        default_style=None,
+        default_flow_style=None,
+        canonical=None,
+        indent=None,
+        width=None,
+        allow_unicode=None,
+        line_break=None,
+        encoding=None,
+        explicit_start=None,
+        explicit_end=None,
+        version=None,
+        tags=None,
+        block_seq_indent=None,
+        top_level_colon_align=None,
+        prefix_colon=None,
+    ):
+        # type: (Any, StreamType, Any, Any, Union[None, bool], Union[None, int], Union[None, int], Union[None, bool], Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> None   # NOQA
+        Emitter.__init__(
+            self,
+            stream,
+            canonical=canonical,
+            indent=indent,
+            width=width,
+            allow_unicode=allow_unicode,
+            line_break=line_break,
+            block_seq_indent=block_seq_indent,
+            dumper=self,
+        )
+        Serializer.__init__(
+            self,
+            encoding=encoding,
+            explicit_start=explicit_start,
+            explicit_end=explicit_end,
+            version=version,
+            tags=tags,
+            dumper=self,
+        )
+        BaseRepresenter.__init__(
+            self,
+            default_style=default_style,
+            default_flow_style=default_flow_style,
+            dumper=self,
+        )
         BaseResolver.__init__(self, loadumper=self)
 
 
 class SafeDumper(Emitter, Serializer, SafeRepresenter, Resolver):
-    def __init__(self, stream,
-                 default_style=None, default_flow_style=None,
-                 canonical=None, indent=None, width=None,
-                 allow_unicode=None, line_break=None,
-                 encoding=None, explicit_start=None, explicit_end=None,
-                 version=None, tags=None, block_seq_indent=None,
-                 top_level_colon_align=None, prefix_colon=None):
-        # type: (Any, StreamType, Any, Any, bool, Union[None, int], Union[None, int], bool, Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> None  # NOQA
-        Emitter.__init__(self, stream, canonical=canonical,
-                         indent=indent, width=width,
-                         allow_unicode=allow_unicode, line_break=line_break,
-                         block_seq_indent=block_seq_indent,
-                         dumper=self)
-        Serializer.__init__(self, encoding=encoding,
-                            explicit_start=explicit_start,
-                            explicit_end=explicit_end,
-                            version=version, tags=tags,
-                            dumper=self)
-        SafeRepresenter.__init__(self, default_style=default_style,
-                                 default_flow_style=default_flow_style,
-                                 dumper=self)
+    def __init__(
+        self,
+        stream,
+        default_style=None,
+        default_flow_style=None,
+        canonical=None,
+        indent=None,
+        width=None,
+        allow_unicode=None,
+        line_break=None,
+        encoding=None,
+        explicit_start=None,
+        explicit_end=None,
+        version=None,
+        tags=None,
+        block_seq_indent=None,
+        top_level_colon_align=None,
+        prefix_colon=None,
+    ):
+        # type: (StreamType, Any, Any, Union[None, bool], Union[None, int], Union[None, int], Union[None, bool], Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> None  # NOQA
+        Emitter.__init__(
+            self,
+            stream,
+            canonical=canonical,
+            indent=indent,
+            width=width,
+            allow_unicode=allow_unicode,
+            line_break=line_break,
+            block_seq_indent=block_seq_indent,
+            dumper=self,
+        )
+        Serializer.__init__(
+            self,
+            encoding=encoding,
+            explicit_start=explicit_start,
+            explicit_end=explicit_end,
+            version=version,
+            tags=tags,
+            dumper=self,
+        )
+        SafeRepresenter.__init__(
+            self,
+            default_style=default_style,
+            default_flow_style=default_flow_style,
+            dumper=self,
+        )
         Resolver.__init__(self, loadumper=self)
 
 
 class Dumper(Emitter, Serializer, Representer, Resolver):
-    def __init__(self, stream,
-                 default_style=None, default_flow_style=None,
-                 canonical=None, indent=None, width=None,
-                 allow_unicode=None, line_break=None,
-                 encoding=None, explicit_start=None, explicit_end=None,
-                 version=None, tags=None, block_seq_indent=None,
-                 top_level_colon_align=None, prefix_colon=None):
-        # type: (Any, StreamType, Any, Any, bool, Union[None, int], Union[None, int], bool, Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> None   # NOQA
-        Emitter.__init__(self, stream, canonical=canonical,
-                         indent=indent, width=width,
-                         allow_unicode=allow_unicode, line_break=line_break,
-                         block_seq_indent=block_seq_indent,
-                         dumper=self)
-        Serializer.__init__(self, encoding=encoding,
-                            explicit_start=explicit_start,
-                            explicit_end=explicit_end,
-                            version=version, tags=tags,
-                            dumper=self)
-        Representer.__init__(self, default_style=default_style,
-                             default_flow_style=default_flow_style,
-                             dumper=self)
+    def __init__(
+        self,
+        stream,
+        default_style=None,
+        default_flow_style=None,
+        canonical=None,
+        indent=None,
+        width=None,
+        allow_unicode=None,
+        line_break=None,
+        encoding=None,
+        explicit_start=None,
+        explicit_end=None,
+        version=None,
+        tags=None,
+        block_seq_indent=None,
+        top_level_colon_align=None,
+        prefix_colon=None,
+    ):
+        # type: (StreamType, Any, Any, Union[None, bool], Union[None, int], Union[None, int], Union[None, bool], Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> None   # NOQA
+        Emitter.__init__(
+            self,
+            stream,
+            canonical=canonical,
+            indent=indent,
+            width=width,
+            allow_unicode=allow_unicode,
+            line_break=line_break,
+            block_seq_indent=block_seq_indent,
+            dumper=self,
+        )
+        Serializer.__init__(
+            self,
+            encoding=encoding,
+            explicit_start=explicit_start,
+            explicit_end=explicit_end,
+            version=version,
+            tags=tags,
+            dumper=self,
+        )
+        Representer.__init__(
+            self,
+            default_style=default_style,
+            default_flow_style=default_flow_style,
+            dumper=self,
+        )
         Resolver.__init__(self, loadumper=self)
 
 
 class RoundTripDumper(Emitter, Serializer, RoundTripRepresenter, VersionedResolver):
-    def __init__(self, stream,
-                 default_style=None, default_flow_style=None,
-                 canonical=None, indent=None, width=None,
-                 allow_unicode=None, line_break=None,
-                 encoding=None, explicit_start=None, explicit_end=None,
-                 version=None, tags=None, block_seq_indent=None,
-                 top_level_colon_align=None, prefix_colon=None):
-        # type: (Any, StreamType, Any, bool, Union[None, int], Union[None, int], bool, Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> None  # NOQA
-        Emitter.__init__(self, stream, canonical=canonical,
-                         indent=indent, width=width,
-                         allow_unicode=allow_unicode, line_break=line_break,
-                         block_seq_indent=block_seq_indent,
-                         top_level_colon_align=top_level_colon_align,
-                         prefix_colon=prefix_colon,
-                         dumper=self)
-        Serializer.__init__(self, encoding=encoding,
-                            explicit_start=explicit_start,
-                            explicit_end=explicit_end,
-                            version=version, tags=tags,
-                            dumper=self)
-        RoundTripRepresenter.__init__(self, default_style=default_style,
-                                      default_flow_style=default_flow_style,
-                                      dumper=self)
+    def __init__(
+        self,
+        stream,
+        default_style=None,
+        default_flow_style=None,
+        canonical=None,
+        indent=None,
+        width=None,
+        allow_unicode=None,
+        line_break=None,
+        encoding=None,
+        explicit_start=None,
+        explicit_end=None,
+        version=None,
+        tags=None,
+        block_seq_indent=None,
+        top_level_colon_align=None,
+        prefix_colon=None,
+    ):
+        # type: (StreamType, Any, Union[None, bool], Union[None, int], Union[None, int], Union[None, int], Union[None, bool], Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> None  # NOQA
+        Emitter.__init__(
+            self,
+            stream,
+            canonical=canonical,
+            indent=indent,
+            width=width,
+            allow_unicode=allow_unicode,
+            line_break=line_break,
+            block_seq_indent=block_seq_indent,
+            top_level_colon_align=top_level_colon_align,
+            prefix_colon=prefix_colon,
+            dumper=self,
+        )
+        Serializer.__init__(
+            self,
+            encoding=encoding,
+            explicit_start=explicit_start,
+            explicit_end=explicit_end,
+            version=version,
+            tags=tags,
+            dumper=self,
+        )
+        RoundTripRepresenter.__init__(
+            self,
+            default_style=default_style,
+            default_flow_style=default_flow_style,
+            dumper=self,
+        )
         VersionedResolver.__init__(self, loader=self)
diff --git a/emitter.py b/emitter.py
index ea28c33..626a69e 100644
--- a/emitter.py
+++ b/emitter.py
@@ -12,9 +12,12 @@ from __future__ import print_function
 
 import sys
 from ruamel.yaml.error import YAMLError, YAMLStreamError
-from ruamel.yaml.events import *                                     # NOQA
+from ruamel.yaml.events import *  # NOQA
+
+# fmt: off
 from ruamel.yaml.compat import utf8, text_type, PY2, nprint, dbg, DBG_EVENT, \
     check_anchorname_char
+# fmt: on
 
 if False:  # MYPY
     from typing import Any, Dict, List, Union, Text, Tuple  # NOQA
@@ -28,10 +31,17 @@ class EmitterError(YAMLError):
 
 
 class ScalarAnalysis(object):
-    def __init__(self, scalar, empty, multiline,
-                 allow_flow_plain, allow_block_plain,
-                 allow_single_quoted, allow_double_quoted,
-                 allow_block):
+    def __init__(
+        self,
+        scalar,
+        empty,
+        multiline,
+        allow_flow_plain,
+        allow_block_plain,
+        allow_single_quoted,
+        allow_double_quoted,
+        allow_block,
+    ):
         # type: (Any, Any, Any, bool, bool, bool, bool, bool) -> None
         self.scalar = scalar
         self.empty = empty
@@ -81,17 +91,29 @@ class Indents(object):
 
 
 class Emitter(object):
+    # fmt: off
     DEFAULT_TAG_PREFIXES = {
         u'!': u'!',
         u'tag:yaml.org,2002:': u'!!',
     }
+    # fmt: on
 
     MAX_SIMPLE_KEY_LENGTH = 128
 
-    def __init__(self, stream, canonical=None, indent=None, width=None,
-                 allow_unicode=None, line_break=None, block_seq_indent=None,
-                 top_level_colon_align=None, prefix_colon=None, dumper=None):
-        # type: (StreamType, Any, int, int, bool, Any, int, bool, Any, Any) -> None
+    def __init__(
+        self,
+        stream,
+        canonical=None,
+        indent=None,
+        width=None,
+        allow_unicode=None,
+        line_break=None,
+        block_seq_indent=None,
+        top_level_colon_align=None,
+        prefix_colon=None,
+        dumper=None,
+    ):
+        # type: (StreamType, Any, Union[None, int], Union[None, int], Union[None, bool], Any, Union[None, int], Union[None, bool], Any, Any) -> None  # NOQA
         self.dumper = dumper
         if self.dumper is not None and getattr(self.dumper, '_emitter', None) is None:
             self.dumper._emitter = self
@@ -195,8 +217,8 @@ class Emitter(object):
         # type: () -> Any
         try:
             if hasattr(self.dumper, 'typ'):
-                return self.dumper.serializer  # type: ignore
-            return self.dumper._serializer  # type: ignore
+                return self.dumper.serializer
+            return self.dumper._serializer
         except AttributeError:
             return self  # cyaml
 
@@ -244,10 +266,10 @@ class Emitter(object):
                 level = -1
             if level < 0:
                 return False
-        return (len(self.events) < count + 1)
+        return len(self.events) < count + 1
 
     def increase_indent(self, flow=False, sequence=None, indentless=False):
-        # type: (bool, bool, bool) -> None
+        # type: (bool, Union[None, bool], bool) -> None
         self.indents.append(self.indent, sequence)
         if self.indent is None:  # top level
             if flow:
@@ -258,8 +280,9 @@ class Emitter(object):
             else:
                 self.indent = 0
         elif not indentless:
-            self.indent += (self.best_sequence_indent if self.indents.last_seq() else
-                            self.best_map_indent)
+            self.indent += (
+                self.best_sequence_indent if self.indents.last_seq() else self.best_map_indent
+            )
             # if self.indents.last_seq():
             #     if self.indent == 0: # top level block sequence
             #         self.indent = self.best_sequence_indent - self.sequence_dash_offset
@@ -276,22 +299,19 @@ class Emitter(object):
         # type: () -> None
         if isinstance(self.event, StreamStartEvent):
             if PY2:
-                if self.event.encoding \
-                   and not getattr(self.stream, 'encoding', None):
+                if self.event.encoding and not getattr(self.stream, 'encoding', None):
                     self.encoding = self.event.encoding
             else:
-                if self.event.encoding \
-                   and not hasattr(self.stream, 'encoding'):
+                if self.event.encoding and not hasattr(self.stream, 'encoding'):
                     self.encoding = self.event.encoding
             self.write_stream_start()
             self.state = self.expect_first_document_start
         else:
-            raise EmitterError("expected StreamStartEvent, but got %s" %
-                               self.event)
+            raise EmitterError('expected StreamStartEvent, but got %s' % self.event)
 
     def expect_nothing(self):
         # type: () -> None
-        raise EmitterError("expected nothing, but got %s" % self.event)
+        raise EmitterError('expected nothing, but got %s' % self.event)
 
     # Document handlers.
 
@@ -317,12 +337,14 @@ class Emitter(object):
                     handle_text = self.prepare_tag_handle(handle)
                     prefix_text = self.prepare_tag_prefix(prefix)
                     self.write_tag_directive(handle_text, prefix_text)
-            implicit = (first and
-                        not self.event.explicit and
-                        not self.canonical and
-                        not self.event.version and
-                        not self.event.tags and
-                        not self.check_empty_document())
+            implicit = (
+                first
+                and not self.event.explicit
+                and not self.canonical
+                and not self.event.version
+                and not self.event.tags
+                and not self.check_empty_document()
+            )
             if not implicit:
                 self.write_indent()
                 self.write_indicator(u'---', True)
@@ -336,8 +358,7 @@ class Emitter(object):
             self.write_stream_end()
             self.state = self.expect_nothing
         else:
-            raise EmitterError("expected DocumentStartEvent, but got %s" %
-                               self.event)
+            raise EmitterError('expected DocumentStartEvent, but got %s' % self.event)
 
     def expect_document_end(self):
         # type: () -> None
@@ -349,8 +370,7 @@ class Emitter(object):
             self.flush_stream()
             self.state = self.expect_document_start
         else:
-            raise EmitterError("expected DocumentEndEvent, but got %s" %
-                               self.event)
+            raise EmitterError('expected DocumentEndEvent, but got %s' % self.event)
 
     def expect_document_root(self):
         # type: () -> None
@@ -359,11 +379,10 @@ class Emitter(object):
 
     # Node handlers.
 
-    def expect_node(self, root=False, sequence=False, mapping=False,
-                    simple_key=False):
+    def expect_node(self, root=False, sequence=False, mapping=False, simple_key=False):
         # type: (bool, bool, bool, bool) -> None
         self.root_context = root
-        self.sequence_context = sequence   # not used in PyYAML
+        self.sequence_context = sequence  # not used in PyYAML
         self.mapping_context = mapping
         self.simple_key_context = simple_key
         if isinstance(self.event, AliasEvent):
@@ -382,8 +401,12 @@ class Emitter(object):
                     if self.write_pre_comment(self.event):
                         self.indention = False
                         self.no_newline = True
-                if self.flow_level or self.canonical or self.event.flow_style or \
-                        self.check_empty_sequence():
+                if (
+                    self.flow_level
+                    or self.canonical
+                    or self.event.flow_style
+                    or self.check_empty_sequence()
+                ):
                     self.expect_flow_sequence()
                 else:
                     self.expect_block_sequence()
@@ -392,18 +415,22 @@ class Emitter(object):
                     self.write_post_comment(self.event)
                 if self.event.comment and self.event.comment[1]:
                     self.write_pre_comment(self.event)
-                if self.flow_level or self.canonical or self.event.flow_style \
-                        or self.check_empty_mapping():
+                if (
+                    self.flow_level
+                    or self.canonical
+                    or self.event.flow_style
+                    or self.check_empty_mapping()
+                ):
                     self.expect_flow_mapping()
                 else:
                     self.expect_block_mapping()
         else:
-            raise EmitterError("expected NodeEvent, but got %s" % self.event)
+            raise EmitterError('expected NodeEvent, but got %s' % self.event)
 
     def expect_alias(self):
         # type: () -> None
         if self.event.anchor is None:
-            raise EmitterError("anchor is not specified for alias")
+            raise EmitterError('anchor is not specified for alias')
         self.process_anchor(u'*')
         self.state = self.states.pop()
 
@@ -540,7 +567,7 @@ class Emitter(object):
 
     def expect_block_sequence(self):
         # type: () -> None
-        indentless = (self.mapping_context and not self.indention)
+        indentless = self.mapping_context and not self.indention
         self.increase_indent(flow=False, sequence=True, indentless=indentless)
         self.state = self.expect_first_block_sequence_item
 
@@ -627,21 +654,32 @@ class Emitter(object):
 
     def check_empty_sequence(self):
         # type: () -> bool
-        return (isinstance(self.event, SequenceStartEvent) and bool(self.events) and
-                isinstance(self.events[0], SequenceEndEvent))
+        return (
+            isinstance(self.event, SequenceStartEvent)
+            and bool(self.events)
+            and isinstance(self.events[0], SequenceEndEvent)
+        )
 
     def check_empty_mapping(self):
         # type: () -> bool
-        return (isinstance(self.event, MappingStartEvent) and bool(self.events) and
-                isinstance(self.events[0], MappingEndEvent))
+        return (
+            isinstance(self.event, MappingStartEvent)
+            and bool(self.events)
+            and isinstance(self.events[0], MappingEndEvent)
+        )
 
     def check_empty_document(self):
         # type: () -> bool
         if not isinstance(self.event, DocumentStartEvent) or not self.events:
             return False
         event = self.events[0]
-        return (isinstance(event, ScalarEvent) and event.anchor is None and
-                event.tag is None and event.implicit and event.value == u'')
+        return (
+            isinstance(event, ScalarEvent)
+            and event.anchor is None
+            and event.tag is None
+            and event.implicit
+            and event.value == ""
+        )
 
     def check_simple_key(self):
         # type: () -> bool
@@ -650,8 +688,10 @@ class Emitter(object):
             if self.prepared_anchor is None:
                 self.prepared_anchor = self.prepare_anchor(self.event.anchor)
             length += len(self.prepared_anchor)
-        if isinstance(self.event, (ScalarEvent, CollectionStartEvent))  \
-                and self.event.tag is not None:
+        if (
+            isinstance(self.event, (ScalarEvent, CollectionStartEvent))
+            and self.event.tag is not None
+        ):
             if self.prepared_tag is None:
                 self.prepared_tag = self.prepare_tag(self.event.tag)
             length += len(self.prepared_tag)
@@ -659,13 +699,17 @@ class Emitter(object):
             if self.analysis is None:
                 self.analysis = self.analyze_scalar(self.event.value)
             length += len(self.analysis.scalar)
-        return (length < self.MAX_SIMPLE_KEY_LENGTH and (
-            isinstance(self.event, AliasEvent) or
-            (isinstance(self.event, SequenceStartEvent) and
-             self.event.flow_style is True) or
-            (isinstance(self.event, ScalarEvent) and
-             not self.analysis.empty and not self.analysis.multiline) or
-            self.check_empty_sequence() or self.check_empty_mapping()))
+        return length < self.MAX_SIMPLE_KEY_LENGTH and (
+            isinstance(self.event, AliasEvent)
+            or (isinstance(self.event, SequenceStartEvent) and self.event.flow_style is True)
+            or (
+                isinstance(self.event, ScalarEvent)
+                and not self.analysis.empty
+                and not self.analysis.multiline
+            )
+            or self.check_empty_sequence()
+            or self.check_empty_mapping()
+        )
 
     # Anchor, Tag, and Scalar processors.
 
@@ -686,9 +730,10 @@ class Emitter(object):
         if isinstance(self.event, ScalarEvent):
             if self.style is None:
                 self.style = self.choose_scalar_style()
-            if ((not self.canonical or tag is None) and
-                ((self.style == '' and self.event.implicit[0]) or
-                 (self.style != '' and self.event.implicit[1]))):
+            if (not self.canonical or tag is None) and (
+                (self.style == "" and self.event.implicit[0])
+                or (self.style != "" and self.event.implicit[1])
+            ):
                 self.prepared_tag = None
                 return
             if self.event.implicit[0] and tag is None:
@@ -699,13 +744,16 @@ class Emitter(object):
                 self.prepared_tag = None
                 return
         if tag is None:
-            raise EmitterError("tag is not specified")
+            raise EmitterError('tag is not specified')
         if self.prepared_tag is None:
             self.prepared_tag = self.prepare_tag(tag)
         if self.prepared_tag:
             self.write_indicator(self.prepared_tag, True)
-            if self.sequence_context and not self.flow_level and \
-               isinstance(self.event, ScalarEvent):
+            if (
+                self.sequence_context
+                and not self.flow_level
+                and isinstance(self.event, ScalarEvent)
+            ):
                 self.no_newline = True
         self.prepared_tag = None
 
@@ -715,25 +763,33 @@ class Emitter(object):
             self.analysis = self.analyze_scalar(self.event.value)
         if self.event.style == '"' or self.canonical:
             return '"'
-        if (not self.event.style or self.event.style == '?') and \
-           (self.event.implicit[0] or not self.event.implicit[2]):
-            if (not (self.simple_key_context and
-                     (self.analysis.empty or self.analysis.multiline)) and
-                (self.flow_level and self.analysis.allow_flow_plain or
-                    (not self.flow_level and self.analysis.allow_block_plain))):
-                return ''
+        if (not self.event.style or self.event.style == '?') and (
+            self.event.implicit[0] or not self.event.implicit[2]
+        ):
+            if not (
+                self.simple_key_context and (self.analysis.empty or self.analysis.multiline)
+            ) and (
+                self.flow_level
+                and self.analysis.allow_flow_plain
+                or (not self.flow_level and self.analysis.allow_block_plain)
+            ):
+                return ""
         self.analysis.allow_block = True
         if self.event.style and self.event.style in '|>':
-            if (not self.flow_level and not self.simple_key_context and
-                    self.analysis.allow_block):
+            if (
+                not self.flow_level
+                and not self.simple_key_context
+                and self.analysis.allow_block
+            ):
                 return self.event.style
         if not self.event.style and self.analysis.allow_double_quoted:
             if "'" in self.event.value or '\n' in self.event.value:
                 return '"'
-        if not self.event.style or self.event.style == '\'':
-            if (self.analysis.allow_single_quoted and
-                    not (self.simple_key_context and self.analysis.multiline)):
-                return '\''
+        if not self.event.style or self.event.style == "'":
+            if self.analysis.allow_single_quoted and not (
+                self.simple_key_context and self.analysis.multiline
+            ):
+                return "'"
         return '"'
 
     def process_scalar(self):
@@ -742,7 +798,7 @@ class Emitter(object):
             self.analysis = self.analyze_scalar(self.event.value)
         if self.style is None:
             self.style = self.choose_scalar_style()
-        split = (not self.simple_key_context)
+        split = not self.simple_key_context
         # if self.analysis.multiline and split    \
         #         and (not self.style or self.style in '\'\"'):
         #     self.write_indent()
@@ -750,7 +806,7 @@ class Emitter(object):
             self.write_indent()
         if self.style == '"':
             self.write_double_quoted(self.analysis.scalar, split)
-        elif self.style == '\'':
+        elif self.style == "'":
             self.write_single_quoted(self.analysis.scalar, split)
         elif self.style == '>':
             self.write_folded(self.analysis.scalar)
@@ -769,36 +825,40 @@ class Emitter(object):
         # type: (Any) -> Any
         major, minor = version
         if major != 1:
-            raise EmitterError("unsupported YAML version: %d.%d" %
-                               (major, minor))
+            raise EmitterError('unsupported YAML version: %d.%d' % (major, minor))
         return u'%d.%d' % (major, minor)
 
     def prepare_tag_handle(self, handle):
         # type: (Any) -> Any
         if not handle:
-            raise EmitterError("tag handle must not be empty")
+            raise EmitterError('tag handle must not be empty')
         if handle[0] != u'!' or handle[-1] != u'!':
-            raise EmitterError("tag handle must start and end with '!': %r"
-                               % (utf8(handle)))
+            raise EmitterError("tag handle must start and end with '!': %r" % (utf8(handle)))
         for ch in handle[1:-1]:
-            if not (u'0' <= ch <= u'9' or u'A' <= ch <= u'Z' or
-                    u'a' <= ch <= u'z' or ch in u'-_'):
-                raise EmitterError("invalid character %r in the tag handle: %r"
-                                   % (utf8(ch), utf8(handle)))
+            if not (
+                u'0' <= ch <= u'9' or u'A' <= ch <= u'Z' or u'a' <= ch <= u'z' or ch in u'-_'
+            ):
+                raise EmitterError(
+                    'invalid character %r in the tag handle: %r' % (utf8(ch), utf8(handle))
+                )
         return handle
 
     def prepare_tag_prefix(self, prefix):
         # type: (Any) -> Any
         if not prefix:
-            raise EmitterError("tag prefix must not be empty")
+            raise EmitterError('tag prefix must not be empty')
         chunks = []  # type: List[Any]
         start = end = 0
         if prefix[0] == u'!':
             end = 1
         while end < len(prefix):
             ch = prefix[end]
-            if u'0' <= ch <= u'9' or u'A' <= ch <= u'Z' or u'a' <= ch <= u'z'   \
-                    or ch in u'-;/?!:@&=+$,_.~*\'()[]':
+            if (
+                u'0' <= ch <= u'9'
+                or u'A' <= ch <= u'Z'
+                or u'a' <= ch <= u'z'
+                or ch in u"-;/?!:@&=+$,_.~*'()[]"
+            ):
                 end += 1
             else:
                 if start < end:
@@ -809,29 +869,32 @@ class Emitter(object):
                     chunks.append(u'%%%02X' % ord(ch))
         if start < end:
             chunks.append(prefix[start:end])
-        return u''.join(chunks)
+        return "".join(chunks)
 
     def prepare_tag(self, tag):
         # type: (Any) -> Any
         if not tag:
-            raise EmitterError("tag must not be empty")
+            raise EmitterError('tag must not be empty')
         if tag == u'!':
             return tag
         handle = None
         suffix = tag
         prefixes = sorted(self.tag_prefixes.keys())
         for prefix in prefixes:
-            if tag.startswith(prefix)   \
-                    and (prefix == u'!' or len(prefix) < len(tag)):
+            if tag.startswith(prefix) and (prefix == u'!' or len(prefix) < len(tag)):
                 handle = self.tag_prefixes[prefix]
-                suffix = tag[len(prefix):]
+                suffix = tag[len(prefix) :]
         chunks = []  # type: List[Any]
         start = end = 0
         while end < len(suffix):
             ch = suffix[end]
-            if u'0' <= ch <= u'9' or u'A' <= ch <= u'Z' or u'a' <= ch <= u'z'   \
-                    or ch in u'-;/?:@&=+$,_.~*\'()[]'   \
-                    or (ch == u'!' and handle != u'!'):
+            if (
+                u'0' <= ch <= u'9'
+                or u'A' <= ch <= u'Z'
+                or u'a' <= ch <= u'z'
+                or ch in u"-;/?:@&=+$,_.~*'()[]"
+                or (ch == u'!' and handle != u'!')
+            ):
                 end += 1
             else:
                 if start < end:
@@ -842,7 +905,7 @@ class Emitter(object):
                     chunks.append(u'%%%02X' % ord(ch))
         if start < end:
             chunks.append(suffix[start:end])
-        suffix_text = u''.join(chunks)
+        suffix_text = "".join(chunks)
         if handle:
             return u'%s%s' % (handle, suffix_text)
         else:
@@ -851,11 +914,12 @@ class Emitter(object):
     def prepare_anchor(self, anchor):
         # type: (Any) -> Any
         if not anchor:
-            raise EmitterError("anchor must not be empty")
+            raise EmitterError('anchor must not be empty')
         for ch in anchor:
             if not check_anchorname_char(ch):
-                raise EmitterError("invalid character %r in the anchor: %r"
-                                   % (utf8(ch), utf8(anchor)))
+                raise EmitterError(
+                    'invalid character %r in the anchor: %r' % (utf8(ch), utf8(anchor))
+                )
         return anchor
 
     def analyze_scalar(self, scalar):
@@ -863,10 +927,15 @@ class Emitter(object):
         # Empty scalar is a special case.
         if not scalar:
             return ScalarAnalysis(
-                scalar=scalar, empty=True, multiline=False,
-                allow_flow_plain=False, allow_block_plain=True,
-                allow_single_quoted=True, allow_double_quoted=True,
-                allow_block=False)
+                scalar=scalar,
+                empty=True,
+                multiline=False,
+                allow_flow_plain=False,
+                allow_block_plain=True,
+                allow_single_quoted=True,
+                allow_double_quoted=True,
+                allow_block=False,
+            )
 
         # Indicators and special characters.
         block_indicators = False
@@ -891,8 +960,7 @@ class Emitter(object):
         preceeded_by_whitespace = True
 
         # Last character or followed by a whitespace.
-        followed_by_whitespace = (len(scalar) == 1 or
-                                  scalar[1] in u'\0 \t\r\n\x85\u2028\u2029')
+        followed_by_whitespace = len(scalar) == 1 or scalar[1] in u'\0 \t\r\n\x85\u2028\u2029'
 
         # The previous character is a space.
         previous_space = False
@@ -907,7 +975,7 @@ class Emitter(object):
             # Check for indicators.
             if index == 0:
                 # Leading indicators are special characters.
-                if ch in u'#,[]{}&*!|>\'\"%@`':
+                if ch in u'#,[]{}&*!|>\'"%@`':
                     flow_indicators = True
                     block_indicators = True
                 if ch in u'?:':  # ToDo
@@ -936,10 +1004,12 @@ class Emitter(object):
             if ch in u'\n\x85\u2028\u2029':
                 line_breaks = True
             if not (ch == u'\n' or u'\x20' <= ch <= u'\x7E'):
-                if (ch == u'\x85' or u'\xA0' <= ch <= u'\uD7FF' or
-                        u'\uE000' <= ch <= u'\uFFFD' or
-                        (self.unicode_supplementary and
-                         (u'\U00010000' <= ch <= u'\U0010FFFF'))) and ch != u'\uFEFF':
+                if (
+                    ch == u'\x85'
+                    or u'\xA0' <= ch <= u'\uD7FF'
+                    or u'\uE000' <= ch <= u'\uFFFD'
+                    or (self.unicode_supplementary and (u'\U00010000' <= ch <= u'\U0010FFFF'))
+                ) and ch != u'\uFEFF':
                     # unicode_characters = True
                     if not self.allow_unicode:
                         special_characters = True
@@ -971,10 +1041,10 @@ class Emitter(object):
 
             # Prepare for the next character.
             index += 1
-            preceeded_by_whitespace = (ch in u'\0 \t\r\n\x85\u2028\u2029')
+            preceeded_by_whitespace = ch in u'\0 \t\r\n\x85\u2028\u2029'
             followed_by_whitespace = (
-                index + 1 >= len(scalar) or
-                scalar[index + 1] in u'\0 \t\r\n\x85\u2028\u2029')
+                index + 1 >= len(scalar) or scalar[index + 1] in u'\0 \t\r\n\x85\u2028\u2029'
+            )
 
         # Let's decide what styles are allowed.
         allow_flow_plain = True
@@ -984,7 +1054,7 @@ class Emitter(object):
         allow_block = True
 
         # Leading and trailing whitespaces are bad for plain scalars.
-        if (leading_space or leading_break or trailing_space or trailing_break):
+        if leading_space or leading_break or trailing_space or trailing_break:
             allow_flow_plain = allow_block_plain = False
 
         # We do not permit trailing spaces for block scalars.
@@ -1018,13 +1088,16 @@ class Emitter(object):
         if block_indicators:
             allow_block_plain = False
 
-        return ScalarAnalysis(scalar=scalar,
-                              empty=False, multiline=line_breaks,
-                              allow_flow_plain=allow_flow_plain,
-                              allow_block_plain=allow_block_plain,
-                              allow_single_quoted=allow_single_quoted,
-                              allow_double_quoted=allow_double_quoted,
-                              allow_block=allow_block)
+        return ScalarAnalysis(
+            scalar=scalar,
+            empty=False,
+            multiline=line_breaks,
+            allow_flow_plain=allow_flow_plain,
+            allow_block_plain=allow_block_plain,
+            allow_single_quoted=allow_single_quoted,
+            allow_double_quoted=allow_double_quoted,
+            allow_block=allow_block,
+        )
 
     # Writers.
 
@@ -1043,8 +1116,7 @@ class Emitter(object):
         # type: () -> None
         self.flush_stream()
 
-    def write_indicator(self, indicator, need_whitespace,
-                        whitespace=False, indention=False):
+    def write_indicator(self, indicator, need_whitespace, whitespace=False, indention=False):
         # type: (Any, Any, bool, bool) -> None
         if self.whitespace or not need_whitespace:
             data = indicator
@@ -1061,8 +1133,11 @@ class Emitter(object):
     def write_indent(self):
         # type: () -> None
         indent = self.indent or 0
-        if not self.indention or self.column > indent   \
-                or (self.column == indent and not self.whitespace):
+        if (
+            not self.indention
+            or self.column > indent
+            or (self.column == indent and not self.whitespace)
+        ):
             if bool(self.no_newline):
                 self.no_newline = False
             else:
@@ -1112,7 +1187,7 @@ class Emitter(object):
                 self.write_line_break()
                 if self.requested_indent != 0:
                     self.write_indent()
-        self.write_indicator(u'\'', True)
+        self.write_indicator(u"'", True)
         spaces = False
         breaks = False
         start = end = 0
@@ -1122,8 +1197,13 @@ class Emitter(object):
                 ch = text[end]
             if spaces:
                 if ch is None or ch != u' ':
-                    if start + 1 == end and self.column > self.best_width and split   \
-                            and start != 0 and end != len(text):
+                    if (
+                        start + 1 == end
+                        and self.column > self.best_width
+                        and split
+                        and start != 0
+                        and end != len(text)
+                    ):
                         self.write_indent()
                     else:
                         data = text[start:end]
@@ -1144,7 +1224,7 @@ class Emitter(object):
                     self.write_indent()
                     start = end
             else:
-                if ch is None or ch in u' \n\x85\u2028\u2029' or ch == u'\'':
+                if ch is None or ch in u' \n\x85\u2028\u2029' or ch == u"'":
                     if start < end:
                         data = text[start:end]
                         self.column += len(data)
@@ -1152,18 +1232,18 @@ class Emitter(object):
                             data = data.encode(self.encoding)
                         self.stream.write(data)
                         start = end
-            if ch == u'\'':
-                data = u'\'\''
+            if ch == u"'":
+                data = u"''"
                 self.column += 2
                 if bool(self.encoding):
                     data = data.encode(self.encoding)
                 self.stream.write(data)
                 start = end + 1
             if ch is not None:
-                spaces = (ch == u' ')
-                breaks = (ch in u'\n\x85\u2028\u2029')
+                spaces = ch == u' '
+                breaks = ch in u'\n\x85\u2028\u2029'
             end += 1
-        self.write_indicator(u'\'', False)
+        self.write_indicator(u"'", False)
 
     ESCAPE_REPLACEMENTS = {
         u'\0': u'0',
@@ -1175,7 +1255,7 @@ class Emitter(object):
         u'\x0C': u'f',
         u'\x0D': u'r',
         u'\x1B': u'e',
-        u'\"': u'\"',
+        u'"': u'"',
         u'\\': u'\\',
         u'\x85': u'N',
         u'\xA0': u'_',
@@ -1196,10 +1276,17 @@ class Emitter(object):
             ch = None
             if end < len(text):
                 ch = text[end]
-            if ch is None or ch in u'"\\\x85\u2028\u2029\uFEFF' \
-               or not (u'\x20' <= ch <= u'\x7E' or
-                       (self.allow_unicode and
-                        (u'\xA0' <= ch <= u'\uD7FF' or u'\uE000' <= ch <= u'\uFFFD'))):
+            if (
+                ch is None
+                or ch in u'"\\\x85\u2028\u2029\uFEFF'
+                or not (
+                    u'\x20' <= ch <= u'\x7E'
+                    or (
+                        self.allow_unicode
+                        and (u'\xA0' <= ch <= u'\uD7FF' or u'\uE000' <= ch <= u'\uFFFD')
+                    )
+                )
+            ):
                 if start < end:
                     data = text[start:end]
                     self.column += len(data)
@@ -1221,8 +1308,12 @@ class Emitter(object):
                         data = data.encode(self.encoding)
                     self.stream.write(data)
                     start = end + 1
-            if 0 < end < len(text) - 1 and (ch == u' ' or start >= end)   \
-                    and self.column + (end - start) > self.best_width and split:
+            if (
+                0 < end < len(text) - 1
+                and (ch == u' ' or start >= end)
+                and self.column + (end - start) > self.best_width
+                and split
+            ):
                 data = text[start:end] + u'\\'
                 if start < end:
                     start = end
@@ -1244,7 +1335,7 @@ class Emitter(object):
 
     def determine_block_hints(self, text):
         # type: (Any) -> Any
-        hints = u''
+        hints = ""
         if text:
             if text[0] in u' \n\x85\u2028\u2029':
                 hints += text_type(self.best_sequence_indent)
@@ -1271,10 +1362,14 @@ class Emitter(object):
                 ch = text[end]
             if breaks:
                 if ch is None or ch not in u'\n\x85\u2028\u2029':
-                    if not leading_space and ch is not None and ch != u' '  \
-                            and text[start] == u'\n':
+                    if (
+                        not leading_space
+                        and ch is not None
+                        and ch != u' '
+                        and text[start] == u'\n'
+                    ):
                         self.write_line_break()
-                    leading_space = (ch == u' ')
+                    leading_space = ch == u' '
                     for br in text[start:end]:
                         if br == u'\n':
                             self.write_line_break()
@@ -1305,8 +1400,8 @@ class Emitter(object):
                         self.write_line_break()
                     start = end
             if ch is not None:
-                breaks = (ch in u'\n\x85\u2028\u2029')
-                spaces = (ch == u' ')
+                breaks = ch in u'\n\x85\u2028\u2029'
+                spaces = ch == u' '
             end += 1
 
     def write_literal(self, text):
@@ -1342,7 +1437,7 @@ class Emitter(object):
                         self.write_line_break()
                     start = end
             if ch is not None:
-                breaks = (ch in u'\n\x85\u2028\u2029')
+                breaks = ch in u'\n\x85\u2028\u2029'
             end += 1
 
     def write_plain(self, text, split=True):
@@ -1410,8 +1505,8 @@ class Emitter(object):
                         raise
                     start = end
             if ch is not None:
-                spaces = (ch == u' ')
-                breaks = (ch in u'\n\x85\u2028\u2029')
+                spaces = ch == u' '
+                breaks = ch in u'\n\x85\u2028\u2029'
             end += 1
 
     def write_comment(self, comment):
@@ -1453,8 +1548,7 @@ class Emitter(object):
         try:
             start_events = (MappingStartEvent, SequenceStartEvent)
             for comment in comments:
-                if isinstance(event, start_events) and \
-                   getattr(comment, 'pre_done', None):
+                if isinstance(event, start_events) and getattr(comment, 'pre_done', None):
                     continue
                 if self.column != 0:
                     self.write_line_break()
diff --git a/error.py b/error.py
index f712a60..ab1072d 100644
--- a/error.py
+++ b/error.py
@@ -12,14 +12,20 @@ if False:  # MYPY
 
 
 __all__ = [
-    'FileMark', 'StringMark', 'CommentMark', 'YAMLError', 'MarkedYAMLError',
-    'ReusedAnchorWarning', 'UnsafeLoaderWarning', 'MarkedYAMLWarning',
+    'FileMark',
+    'StringMark',
+    'CommentMark',
+    'YAMLError',
+    'MarkedYAMLError',
+    'ReusedAnchorWarning',
+    'UnsafeLoaderWarning',
+    'MarkedYAMLWarning',
     'MarkedYAMLFutureWarning',
 ]
 
 
 class StreamMark(object):
-    __slots__ = 'name', 'index', 'line', 'column',
+    __slots__ = 'name', 'index', 'line', 'column'
 
     def __init__(self, name, index, line, column):
         # type: (Any, int, int, int) -> None
@@ -30,8 +36,7 @@ class StreamMark(object):
 
     def __str__(self):
         # type: () -> Any
-        where = "  in \"%s\", line %d, column %d"   \
-                % (self.name, self.line + 1, self.column + 1)
+        where = '  in "%s", line %d, column %d' % (self.name, self.line + 1, self.column + 1)
         return where
 
 
@@ -40,7 +45,7 @@ class FileMark(StreamMark):
 
 
 class StringMark(StreamMark):
-    __slots__ = 'name', 'index', 'line', 'column', 'buffer', 'pointer',
+    __slots__ = 'name', 'index', 'line', 'column', 'buffer', 'pointer'
 
     def __init__(self, name, index, line, column, buffer, pointer):
         # type: (Any, int, int, int, Any, Any) -> None
@@ -52,19 +57,17 @@ class StringMark(StreamMark):
         # type: (int, int) -> Any
         if self.buffer is None:  # always False
             return None
-        head = ''
+        head = ""
         start = self.pointer
-        while (start > 0 and
-               self.buffer[start - 1] not in u'\0\r\n\x85\u2028\u2029'):
+        while start > 0 and self.buffer[start - 1] not in u'\0\r\n\x85\u2028\u2029':
             start -= 1
             if self.pointer - start > max_length / 2 - 1:
                 head = ' ... '
                 start += 5
                 break
-        tail = ''
+        tail = ""
         end = self.pointer
-        while (end < len(self.buffer) and
-               self.buffer[end] not in u'\0\r\n\x85\u2028\u2029'):
+        while end < len(self.buffer) and self.buffer[end] not in u'\0\r\n\x85\u2028\u2029':
             end += 1
             if end - self.pointer > max_length / 2 - 1:
                 tail = ' ... '
@@ -73,21 +76,27 @@ class StringMark(StreamMark):
         snippet = utf8(self.buffer[start:end])
         caret = '^'
         caret = '^ (line: {})'.format(self.line + 1)
-        return ' ' * indent + head + snippet + tail + '\n' \
-               + ' ' * (indent + self.pointer - start + len(head)) + caret
+        return (
+            ' ' * indent
+            + head
+            + snippet
+            + tail
+            + '\n'
+            + ' ' * (indent + self.pointer - start + len(head))
+            + caret
+        )
 
     def __str__(self):
         # type: () -> Any
         snippet = self.get_snippet()
-        where = "  in \"%s\", line %d, column %d"   \
-                % (self.name, self.line + 1, self.column + 1)
+        where = '  in "%s", line %d, column %d' % (self.name, self.line + 1, self.column + 1)
         if snippet is not None:
-            where += ":\n" + snippet
+            where += ':\n' + snippet
         return where
 
 
 class CommentMark(object):
-    __slots__ = 'column',
+    __slots__ = ('column',)
 
     def __init__(self, column):
         # type: (Any) -> None
@@ -99,8 +108,15 @@ class YAMLError(Exception):
 
 
 class MarkedYAMLError(YAMLError):
-    def __init__(self, context=None, context_mark=None,
-                 problem=None, problem_mark=None, note=None, warn=None):
+    def __init__(
+        self,
+        context=None,
+        context_mark=None,
+        problem=None,
+        problem_mark=None,
+        note=None,
+        warn=None,
+    ):
         # type: (Any, Any, Any, Any, Any, Any) -> None
         self.context = context
         self.context_mark = context_mark
@@ -114,18 +130,20 @@ class MarkedYAMLError(YAMLError):
         lines = []  # type: List[str]
         if self.context is not None:
             lines.append(self.context)
-        if self.context_mark is not None  \
-           and (self.problem is None or self.problem_mark is None or
-                self.context_mark.name != self.problem_mark.name or
-                self.context_mark.line != self.problem_mark.line or
-                self.context_mark.column != self.problem_mark.column):
+        if self.context_mark is not None and (
+            self.problem is None
+            or self.problem_mark is None
+            or self.context_mark.name != self.problem_mark.name
+            or self.context_mark.line != self.problem_mark.line
+            or self.context_mark.column != self.problem_mark.column
+        ):
             lines.append(str(self.context_mark))
         if self.problem is not None:
             lines.append(self.problem)
         if self.problem_mark is not None:
             lines.append(str(self.problem_mark))
         if self.note is not None and self.note:
-            note = textwrap.dedent(self.note)  # type: ignore
+            note = textwrap.dedent(self.note)
             lines.append(note)
         return '\n'.join(lines)
 
@@ -139,8 +157,15 @@ class YAMLWarning(Warning):
 
 
 class MarkedYAMLWarning(YAMLWarning):
-    def __init__(self, context=None, context_mark=None,
-                 problem=None, problem_mark=None, note=None, warn=None):
+    def __init__(
+        self,
+        context=None,
+        context_mark=None,
+        problem=None,
+        problem_mark=None,
+        note=None,
+        warn=None,
+    ):
         # type: (Any, Any, Any, Any, Any, Any) -> None
         self.context = context
         self.context_mark = context_mark
@@ -154,21 +179,23 @@ class MarkedYAMLWarning(YAMLWarning):
         lines = []  # type: List[str]
         if self.context is not None:
             lines.append(self.context)
-        if self.context_mark is not None  \
-           and (self.problem is None or self.problem_mark is None or
-                self.context_mark.name != self.problem_mark.name or
-                self.context_mark.line != self.problem_mark.line or
-                self.context_mark.column != self.problem_mark.column):
+        if self.context_mark is not None and (
+            self.problem is None
+            or self.problem_mark is None
+            or self.context_mark.name != self.problem_mark.name
+            or self.context_mark.line != self.problem_mark.line
+            or self.context_mark.column != self.problem_mark.column
+        ):
             lines.append(str(self.context_mark))
         if self.problem is not None:
             lines.append(self.problem)
         if self.problem_mark is not None:
             lines.append(str(self.problem_mark))
         if self.note is not None and self.note:
-            note = textwrap.dedent(self.note)  # type: ignore
+            note = textwrap.dedent(self.note)
             lines.append(note)
         if self.warn is not None and self.warn:
-            warn = textwrap.dedent(self.warn)  # type: ignore
+            warn = textwrap.dedent(self.warn)
             lines.append(warn)
         return '\n'.join(lines)
 
@@ -215,7 +242,9 @@ or alternatively include the following in your code:
   import warnings
   warnings.simplefilter('ignore', ruamel.yaml.error.MantissaNoDotYAML1_1Warning)
 
-""".format(self.flt, line, col)
+""".format(
+            self.flt, line, col
+        )
 
 
 warnings.simplefilter('once', MantissaNoDotYAML1_1Warning)
@@ -226,8 +255,15 @@ class YAMLFutureWarning(Warning):
 
 
 class MarkedYAMLFutureWarning(YAMLFutureWarning):
-    def __init__(self, context=None, context_mark=None,
-                 problem=None, problem_mark=None, note=None, warn=None):
+    def __init__(
+        self,
+        context=None,
+        context_mark=None,
+        problem=None,
+        problem_mark=None,
+        note=None,
+        warn=None,
+    ):
         # type: (Any, Any, Any, Any, Any, Any) -> None
         self.context = context
         self.context_mark = context_mark
@@ -242,20 +278,22 @@ class MarkedYAMLFutureWarning(YAMLFutureWarning):
         if self.context is not None:
             lines.append(self.context)
 
-        if self.context_mark is not None  \
-           and (self.problem is None or self.problem_mark is None or
-                self.context_mark.name != self.problem_mark.name or
-                self.context_mark.line != self.problem_mark.line or
-                self.context_mark.column != self.problem_mark.column):
+        if self.context_mark is not None and (
+            self.problem is None
+            or self.problem_mark is None
+            or self.context_mark.name != self.problem_mark.name
+            or self.context_mark.line != self.problem_mark.line
+            or self.context_mark.column != self.problem_mark.column
+        ):
             lines.append(str(self.context_mark))
         if self.problem is not None:
             lines.append(self.problem)
         if self.problem_mark is not None:
             lines.append(str(self.problem_mark))
         if self.note is not None and self.note:
-            note = textwrap.dedent(self.note)  # type: ignore
+            note = textwrap.dedent(self.note)
             lines.append(note)
         if self.warn is not None and self.warn:
-            warn = textwrap.dedent(self.warn)  # type: ignore
+            warn = textwrap.dedent(self.warn)
             lines.append(warn)
         return '\n'.join(lines)
diff --git a/events.py b/events.py
index 515274a..672042d 100644
--- a/events.py
+++ b/events.py
@@ -12,7 +12,7 @@ def CommentCheck():
 
 
 class Event(object):
-    __slots__ = 'start_mark', 'end_mark', 'comment',
+    __slots__ = 'start_mark', 'end_mark', 'comment'
 
     def __init__(self, start_mark=None, end_mark=None, comment=CommentCheck):
         # type: (Any, Any, Any) -> None
@@ -25,18 +25,19 @@ class Event(object):
 
     def __repr__(self):
         # type: () -> Any
-        attributes = [key for key in ['anchor', 'tag', 'implicit', 'value',
-                                      'flow_style', 'style']
-                      if hasattr(self, key)]
-        arguments = ', '.join(['%s=%r' % (key, getattr(self, key))
-                               for key in attributes])
+        attributes = [
+            key
+            for key in ['anchor', 'tag', 'implicit', 'value', 'flow_style', 'style']
+            if hasattr(self, key)
+        ]
+        arguments = ', '.join(['%s=%r' % (key, getattr(self, key)) for key in attributes])
         if self.comment not in [None, CommentCheck]:
             arguments += ', comment={!r}'.format(self.comment)
         return '%s(%s)' % (self.__class__.__name__, arguments)
 
 
 class NodeEvent(Event):
-    __slots__ = 'anchor',
+    __slots__ = ('anchor',)
 
     def __init__(self, anchor, start_mark=None, end_mark=None, comment=None):
         # type: (Any, Any, Any, Any) -> None
@@ -45,10 +46,18 @@ class NodeEvent(Event):
 
 
 class CollectionStartEvent(NodeEvent):
-    __slots__ = 'tag', 'implicit', 'flow_style',
-
-    def __init__(self, anchor, tag, implicit, start_mark=None, end_mark=None,
-                 flow_style=None, comment=None):
+    __slots__ = 'tag', 'implicit', 'flow_style'
+
+    def __init__(
+        self,
+        anchor,
+        tag,
+        implicit,
+        start_mark=None,
+        end_mark=None,
+        flow_style=None,
+        comment=None,
+    ):
         # type: (Any, Any, Any, Any, Any, Any, Any) -> None
         NodeEvent.__init__(self, anchor, start_mark, end_mark, comment)
         self.tag = tag
@@ -62,11 +71,11 @@ class CollectionEndEvent(Event):
 
 # Implementations.
 
+
 class StreamStartEvent(Event):
-    __slots__ = 'encoding',
+    __slots__ = ('encoding',)
 
-    def __init__(self, start_mark=None, end_mark=None, encoding=None,
-                 comment=None):
+    def __init__(self, start_mark=None, end_mark=None, encoding=None, comment=None):
         # type: (Any, Any, Any, Any) -> None
         Event.__init__(self, start_mark, end_mark, comment)
         self.encoding = encoding
@@ -77,10 +86,17 @@ class StreamEndEvent(Event):
 
 
 class DocumentStartEvent(Event):
-    __slots__ = 'explicit', 'version', 'tags',
-
-    def __init__(self, start_mark=None, end_mark=None,
-                 explicit=None, version=None, tags=None, comment=None):
+    __slots__ = 'explicit', 'version', 'tags'
+
+    def __init__(
+        self,
+        start_mark=None,
+        end_mark=None,
+        explicit=None,
+        version=None,
+        tags=None,
+        comment=None,
+    ):
         # type: (Any, Any, Any, Any, Any, Any) -> None
         Event.__init__(self, start_mark, end_mark, comment)
         self.explicit = explicit
@@ -89,10 +105,9 @@ class DocumentStartEvent(Event):
 
 
 class DocumentEndEvent(Event):
-    __slots__ = 'explicit',
+    __slots__ = ('explicit',)
 
-    def __init__(self, start_mark=None, end_mark=None,
-                 explicit=None, comment=None):
+    def __init__(self, start_mark=None, end_mark=None, explicit=None, comment=None):
         # type: (Any, Any, Any, Any) -> None
         Event.__init__(self, start_mark, end_mark, comment)
         self.explicit = explicit
@@ -103,10 +118,19 @@ class AliasEvent(NodeEvent):
 
 
 class ScalarEvent(NodeEvent):
-    __slots__ = 'tag', 'implicit', 'value', 'style',
-
-    def __init__(self, anchor, tag, implicit, value,
-                 start_mark=None, end_mark=None, style=None, comment=None):
+    __slots__ = 'tag', 'implicit', 'value', 'style'
+
+    def __init__(
+        self,
+        anchor,
+        tag,
+        implicit,
+        value,
+        start_mark=None,
+        end_mark=None,
+        style=None,
+        comment=None,
+    ):
         # type: (Any, Any, Any, Any, Any, Any, Any, Any) -> None
         NodeEvent.__init__(self, anchor, start_mark, end_mark, comment)
         self.tag = tag
diff --git a/loader.py b/loader.py
index 725c326..d8cbe31 100644
--- a/loader.py
+++ b/loader.py
@@ -7,12 +7,16 @@ from ruamel.yaml.reader import Reader
 from ruamel.yaml.scanner import Scanner, RoundTripScanner
 from ruamel.yaml.parser import Parser, RoundTripParser
 from ruamel.yaml.composer import Composer
-from ruamel.yaml.constructor import BaseConstructor, SafeConstructor, Constructor, \
-    RoundTripConstructor
+from ruamel.yaml.constructor import (
+    BaseConstructor,
+    SafeConstructor,
+    Constructor,
+    RoundTripConstructor,
+)
 from ruamel.yaml.resolver import VersionedResolver
 
 if False:  # MYPY
-    from typing import Any, Dict, List                          # NOQA
+    from typing import Any, Dict, List, Union  # NOQA
     from ruamel.yaml.compat import StreamTextType, VersionType  # NOQA
 
 __all__ = ['BaseLoader', 'SafeLoader', 'Loader', 'RoundTripLoader']
@@ -20,7 +24,7 @@ __all__ = ['BaseLoader', 'SafeLoader', 'Loader', 'RoundTripLoader']
 
 class BaseLoader(Reader, Scanner, Parser, Composer, BaseConstructor, VersionedResolver):
     def __init__(self, stream, version=None, preserve_quotes=None):
-        # type: (StreamTextType, VersionType, bool) -> None
+        # type: (StreamTextType, Union[None, VersionType], Union[None, bool]) -> None
         Reader.__init__(self, stream, loader=self)
         Scanner.__init__(self, loader=self)
         Parser.__init__(self, loader=self)
@@ -31,7 +35,7 @@ class BaseLoader(Reader, Scanner, Parser, Composer, BaseConstructor, VersionedRe
 
 class SafeLoader(Reader, Scanner, Parser, Composer, SafeConstructor, VersionedResolver):
     def __init__(self, stream, version=None, preserve_quotes=None):
-        # type: (StreamTextType, VersionType, bool) -> None
+        # type: (StreamTextType, Union[None, VersionType], Union[None, bool]) -> None
         Reader.__init__(self, stream, loader=self)
         Scanner.__init__(self, loader=self)
         Parser.__init__(self, loader=self)
@@ -42,7 +46,7 @@ class SafeLoader(Reader, Scanner, Parser, Composer, SafeConstructor, VersionedRe
 
 class Loader(Reader, Scanner, Parser, Composer, Constructor, VersionedResolver):
     def __init__(self, stream, version=None, preserve_quotes=None):
-        # type: (StreamTextType, VersionType, bool) -> None
+        # type: (StreamTextType, Union[None, VersionType], Union[None, bool]) -> None
         Reader.__init__(self, stream, loader=self)
         Scanner.__init__(self, loader=self)
         Parser.__init__(self, loader=self)
@@ -51,10 +55,16 @@ class Loader(Reader, Scanner, Parser, Composer, Constructor, VersionedResolver):
         VersionedResolver.__init__(self, version, loader=self)
 
 
-class RoundTripLoader(Reader, RoundTripScanner, RoundTripParser, Composer,
-                      RoundTripConstructor, VersionedResolver):
+class RoundTripLoader(
+    Reader,
+    RoundTripScanner,
+    RoundTripParser,
+    Composer,
+    RoundTripConstructor,
+    VersionedResolver,
+):
     def __init__(self, stream, version=None, preserve_quotes=None):
-        # type: (StreamTextType, VersionType, bool) -> None
+        # type: (StreamTextType, Union[None, VersionType], Union[None, bool]) -> None
         # self.reader = Reader.__init__(self, stream)
         Reader.__init__(self, stream, loader=self)
         RoundTripScanner.__init__(self, loader=self)
diff --git a/main.py b/main.py
index b2bd808..93c89ca 100644
--- a/main.py
+++ b/main.py
@@ -10,28 +10,36 @@ from importlib import import_module
 
 
 import ruamel.yaml
-from ruamel.yaml.error import *                                # NOQA
+from ruamel.yaml.error import UnsafeLoaderWarning, YAMLError  # NOQA
 
-from ruamel.yaml.tokens import *                               # NOQA
-from ruamel.yaml.events import *                               # NOQA
-from ruamel.yaml.nodes import *                                # NOQA
+from ruamel.yaml.tokens import *  # NOQA
+from ruamel.yaml.events import *  # NOQA
+from ruamel.yaml.nodes import *  # NOQA
 
 from ruamel.yaml.loader import BaseLoader, SafeLoader, Loader, RoundTripLoader  # NOQA
 from ruamel.yaml.dumper import BaseDumper, SafeDumper, Dumper, RoundTripDumper  # NOQA
 from ruamel.yaml.compat import StringIO, BytesIO, with_metaclass, PY3
 from ruamel.yaml.resolver import VersionedResolver, Resolver  # NOQA
-from ruamel.yaml.representer import (BaseRepresenter, SafeRepresenter, Representer,
-                                     RoundTripRepresenter)
-from ruamel.yaml.constructor import (BaseConstructor, SafeConstructor, Constructor,
-                                     RoundTripConstructor)
+from ruamel.yaml.representer import (
+    BaseRepresenter,
+    SafeRepresenter,
+    Representer,
+    RoundTripRepresenter,
+)
+from ruamel.yaml.constructor import (
+    BaseConstructor,
+    SafeConstructor,
+    Constructor,
+    RoundTripConstructor,
+)
 from ruamel.yaml.loader import Loader as UnsafeLoader
 
 if False:  # MYPY
-    from typing import List, Set, Dict, Union, Any                          # NOQA
+    from typing import List, Set, Dict, Union, Any  # NOQA
     from ruamel.yaml.compat import StreamType, StreamTextType, VersionType  # NOQA
 
 try:
-    from _ruamel_yaml import CParser, CEmitter   # type: ignore
+    from _ruamel_yaml import CParser, CEmitter  # type: ignore
 except:  # NOQA
     CParser = CEmitter = None
 
@@ -43,6 +51,7 @@ enforce = object()
 # YAML is an acronym, i.e. spoken: rhymes with "camel". And thus a
 # subset of abbreviations, which should be all caps according to PEP8
 
+
 class YAML(object):
     def __init__(self, _kw=enforce, typ=None, pure=False, plug_ins=None):
         # type: (Any, Any, Any, Any) -> None
@@ -56,8 +65,10 @@ class YAML(object):
         plug_ins: a list of plug-in files
         """
         if _kw is not enforce:
-            raise TypeError("{}.__init__() takes no positional argument but at least "
-                            "one was given ({!r})".format(self.__class__.__name__, _kw))
+            raise TypeError(
+                '{}.__init__() takes no positional argument but at least '
+                'one was given ({!r})'.format(self.__class__.__name__, _kw)
+            )
 
         self.typ = 'rt' if typ is None else typ
         self.pure = pure
@@ -65,26 +76,27 @@ class YAML(object):
         for pu in ([] if plug_ins is None else plug_ins) + self.official_plug_ins():
             file_name = pu.replace(os.sep, '.')
             self.plug_ins.append(import_module(file_name))
-        self.Resolver = ruamel.yaml.resolver.VersionedResolver               # type: Any
+        self.Resolver = ruamel.yaml.resolver.VersionedResolver  # type: Any
         self.allow_unicode = True
-        self.Reader = None       # type: Any
-        self.Scanner = None      # type: Any
-        self.Serializer = None   # type: Any
+        self.Reader = None  # type: Any
+        self.Scanner = None  # type: Any
+        self.Serializer = None  # type: Any
         self.default_flow_style = None  # type: Any
         if self.typ == 'rt':
             self.default_flow_style = False
             # no optimized rt-dumper yet
-            self.Emitter = ruamel.yaml.emitter.Emitter                       # type: Any
-            self.Serializer = ruamel.yaml.serializer.Serializer              # type: Any
+            self.Emitter = ruamel.yaml.emitter.Emitter  # type: Any
+            self.Serializer = ruamel.yaml.serializer.Serializer  # type: Any
             self.Representer = ruamel.yaml.representer.RoundTripRepresenter  # type: Any
-            self.Scanner = ruamel.yaml.scanner.RoundTripScanner              # type: Any
+            self.Scanner = ruamel.yaml.scanner.RoundTripScanner  # type: Any
             # no optimized rt-parser yet
-            self.Parser = ruamel.yaml.parser.RoundTripParser                 # type: Any
-            self.Composer = ruamel.yaml.composer.Composer                    # type: Any
+            self.Parser = ruamel.yaml.parser.RoundTripParser  # type: Any
+            self.Composer = ruamel.yaml.composer.Composer  # type: Any
             self.Constructor = ruamel.yaml.constructor.RoundTripConstructor  # type: Any
         elif self.typ == 'safe':
-            self.Emitter = ruamel.yaml.emitter.Emitter if pure or CEmitter is None \
-                else CEmitter
+            self.Emitter = (
+                ruamel.yaml.emitter.Emitter if pure or CEmitter is None else CEmitter
+            )
             self.Representer = ruamel.yaml.representer.SafeRepresenter
             self.Parser = ruamel.yaml.parser.Parser if pure or CParser is None else CParser
             self.Composer = ruamel.yaml.composer.Composer
@@ -96,8 +108,9 @@ class YAML(object):
             self.Composer = ruamel.yaml.composer.Composer
             self.Constructor = ruamel.yaml.constructor.BaseConstructor
         elif self.typ == 'unsafe':
-            self.Emitter = ruamel.yaml.emitter.Emitter if pure or CEmitter is None \
-                else CEmitter
+            self.Emitter = (
+                ruamel.yaml.emitter.Emitter if pure or CEmitter is None else CEmitter
+            )
             self.Representer = ruamel.yaml.representer.Representer
             self.Parser = ruamel.yaml.parser.Parser if pure or CParser is None else CParser
             self.Composer = ruamel.yaml.composer.Composer
@@ -109,7 +122,8 @@ class YAML(object):
                     break
             else:
                 raise NotImplementedError(
-                    'typ "{}"not recognised (need to install plug-in?)'.format(self.typ))
+                    'typ "{}"not recognised (need to install plug-in?)'.format(self.typ)
+                )
         self.stream = None
         self.canonical = None
         self.old_indent = None
@@ -193,8 +207,7 @@ class YAML(object):
         # type: () -> Any
         attr = '_' + sys._getframe().f_code.co_name
         if not hasattr(self, attr):
-            setattr(self, attr, self.Resolver(
-                version=self.version, loader=self))
+            setattr(self, attr, self.Resolver(version=self.version, loader=self))
         return getattr(self, attr)
 
     @property
@@ -204,11 +217,15 @@ class YAML(object):
         if not hasattr(self, attr):
             if self.Emitter is not CEmitter:
                 _emitter = self.Emitter(
-                    None, canonical=self.canonical,
-                    indent=self.old_indent, width=self.width,
-                    allow_unicode=self.allow_unicode, line_break=self.line_break,
+                    None,
+                    canonical=self.canonical,
+                    indent=self.old_indent,
+                    width=self.width,
+                    allow_unicode=self.allow_unicode,
+                    line_break=self.line_break,
                     prefix_colon=self.prefix_colon,
-                    dumper=self)
+                    dumper=self,
+                )
                 setattr(self, attr, _emitter)
                 if self.map_indent is not None:
                     _emitter.best_map_indent = self.map_indent
@@ -229,10 +246,18 @@ class YAML(object):
         # type: () -> Any
         attr = '_' + sys._getframe().f_code.co_name
         if not hasattr(self, attr):
-            setattr(self, attr, self.Serializer(
-                encoding=self.encoding,
-                explicit_start=self.explicit_start, explicit_end=self.explicit_end,
-                version=self.version, tags=self.tags, dumper=self))
+            setattr(
+                self,
+                attr,
+                self.Serializer(
+                    encoding=self.encoding,
+                    explicit_start=self.explicit_start,
+                    explicit_end=self.explicit_end,
+                    version=self.version,
+                    tags=self.tags,
+                    dumper=self,
+                ),
+            )
         return getattr(self, attr)
 
     @property
@@ -240,10 +265,15 @@ class YAML(object):
         # type: () -> Any
         attr = '_' + sys._getframe().f_code.co_name
         if not hasattr(self, attr):
-            setattr(self, attr, self.Representer(
-                default_style=self.default_style,
-                default_flow_style=self.default_flow_style,
-                dumper=self))
+            setattr(
+                self,
+                attr,
+                self.Representer(
+                    default_style=self.default_style,
+                    default_flow_style=self.default_flow_style,
+                    dumper=self,
+                ),
+            )
         return getattr(self, attr)
 
     # separate output resolver?
@@ -278,8 +308,10 @@ class YAML(object):
     def load_all(self, stream, _kw=enforce):  # , skip=None):
         # type: (StreamTextType, Any) -> Any
         if _kw is not enforce:
-            raise TypeError("{}.__init__() takes no positional argument but at least "
-                            "one was given ({!r})".format(self.__class__.__name__, _kw))
+            raise TypeError(
+                '{}.__init__() takes no positional argument but at least '
+                'one was given ({!r})'.format(self.__class__.__name__, _kw)
+            )
         if not hasattr(stream, 'read') and hasattr(stream, 'open'):
             # pathlib.Path() instance
             with stream.open('r') as fp:  # type: ignore
@@ -338,12 +370,13 @@ class YAML(object):
 
                 class XLoader(self.Parser, self.Constructor, rslvr):  # type: ignore
                     def __init__(selfx, stream, version=None, preserve_quotes=None):
-                        # type: (StreamTextType, VersionType, bool) -> None
+                        # type: (StreamTextType, Union[None, VersionType], Union[None, bool]) -> None  # NOQA
                         CParser.__init__(selfx, stream)
                         selfx._parser = selfx._composer = selfx
                         self.Constructor.__init__(selfx, loader=selfx)
                         selfx.allow_duplicate_keys = self.allow_duplicate_keys
                         rslvr.__init__(selfx, loadumper=selfx)
+
                 self._stream = stream
                 loader = XLoader(stream)
                 return loader, loader
@@ -360,11 +393,13 @@ class YAML(object):
         """
         if not hasattr(stream, 'write') and hasattr(stream, 'open'):
             # pathlib.Path() instance
-            with stream.open('w') as fp:   # type: ignore
+            with stream.open('w') as fp:  # type: ignore
                 return self.dump_all(documents, fp, _kw, transform=transform)
         if _kw is not enforce:
-            raise TypeError("{}.dump(_all) takes two positional argument but at least "
-                            "three were given ({!r})".format(self.__class__.__name__, _kw))
+            raise TypeError(
+                '{}.dump(_all) takes two positional argument but at least '
+                'three were given ({!r})'.format(self.__class__.__name__, _kw)
+            )
         # The stream should have the methods `write` and possibly `flush`.
         if self.top_level_colon_align is True:
             tlca = max([len(str(x)) for x in documents[0]])  # type: Any
@@ -376,8 +411,9 @@ class YAML(object):
                 stream = StringIO()
             else:
                 stream = BytesIO()
-        serializer, representer, emitter = \
-            self.get_serializer_representer_emitter(stream, tlca)
+        serializer, representer, emitter = self.get_serializer_representer_emitter(
+            stream, tlca
+        )
         try:
             self.serializer.open()
             for data in documents:
@@ -393,8 +429,8 @@ class YAML(object):
             except AttributeError:
                 raise
                 # self.dumper.dispose()  # cyaml
-            delattr(self, "_serializer")
-            delattr(self, "_emitter")
+            delattr(self, '_serializer')
+            delattr(self, '_emitter')
         if transform:
             val = stream.getvalue()  # type: ignore
             if self.encoding:
@@ -422,36 +458,68 @@ class YAML(object):
             return self.serializer, self.representer, self.emitter
         # C routines
 
-        rslvr = ruamel.yaml.resolver.BaseResolver if self.typ == 'base' \
+        rslvr = (
+            ruamel.yaml.resolver.BaseResolver
+            if self.typ == 'base'
             else ruamel.yaml.resolver.Resolver
+        )
 
         class XDumper(CEmitter, self.Representer, rslvr):  # type: ignore
-            def __init__(selfx, stream,
-                         default_style=None, default_flow_style=None,
-                         canonical=None, indent=None, width=None,
-                         allow_unicode=None, line_break=None,
-                         encoding=None, explicit_start=None, explicit_end=None,
-                         version=None, tags=None, block_seq_indent=None,
-                         top_level_colon_align=None, prefix_colon=None):
-                # type: (StreamType, Any, Any, Any, bool, Union[None, int], Union[None, int], bool, Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> None   # NOQA
-                CEmitter.__init__(selfx, stream, canonical=canonical,
-                                  indent=indent, width=width, encoding=encoding,
-                                  allow_unicode=allow_unicode, line_break=line_break,
-                                  explicit_start=explicit_start,
-                                  explicit_end=explicit_end,
-                                  version=version, tags=tags)
+            def __init__(
+                selfx,
+                stream,
+                default_style=None,
+                default_flow_style=None,
+                canonical=None,
+                indent=None,
+                width=None,
+                allow_unicode=None,
+                line_break=None,
+                encoding=None,
+                explicit_start=None,
+                explicit_end=None,
+                version=None,
+                tags=None,
+                block_seq_indent=None,
+                top_level_colon_align=None,
+                prefix_colon=None,
+            ):
+                # type: (StreamType, Any, Any, Any, Union[None, bool], Union[None, int], Union[None, int], Union[None, bool], Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> None   # NOQA
+                CEmitter.__init__(
+                    selfx,
+                    stream,
+                    canonical=canonical,
+                    indent=indent,
+                    width=width,
+                    encoding=encoding,
+                    allow_unicode=allow_unicode,
+                    line_break=line_break,
+                    explicit_start=explicit_start,
+                    explicit_end=explicit_end,
+                    version=version,
+                    tags=tags,
+                )
                 selfx._emitter = selfx._serializer = selfx._representer = selfx
-                self.Representer.__init__(selfx, default_style=default_style,
-                                          default_flow_style=default_flow_style)
+                self.Representer.__init__(
+                    selfx, default_style=default_style, default_flow_style=default_flow_style
+                )
                 rslvr.__init__(selfx)
+
         self._stream = stream
-        dumper = XDumper(stream, default_style=self.default_style,
-                         default_flow_style=self.default_flow_style,
-                         canonical=self.canonical, indent=self.old_indent, width=self.width,
-                         allow_unicode=self.allow_unicode, line_break=self.line_break,
-                         explicit_start=self.explicit_start,
-                         explicit_end=self.explicit_end,
-                         version=self.version, tags=self.tags)
+        dumper = XDumper(
+            stream,
+            default_style=self.default_style,
+            default_flow_style=self.default_flow_style,
+            canonical=self.canonical,
+            indent=self.old_indent,
+            width=self.width,
+            allow_unicode=self.allow_unicode,
+            line_break=self.line_break,
+            explicit_start=self.explicit_start,
+            explicit_end=self.explicit_end,
+            version=self.version,
+            tags=self.tags,
+        )
         self._emitter = self._serializer = dumper
         return dumper, dumper, dumper
 
@@ -460,6 +528,7 @@ class YAML(object):
         # type: (Any) -> Any
         if self.typ == 'rt':
             from ruamel.yaml.comments import CommentedMap
+
             return CommentedMap(**kw)
         else:
             return dict(**kw)
@@ -468,6 +537,7 @@ class YAML(object):
         # type: (Any) -> Any
         if self.typ == 'rt':
             from ruamel.yaml.comments import CommentedSeq
+
             return CommentedSeq(*args)
         else:
             return list(*args)
@@ -477,7 +547,7 @@ class YAML(object):
         # type: () -> Any
         bd = os.path.dirname(__file__)
         gpbd = os.path.dirname(os.path.dirname(bd))
-        res = [x.replace(gpbd, '')[1:-3] for x in glob.glob(bd + '/*/__plug_in__.py')]
+        res = [x.replace(gpbd, "")[1:-3] for x in glob.glob(bd + '/*/__plug_in__.py')]
         return res
 
     def register_class(self, cls):
@@ -492,15 +562,18 @@ class YAML(object):
         try:
             self.representer.add_representer(cls, cls.to_yaml)
         except AttributeError:
+
             def t_y(representer, data):
                 # type: (Any, Any) -> Any
                 return representer.represent_yaml_object(
-                    tag, data, cls, flow_style=representer.default_flow_style)
+                    tag, data, cls, flow_style=representer.default_flow_style
+                )
 
             self.representer.add_representer(cls, t_y)
         try:
             self.constructor.add_constructor(tag, cls.from_yaml)
         except AttributeError:
+
             def f_y(constructor, node):
                 # type: (Any, Any) -> Any
                 return constructor.construct_yaml_object(node, cls)
@@ -547,29 +620,35 @@ def yaml_object(yml):
     If methods to_yaml and/or from_yaml are available, these are called for dumping resp.
     loading, default routines (dumping a mapping of the attributes) used otherwise.
     """
+
     def yo_deco(cls):
         # type: (Any) -> Any
         tag = getattr(cls, 'yaml_tag', '!' + cls.__name__)
         try:
             yml.representer.add_representer(cls, cls.to_yaml)
         except AttributeError:
+
             def t_y(representer, data):
                 # type: (Any, Any) -> Any
                 return representer.represent_yaml_object(
-                    tag, data, cls, flow_style=representer.default_flow_style)
+                    tag, data, cls, flow_style=representer.default_flow_style
+                )
 
             yml.representer.add_representer(cls, t_y)
         try:
             yml.constructor.add_constructor(tag, cls.from_yaml)
         except AttributeError:
+
             def f_y(constructor, node):
                 # type: (Any, Any) -> Any
                 return constructor.construct_yaml_object(node, cls)
 
             yml.constructor.add_constructor(tag, f_y)
         return cls
+
     return yo_deco
 
+
 ########################################################################################
 
 
@@ -627,7 +706,7 @@ def compose_all(stream, Loader=Loader):
 
 
 def load(stream, Loader=None, version=None, preserve_quotes=None):
-    # type: (StreamTextType, Any, VersionType, Any) -> Any
+    # type: (StreamTextType, Any, Union[None, VersionType], Any) -> Any
     """
     Parse the first YAML document in a stream
     and produce the corresponding Python object.
@@ -637,13 +716,13 @@ def load(stream, Loader=None, version=None, preserve_quotes=None):
         Loader = UnsafeLoader
     loader = Loader(stream, version, preserve_quotes=preserve_quotes)
     try:
-        return loader._constructor.get_single_data()  # type: ignore
+        return loader._constructor.get_single_data()
     finally:
-        loader._parser.dispose()  # type: ignore
+        loader._parser.dispose()
 
 
 def load_all(stream, Loader=None, version=None, preserve_quotes=None):
-    # type: (StreamTextType, Any, VersionType, bool) -> Any
+    # type: (Union[None, StreamTextType], Any, Union[None, VersionType], Union[None, bool]) -> Any  # NOQA
     """
     Parse all YAML documents in a stream
     and produce corresponding Python objects.
@@ -653,14 +732,14 @@ def load_all(stream, Loader=None, version=None, preserve_quotes=None):
         Loader = UnsafeLoader
     loader = Loader(stream, version, preserve_quotes=preserve_quotes)
     try:
-        while loader._constructor.check_data():  # type: ignore
-            yield loader._constructor.get_data()  # type: ignore
+        while loader._constructor.check_data():
+            yield loader._constructor.get_data()
     finally:
-        loader._parser.dispose()  # type: ignore
+        loader._parser.dispose()
 
 
 def safe_load(stream, version=None):
-    # type: (StreamTextType, VersionType) -> Any
+    # type: (StreamTextType, Union[None, VersionType]) -> Any
     """
     Parse the first YAML document in a stream
     and produce the corresponding Python object.
@@ -670,7 +749,7 @@ def safe_load(stream, version=None):
 
 
 def safe_load_all(stream, version=None):
-    # type: (StreamTextType, VersionType) -> Any
+    # type: (StreamTextType, Union[None, VersionType]) -> Any
     """
     Parse all YAML documents in a stream
     and produce corresponding Python objects.
@@ -680,7 +759,7 @@ def safe_load_all(stream, version=None):
 
 
 def round_trip_load(stream, version=None, preserve_quotes=None):
-    # type: (StreamTextType, VersionType, bool) -> Any
+    # type: (StreamTextType, Union[None, VersionType], Union[None, bool]) -> Any
     """
     Parse the first YAML document in a stream
     and produce the corresponding Python object.
@@ -690,7 +769,7 @@ def round_trip_load(stream, version=None, preserve_quotes=None):
 
 
 def round_trip_load_all(stream, version=None, preserve_quotes=None):
-    # type: (StreamTextType, VersionType, bool) -> Any
+    # type: (StreamTextType, Union[None, VersionType], Union[None, bool]) -> Any
     """
     Parse all YAML documents in a stream
     and produce corresponding Python objects.
@@ -699,10 +778,17 @@ def round_trip_load_all(stream, version=None, preserve_quotes=None):
     return load_all(stream, RoundTripLoader, version, preserve_quotes=preserve_quotes)
 
 
-def emit(events, stream=None, Dumper=Dumper,
-         canonical=None, indent=None, width=None,
-         allow_unicode=None, line_break=None):
-    # type: (Any, StreamType, Any, bool, Union[int, None], int, bool, Any) -> Any
+def emit(
+    events,
+    stream=None,
+    Dumper=Dumper,
+    canonical=None,
+    indent=None,
+    width=None,
+    allow_unicode=None,
+    line_break=None,
+):
+    # type: (Any, Union[None, StreamType], Any, Union[None, bool], Union[int, None], Union[None, int], Union[None, bool], Any) -> Any  # NOQA
     """
     Emit YAML parsing events into a stream.
     If stream is None, return the produced string instead.
@@ -711,8 +797,14 @@ def emit(events, stream=None, Dumper=Dumper,
     if stream is None:
         stream = StringIO()
         getvalue = stream.getvalue
-    dumper = Dumper(stream, canonical=canonical, indent=indent, width=width,
-                    allow_unicode=allow_unicode, line_break=line_break)
+    dumper = Dumper(
+        stream,
+        canonical=canonical,
+        indent=indent,
+        width=width,
+        allow_unicode=allow_unicode,
+        line_break=line_break,
+    )
     try:
         for event in events:
             dumper.emit(event)
@@ -721,7 +813,7 @@ def emit(events, stream=None, Dumper=Dumper,
             dumper._emitter.dispose()
         except AttributeError:
             raise
-            dumper.dispose()   # cyaml
+            dumper.dispose()  # cyaml
     if getvalue is not None:
         return getvalue()
 
@@ -729,12 +821,22 @@ def emit(events, stream=None, Dumper=Dumper,
 enc = None if PY3 else 'utf-8'
 
 
-def serialize_all(nodes, stream=None, Dumper=Dumper,
-                  canonical=None, indent=None, width=None,
-                  allow_unicode=None, line_break=None,
-                  encoding=enc, explicit_start=None, explicit_end=None,
-                  version=None, tags=None):
-    # type: (Any, StreamType, Any, Any, Union[None, int], Union[None, int], bool, Any, Any, Union[None, bool], Union[None, bool], VersionType, Any) -> Any # NOQA
+def serialize_all(
+    nodes,
+    stream=None,
+    Dumper=Dumper,
+    canonical=None,
+    indent=None,
+    width=None,
+    allow_unicode=None,
+    line_break=None,
+    encoding=enc,
+    explicit_start=None,
+    explicit_end=None,
+    version=None,
+    tags=None,
+):
+    # type: (Any, Union[None, StreamType], Any, Any, Union[None, int], Union[None, int], Union[None, bool], Any, Any, Union[None, bool], Union[None, bool], Union[None, VersionType], Any) -> Any # NOQA
     """
     Serialize a sequence of representation trees into a YAML stream.
     If stream is None, return the produced string instead.
@@ -746,10 +848,19 @@ def serialize_all(nodes, stream=None, Dumper=Dumper,
         else:
             stream = BytesIO()
         getvalue = stream.getvalue
-    dumper = Dumper(stream, canonical=canonical, indent=indent, width=width,
-                    allow_unicode=allow_unicode, line_break=line_break,
-                    encoding=encoding, version=version, tags=tags,
-                    explicit_start=explicit_start, explicit_end=explicit_end)
+    dumper = Dumper(
+        stream,
+        canonical=canonical,
+        indent=indent,
+        width=width,
+        allow_unicode=allow_unicode,
+        line_break=line_break,
+        encoding=encoding,
+        version=version,
+        tags=tags,
+        explicit_start=explicit_start,
+        explicit_end=explicit_end,
+    )
     try:
         dumper._serializer.open()
         for node in nodes:
@@ -760,13 +871,13 @@ def serialize_all(nodes, stream=None, Dumper=Dumper,
             dumper._emitter.dispose()
         except AttributeError:
             raise
-            dumper.dispose()   # cyaml
+            dumper.dispose()  # cyaml
     if getvalue is not None:
         return getvalue()
 
 
 def serialize(node, stream=None, Dumper=Dumper, **kwds):
-    # type: (Any, StreamType, Any, Any) -> Any
+    # type: (Any, Union[None, StreamType], Any, Any) -> Any
     """
     Serialize a representation tree into a YAML stream.
     If stream is None, return the produced string instead.
@@ -774,14 +885,27 @@ def serialize(node, stream=None, Dumper=Dumper, **kwds):
     return serialize_all([node], stream, Dumper=Dumper, **kwds)
 
 
-def dump_all(documents, stream=None, Dumper=Dumper,
-             default_style=None, default_flow_style=None,
-             canonical=None, indent=None, width=None,
-             allow_unicode=None, line_break=None,
-             encoding=enc, explicit_start=None, explicit_end=None,
-             version=None, tags=None, block_seq_indent=None,
-             top_level_colon_align=None, prefix_colon=None):
-    # type: (Any, StreamType, Any, Any, Any, bool, Union[None, int], Union[None, int], bool, Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> Union[None, str]   # NOQA
+def dump_all(
+    documents,
+    stream=None,
+    Dumper=Dumper,
+    default_style=None,
+    default_flow_style=None,
+    canonical=None,
+    indent=None,
+    width=None,
+    allow_unicode=None,
+    line_break=None,
+    encoding=enc,
+    explicit_start=None,
+    explicit_end=None,
+    version=None,
+    tags=None,
+    block_seq_indent=None,
+    top_level_colon_align=None,
+    prefix_colon=None,
+):
+    # type: (Any, Union[None, StreamType], Any, Any, Any, Union[None, bool], Union[None, int], Union[None, int], Union[None, bool], Any, Any, Union[None, bool], Union[None, bool], Any, Any, Any, Any, Any) -> Union[None, str]   # NOQA
     """
     Serialize a sequence of Python objects into a YAML stream.
     If stream is None, return the produced string instead.
@@ -795,15 +919,24 @@ def dump_all(documents, stream=None, Dumper=Dumper,
         else:
             stream = BytesIO()
         getvalue = stream.getvalue
-    dumper = Dumper(stream, default_style=default_style,
-                    default_flow_style=default_flow_style,
-                    canonical=canonical, indent=indent, width=width,
-                    allow_unicode=allow_unicode, line_break=line_break,
-                    encoding=encoding, explicit_start=explicit_start,
-                    explicit_end=explicit_end, version=version,
-                    tags=tags, block_seq_indent=block_seq_indent,
-                    top_level_colon_align=top_level_colon_align, prefix_colon=prefix_colon,
-                    )
+    dumper = Dumper(
+        stream,
+        default_style=default_style,
+        default_flow_style=default_flow_style,
+        canonical=canonical,
+        indent=indent,
+        width=width,
+        allow_unicode=allow_unicode,
+        line_break=line_break,
+        encoding=encoding,
+        explicit_start=explicit_start,
+        explicit_end=explicit_end,
+        version=version,
+        tags=tags,
+        block_seq_indent=block_seq_indent,
+        top_level_colon_align=top_level_colon_align,
+        prefix_colon=prefix_colon,
+    )
     try:
         dumper._serializer.open()
         for data in documents:
@@ -824,13 +957,25 @@ def dump_all(documents, stream=None, Dumper=Dumper,
     return None
 
 
-def dump(data, stream=None, Dumper=Dumper,
-         default_style=None, default_flow_style=None,
-         canonical=None, indent=None, width=None,
-         allow_unicode=None, line_break=None,
-         encoding=enc, explicit_start=None, explicit_end=None,
-         version=None, tags=None, block_seq_indent=None):
-    # type: (Any, StreamType, Any, Any, Any, bool, Union[None, int], Union[None, int], bool, Any, Any, Union[None, bool], Union[None, bool], VersionType, Any, Any) -> Union[None, str]   # NOQA
+def dump(
+    data,
+    stream=None,
+    Dumper=Dumper,
+    default_style=None,
+    default_flow_style=None,
+    canonical=None,
+    indent=None,
+    width=None,
+    allow_unicode=None,
+    line_break=None,
+    encoding=enc,
+    explicit_start=None,
+    explicit_end=None,
+    version=None,
+    tags=None,
+    block_seq_indent=None,
+):
+    # type: (Any, Union[None, StreamType], Any, Any, Any, Union[None, bool], Union[None, int], Union[None, int], Union[None, bool], Any, Any, Union[None, bool], Union[None, bool], Union[None, VersionType], Any, Any) -> Union[None, str]   # NOQA
     """
     Serialize a Python object into a YAML stream.
     If stream is None, return the produced string instead.
@@ -838,20 +983,28 @@ def dump(data, stream=None, Dumper=Dumper,
     default_style ∈ None, '', '"', "'", '|', '>'
 
     """
-    return dump_all([data], stream, Dumper=Dumper,
-                    default_style=default_style,
-                    default_flow_style=default_flow_style,
-                    canonical=canonical,
-                    indent=indent, width=width,
-                    allow_unicode=allow_unicode,
-                    line_break=line_break,
-                    encoding=encoding, explicit_start=explicit_start,
-                    explicit_end=explicit_end,
-                    version=version, tags=tags, block_seq_indent=block_seq_indent)
+    return dump_all(
+        [data],
+        stream,
+        Dumper=Dumper,
+        default_style=default_style,
+        default_flow_style=default_flow_style,
+        canonical=canonical,
+        indent=indent,
+        width=width,
+        allow_unicode=allow_unicode,
+        line_break=line_break,
+        encoding=encoding,
+        explicit_start=explicit_start,
+        explicit_end=explicit_end,
+        version=version,
+        tags=tags,
+        block_seq_indent=block_seq_indent,
+    )
 
 
 def safe_dump_all(documents, stream=None, **kwds):
-    # type: (Any, StreamType, Any) -> Union[None, str]
+    # type: (Any, Union[None, StreamType], Any) -> Union[None, str]
     """
     Serialize a sequence of Python objects into a YAML stream.
     Produce only basic YAML tags.
@@ -861,7 +1014,7 @@ def safe_dump_all(documents, stream=None, **kwds):
 
 
 def safe_dump(data, stream=None, **kwds):
-    # type: (Any, StreamType, Any) -> Union[None, str]
+    # type: (Any, Union[None, StreamType], Any) -> Union[None, str]
     """
     Serialize a Python object into a YAML stream.
     Produce only basic YAML tags.
@@ -870,33 +1023,57 @@ def safe_dump(data, stream=None, **kwds):
     return dump_all([data], stream, Dumper=SafeDumper, **kwds)
 
 
-def round_trip_dump(data, stream=None, Dumper=RoundTripDumper,
-                    default_style=None, default_flow_style=None,
-                    canonical=None, indent=None, width=None,
-                    allow_unicode=None, line_break=None,
-                    encoding=enc, explicit_start=None, explicit_end=None,
-                    version=None, tags=None, block_seq_indent=None,
-                    top_level_colon_align=None, prefix_colon=None):
-    # type: (Any, StreamType, Any, Any, Any, bool, Union[None, int], Union[None, int], bool, Any, Any, Union[None, bool], Union[None, bool], VersionType, Any, Any, Any, Any) -> Union[None, str]   # NOQA
+def round_trip_dump(
+    data,
+    stream=None,
+    Dumper=RoundTripDumper,
+    default_style=None,
+    default_flow_style=None,
+    canonical=None,
+    indent=None,
+    width=None,
+    allow_unicode=None,
+    line_break=None,
+    encoding=enc,
+    explicit_start=None,
+    explicit_end=None,
+    version=None,
+    tags=None,
+    block_seq_indent=None,
+    top_level_colon_align=None,
+    prefix_colon=None,
+):
+    # type: (Any, Union[None, StreamType], Any, Any, Any, Union[None, bool], Union[None, int], Union[None, int], Union[None, bool], Any, Any, Union[None, bool], Union[None, bool], Union[None, VersionType], Any, Any, Any, Any) -> Union[None, str]   # NOQA
     allow_unicode = True if allow_unicode is None else allow_unicode
-    return dump_all([data], stream, Dumper=Dumper,
-                    default_style=default_style,
-                    default_flow_style=default_flow_style,
-                    canonical=canonical,
-                    indent=indent, width=width,
-                    allow_unicode=allow_unicode,
-                    line_break=line_break,
-                    encoding=encoding, explicit_start=explicit_start,
-                    explicit_end=explicit_end,
-                    version=version, tags=tags, block_seq_indent=block_seq_indent,
-                    top_level_colon_align=top_level_colon_align, prefix_colon=prefix_colon)
+    return dump_all(
+        [data],
+        stream,
+        Dumper=Dumper,
+        default_style=default_style,
+        default_flow_style=default_flow_style,
+        canonical=canonical,
+        indent=indent,
+        width=width,
+        allow_unicode=allow_unicode,
+        line_break=line_break,
+        encoding=encoding,
+        explicit_start=explicit_start,
+        explicit_end=explicit_end,
+        version=version,
+        tags=tags,
+        block_seq_indent=block_seq_indent,
+        top_level_colon_align=top_level_colon_align,
+        prefix_colon=prefix_colon,
+    )
 
 
 # Loader/Dumper are no longer composites, to get to the associated
 # Resolver()/Representer(), etc., you need to instantiate the class
 
-def add_implicit_resolver(tag, regexp, first=None, Loader=None, Dumper=None,
-                          resolver=Resolver):
+
+def add_implicit_resolver(
+    tag, regexp, first=None, Loader=None, Dumper=None, resolver=Resolver
+):
     # type: (Any, Any, Any, Any, Any, Any) -> None
     """
     Add an implicit scalar detector.
@@ -910,24 +1087,25 @@ def add_implicit_resolver(tag, regexp, first=None, Loader=None, Dumper=None,
     if Loader:
         if hasattr(Loader, 'add_implicit_resolver'):
             Loader.add_implicit_resolver(tag, regexp, first)
-        elif issubclass(Loader, (BaseLoader, SafeLoader, ruamel.yaml.loader.Loader,
-                                 RoundTripLoader)):
+        elif issubclass(
+            Loader, (BaseLoader, SafeLoader, ruamel.yaml.loader.Loader, RoundTripLoader)
+        ):
             Resolver.add_implicit_resolver(tag, regexp, first)
         else:
             raise NotImplementedError
     if Dumper:
         if hasattr(Dumper, 'add_implicit_resolver'):
             Dumper.add_implicit_resolver(tag, regexp, first)
-        elif issubclass(Dumper, (BaseDumper, SafeDumper, ruamel.yaml.dumper.Dumper,
-                                 RoundTripDumper)):
+        elif issubclass(
+            Dumper, (BaseDumper, SafeDumper, ruamel.yaml.dumper.Dumper, RoundTripDumper)
+        ):
             Resolver.add_implicit_resolver(tag, regexp, first)
         else:
             raise NotImplementedError
 
 
 # this code currently not tested
-def add_path_resolver(tag, path, kind=None, Loader=None, Dumper=None,
-                      resolver=Resolver):
+def add_path_resolver(tag, path, kind=None, Loader=None, Dumper=None, resolver=Resolver):
     # type: (Any, Any, Any, Any, Any, Any) -> None
     """
     Add a path based resolver for the given tag.
@@ -941,16 +1119,18 @@ def add_path_resolver(tag, path, kind=None, Loader=None, Dumper=None,
     if Loader:
         if hasattr(Loader, 'add_path_resolver'):
             Loader.add_path_resolver(tag, path, kind)
-        elif issubclass(Loader, (BaseLoader, SafeLoader, ruamel.yaml.loader.Loader,
-                                 RoundTripLoader)):
+        elif issubclass(
+            Loader, (BaseLoader, SafeLoader, ruamel.yaml.loader.Loader, RoundTripLoader)
+        ):
             Resolver.add_path_resolver(tag, path, kind)
         else:
             raise NotImplementedError
     if Dumper:
         if hasattr(Dumper, 'add_path_resolver'):
             Dumper.add_path_resolver(tag, path, kind)
-        elif issubclass(Dumper, (BaseDumper, SafeDumper, ruamel.yaml.dumper.Dumper,
-                                 RoundTripDumper)):
+        elif issubclass(
+            Dumper, (BaseDumper, SafeDumper, ruamel.yaml.dumper.Dumper, RoundTripDumper)
+        ):
             Resolver.add_path_resolver(tag, path, kind)
         else:
             raise NotImplementedError
@@ -981,8 +1161,7 @@ def add_constructor(tag, object_constructor, Loader=None, constructor=Constructo
             raise NotImplementedError
 
 
-def add_multi_constructor(tag_prefix, multi_constructor, Loader=None,
-                          constructor=Constructor):
+def add_multi_constructor(tag_prefix, multi_constructor, Loader=None, constructor=Constructor):
     # type: (Any, Any, Any, Any) -> None
     """
     Add a multi-constructor for the given tag prefix.
@@ -1065,12 +1244,13 @@ class YAMLObjectMetaclass(type):
     """
     The metaclass for YAMLObject.
     """
+
     def __init__(cls, name, bases, kwds):
         # type: (Any, Any, Any) -> None
         super(YAMLObjectMetaclass, cls).__init__(name, bases, kwds)
         if 'yaml_tag' in kwds and kwds['yaml_tag'] is not None:
             cls.yaml_constructor.add_constructor(cls.yaml_tag, cls.from_yaml)  # type: ignore
-            cls.yaml_representer.add_representer(cls, cls.to_yaml)             # type: ignore
+            cls.yaml_representer.add_representer(cls, cls.to_yaml)  # type: ignore
 
 
 class YAMLObject(with_metaclass(YAMLObjectMetaclass)):  # type: ignore
@@ -1078,6 +1258,7 @@ class YAMLObject(with_metaclass(YAMLObjectMetaclass)):  # type: ignore
     An object that can dump itself to a YAML stream
     and load itself from a YAML stream.
     """
+
     __slots__ = ()  # no direct instantiation, so allow immutable subclasses
 
     yaml_constructor = Constructor
@@ -1100,5 +1281,6 @@ class YAMLObject(with_metaclass(YAMLObjectMetaclass)):  # type: ignore
         """
         Convert a Python object to a representation node.
         """
-        return representer.represent_yaml_object(cls.yaml_tag, data, cls,
-                                                 flow_style=cls.yaml_flow_style)
+        return representer.represent_yaml_object(
+            cls.yaml_tag, data, cls, flow_style=cls.yaml_flow_style
+        )
diff --git a/nodes.py b/nodes.py
index 781df94..df90be7 100644
--- a/nodes.py
+++ b/nodes.py
@@ -5,11 +5,11 @@ from __future__ import print_function
 from .compat import string_types
 
 if False:  # MYPY
-    from typing import Dict, Any, Text   # NOQA
+    from typing import Dict, Any, Text  # NOQA
 
 
 class Node(object):
-    __slots__ = 'tag', 'value', 'start_mark', 'end_mark', 'comment', 'anchor',
+    __slots__ = 'tag', 'value', 'start_mark', 'end_mark', 'comment', 'anchor'
 
     def __init__(self, tag, value, start_mark, end_mark, comment=None):
         # type: (Any, Any, Any, Any, Any) -> None
@@ -36,23 +36,22 @@ class Node(object):
         #     else:
         #         value = repr(value)
         value = repr(value)
-        return '%s(tag=%r, value=%s)' % (self.__class__.__name__,
-                                         self.tag, value)
+        return '%s(tag=%r, value=%s)' % (self.__class__.__name__, self.tag, value)
 
     def dump(self, indent=0):
         # type: (int) -> None
         if isinstance(self.value, string_types):
-            print('{}{}(tag={!r}, value={!r})'.format(
-                '  ' * indent, self.__class__.__name__, self.tag, self.value))
+            print(
+                '{}{}(tag={!r}, value={!r})'.format(
+                    '  ' * indent, self.__class__.__name__, self.tag, self.value
+                )
+            )
             if self.comment:
-                print('    {}comment: {})'.format(
-                    '  ' * indent, self.comment))
+                print('    {}comment: {})'.format('  ' * indent, self.comment))
             return
-        print('{}{}(tag={!r})'.format(
-            '  ' * indent, self.__class__.__name__, self.tag))
+        print('{}{}(tag={!r})'.format('  ' * indent, self.__class__.__name__, self.tag))
         if self.comment:
-            print('    {}comment: {})'.format(
-                '  ' * indent, self.comment))
+            print('    {}comment: {})'.format('  ' * indent, self.comment))
         for v in self.value:
             if isinstance(v, tuple):
                 for v1 in v:
@@ -72,21 +71,29 @@ class ScalarNode(Node):
       | -> literal style
       > -> folding style
     """
-    __slots__ = 'style',
+
+    __slots__ = ('style',)
     id = 'scalar'
 
-    def __init__(self, tag, value, start_mark=None, end_mark=None, style=None,
-                 comment=None):
+    def __init__(self, tag, value, start_mark=None, end_mark=None, style=None, comment=None):
         # type: (Any, Any, Any, Any, Any, Any) -> None
         Node.__init__(self, tag, value, start_mark, end_mark, comment=comment)
         self.style = style
 
 
 class CollectionNode(Node):
-    __slots__ = 'flow_style', 'anchor',
-
-    def __init__(self, tag, value, start_mark=None, end_mark=None,
-                 flow_style=None, comment=None, anchor=None):
+    __slots__ = 'flow_style', 'anchor'
+
+    def __init__(
+        self,
+        tag,
+        value,
+        start_mark=None,
+        end_mark=None,
+        flow_style=None,
+        comment=None,
+        anchor=None,
+    ):
         # type: (Any, Any, Any, Any, Any, Any, Any) -> None
         Node.__init__(self, tag, value, start_mark, end_mark, comment=comment)
         self.flow_style = flow_style
@@ -99,12 +106,21 @@ class SequenceNode(CollectionNode):
 
 
 class MappingNode(CollectionNode):
-    __slots__ = ('merge', )
+    __slots__ = ('merge',)
     id = 'mapping'
 
-    def __init__(self, tag, value, start_mark=None, end_mark=None,
-                 flow_style=None, comment=None, anchor=None):
+    def __init__(
+        self,
+        tag,
+        value,
+        start_mark=None,
+        end_mark=None,
+        flow_style=None,
+        comment=None,
+        anchor=None,
+    ):
         # type: (Any, Any, Any, Any, Any, Any, Any) -> None
-        CollectionNode.__init__(self, tag, value, start_mark, end_mark,
-                                flow_style, comment, anchor)
+        CollectionNode.__init__(
+            self, tag, value, start_mark, end_mark, flow_style, comment, anchor
+        )
         self.merge = None
diff --git a/parser.py b/parser.py
index 83510bb..9c6041d 100644
--- a/parser.py
+++ b/parser.py
@@ -77,10 +77,10 @@ from __future__ import absolute_import
 
 
 from ruamel.yaml.error import MarkedYAMLError
-from ruamel.yaml.tokens import *                               # NOQA
-from ruamel.yaml.events import *                               # NOQA
-from ruamel.yaml.scanner import Scanner, RoundTripScanner, ScannerError      # NOQA
-from ruamel.yaml.compat import utf8, nprint                    # NOQA
+from ruamel.yaml.tokens import *  # NOQA
+from ruamel.yaml.events import *  # NOQA
+from ruamel.yaml.scanner import Scanner, RoundTripScanner, ScannerError  # NOQA
+from ruamel.yaml.compat import utf8, nprint  # NOQA
 
 if False:  # MYPY
     from typing import Any, Dict, Optional, List  # NOQA
@@ -96,10 +96,7 @@ class Parser(object):
     # Since writing a recursive-descendant parser is a straightforward task, we
     # do not give many comments here.
 
-    DEFAULT_TAGS = {
-        u'!': u'!',
-        u'!!': u'tag:yaml.org,2002:',
-    }
+    DEFAULT_TAGS = {u'!': u'!', u'!!': u'tag:yaml.org,2002:'}
 
     def __init__(self, loader):
         # type: (Any) -> None
@@ -115,7 +112,7 @@ class Parser(object):
         self.yaml_version = None
         self.tag_handles = {}  # type: Dict[Any, Any]
         self.states = []  # type: List[Any]
-        self.marks = []   # type: List[Any]
+        self.marks = []  # type: List[Any]
         self.state = self.parse_stream_start  # type: Any
 
     def dispose(self):
@@ -178,8 +175,7 @@ class Parser(object):
         # Parse the stream start.
         token = self.scanner.get_token()
         token.move_comment(self.scanner.peek_token())
-        event = StreamStartEvent(token.start_mark, token.end_mark,
-                                 encoding=token.encoding)
+        event = StreamStartEvent(token.start_mark, token.end_mark, encoding=token.encoding)
 
         # Prepare the next state.
         self.state = self.parse_implicit_document_start
@@ -189,13 +185,11 @@ class Parser(object):
     def parse_implicit_document_start(self):
         # type: () -> Any
         # Parse an implicit document.
-        if not self.scanner.check_token(DirectiveToken, DocumentStartToken,
-                                        StreamEndToken):
+        if not self.scanner.check_token(DirectiveToken, DocumentStartToken, StreamEndToken):
             self.tag_handles = self.DEFAULT_TAGS
             token = self.scanner.peek_token()
             start_mark = end_mark = token.start_mark
-            event = DocumentStartEvent(start_mark, end_mark,
-                                       explicit=False)
+            event = DocumentStartEvent(start_mark, end_mark, explicit=False)
 
             # Prepare the next state.
             self.states.append(self.parse_document_end)
@@ -217,22 +211,23 @@ class Parser(object):
             start_mark = token.start_mark
             version, tags = self.process_directives()
             if not self.scanner.check_token(DocumentStartToken):
-                raise ParserError(None, None,
-                                  "expected '<document start>', but found %r"
-                                  % self.scanner.peek_token().id,
-                                  self.scanner.peek_token().start_mark)
+                raise ParserError(
+                    None,
+                    None,
+                    "expected '<document start>', but found %r" % self.scanner.peek_token().id,
+                    self.scanner.peek_token().start_mark,
+                )
             token = self.scanner.get_token()
             end_mark = token.end_mark
             event = DocumentStartEvent(
-                start_mark, end_mark,
-                explicit=True, version=version, tags=tags)        # type: Any
+                start_mark, end_mark, explicit=True, version=version, tags=tags
+            )  # type: Any
             self.states.append(self.parse_document_end)
             self.state = self.parse_document_content
         else:
             # Parse the end of the stream.
             token = self.scanner.get_token()
-            event = StreamEndEvent(token.start_mark, token.end_mark,
-                                   comment=token.comment)
+            event = StreamEndEvent(token.start_mark, token.end_mark, comment=token.comment)
             assert not self.states
             assert not self.marks
             self.state = None
@@ -261,8 +256,8 @@ class Parser(object):
     def parse_document_content(self):
         # type: () -> Any
         if self.scanner.check_token(
-           DirectiveToken,
-           DocumentStartToken, DocumentEndToken, StreamEndToken):
+            DirectiveToken, DocumentStartToken, DocumentEndToken, StreamEndToken
+        ):
             event = self.process_empty_scalar(self.scanner.peek_token().start_mark)
             self.state = self.states.pop()
             return event
@@ -278,22 +273,23 @@ class Parser(object):
             if token.name == u'YAML':
                 if self.yaml_version is not None:
                     raise ParserError(
-                        None, None,
-                        "found duplicate YAML directive", token.start_mark)
+                        None, None, 'found duplicate YAML directive', token.start_mark
+                    )
                 major, minor = token.value
                 if major != 1:
                     raise ParserError(
-                        None, None,
-                        "found incompatible YAML document (version 1.* is "
-                        "required)",
-                        token.start_mark)
+                        None,
+                        None,
+                        'found incompatible YAML document (version 1.* is ' 'required)',
+                        token.start_mark,
+                    )
                 self.yaml_version = token.value
             elif token.name == u'TAG':
                 handle, prefix = token.value
                 if handle in self.tag_handles:
-                    raise ParserError(None, None,
-                                      "duplicate tag handle %r" % utf8(handle),
-                                      token.start_mark)
+                    raise ParserError(
+                        None, None, 'duplicate tag handle %r' % utf8(handle), token.start_mark
+                    )
                 self.tag_handles[handle] = prefix
         if bool(self.tag_handles):
             value = self.yaml_version, self.tag_handles.copy()  # type: Any
@@ -372,9 +368,11 @@ class Parser(object):
             if handle is not None:
                 if handle not in self.tag_handles:
                     raise ParserError(
-                        "while parsing a node", start_mark,
-                        "found undefined tag handle %r" % utf8(handle),
-                        tag_mark)
+                        'while parsing a node',
+                        start_mark,
+                        'found undefined tag handle %r' % utf8(handle),
+                        tag_mark,
+                    )
                 tag = self.transform_tag(handle, suffix)
             else:
                 tag = suffix
@@ -386,7 +384,7 @@ class Parser(object):
         if start_mark is None:
             start_mark = end_mark = self.scanner.peek_token().start_mark
         event = None
-        implicit = (tag is None or tag == u'!')
+        implicit = tag is None or tag == u'!'
         if indentless_sequence and self.scanner.check_token(BlockEntryToken):
             comment = None
             pt = self.scanner.peek_token()
@@ -394,8 +392,9 @@ class Parser(object):
                 comment = [pt.comment[0], []]
                 pt.comment[0] = None
             end_mark = self.scanner.peek_token().end_mark
-            event = SequenceStartEvent(anchor, tag, implicit, start_mark, end_mark,
-                                       flow_style=False, comment=comment)
+            event = SequenceStartEvent(
+                anchor, tag, implicit, start_mark, end_mark, flow_style=False, comment=comment
+            )
             self.state = self.parse_indentless_sequence_entry
             return event
 
@@ -411,23 +410,34 @@ class Parser(object):
                 implicit = (False, False)
             # nprint('se', token.value, token.comment)
             event = ScalarEvent(
-                anchor, tag, implicit, token.value,
-                start_mark, end_mark, style=token.style,
-                comment=token.comment
+                anchor,
+                tag,
+                implicit,
+                token.value,
+                start_mark,
+                end_mark,
+                style=token.style,
+                comment=token.comment,
             )
             self.state = self.states.pop()
         elif self.scanner.check_token(FlowSequenceStartToken):
             pt = self.scanner.peek_token()
             end_mark = pt.end_mark
             event = SequenceStartEvent(
-                anchor, tag, implicit,
-                start_mark, end_mark, flow_style=True, comment=pt.comment)
+                anchor,
+                tag,
+                implicit,
+                start_mark,
+                end_mark,
+                flow_style=True,
+                comment=pt.comment,
+            )
             self.state = self.parse_flow_sequence_first_entry
         elif self.scanner.check_token(FlowMappingStartToken):
             end_mark = self.scanner.peek_token().end_mark
             event = MappingStartEvent(
-                anchor, tag, implicit,
-                start_mark, end_mark, flow_style=True)
+                anchor, tag, implicit, start_mark, end_mark, flow_style=True
+            )
             self.state = self.parse_flow_mapping_first_key
         elif block and self.scanner.check_token(BlockSequenceStartToken):
             end_mark = self.scanner.peek_token().start_mark
@@ -440,23 +450,20 @@ class Parser(object):
                 comment = pt.split_comment()
             # nprint('pt1', comment)
             event = SequenceStartEvent(
-                anchor, tag, implicit, start_mark, end_mark,
-                flow_style=False,
-                comment=comment,
+                anchor, tag, implicit, start_mark, end_mark, flow_style=False, comment=comment
             )
             self.state = self.parse_block_sequence_first_entry
         elif block and self.scanner.check_token(BlockMappingStartToken):
             end_mark = self.scanner.peek_token().start_mark
             comment = self.scanner.peek_token().comment
             event = MappingStartEvent(
-                anchor, tag, implicit, start_mark, end_mark,
-                flow_style=False, comment=comment)
+                anchor, tag, implicit, start_mark, end_mark, flow_style=False, comment=comment
+            )
             self.state = self.parse_block_mapping_first_key
         elif anchor is not None or tag is not None:
             # Empty scalars are allowed even if a tag or an anchor is
             # specified.
-            event = ScalarEvent(anchor, tag, (implicit, False), u'',
-                                start_mark, end_mark)
+            event = ScalarEvent(anchor, tag, (implicit, False), "", start_mark, end_mark)
             self.state = self.states.pop()
         else:
             if block:
@@ -465,9 +472,11 @@ class Parser(object):
                 node = 'flow'
             token = self.scanner.peek_token()
             raise ParserError(
-                "while parsing a %s node" % node, start_mark,
-                "expected the node content, but found %r" % token.id,
-                token.start_mark)
+                'while parsing a %s node' % node,
+                start_mark,
+                'expected the node content, but found %r' % token.id,
+                token.start_mark,
+            )
         return event
 
     # block_sequence ::= BLOCK-SEQUENCE-START (BLOCK-ENTRY block_node?)*
@@ -495,12 +504,13 @@ class Parser(object):
         if not self.scanner.check_token(BlockEndToken):
             token = self.scanner.peek_token()
             raise ParserError(
-                "while parsing a block collection", self.marks[-1],
-                "expected <block end>, but found %r" %
-                token.id, token.start_mark)
+                'while parsing a block collection',
+                self.marks[-1],
+                'expected <block end>, but found %r' % token.id,
+                token.start_mark,
+            )
         token = self.scanner.get_token()  # BlockEndToken
-        event = SequenceEndEvent(token.start_mark, token.end_mark,
-                                 comment=token.comment)
+        event = SequenceEndEvent(token.start_mark, token.end_mark, comment=token.comment)
         self.state = self.states.pop()
         self.marks.pop()
         return event
@@ -517,16 +527,16 @@ class Parser(object):
         if self.scanner.check_token(BlockEntryToken):
             token = self.scanner.get_token()
             token.move_comment(self.scanner.peek_token())
-            if not self.scanner.check_token(BlockEntryToken,
-                                            KeyToken, ValueToken, BlockEndToken):
+            if not self.scanner.check_token(
+                BlockEntryToken, KeyToken, ValueToken, BlockEndToken
+            ):
                 self.states.append(self.parse_indentless_sequence_entry)
                 return self.parse_block_node()
             else:
                 self.state = self.parse_indentless_sequence_entry
                 return self.process_empty_scalar(token.end_mark)
         token = self.scanner.peek_token()
-        event = SequenceEndEvent(token.start_mark, token.start_mark,
-                                 comment=token.comment)
+        event = SequenceEndEvent(token.start_mark, token.start_mark, comment=token.comment)
         self.state = self.states.pop()
         return event
 
@@ -556,13 +566,14 @@ class Parser(object):
         if not self.scanner.check_token(BlockEndToken):
             token = self.scanner.peek_token()
             raise ParserError(
-                "while parsing a block mapping", self.marks[-1],
-                "expected <block end>, but found %r" % token.id,
-                token.start_mark)
+                'while parsing a block mapping',
+                self.marks[-1],
+                'expected <block end>, but found %r' % token.id,
+                token.start_mark,
+            )
         token = self.scanner.get_token()
         token.move_comment(self.scanner.peek_token())
-        event = MappingEndEvent(token.start_mark, token.end_mark,
-                                comment=token.comment)
+        event = MappingEndEvent(token.start_mark, token.end_mark, comment=token.comment)
         self.state = self.states.pop()
         self.marks.pop()
         return event
@@ -620,23 +631,24 @@ class Parser(object):
                 else:
                     token = self.scanner.peek_token()
                     raise ParserError(
-                        "while parsing a flow sequence", self.marks[-1],
+                        'while parsing a flow sequence',
+                        self.marks[-1],
                         "expected ',' or ']', but got %r" % token.id,
-                        token.start_mark)
+                        token.start_mark,
+                    )
 
             if self.scanner.check_token(KeyToken):
                 token = self.scanner.peek_token()
-                event = MappingStartEvent(None, None, True,
-                                          token.start_mark, token.end_mark,
-                                          flow_style=True)        # type: Any
+                event = MappingStartEvent(
+                    None, None, True, token.start_mark, token.end_mark, flow_style=True
+                )  # type: Any
                 self.state = self.parse_flow_sequence_entry_mapping_key
                 return event
             elif not self.scanner.check_token(FlowSequenceEndToken):
                 self.states.append(self.parse_flow_sequence_entry)
                 return self.parse_flow_node()
         token = self.scanner.get_token()
-        event = SequenceEndEvent(token.start_mark, token.end_mark,
-                                 comment=token.comment)
+        event = SequenceEndEvent(token.start_mark, token.end_mark, comment=token.comment)
         self.state = self.states.pop()
         self.marks.pop()
         return event
@@ -644,8 +656,7 @@ class Parser(object):
     def parse_flow_sequence_entry_mapping_key(self):
         # type: () -> Any
         token = self.scanner.get_token()
-        if not self.scanner.check_token(ValueToken,
-                                        FlowEntryToken, FlowSequenceEndToken):
+        if not self.scanner.check_token(ValueToken, FlowEntryToken, FlowSequenceEndToken):
             self.states.append(self.parse_flow_sequence_entry_mapping_value)
             return self.parse_flow_node()
         else:
@@ -694,13 +705,16 @@ class Parser(object):
                 else:
                     token = self.scanner.peek_token()
                     raise ParserError(
-                        "while parsing a flow mapping", self.marks[-1],
+                        'while parsing a flow mapping',
+                        self.marks[-1],
                         "expected ',' or '}', but got %r" % token.id,
-                        token.start_mark)
+                        token.start_mark,
+                    )
             if self.scanner.check_token(KeyToken):
                 token = self.scanner.get_token()
-                if not self.scanner.check_token(ValueToken,
-                                                FlowEntryToken, FlowMappingEndToken):
+                if not self.scanner.check_token(
+                    ValueToken, FlowEntryToken, FlowMappingEndToken
+                ):
                     self.states.append(self.parse_flow_mapping_value)
                     return self.parse_flow_node()
                 else:
@@ -710,8 +724,7 @@ class Parser(object):
                 self.states.append(self.parse_flow_mapping_empty_value)
                 return self.parse_flow_node()
         token = self.scanner.get_token()
-        event = MappingEndEvent(token.start_mark, token.end_mark,
-                                comment=token.comment)
+        event = MappingEndEvent(token.start_mark, token.end_mark, comment=token.comment)
         self.state = self.states.pop()
         self.marks.pop()
         return event
@@ -738,16 +751,28 @@ class Parser(object):
 
     def process_empty_scalar(self, mark, comment=None):
         # type: (Any, Any) -> Any
-        return ScalarEvent(None, None, (True, False), u'', mark, mark, comment=comment)
+        return ScalarEvent(None, None, (True, False), "", mark, mark, comment=comment)
 
 
 class RoundTripParser(Parser):
     """roundtrip is a safe loader, that wants to see the unmangled tag"""
+
     def transform_tag(self, handle, suffix):
         # type: (Any, Any) -> Any
         # return self.tag_handles[handle]+suffix
-        if handle == '!!' and suffix in (u'null', u'bool', u'int', u'float', u'binary',
-                                         u'timestamp', u'omap', u'pairs', u'set', u'str',
-                                         u'seq', u'map'):
+        if handle == '!!' and suffix in (
+            u'null',
+            u'bool',
+            u'int',
+            u'float',
+            u'binary',
+            u'timestamp',
+            u'omap',
+            u'pairs',
+            u'set',
+            u'str',
+            u'seq',
+            u'map',
+        ):
             return Parser.transform_tag(self, handle, suffix)
         return handle + suffix
diff --git a/reader.py b/reader.py
index 96bb96b..4d0ddb4 100644
--- a/reader.py
+++ b/reader.py
@@ -1,6 +1,7 @@
 # coding: utf-8
 
 from __future__ import absolute_import
+
 # This module contains abstractions for the input stream. You don't have to
 # looks further, there are no pretty code.
 #
@@ -34,7 +35,6 @@ __all__ = ['Reader', 'ReaderError']
 
 
 class ReaderError(YAMLError):
-
     def __init__(self, name, position, character, encoding, reason):
         # type: (Any, Any, Any, Any, Any) -> None
         self.name = name
@@ -46,15 +46,20 @@ class ReaderError(YAMLError):
     def __str__(self):
         # type: () -> str
         if isinstance(self.character, binary_type):
-            return "'%s' codec can't decode byte #x%02x: %s\n"  \
-                   "  in \"%s\", position %d"    \
-                   % (self.encoding, ord(self.character), self.reason,
-                      self.name, self.position)
+            return "'%s' codec can't decode byte #x%02x: %s\n" '  in "%s", position %d' % (
+                self.encoding,
+                ord(self.character),
+                self.reason,
+                self.name,
+                self.position,
+            )
         else:
-            return "unacceptable character #x%04x: %s\n"    \
-                   "  in \"%s\", position %d"    \
-                   % (self.character, self.reason,
-                      self.name, self.position)
+            return 'unacceptable character #x%04x: %s\n' '  in "%s", position %d' % (
+                self.character,
+                self.reason,
+                self.name,
+                self.position,
+            )
 
 
 class Reader(object):
@@ -81,10 +86,10 @@ class Reader(object):
 
     def reset_reader(self):
         # type: () -> None
-        self.name = None        # type: Any
+        self.name = None  # type: Any
         self.stream_pointer = 0
         self.eof = True
-        self.buffer = u''
+        self.buffer = ""
         self.pointer = 0
         self.raw_buffer = None  # type: Any
         self.raw_decode = None
@@ -108,18 +113,18 @@ class Reader(object):
             return
         self._stream = None
         if isinstance(val, text_type):
-            self.name = "<unicode string>"
+            self.name = '<unicode string>'
             self.check_printable(val)
-            self.buffer = val + u'\0'
+            self.buffer = val + u'\0'  # type: ignore
         elif isinstance(val, binary_type):
-            self.name = "<byte string>"
+            self.name = '<byte string>'
             self.raw_buffer = val
             self.determine_encoding()
         else:
             if not hasattr(val, 'read'):
                 raise YAMLStreamError('stream argument needs to have a read() method')
             self._stream = val
-            self.name = getattr(self.stream, 'name', "<file>")
+            self.name = getattr(self.stream, 'name', '<file>')
             self.eof = False
             self.raw_buffer = None
             self.determine_encoding()
@@ -136,7 +141,7 @@ class Reader(object):
         # type: (int) -> Any
         if self.pointer + length >= len(self.buffer):
             self.update(length)
-        return self.buffer[self.pointer:self.pointer + length]
+        return self.buffer[self.pointer : self.pointer + length]
 
     def forward(self, length=1):
         # type: (int) -> None
@@ -146,8 +151,9 @@ class Reader(object):
             ch = self.buffer[self.pointer]
             self.pointer += 1
             self.index += 1
-            if ch in u'\n\x85\u2028\u2029'  \
-                    or (ch == u'\r' and self.buffer[self.pointer] != u'\n'):
+            if ch in u'\n\x85\u2028\u2029' or (
+                ch == u'\r' and self.buffer[self.pointer] != u'\n'
+            ):
                 self.line += 1
                 self.column = 0
             elif ch != u'\uFEFF':
@@ -157,15 +163,15 @@ class Reader(object):
     def get_mark(self):
         # type: () -> Any
         if self.stream is None:
-            return StringMark(self.name, self.index, self.line, self.column,
-                              self.buffer, self.pointer)
+            return StringMark(
+                self.name, self.index, self.line, self.column, self.buffer, self.pointer
+            )
         else:
             return FileMark(self.name, self.index, self.line, self.column)
 
     def determine_encoding(self):
         # type: () -> None
-        while not self.eof and (self.raw_buffer is None or
-                                len(self.raw_buffer) < 2):
+        while not self.eof and (self.raw_buffer is None or len(self.raw_buffer) < 2):
             self.update_raw()
         if isinstance(self.raw_buffer, binary_type):
             if self.raw_buffer.startswith(codecs.BOM_UTF16_LE):
@@ -181,10 +187,7 @@ class Reader(object):
 
     if UNICODE_SIZE == 2:
         NON_PRINTABLE = RegExp(
-            u'[^\x09\x0A\x0D\x20-\x7E\x85'
-            u'\xA0-\uD7FF'
-            u'\uE000-\uFFFD'
-            u']'
+            u'[^\x09\x0A\x0D\x20-\x7E\x85' u'\xA0-\uD7FF' u'\uE000-\uFFFD' u']'
         )
     else:
         NON_PRINTABLE = RegExp(
@@ -195,13 +198,13 @@ class Reader(object):
             u']'
         )
 
-    _printable_ascii = ('\x09\x0A\x0D' + ''.join(map(chr, range(0x20, 0x7F)))).encode('ascii')
+    _printable_ascii = ('\x09\x0A\x0D' + "".join(map(chr, range(0x20, 0x7F)))).encode('ascii')
 
     @classmethod
-    def _get_non_printable_ascii(cls, data):
+    def _get_non_printable_ascii(cls, data):  # type: ignore
         # type: (Text, bytes) -> Union[None, Tuple[int, Text]]
         ascii_bytes = data.encode('ascii')
-        non_printables = ascii_bytes.translate(None, cls._printable_ascii)
+        non_printables = ascii_bytes.translate(None, cls._printable_ascii)  # type: ignore
         if not non_printables:
             return None
         non_printable = non_printables[:1]
@@ -219,7 +222,7 @@ class Reader(object):
     def _get_non_printable(cls, data):
         # type: (Text) -> Union[None, Tuple[int, Text]]
         try:
-            return cls._get_non_printable_ascii(data)
+            return cls._get_non_printable_ascii(data)  # type: ignore
         except UnicodeEncodeError:
             return cls._get_non_printable_regex(data)
 
@@ -229,37 +232,38 @@ class Reader(object):
         if non_printable_match is not None:
             start, character = non_printable_match
             position = self.index + (len(self.buffer) - self.pointer) + start
-            raise ReaderError(self.name, position, ord(character),
-                              'unicode', "special characters are not allowed")
+            raise ReaderError(
+                self.name,
+                position,
+                ord(character),
+                'unicode',
+                'special characters are not allowed',
+            )
 
     def update(self, length):
         # type: (int) -> None
         if self.raw_buffer is None:
             return
-        self.buffer = self.buffer[self.pointer:]
+        self.buffer = self.buffer[self.pointer :]
         self.pointer = 0
         while len(self.buffer) < length:
             if not self.eof:
                 self.update_raw()
             if self.raw_decode is not None:
                 try:
-                    data, converted = self.raw_decode(self.raw_buffer,
-                                                      'strict', self.eof)
+                    data, converted = self.raw_decode(self.raw_buffer, 'strict', self.eof)
                 except UnicodeDecodeError as exc:
                     if PY3:
                         character = self.raw_buffer[exc.start]
                     else:
                         character = exc.object[exc.start]
                     if self.stream is not None:
-                        position = self.stream_pointer - \
-                            len(self.raw_buffer) + exc.start
+                        position = self.stream_pointer - len(self.raw_buffer) + exc.start
                     elif self.stream is not None:
-                        position = self.stream_pointer - \
-                            len(self.raw_buffer) + exc.start
+                        position = self.stream_pointer - len(self.raw_buffer) + exc.start
                     else:
                         position = exc.start
-                    raise ReaderError(self.name, position, character,
-                                      exc.encoding, exc.reason)
+                    raise ReaderError(self.name, position, character, exc.encoding, exc.reason)
             else:
                 data = self.raw_buffer
                 converted = len(data)
@@ -267,12 +271,12 @@ class Reader(object):
             self.buffer += data
             self.raw_buffer = self.raw_buffer[converted:]
             if self.eof:
-                self.buffer += u'\0'
+                self.buffer += '\0'
                 self.raw_buffer = None
                 break
 
     def update_raw(self, size=None):
-        # type: (int) -> None
+        # type: (Union[None, int]) -> None
         if size is None:
             size = 4096 if PY3 else 1024
         data = self.stream.read(size)
@@ -284,6 +288,7 @@ class Reader(object):
         if not data:
             self.eof = True
 
+
 # try:
 #     import psyco
 #     psyco.bind(Reader)
diff --git a/representer.py b/representer.py
index 43f2c06..7b821fe 100644
--- a/representer.py
+++ b/representer.py
@@ -3,11 +3,14 @@
 from __future__ import print_function, absolute_import, division
 
 
-from ruamel.yaml.error import *                       # NOQA
-from ruamel.yaml.nodes import *                       # NOQA
+from ruamel.yaml.error import *  # NOQA
+from ruamel.yaml.nodes import *  # NOQA
 from ruamel.yaml.compat import text_type, binary_type, to_unicode, PY2, PY3, ordereddict
-from ruamel.yaml.scalarstring import (PreservedScalarString, SingleQuotedScalarString,
-                                      DoubleQuotedScalarString)
+from ruamel.yaml.scalarstring import (
+    PreservedScalarString,
+    SingleQuotedScalarString,
+    DoubleQuotedScalarString,
+)
 from ruamel.yaml.scalarint import ScalarInt, BinaryInt, OctalInt, HexInt, HexCapsInt
 from ruamel.yaml.scalarfloat import ScalarFloat
 from ruamel.yaml.timestamp import TimeStamp
@@ -15,6 +18,7 @@ from ruamel.yaml.timestamp import TimeStamp
 import datetime
 import sys
 import types
+
 if PY3:
     import copyreg
     import base64
@@ -22,11 +26,12 @@ else:
     import copy_reg as copyreg  # type: ignore
 
 if False:  # MYPY
-    from typing import Dict, List, Any, Union, Text   # NOQA
-
+    from typing import Dict, List, Any, Union, Text  # NOQA
 
+# fmt: off
 __all__ = ['BaseRepresenter', 'SafeRepresenter', 'Representer',
            'RepresenterError', 'RoundTripRepresenter']
+# fmt: on
 
 
 class RepresenterError(YAMLError):
@@ -34,6 +39,7 @@ class RepresenterError(YAMLError):
 
 
 if PY2:
+
     def get_classobj_bases(cls):
         # type: (Any) -> Any
         bases = [cls]
@@ -44,7 +50,7 @@ if PY2:
 
 class BaseRepresenter(object):
 
-    yaml_representers = {}   # type: Dict[Any, Any]
+    yaml_representers = {}  # type: Dict[Any, Any]
     yaml_multi_representers = {}  # type: Dict[Any, Any]
 
     def __init__(self, default_style=None, default_flow_style=None, dumper=None):
@@ -63,8 +69,8 @@ class BaseRepresenter(object):
         # type: () -> Any
         try:
             if hasattr(self.dumper, 'typ'):
-                return self.dumper.serializer  # type: ignore
-            return self.dumper._serializer  # type: ignore
+                return self.dumper.serializer
+            return self.dumper._serializer
         except AttributeError:
             return self  # cyaml
 
@@ -95,8 +101,7 @@ class BaseRepresenter(object):
         if PY2:
             # if type(data) is types.InstanceType:
             if isinstance(data, types.InstanceType):
-                data_types = get_classobj_bases(data.__class__) + \
-                    list(data_types)
+                data_types = get_classobj_bases(data.__class__) + list(data_types)
         if data_types[0] in self.yaml_representers:
             node = self.yaml_representers[data_types[0]](self, data)
         else:
@@ -206,8 +211,7 @@ class BaseRepresenter(object):
             node_value = self.represent_data(item_value)
             if not (isinstance(node_key, ScalarNode) and not node_key.style):
                 best_style = False
-            if not (isinstance(node_value, ScalarNode) and not
-                    node_value.style):
+            if not (isinstance(node_value, ScalarNode) and not node_value.style):
                 best_style = False
             value.append((node_key, node_value))
         if flow_style is None:
@@ -223,7 +227,6 @@ class BaseRepresenter(object):
 
 
 class SafeRepresenter(BaseRepresenter):
-
     def ignore_aliases(self, data):
         # type: (Any) -> bool
         # https://docs.python.org/3/reference/expressions.html#parenthesized-forms :
@@ -240,6 +243,7 @@ class SafeRepresenter(BaseRepresenter):
         return self.represent_scalar(u'tag:yaml.org,2002:null', u'null')
 
     if PY3:
+
         def represent_str(self, data):
             # type: (Any) -> Any
             return self.represent_scalar(u'tag:yaml.org,2002:str', data)
@@ -250,9 +254,10 @@ class SafeRepresenter(BaseRepresenter):
                 data = base64.encodebytes(data).decode('ascii')
             else:
                 data = base64.encodestring(data).decode('ascii')
-            return self.represent_scalar(u'tag:yaml.org,2002:binary', data,
-                                         style='|')
+            return self.represent_scalar(u'tag:yaml.org,2002:binary', data, style='|')
+
     else:
+
         def represent_str(self, data):
             # type: (Any) -> Any
             tag = None
@@ -277,7 +282,7 @@ class SafeRepresenter(BaseRepresenter):
     def represent_bool(self, data):
         # type: (Any) -> Any
         try:
-            value = self.dumper.boolean_representation[bool(data)]  # type: ignore
+            value = self.dumper.boolean_representation[bool(data)]
         except AttributeError:
             if data:
                 value = u'true'
@@ -290,10 +295,10 @@ class SafeRepresenter(BaseRepresenter):
         return self.represent_scalar(u'tag:yaml.org,2002:int', text_type(data))
 
     if PY2:
+
         def represent_long(self, data):
             # type: (Any) -> Any
-            return self.represent_scalar(u'tag:yaml.org,2002:int',
-                                         text_type(data))
+            return self.represent_scalar(u'tag:yaml.org,2002:int', text_type(data))
 
     inf_value = 1e300
     while repr(inf_value) != repr(inf_value * inf_value):
@@ -330,12 +335,13 @@ class SafeRepresenter(BaseRepresenter):
         #             pairs = False
         #             break
         # if not pairs:
-            return self.represent_sequence(u'tag:yaml.org,2002:seq', data)
-        # value = []
-        # for item_key, item_value in data:
-        #     value.append(self.represent_mapping(u'tag:yaml.org,2002:map',
-        #         [(item_key, item_value)]))
-        # return SequenceNode(u'tag:yaml.org,2002:pairs', value)
+        return self.represent_sequence(u'tag:yaml.org,2002:seq', data)
+
+    # value = []
+    # for item_key, item_value in data:
+    #     value.append(self.represent_mapping(u'tag:yaml.org,2002:map',
+    #         [(item_key, item_value)]))
+    # return SequenceNode(u'tag:yaml.org,2002:pairs', value)
 
     def represent_dict(self, data):
         # type: (Any) -> Any
@@ -372,67 +378,54 @@ class SafeRepresenter(BaseRepresenter):
 
     def represent_undefined(self, data):
         # type: (Any) -> None
-        raise RepresenterError("cannot represent an object: %s" % data)
+        raise RepresenterError('cannot represent an object: %s' % data)
 
 
-SafeRepresenter.add_representer(type(None),
-                                SafeRepresenter.represent_none)
+SafeRepresenter.add_representer(type(None), SafeRepresenter.represent_none)
 
-SafeRepresenter.add_representer(str,
-                                SafeRepresenter.represent_str)
+SafeRepresenter.add_representer(str, SafeRepresenter.represent_str)
 
 if PY2:
-    SafeRepresenter.add_representer(unicode,
-                                    SafeRepresenter.represent_unicode)
+    SafeRepresenter.add_representer(unicode, SafeRepresenter.represent_unicode)
 else:
-    SafeRepresenter.add_representer(bytes,
-                                    SafeRepresenter.represent_binary)
+    SafeRepresenter.add_representer(bytes, SafeRepresenter.represent_binary)
 
-SafeRepresenter.add_representer(bool,
-                                SafeRepresenter.represent_bool)
+SafeRepresenter.add_representer(bool, SafeRepresenter.represent_bool)
 
-SafeRepresenter.add_representer(int,
-                                SafeRepresenter.represent_int)
+SafeRepresenter.add_representer(int, SafeRepresenter.represent_int)
 
 if PY2:
-    SafeRepresenter.add_representer(long,
-                                    SafeRepresenter.represent_long)
+    SafeRepresenter.add_representer(long, SafeRepresenter.represent_long)
 
-SafeRepresenter.add_representer(float,
-                                SafeRepresenter.represent_float)
+SafeRepresenter.add_representer(float, SafeRepresenter.represent_float)
 
-SafeRepresenter.add_representer(list,
-                                SafeRepresenter.represent_list)
+SafeRepresenter.add_representer(list, SafeRepresenter.represent_list)
 
-SafeRepresenter.add_representer(tuple,
-                                SafeRepresenter.represent_list)
+SafeRepresenter.add_representer(tuple, SafeRepresenter.represent_list)
 
-SafeRepresenter.add_representer(dict,
-                                SafeRepresenter.represent_dict)
+SafeRepresenter.add_representer(dict, SafeRepresenter.represent_dict)
 
-SafeRepresenter.add_representer(set,
-                                SafeRepresenter.represent_set)
+SafeRepresenter.add_representer(set, SafeRepresenter.represent_set)
 
-SafeRepresenter.add_representer(ordereddict,
-                                SafeRepresenter.represent_ordereddict)
+SafeRepresenter.add_representer(ordereddict, SafeRepresenter.represent_ordereddict)
 
 if sys.version_info >= (2, 7):
     import collections
-    SafeRepresenter.add_representer(collections.OrderedDict,
-                                    SafeRepresenter.represent_ordereddict)
 
-SafeRepresenter.add_representer(datetime.date,
-                                SafeRepresenter.represent_date)
+    SafeRepresenter.add_representer(
+        collections.OrderedDict, SafeRepresenter.represent_ordereddict
+    )
+
+SafeRepresenter.add_representer(datetime.date, SafeRepresenter.represent_date)
 
-SafeRepresenter.add_representer(datetime.datetime,
-                                SafeRepresenter.represent_datetime)
+SafeRepresenter.add_representer(datetime.datetime, SafeRepresenter.represent_datetime)
 
-SafeRepresenter.add_representer(None,
-                                SafeRepresenter.represent_undefined)
+SafeRepresenter.add_representer(None, SafeRepresenter.represent_undefined)
 
 
 class Representer(SafeRepresenter):
     if PY2:
+
         def represent_str(self, data):
             # type: (Any) -> Any
             tag = None
@@ -486,15 +479,14 @@ class Representer(SafeRepresenter):
     def represent_name(self, data):
         # type: (Any) -> Any
         name = u'%s.%s' % (data.__module__, data.__name__)
-        return self.represent_scalar(u'tag:yaml.org,2002:python/name:' +
-                                     name, u'')
+        return self.represent_scalar(u'tag:yaml.org,2002:python/name:' + name, "")
 
     def represent_module(self, data):
         # type: (Any) -> Any
-        return self.represent_scalar(
-            u'tag:yaml.org,2002:python/module:' + data.__name__, u'')
+        return self.represent_scalar(u'tag:yaml.org,2002:python/module:' + data.__name__, "")
 
     if PY2:
+
         def represent_instance(self, data):
             # type: (Any) -> Any
             # For instances of classic classes, we use __getinitargs__ and
@@ -526,17 +518,19 @@ class Representer(SafeRepresenter):
                 state = data.__dict__
             if args is None and isinstance(state, dict):
                 return self.represent_mapping(
-                    u'tag:yaml.org,2002:python/object:' + class_name, state)
+                    u'tag:yaml.org,2002:python/object:' + class_name, state
+                )
             if isinstance(state, dict) and not state:
                 return self.represent_sequence(
-                    u'tag:yaml.org,2002:python/object/new:' +
-                    class_name, args)
+                    u'tag:yaml.org,2002:python/object/new:' + class_name, args
+                )
             value = {}
             if bool(args):
                 value['args'] = args
             value['state'] = state  # type: ignore
             return self.represent_mapping(
-                u'tag:yaml.org,2002:python/object/new:' + class_name, value)
+                u'tag:yaml.org,2002:python/object/new:' + class_name, value
+            )
 
     def represent_object(self, data):
         # type: (Any) -> Any
@@ -564,7 +558,7 @@ class Representer(SafeRepresenter):
         elif hasattr(data, '__reduce__'):
             reduce = data.__reduce__()
         else:
-            raise RepresenterError("cannot represent object: %r" % data)
+            raise RepresenterError('cannot represent object: %r' % data)
         reduce = (list(reduce) + [None] * 5)[:5]
         function, args, state, listitems, dictitems = reduce
         args = list(args)
@@ -583,12 +577,11 @@ class Representer(SafeRepresenter):
             tag = u'tag:yaml.org,2002:python/object/apply:'
             newobj = False
         function_name = u'%s.%s' % (function.__module__, function.__name__)
-        if not args and not listitems and not dictitems \
-                and isinstance(state, dict) and newobj:
+        if not args and not listitems and not dictitems and isinstance(state, dict) and newobj:
             return self.represent_mapping(
-                u'tag:yaml.org,2002:python/object:' + function_name, state)
-        if not listitems and not dictitems  \
-                and isinstance(state, dict) and not state:
+                u'tag:yaml.org,2002:python/object:' + function_name, state
+            )
+        if not listitems and not dictitems and isinstance(state, dict) and not state:
             return self.represent_sequence(tag + function_name, args)
         value = {}
         if args:
@@ -603,47 +596,43 @@ class Representer(SafeRepresenter):
 
 
 if PY2:
-    Representer.add_representer(str,
-                                Representer.represent_str)
+    Representer.add_representer(str, Representer.represent_str)
 
-    Representer.add_representer(unicode,
-                                Representer.represent_unicode)
+    Representer.add_representer(unicode, Representer.represent_unicode)
 
-    Representer.add_representer(long,
-                                Representer.represent_long)
+    Representer.add_representer(long, Representer.represent_long)
 
-Representer.add_representer(complex,
-                            Representer.represent_complex)
+Representer.add_representer(complex, Representer.represent_complex)
 
-Representer.add_representer(tuple,
-                            Representer.represent_tuple)
+Representer.add_representer(tuple, Representer.represent_tuple)
 
-Representer.add_representer(type,
-                            Representer.represent_name)
+Representer.add_representer(type, Representer.represent_name)
 
 if PY2:
-    Representer.add_representer(types.ClassType,
-                                Representer.represent_name)
+    Representer.add_representer(types.ClassType, Representer.represent_name)
 
-Representer.add_representer(types.FunctionType,
-                            Representer.represent_name)
+Representer.add_representer(types.FunctionType, Representer.represent_name)
 
-Representer.add_representer(types.BuiltinFunctionType,
-                            Representer.represent_name)
+Representer.add_representer(types.BuiltinFunctionType, Representer.represent_name)
 
-Representer.add_representer(types.ModuleType,
-                            Representer.represent_module)
+Representer.add_representer(types.ModuleType, Representer.represent_module)
 
 if PY2:
-    Representer.add_multi_representer(types.InstanceType,
-                                      Representer.represent_instance)
+    Representer.add_multi_representer(types.InstanceType, Representer.represent_instance)
 
-Representer.add_multi_representer(object,
-                                  Representer.represent_object)
+Representer.add_multi_representer(object, Representer.represent_object)
 
 
-from ruamel.yaml.comments import (CommentedMap, CommentedOrderedMap, CommentedSeq,
-    CommentedKeySeq, CommentedSet, comment_attrib, merge_attrib, TaggedScalar)    # NOQA
+from ruamel.yaml.comments import (
+    CommentedMap,
+    CommentedOrderedMap,
+    CommentedSeq,
+    CommentedKeySeq,
+    CommentedSet,
+    comment_attrib,
+    merge_attrib,
+    TaggedScalar,
+)  # NOQA
 
 
 class RoundTripRepresenter(SafeRepresenter):
@@ -654,16 +643,19 @@ class RoundTripRepresenter(SafeRepresenter):
         # type: (Any, Any, Any) -> None
         if not hasattr(dumper, 'typ') and default_flow_style is None:
             default_flow_style = False
-        SafeRepresenter.__init__(self, default_style=default_style,
-                                 default_flow_style=default_flow_style,
-                                 dumper=dumper)
+        SafeRepresenter.__init__(
+            self,
+            default_style=default_style,
+            default_flow_style=default_flow_style,
+            dumper=dumper,
+        )
 
     def represent_none(self, data):
         # type: (Any) -> Any
         if len(self.represented_objects) == 0 and not self.serializer.use_explicit_start:
             # this will be open ended (although it is not yet)
             return self.represent_scalar(u'tag:yaml.org,2002:null', u'null')
-        return self.represent_scalar(u'tag:yaml.org,2002:null', u'')
+        return self.represent_scalar(u'tag:yaml.org,2002:null', "")
 
     def represent_preserved_scalarstring(self, data):
         # type: (Any) -> Any
@@ -702,7 +694,7 @@ class RoundTripRepresenter(SafeRepresenter):
             while pos > 0:
                 sl.insert(pos, '_')
                 pos -= underscore[0]
-            s = ''.join(sl)
+            s = "".join(sl)
         if underscore[1]:
             s = '_' + s
         if underscore[2]:
@@ -715,7 +707,7 @@ class RoundTripRepresenter(SafeRepresenter):
             s = '{:0{}d}'.format(data, data._width)
         else:
             s = format(data, 'd')
-        return self.insert_underscore('', s, data._underscore)
+        return self.insert_underscore("", s, data._underscore)
 
     def represent_binary_int(self, data):
         # type: (Any) -> Any
@@ -767,17 +759,18 @@ class RoundTripRepresenter(SafeRepresenter):
             return self.represent_scalar(u'tag:yaml.org,2002:float', value)
         if data._exp is None and data._prec > 0 and data._prec == data._width - 1:
             # no exponent, but trailing dot
-            value = u'{}{:d}.'.format(data._m_sign if data._m_sign else u'', abs(int(data)))
+            value = u'{}{:d}.'.format(data._m_sign if data._m_sign else "", abs(int(data)))
         elif data._exp is None:
             # no exponent, "normal" dot
             prec = data._prec
             if prec < 1:
                 prec = 1
             # print('dw2', data._width, prec)
-            ms = data._m_sign if data._m_sign else u''
+            ms = data._m_sign if data._m_sign else ""
             # -1 for the dot
-            value = u'{}{:0{}.{}f}'.format(ms, abs(data), data._width - len(ms),
-                                           data._width - prec - 1)
+            value = u'{}{:0{}.{}f}'.format(
+                ms, abs(data), data._width - len(ms), data._width - prec - 1
+            )
             while len(value) < data._width:
                 value += u'0'
         else:
@@ -795,32 +788,34 @@ class RoundTripRepresenter(SafeRepresenter):
                 m2 += u'0'
             if data._m_sign and data > 0:
                 m1 = '+' + m1
-            esgn = u'+' if data._e_sign else u''
-            if data._prec < 0:   # mantissa without dot
+            esgn = u'+' if data._e_sign else ""
+            if data._prec < 0:  # mantissa without dot
                 if m2 != u'0':
                     e -= len(m2)
                 else:
-                    m2 = u''
+                    m2 = ""
                 while (len(m1) + len(m2) - (1 if data._m_sign else 0)) < data._width:
                     m2 += u'0'
                     e -= 1
                 value = m1 + m2 + data._exp + u'{:{}0{}d}'.format(e, esgn, data._e_width)
-            elif data._prec == 0:   # mantissa with trailing dot
+            elif data._prec == 0:  # mantissa with trailing dot
                 e -= len(m2)
-                value = m1 + m2 + u'.' + data._exp + u'{:{}0{}d}'.format(
-                    e, esgn, data._e_width)
+                value = (
+                    m1 + m2 + u'.' + data._exp + u'{:{}0{}d}'.format(e, esgn, data._e_width)
+                )
             else:
                 if data._m_lead0 > 0:
                     m2 = u'0' * (data._m_lead0 - 1) + m1 + m2
                     m1 = u'0'
-                    m2 = m2[:-data._m_lead0]  # these should be zeros
+                    m2 = m2[: -data._m_lead0]  # these should be zeros
                     e += data._m_lead0
                 while len(m1) < data._prec:
                     m1 += m2[0]
                     m2 = m2[1:]
                     e -= 1
-                value = m1 + u'.' + m2 + data._exp + u'{:{}0{}d}'.format(
-                    e, esgn, data._e_width)
+                value = (
+                    m1 + u'.' + m2 + data._exp + u'{:{}0{}d}'.format(e, esgn, data._e_width)
+                )
 
         if value is None:
             value = to_unicode(repr(data)).lower()
@@ -881,8 +876,7 @@ class RoundTripRepresenter(SafeRepresenter):
         # type: (Any) -> Any
         if isinstance(data, CommentedKeySeq):
             self.alias_key = None
-            return self.represent_sequence(u'tag:yaml.org,2002:seq', data,
-                                           flow_style=True)
+            return self.represent_sequence(u'tag:yaml.org,2002:seq', data, flow_style=True)
         return SafeRepresenter.represent_key(self, data)
 
     def represent_mapping(self, tag, mapping, flow_style=None):
@@ -938,8 +932,7 @@ class RoundTripRepresenter(SafeRepresenter):
                     node_value.comment = item_comment[2:]
             if not (isinstance(node_key, ScalarNode) and not node_key.style):
                 best_style = False
-            if not (isinstance(node_value, ScalarNode) and not
-                    node_value.style):
+            if not (isinstance(node_value, ScalarNode) and not node_value.style):
                 best_style = False
             value.append((node_key, node_value))
         if flow_style is None:
@@ -955,8 +948,7 @@ class RoundTripRepresenter(SafeRepresenter):
             else:
                 arg = self.represent_data(merge_list)
                 arg.flow_style = True
-            value.insert(0,
-                         (ScalarNode(u'tag:yaml.org,2002:merge', '<<'), arg))
+            value.insert(0, (ScalarNode(u'tag:yaml.org,2002:merge', '<<'), arg))
         return node
 
     def represent_omap(self, tag, omap, flow_style=None):
@@ -1059,11 +1051,10 @@ class RoundTripRepresenter(SafeRepresenter):
             if item_comment:
                 assert getattr(node_key, 'comment', None) is None
                 node_key.comment = item_comment[:2]
-            node_key.style = node_value.style = "?"
+            node_key.style = node_value.style = '?'
             if not (isinstance(node_key, ScalarNode) and not node_key.style):
                 best_style = False
-            if not (isinstance(node_value, ScalarNode) and not
-                    node_value.style):
+            if not (isinstance(node_value, ScalarNode) and not node_value.style):
                 best_style = False
             value.append((node_key, node_value))
         best_style = best_style
@@ -1099,6 +1090,7 @@ class RoundTripRepresenter(SafeRepresenter):
         return self.represent_scalar(u'tag:yaml.org,2002:timestamp', to_unicode(value))
 
     def represent_tagged_scalar(self, data):
+        # type: (Any) -> Any
         try:
             tag = data.tag.value
         except AttributeError:
@@ -1106,64 +1098,51 @@ class RoundTripRepresenter(SafeRepresenter):
         return self.represent_scalar(tag, data.value, style=data.style)
 
 
-RoundTripRepresenter.add_representer(type(None),
-                                     RoundTripRepresenter.represent_none)
+RoundTripRepresenter.add_representer(type(None), RoundTripRepresenter.represent_none)
 
 RoundTripRepresenter.add_representer(
-    PreservedScalarString,
-    RoundTripRepresenter.represent_preserved_scalarstring)
+    PreservedScalarString, RoundTripRepresenter.represent_preserved_scalarstring
+)
 
 RoundTripRepresenter.add_representer(
-    SingleQuotedScalarString,
-    RoundTripRepresenter.represent_single_quoted_scalarstring)
+    SingleQuotedScalarString, RoundTripRepresenter.represent_single_quoted_scalarstring
+)
 
 RoundTripRepresenter.add_representer(
-    DoubleQuotedScalarString,
-    RoundTripRepresenter.represent_double_quoted_scalarstring)
+    DoubleQuotedScalarString, RoundTripRepresenter.represent_double_quoted_scalarstring
+)
 
-RoundTripRepresenter.add_representer(
-    ScalarInt,
-    RoundTripRepresenter.represent_scalar_int)
+RoundTripRepresenter.add_representer(ScalarInt, RoundTripRepresenter.represent_scalar_int)
 
-RoundTripRepresenter.add_representer(
-    BinaryInt,
-    RoundTripRepresenter.represent_binary_int)
+RoundTripRepresenter.add_representer(BinaryInt, RoundTripRepresenter.represent_binary_int)
 
-RoundTripRepresenter.add_representer(
-    OctalInt,
-    RoundTripRepresenter.represent_octal_int)
+RoundTripRepresenter.add_representer(OctalInt, RoundTripRepresenter.represent_octal_int)
 
-RoundTripRepresenter.add_representer(
-    HexInt,
-    RoundTripRepresenter.represent_hex_int)
+RoundTripRepresenter.add_representer(HexInt, RoundTripRepresenter.represent_hex_int)
 
-RoundTripRepresenter.add_representer(
-    HexCapsInt,
-    RoundTripRepresenter.represent_hex_caps_int)
+RoundTripRepresenter.add_representer(HexCapsInt, RoundTripRepresenter.represent_hex_caps_int)
 
-RoundTripRepresenter.add_representer(
-    ScalarFloat,
-    RoundTripRepresenter.represent_scalar_float)
+RoundTripRepresenter.add_representer(ScalarFloat, RoundTripRepresenter.represent_scalar_float)
 
-RoundTripRepresenter.add_representer(CommentedSeq,
-                                     RoundTripRepresenter.represent_list)
+RoundTripRepresenter.add_representer(CommentedSeq, RoundTripRepresenter.represent_list)
 
-RoundTripRepresenter.add_representer(CommentedMap,
-                                     RoundTripRepresenter.represent_dict)
+RoundTripRepresenter.add_representer(CommentedMap, RoundTripRepresenter.represent_dict)
 
-RoundTripRepresenter.add_representer(CommentedOrderedMap,
-                                     RoundTripRepresenter.represent_ordereddict)
+RoundTripRepresenter.add_representer(
+    CommentedOrderedMap, RoundTripRepresenter.represent_ordereddict
+)
 
 if sys.version_info >= (2, 7):
     import collections
-    RoundTripRepresenter.add_representer(collections.OrderedDict,
-                                         RoundTripRepresenter.represent_ordereddict)
 
-RoundTripRepresenter.add_representer(CommentedSet,
-                                     RoundTripRepresenter.represent_set)
+    RoundTripRepresenter.add_representer(
+        collections.OrderedDict, RoundTripRepresenter.represent_ordereddict
+    )
+
+RoundTripRepresenter.add_representer(CommentedSet, RoundTripRepresenter.represent_set)
 
-RoundTripRepresenter.add_representer(TaggedScalar,
-                                     RoundTripRepresenter.represent_tagged_scalar)
+RoundTripRepresenter.add_representer(
+    TaggedScalar, RoundTripRepresenter.represent_tagged_scalar
+)
 
-RoundTripRepresenter.add_representer(TimeStamp,
-                                     RoundTripRepresenter.represent_datetime)
+RoundTripRepresenter.add_representer(TimeStamp, RoundTripRepresenter.represent_datetime)
diff --git a/resolver.py b/resolver.py
index 905bebe..6b8c56e 100644
--- a/resolver.py
+++ b/resolver.py
@@ -5,17 +5,18 @@ from __future__ import absolute_import
 import re
 
 if False:  # MYPY
-    from typing import Any, Dict, List, Union  # NOQA
+    from typing import Any, Dict, List, Union, Text  # NOQA
     from ruamel.yaml.compat import VersionType  # NOQA
 
 from ruamel.yaml.compat import string_types, _DEFAULT_YAML_VERSION  # NOQA
-from ruamel.yaml.error import *                               # NOQA
-from ruamel.yaml.nodes import *                               # NOQA
+from ruamel.yaml.error import *  # NOQA
+from ruamel.yaml.nodes import MappingNode, ScalarNode, SequenceNode  # NOQA
 from ruamel.yaml.util import RegExp  # NOQA
 
 __all__ = ['BaseResolver', 'Resolver', 'VersionedResolver']
 
 
+# fmt: off
 # resolvers consist of
 # - a list of applicable version
 # - a tag
@@ -95,6 +96,7 @@ implicit_resolvers = [
         RegExp(u'^(?:!|&|\\*)$'),
         list(u'!&*')),
 ]
+# fmt: on
 
 
 class ResolverError(YAMLError):
@@ -108,7 +110,7 @@ class BaseResolver(object):
     DEFAULT_MAPPING_TAG = u'tag:yaml.org,2002:map'
 
     yaml_implicit_resolvers = {}  # type: Dict[Any, Any]
-    yaml_path_resolvers = {}      # type: Dict[Any, Any]
+    yaml_path_resolvers = {}  # type: Dict[Any, Any]
 
     def __init__(self, loadumper=None):
         # type: (Any, Any) -> None
@@ -133,26 +135,26 @@ class BaseResolver(object):
         # type: (Any, Any, Any) -> None
         if 'yaml_implicit_resolvers' not in cls.__dict__:
             # deepcopy doesn't work here
-            cls.yaml_implicit_resolvers = dict((k, cls.yaml_implicit_resolvers[k][:])
-                                               for k in cls.yaml_implicit_resolvers)
+            cls.yaml_implicit_resolvers = dict(
+                (k, cls.yaml_implicit_resolvers[k][:]) for k in cls.yaml_implicit_resolvers
+            )
         if first is None:
             first = [None]
         for ch in first:
-            cls.yaml_implicit_resolvers.setdefault(ch, []).append(
-                (tag, regexp))
+            cls.yaml_implicit_resolvers.setdefault(ch, []).append((tag, regexp))
 
     @classmethod
     def add_implicit_resolver(cls, tag, regexp, first):
         # type: (Any, Any, Any) -> None
         if 'yaml_implicit_resolvers' not in cls.__dict__:
             # deepcopy doesn't work here
-            cls.yaml_implicit_resolvers = dict((k, cls.yaml_implicit_resolvers[k][:])
-                                               for k in cls.yaml_implicit_resolvers)
+            cls.yaml_implicit_resolvers = dict(
+                (k, cls.yaml_implicit_resolvers[k][:]) for k in cls.yaml_implicit_resolvers
+            )
         if first is None:
             first = [None]
         for ch in first:
-            cls.yaml_implicit_resolvers.setdefault(ch, []).append(
-                (tag, regexp))
+            cls.yaml_implicit_resolvers.setdefault(ch, []).append((tag, regexp))
         implicit_resolvers.append(([(1, 2), (1, 1)], tag, regexp, first))
 
     # @classmethod
@@ -179,12 +181,12 @@ class BaseResolver(object):
         for element in path:
             if isinstance(element, (list, tuple)):
                 if len(element) == 2:
-                    node_check, index_check = element  # type: ignore
+                    node_check, index_check = element
                 elif len(element) == 1:
                     node_check = element[0]
                     index_check = True
                 else:
-                    raise ResolverError("Invalid path element: %s" % element)
+                    raise ResolverError('Invalid path element: %s' % element)
             else:
                 node_check = None
                 index_check = element
@@ -194,13 +196,14 @@ class BaseResolver(object):
                 node_check = SequenceNode
             elif node_check is dict:
                 node_check = MappingNode
-            elif node_check not in [ScalarNode, SequenceNode, MappingNode]  \
-                    and not isinstance(node_check, string_types)  \
-                    and node_check is not None:
-                raise ResolverError("Invalid node checker: %s" % node_check)
-            if not isinstance(index_check, (string_types, int))   \
-                    and index_check is not None:
-                raise ResolverError("Invalid index checker: %s" % index_check)
+            elif (
+                node_check not in [ScalarNode, SequenceNode, MappingNode]
+                and not isinstance(node_check, string_types)
+                and node_check is not None
+            ):
+                raise ResolverError('Invalid node checker: %s' % node_check)
+            if not isinstance(index_check, (string_types, int)) and index_check is not None:
+                raise ResolverError('Invalid index checker: %s' % index_check)
             new_path.append((node_check, index_check))
         if kind is str:
             kind = ScalarNode
@@ -208,9 +211,8 @@ class BaseResolver(object):
             kind = SequenceNode
         elif kind is dict:
             kind = MappingNode
-        elif kind not in [ScalarNode, SequenceNode, MappingNode]    \
-                and kind is not None:
-            raise ResolverError("Invalid node kind: %s" % kind)
+        elif kind not in [ScalarNode, SequenceNode, MappingNode] and kind is not None:
+            raise ResolverError('Invalid node kind: %s' % kind)
         cls.yaml_path_resolvers[tuple(new_path), kind] = tag
 
     def descend_resolver(self, current_node, current_index):
@@ -224,13 +226,11 @@ class BaseResolver(object):
         if current_node:
             depth = len(self.resolver_prefix_paths)
             for path, kind in self.resolver_prefix_paths[-1]:
-                if self.check_resolver_prefix(depth, path, kind,
-                                              current_node, current_index):
+                if self.check_resolver_prefix(depth, path, kind, current_node, current_index):
                     if len(path) > depth:
                         prefix_paths.append((path, kind))
                     else:
-                        exact_paths[kind] = self.yaml_path_resolvers[path,
-                                                                     kind]
+                        exact_paths[kind] = self.yaml_path_resolvers[path, kind]
         else:
             for path, kind in self.yaml_path_resolvers:
                 if not path:
@@ -247,8 +247,7 @@ class BaseResolver(object):
         self.resolver_exact_paths.pop()
         self.resolver_prefix_paths.pop()
 
-    def check_resolver_prefix(self, depth, path, kind,
-                              current_node, current_index):
+    def check_resolver_prefix(self, depth, path, kind, current_node, current_index):
         # type: (int, Text, Any, Any, Any) -> bool
         node_check, index_check = path[depth - 1]
         if isinstance(node_check, string_types):
@@ -259,15 +258,14 @@ class BaseResolver(object):
                 return False
         if index_check is True and current_index is not None:
             return False
-        if (index_check is False or index_check is None)    \
-                and current_index is None:
+        if (index_check is False or index_check is None) and current_index is None:
             return False
         if isinstance(index_check, string_types):
-            if not (isinstance(current_index, ScalarNode) and
-                    index_check == current_index.value):
+            if not (
+                isinstance(current_index, ScalarNode) and index_check == current_index.value
+            ):
                 return False
-        elif isinstance(index_check, int) and not isinstance(index_check,
-                                                             bool):
+        elif isinstance(index_check, int) and not isinstance(index_check, bool):
             if index_check != current_index:
                 return False
         return True
@@ -275,8 +273,8 @@ class BaseResolver(object):
     def resolve(self, kind, value, implicit):
         # type: (Any, Any, Any) -> Any
         if kind is ScalarNode and implicit[0]:
-            if value == u'':
-                resolvers = self.yaml_implicit_resolvers.get(u'', [])
+            if value == "":
+                resolvers = self.yaml_implicit_resolvers.get("", [])
             else:
                 resolvers = self.yaml_implicit_resolvers.get(value[0], [])
             resolvers += self.yaml_implicit_resolvers.get(None, [])
@@ -307,6 +305,7 @@ class Resolver(BaseResolver):
     pass
 
 
+# fmt: off
 Resolver.add_implicit_resolver_base(
     u'tag:yaml.org,2002:bool',
     RegExp(u'''^(?:yes|Yes|YES|no|No|NO
@@ -366,6 +365,7 @@ Resolver.add_implicit_resolver_base(
     u'tag:yaml.org,2002:yaml',
     RegExp(u'^(?:!|&|\\*)$'),
     list(u'!&*'))
+# fmt: on
 
 
 class VersionedResolver(BaseResolver):
@@ -377,7 +377,7 @@ class VersionedResolver(BaseResolver):
     """
 
     def __init__(self, version=None, loader=None):
-        # type: (VersionType, Any) -> None
+        # type: (Union[None, VersionType], Any) -> None
         BaseResolver.__init__(self, loader)
         self._loader_version = self.get_loader_version(version)
         self._version_implicit_resolver = {}  # type: Dict[Any, Any]
@@ -415,8 +415,8 @@ class VersionedResolver(BaseResolver):
     def resolve(self, kind, value, implicit):
         # type: (Any, Any, Any) -> Any
         if kind is ScalarNode and implicit[0]:
-            if value == u'':
-                resolvers = self.versioned_resolver.get(u'', [])
+            if value == "":
+                resolvers = self.versioned_resolver.get("", [])
             else:
                 resolvers = self.versioned_resolver.get(value[0], [])
             resolvers += self.versioned_resolver.get(None, [])
@@ -444,9 +444,9 @@ class VersionedResolver(BaseResolver):
             version = self.parser.yaml_version
         except AttributeError:
             if hasattr(self.loadumper, 'typ'):
-                version = self.loadumper.version  # type: ignore
+                version = self.loadumper.version
             else:
-                version = self.loadumper._serializer.use_version  # type: ignore  # dumping
+                version = self.loadumper._serializer.use_version  # dumping
         if version is None:
             version = self._loader_version
             if version is None:
diff --git a/scalarfloat.py b/scalarfloat.py
index fca8be2..83e0125 100644
--- a/scalarfloat.py
+++ b/scalarfloat.py
@@ -8,21 +8,21 @@ from .compat import no_limit_int  # NOQA
 if False:  # MYPY
     from typing import Text, Any, Dict, List  # NOQA
 
-__all__ = ["ScalarFloat", "ExponentialFloat", "ExponentialCapsFloat"]
+__all__ = ['ScalarFloat', 'ExponentialFloat', 'ExponentialCapsFloat']
 
 
 class ScalarFloat(float):
     def __new__(cls, *args, **kw):
         # type: (Any, Any, Any) -> Any
-        width = kw.pop('width', None)            # type: ignore
-        prec = kw.pop('prec', None)              # type: ignore
-        m_sign = kw.pop('m_sign', None)          # type: ignore
-        m_lead0 = kw.pop('m_lead0', 0)           # type: ignore
-        exp = kw.pop('exp', None)                # type: ignore
-        e_width = kw.pop('e_width', None)        # type: ignore
-        e_sign = kw.pop('e_sign', None)          # type: ignore
+        width = kw.pop('width', None)  # type: ignore
+        prec = kw.pop('prec', None)  # type: ignore
+        m_sign = kw.pop('m_sign', None)  # type: ignore
+        m_lead0 = kw.pop('m_lead0', 0)  # type: ignore
+        exp = kw.pop('exp', None)  # type: ignore
+        e_width = kw.pop('e_width', None)  # type: ignore
+        e_sign = kw.pop('e_sign', None)  # type: ignore
         underscore = kw.pop('underscore', None)  # type: ignore
-        v = float.__new__(cls, *args, **kw)      # type: ignore
+        v = float.__new__(cls, *args, **kw)  # type: ignore
         v._width = width
         v._prec = prec
         v._m_sign = m_sign
@@ -37,48 +37,58 @@ class ScalarFloat(float):
         # type: (Any) -> Any
         return float(self) + a
         x = type(self)(self + a)
-        x._width = self._width  # type: ignore
-        x._underscore = self._underscore[:] if self._underscore is not None else None  # type: ignore  # NOQA
+        x._width = self._width
+        x._underscore = self._underscore[:] if self._underscore is not None else None  # NOQA
         return x
 
     def __ifloordiv__(self, a):  # type: ignore
         # type: (Any) -> Any
         return float(self) // a
         x = type(self)(self // a)
-        x._width = self._width  # type: ignore
-        x._underscore = self._underscore[:] if self._underscore is not None else None  # type: ignore  # NOQA
+        x._width = self._width
+        x._underscore = self._underscore[:] if self._underscore is not None else None  # NOQA
         return x
 
     def __imul__(self, a):  # type: ignore
         # type: (Any) -> Any
         return float(self) * a
         x = type(self)(self * a)
-        x._width = self._width  # type: ignore
-        x._underscore = self._underscore[:] if self._underscore is not None else None  # type: ignore  # NOQA
-        x._prec = self._prec   # check for others
+        x._width = self._width
+        x._underscore = self._underscore[:] if self._underscore is not None else None  # NOQA
+        x._prec = self._prec  # check for others
         return x
 
     def __ipow__(self, a):  # type: ignore
         # type: (Any) -> Any
         return float(self) ** a
         x = type(self)(self ** a)
-        x._width = self._width  # type: ignore
-        x._underscore = self._underscore[:] if self._underscore is not None else None  # type: ignore  # NOQA
+        x._width = self._width
+        x._underscore = self._underscore[:] if self._underscore is not None else None  # NOQA
         return x
 
     def __isub__(self, a):  # type: ignore
         # type: (Any) -> Any
         return float(self) - a
         x = type(self)(self - a)
-        x._width = self._width  # type: ignore
-        x._underscore = self._underscore[:] if self._underscore is not None else None  # type: ignore  # NOQA
+        x._width = self._width
+        x._underscore = self._underscore[:] if self._underscore is not None else None  # NOQA
         return x
 
     def dump(self, out=sys.stdout):
         # type: (Any) -> Any
-        print('ScalarFloat({}| w:{}, p:{}, s:{}, lz:{}|{}, w:{}, s:{})'.format(
-            self, self._width, self._prec, self._m_sign, self._m_lead0,  # type: ignore
-            self._exp, self._e_width, self._e_sign), file=out)           # type: ignore
+        print(
+            'ScalarFloat({}| w:{}, p:{}, s:{}, lz:{}|{}, w:{}, s:{})'.format(
+                self,
+                self._width,  # type: ignore
+                self._prec,  # type: ignore
+                self._m_sign,  # type: ignore
+                self._m_lead0,  # type: ignore
+                self._exp,  # type: ignore
+                self._e_width,  # type: ignore
+                self._e_sign,  # type: ignore
+            ),
+            file=out,
+        )
 
 
 class ExponentialFloat(ScalarFloat):
diff --git a/scalarint.py b/scalarint.py
index d609236..2bd605d 100644
--- a/scalarint.py
+++ b/scalarint.py
@@ -5,7 +5,7 @@ from __future__ import print_function, absolute_import, division, unicode_litera
 if False:  # MYPY
     from typing import Text, Any, Dict, List  # NOQA
 
-__all__ = ["ScalarInt", "BinaryInt", "OctalInt", "HexInt", "HexCapsInt"]
+__all__ = ['ScalarInt', 'BinaryInt', 'OctalInt', 'HexInt', 'HexCapsInt']
 
 from .compat import no_limit_int  # NOQA
 
@@ -13,9 +13,9 @@ from .compat import no_limit_int  # NOQA
 class ScalarInt(no_limit_int):
     def __new__(cls, *args, **kw):
         # type: (Any, Any, Any) -> Any
-        width = kw.pop('width', None)            # type: ignore
+        width = kw.pop('width', None)  # type: ignore
         underscore = kw.pop('underscore', None)  # type: ignore
-        v = no_limit_int.__new__(cls, *args, **kw)        # type: ignore
+        v = no_limit_int.__new__(cls, *args, **kw)  # type: ignore
         v._width = width
         v._underscore = underscore
         return v
@@ -24,35 +24,45 @@ class ScalarInt(no_limit_int):
         # type: (Any) -> Any
         x = type(self)(self + a)
         x._width = self._width  # type: ignore
-        x._underscore = self._underscore[:] if self._underscore is not None else None  # type: ignore  # NOQA
+        x._underscore = (  # type: ignore
+            self._underscore[:] if self._underscore is not None else None  # type: ignore
+        )  # NOQA
         return x
 
     def __ifloordiv__(self, a):  # type: ignore
         # type: (Any) -> Any
         x = type(self)(self // a)
         x._width = self._width  # type: ignore
-        x._underscore = self._underscore[:] if self._underscore is not None else None  # type: ignore  # NOQA
+        x._underscore = (  # type: ignore
+            self._underscore[:] if self._underscore is not None else None  # type: ignore
+        )  # NOQA
         return x
 
     def __imul__(self, a):  # type: ignore
         # type: (Any) -> Any
         x = type(self)(self * a)
         x._width = self._width  # type: ignore
-        x._underscore = self._underscore[:] if self._underscore is not None else None  # type: ignore  # NOQA
+        x._underscore = (  # type: ignore
+            self._underscore[:] if self._underscore is not None else None  # type: ignore
+        )  # NOQA
         return x
 
     def __ipow__(self, a):  # type: ignore
         # type: (Any) -> Any
         x = type(self)(self ** a)
         x._width = self._width  # type: ignore
-        x._underscore = self._underscore[:] if self._underscore is not None else None  # type: ignore  # NOQA
+        x._underscore = (  # type: ignore
+            self._underscore[:] if self._underscore is not None else None  # type: ignore
+        )  # NOQA
         return x
 
     def __isub__(self, a):  # type: ignore
         # type: (Any) -> Any
         x = type(self)(self - a)
         x._width = self._width  # type: ignore
-        x._underscore = self._underscore[:] if self._underscore is not None else None  # type: ignore  # NOQA
+        x._underscore = (  # type: ignore
+            self._underscore[:] if self._underscore is not None else None  # type: ignore
+        )  # NOQA
         return x
 
 
@@ -71,8 +81,10 @@ class OctalInt(ScalarInt):
 # mixed casing of A-F is not supported, when loading the first non digit
 # determines the case
 
+
 class HexInt(ScalarInt):
     """uses lower case (a-f)"""
+
     def __new__(cls, value, width=None, underscore=None):
         # type: (Any, Any, Any) -> Any
         return ScalarInt.__new__(cls, value, width=width, underscore=underscore)
@@ -80,6 +92,7 @@ class HexInt(ScalarInt):
 
 class HexCapsInt(ScalarInt):
     """uses upper case (A-F)"""
+
     def __new__(cls, value, width=None, underscore=None):
         # type: (Any, Any, Any) -> Any
         return ScalarInt.__new__(cls, value, width=width, underscore=underscore)
diff --git a/scalarstring.py b/scalarstring.py
index 571230f..4b1a317 100644
--- a/scalarstring.py
+++ b/scalarstring.py
@@ -7,8 +7,12 @@ from ruamel.yaml.compat import text_type
 if False:  # MYPY
     from typing import Text, Any, Dict, List  # NOQA
 
-__all__ = ["ScalarString", "PreservedScalarString", "SingleQuotedScalarString",
-           "DoubleQuotedScalarString"]
+__all__ = [
+    'ScalarString',
+    'PreservedScalarString',
+    'SingleQuotedScalarString',
+    'DoubleQuotedScalarString',
+]
 
 
 class ScalarString(text_type):
@@ -26,7 +30,7 @@ class ScalarString(text_type):
 class PreservedScalarString(ScalarString):
     __slots__ = ()
 
-    style = "|"
+    style = '|'
 
     def __new__(cls, value):
         # type: (Text) -> Any
diff --git a/scanner.py b/scanner.py
index 0aab137..92fbf52 100644
--- a/scanner.py
+++ b/scanner.py
@@ -31,7 +31,7 @@ from __future__ import print_function, absolute_import, division, unicode_litera
 #
 
 from ruamel.yaml.error import MarkedYAMLError
-from ruamel.yaml.tokens import *                # NOQA
+from ruamel.yaml.tokens import *  # NOQA
 from ruamel.yaml.compat import utf8, unichr, PY3, check_anchorname_char, nprint  # NOQA
 
 if False:  # MYPY
@@ -41,9 +41,9 @@ if False:  # MYPY
 __all__ = ['Scanner', 'RoundTripScanner', 'ScannerError']
 
 
-_THE_END = u'\0\r\n\x85\u2028\u2029'
-_THE_END_SPACE_TAB = u'\0 \t\r\n\x85\u2028\u2029'
-_SPACE_TAB = u' \t'
+_THE_END = '\0\r\n\x85\u2028\u2029'
+_THE_END_SPACE_TAB = '\0 \t\r\n\x85\u2028\u2029'
+_SPACE_TAB = ' \t'
 
 
 class ScannerError(MarkedYAMLError):
@@ -64,7 +64,6 @@ class SimpleKey(object):
 
 
 class Scanner(object):
-
     def __init__(self, loader=None):
         # type: (Any) -> None
         """Initialize the scanner."""
@@ -141,8 +140,8 @@ class Scanner(object):
     def reader(self):
         # type: () -> Any
         if hasattr(self.loader, 'typ'):
-            self.loader.reader  # type: ignore
-        return self.loader._reader  # type: ignore
+            self.loader.reader
+        return self.loader._reader
 
     @property
     def scanner_processing_version(self):  # prefix until un-composited
@@ -219,19 +218,19 @@ class Scanner(object):
         ch = self.reader.peek()
 
         # Is it the end of stream?
-        if ch == u'\0':
+        if ch == '\0':
             return self.fetch_stream_end()
 
         # Is it a directive?
-        if ch == u'%' and self.check_directive():
+        if ch == '%' and self.check_directive():
             return self.fetch_directive()
 
         # Is it the document start?
-        if ch == u'-' and self.check_document_start():
+        if ch == '-' and self.check_document_start():
             return self.fetch_document_start()
 
         # Is it the document end?
-        if ch == u'.' and self.check_document_end():
+        if ch == '.' and self.check_document_end():
             return self.fetch_document_end()
 
         # TODO: support for BOM within a stream.
@@ -241,63 +240,63 @@ class Scanner(object):
         # Note: the order of the following checks is NOT significant.
 
         # Is it the flow sequence start indicator?
-        if ch == u'[':
+        if ch == '[':
             return self.fetch_flow_sequence_start()
 
         # Is it the flow mapping start indicator?
-        if ch == u'{':
+        if ch == '{':
             return self.fetch_flow_mapping_start()
 
         # Is it the flow sequence end indicator?
-        if ch == u']':
+        if ch == ']':
             return self.fetch_flow_sequence_end()
 
         # Is it the flow mapping end indicator?
-        if ch == u'}':
+        if ch == '}':
             return self.fetch_flow_mapping_end()
 
         # Is it the flow entry indicator?
-        if ch == u',':
+        if ch == ',':
             return self.fetch_flow_entry()
 
         # Is it the block entry indicator?
-        if ch == u'-' and self.check_block_entry():
+        if ch == '-' and self.check_block_entry():
             return self.fetch_block_entry()
 
         # Is it the key indicator?
-        if ch == u'?' and self.check_key():
+        if ch == '?' and self.check_key():
             return self.fetch_key()
 
         # Is it the value indicator?
-        if ch == u':' and self.check_value():
+        if ch == ':' and self.check_value():
             return self.fetch_value()
 
         # Is it an alias?
-        if ch == u'*':
+        if ch == '*':
             return self.fetch_alias()
 
         # Is it an anchor?
-        if ch == u'&':
+        if ch == '&':
             return self.fetch_anchor()
 
         # Is it a tag?
-        if ch == u'!':
+        if ch == '!':
             return self.fetch_tag()
 
         # Is it a literal scalar?
-        if ch == u'|' and not self.flow_level:
+        if ch == '|' and not self.flow_level:
             return self.fetch_literal()
 
         # Is it a folded scalar?
-        if ch == u'>' and not self.flow_level:
+        if ch == '>' and not self.flow_level:
             return self.fetch_folded()
 
         # Is it a single quoted scalar?
-        if ch == u'\'':
+        if ch == "'":
             return self.fetch_single()
 
         # Is it a double quoted scalar?
-        if ch == u'\"':
+        if ch == '"':
             return self.fetch_double()
 
         # It must be a plain scalar then.
@@ -305,9 +304,12 @@ class Scanner(object):
             return self.fetch_plain()
 
         # No? It's an error. Let's produce a nice error message.
-        raise ScannerError("while scanning for the next token", None,
-                           "found character %r that cannot start any token"
-                           % utf8(ch), self.reader.get_mark())
+        raise ScannerError(
+            'while scanning for the next token',
+            None,
+            'found character %r that cannot start any token' % utf8(ch),
+            self.reader.get_mark(),
+        )
 
     # Simple keys treatment.
 
@@ -337,12 +339,14 @@ class Scanner(object):
         # height (may cause problems if indentation is broken though).
         for level in list(self.possible_simple_keys):
             key = self.possible_simple_keys[level]
-            if key.line != self.reader.line  \
-                    or self.reader.index - key.index > 1024:
+            if key.line != self.reader.line or self.reader.index - key.index > 1024:
                 if key.required:
                     raise ScannerError(
-                        "while scanning a simple key", key.mark,
-                        "could not find expected ':'", self.reader.get_mark())
+                        'while scanning a simple key',
+                        key.mark,
+                        "could not find expected ':'",
+                        self.reader.get_mark(),
+                    )
                 del self.possible_simple_keys[level]
 
     def save_possible_simple_key(self):
@@ -360,9 +364,13 @@ class Scanner(object):
             self.remove_possible_simple_key()
             token_number = self.tokens_taken + len(self.tokens)
             key = SimpleKey(
-                token_number, required,
-                self.reader.index, self.reader.line, self.reader.column,
-                self.reader.get_mark())
+                token_number,
+                required,
+                self.reader.index,
+                self.reader.line,
+                self.reader.column,
+                self.reader.get_mark(),
+            )
             self.possible_simple_keys[self.flow_level] = key
 
     def remove_possible_simple_key(self):
@@ -373,8 +381,11 @@ class Scanner(object):
 
             if key.required:
                 raise ScannerError(
-                    "while scanning a simple key", key.mark,
-                    "could not find expected ':'", self.reader.get_mark())
+                    'while scanning a simple key',
+                    key.mark,
+                    "could not find expected ':'",
+                    self.reader.get_mark(),
+                )
 
             del self.possible_simple_keys[self.flow_level]
 
@@ -423,8 +434,7 @@ class Scanner(object):
         # Read the token.
         mark = self.reader.get_mark()
         # Add STREAM-START.
-        self.tokens.append(StreamStartToken(mark, mark,
-                                            encoding=self.reader.encoding))
+        self.tokens.append(StreamStartToken(mark, mark, encoding=self.reader.encoding))
 
     def fetch_stream_end(self):
         # type: () -> None
@@ -539,9 +549,9 @@ class Scanner(object):
         if not self.flow_level:
             # Are we allowed to start a new entry?
             if not self.allow_simple_key:
-                raise ScannerError(None, None,
-                                   "sequence entries are not allowed here",
-                                   self.reader.get_mark())
+                raise ScannerError(
+                    None, None, 'sequence entries are not allowed here', self.reader.get_mark()
+                )
             # We may need to add BLOCK-SEQUENCE-START.
             if self.add_indent(self.reader.column):
                 mark = self.reader.get_mark()
@@ -568,9 +578,9 @@ class Scanner(object):
 
             # Are we allowed to start a key (not nessesary a simple)?
             if not self.allow_simple_key:
-                raise ScannerError(None, None,
-                                   "mapping keys are not allowed here",
-                                   self.reader.get_mark())
+                raise ScannerError(
+                    None, None, 'mapping keys are not allowed here', self.reader.get_mark()
+                )
 
             # We may need to add BLOCK-MAPPING-START.
             if self.add_indent(self.reader.column):
@@ -596,8 +606,9 @@ class Scanner(object):
             # Add KEY.
             key = self.possible_simple_keys[self.flow_level]
             del self.possible_simple_keys[self.flow_level]
-            self.tokens.insert(key.token_number - self.tokens_taken,
-                               KeyToken(key.mark, key.mark))
+            self.tokens.insert(
+                key.token_number - self.tokens_taken, KeyToken(key.mark, key.mark)
+            )
 
             # If this key starts a new block mapping, we need to add
             # BLOCK-MAPPING-START.
@@ -605,7 +616,8 @@ class Scanner(object):
                 if self.add_indent(key.column):
                     self.tokens.insert(
                         key.token_number - self.tokens_taken,
-                        BlockMappingStartToken(key.mark, key.mark))
+                        BlockMappingStartToken(key.mark, key.mark),
+                    )
 
             # There cannot be two simple keys one after another.
             self.allow_simple_key = False
@@ -621,9 +633,12 @@ class Scanner(object):
                 # We are allowed to start a complex value if and only if
                 # we can start a simple key.
                 if not self.allow_simple_key:
-                    raise ScannerError(None, None,
-                                       "mapping values are not allowed here",
-                                       self.reader.get_mark())
+                    raise ScannerError(
+                        None,
+                        None,
+                        'mapping values are not allowed here',
+                        self.reader.get_mark(),
+                    )
 
             # If this value starts a new block mapping, we need to add
             # BLOCK-MAPPING-START.  It will be detected as an error later by
@@ -691,7 +706,7 @@ class Scanner(object):
 
     def fetch_single(self):
         # type: () -> None
-        self.fetch_flow_scalar(style='\'')
+        self.fetch_flow_scalar(style="'")
 
     def fetch_double(self):
         # type: () -> None
@@ -731,8 +746,7 @@ class Scanner(object):
         # type: () -> Any
         # DOCUMENT-START:   ^ '---' (' '|'\n')
         if self.reader.column == 0:
-            if self.reader.prefix(3) == u'---'  \
-                    and self.reader.peek(3) in _THE_END_SPACE_TAB:
+            if self.reader.prefix(3) == '---' and self.reader.peek(3) in _THE_END_SPACE_TAB:
                 return True
         return None
 
@@ -740,8 +754,7 @@ class Scanner(object):
         # type: () -> Any
         # DOCUMENT-END:     ^ '...' (' '|'\n')
         if self.reader.column == 0:
-            if self.reader.prefix(3) == u'...'  \
-                    and self.reader.peek(3) in _THE_END_SPACE_TAB:
+            if self.reader.prefix(3) == '...' and self.reader.peek(3) in _THE_END_SPACE_TAB:
                 return True
         return None
 
@@ -786,11 +799,12 @@ class Scanner(object):
         # independent.
         ch = self.reader.peek()
         if self.scanner_processing_version == (1, 1):
-            return ch not in u'\0 \t\r\n\x85\u2028\u2029-?:,[]{}#&*!|>\'\"%@`' or \
-                (self.reader.peek(1) not in _THE_END_SPACE_TAB and
-                 (ch == u'-' or (not self.flow_level and ch in u'?:')))
+            return ch not in '\0 \t\r\n\x85\u2028\u2029-?:,[]{}#&*!|>\'"%@`' or (
+                self.reader.peek(1) not in _THE_END_SPACE_TAB
+                and (ch == '-' or (not self.flow_level and ch in '?:'))
+            )
         # YAML 1.2
-        if ch not in u'\0 \t\r\n\x85\u2028\u2029-?:,[]{}#&*!|>\'\"%@`':
+        if ch not in '\0 \t\r\n\x85\u2028\u2029-?:,[]{}#&*!|>\'"%@`':
             # ###################                ^ ???
             return True
         ch1 = self.reader.peek(1)
@@ -799,8 +813,9 @@ class Scanner(object):
         if ch == ':' and bool(self.flow_level) and ch1 not in _SPACE_TAB:
             return True
 
-        return (self.reader.peek(1) not in _THE_END_SPACE_TAB and
-                (ch == u'-' or (not self.flow_level and ch in u'?:')))
+        return self.reader.peek(1) not in _THE_END_SPACE_TAB and (
+            ch == '-' or (not self.flow_level and ch in '?:')
+        )
 
     # Scanners.
 
@@ -825,13 +840,13 @@ class Scanner(object):
         # `unwind_indent` before issuing BLOCK-END.
         # Scanners for block, flow, and plain scalars need to be modified.
 
-        if self.reader.index == 0 and self.reader.peek() == u'\uFEFF':
+        if self.reader.index == 0 and self.reader.peek() == '\uFEFF':
             self.reader.forward()
         found = False
         while not found:
-            while self.reader.peek() == u' ':
+            while self.reader.peek() == ' ':
                 self.reader.forward()
-            if self.reader.peek() == u'#':
+            if self.reader.peek() == '#':
                 while self.reader.peek() not in _THE_END:
                     self.reader.forward()
             if self.scan_line_break():
@@ -848,10 +863,10 @@ class Scanner(object):
         self.reader.forward()
         name = self.scan_directive_name(start_mark)
         value = None
-        if name == u'YAML':
+        if name == 'YAML':
             value = self.scan_yaml_directive_value(start_mark)
             end_mark = self.reader.get_mark()
-        elif name == u'TAG':
+        elif name == 'TAG':
             value = self.scan_tag_directive_value(start_mark)
             end_mark = self.reader.get_mark()
         else:
@@ -866,58 +881,65 @@ class Scanner(object):
         # See the specification for details.
         length = 0
         ch = self.reader.peek(length)
-        while u'0' <= ch <= u'9' or u'A' <= ch <= u'Z' or u'a' <= ch <= u'z' \
-                or ch in u'-_:.':
+        while '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z' or ch in '-_:.':
             length += 1
             ch = self.reader.peek(length)
         if not length:
             raise ScannerError(
-                "while scanning a directive", start_mark,
-                "expected alphabetic or numeric character, but found %r"
-                % utf8(ch), self.reader.get_mark())
+                'while scanning a directive',
+                start_mark,
+                'expected alphabetic or numeric character, but found %r' % utf8(ch),
+                self.reader.get_mark(),
+            )
         value = self.reader.prefix(length)
         self.reader.forward(length)
         ch = self.reader.peek()
-        if ch not in u'\0 \r\n\x85\u2028\u2029':
+        if ch not in '\0 \r\n\x85\u2028\u2029':
             raise ScannerError(
-                "while scanning a directive", start_mark,
-                "expected alphabetic or numeric character, but found %r"
-                % utf8(ch), self.reader.get_mark())
+                'while scanning a directive',
+                start_mark,
+                'expected alphabetic or numeric character, but found %r' % utf8(ch),
+                self.reader.get_mark(),
+            )
         return value
 
     def scan_yaml_directive_value(self, start_mark):
         # type: (Any) -> Any
         # See the specification for details.
-        while self.reader.peek() == u' ':
+        while self.reader.peek() == ' ':
             self.reader.forward()
         major = self.scan_yaml_directive_number(start_mark)
         if self.reader.peek() != '.':
             raise ScannerError(
-                "while scanning a directive", start_mark,
-                "expected a digit or '.', but found %r"
-                % utf8(self.reader.peek()),
-                self.reader.get_mark())
+                'while scanning a directive',
+                start_mark,
+                "expected a digit or '.', but found %r" % utf8(self.reader.peek()),
+                self.reader.get_mark(),
+            )
         self.reader.forward()
         minor = self.scan_yaml_directive_number(start_mark)
-        if self.reader.peek() not in u'\0 \r\n\x85\u2028\u2029':
+        if self.reader.peek() not in '\0 \r\n\x85\u2028\u2029':
             raise ScannerError(
-                "while scanning a directive", start_mark,
-                "expected a digit or ' ', but found %r"
-                % utf8(self.reader.peek()),
-                self.reader.get_mark())
+                'while scanning a directive',
+                start_mark,
+                "expected a digit or ' ', but found %r" % utf8(self.reader.peek()),
+                self.reader.get_mark(),
+            )
         return (major, minor)
 
     def scan_yaml_directive_number(self, start_mark):
         # type: (Any) -> Any
         # See the specification for details.
         ch = self.reader.peek()
-        if not (u'0' <= ch <= u'9'):
+        if not ('0' <= ch <= '9'):
             raise ScannerError(
-                "while scanning a directive", start_mark,
-                "expected a digit, but found %r" % utf8(ch),
-                self.reader.get_mark())
+                'while scanning a directive',
+                start_mark,
+                'expected a digit, but found %r' % utf8(ch),
+                self.reader.get_mark(),
+            )
         length = 0
-        while u'0' <= self.reader.peek(length) <= u'9':
+        while '0' <= self.reader.peek(length) <= '9':
             length += 1
         value = int(self.reader.prefix(length))
         self.reader.forward(length)
@@ -926,10 +948,10 @@ class Scanner(object):
     def scan_tag_directive_value(self, start_mark):
         # type: (Any) -> Any
         # See the specification for details.
-        while self.reader.peek() == u' ':
+        while self.reader.peek() == ' ':
             self.reader.forward()
         handle = self.scan_tag_directive_handle(start_mark)
-        while self.reader.peek() == u' ':
+        while self.reader.peek() == ' ':
             self.reader.forward()
         prefix = self.scan_tag_directive_prefix(start_mark)
         return (handle, prefix)
@@ -939,10 +961,13 @@ class Scanner(object):
         # See the specification for details.
         value = self.scan_tag_handle('directive', start_mark)
         ch = self.reader.peek()
-        if ch != u' ':
-            raise ScannerError("while scanning a directive", start_mark,
-                               "expected ' ', but found %r" % utf8(ch),
-                               self.reader.get_mark())
+        if ch != ' ':
+            raise ScannerError(
+                'while scanning a directive',
+                start_mark,
+                "expected ' ', but found %r" % utf8(ch),
+                self.reader.get_mark(),
+            )
         return value
 
     def scan_tag_directive_prefix(self, start_mark):
@@ -950,26 +975,31 @@ class Scanner(object):
         # See the specification for details.
         value = self.scan_tag_uri('directive', start_mark)
         ch = self.reader.peek()
-        if ch not in u'\0 \r\n\x85\u2028\u2029':
-            raise ScannerError("while scanning a directive", start_mark,
-                               "expected ' ', but found %r" % utf8(ch),
-                               self.reader.get_mark())
+        if ch not in '\0 \r\n\x85\u2028\u2029':
+            raise ScannerError(
+                'while scanning a directive',
+                start_mark,
+                "expected ' ', but found %r" % utf8(ch),
+                self.reader.get_mark(),
+            )
         return value
 
     def scan_directive_ignored_line(self, start_mark):
         # type: (Any) -> None
         # See the specification for details.
-        while self.reader.peek() == u' ':
+        while self.reader.peek() == ' ':
             self.reader.forward()
-        if self.reader.peek() == u'#':
+        if self.reader.peek() == '#':
             while self.reader.peek() not in _THE_END:
                 self.reader.forward()
         ch = self.reader.peek()
         if ch not in _THE_END:
             raise ScannerError(
-                "while scanning a directive", start_mark,
-                "expected a comment or a line break, but found %r"
-                % utf8(ch), self.reader.get_mark())
+                'while scanning a directive',
+                start_mark,
+                'expected a comment or a line break, but found %r' % utf8(ch),
+                self.reader.get_mark(),
+            )
         self.scan_line_break()
 
     def scan_anchor(self, TokenClass):
@@ -984,7 +1014,7 @@ class Scanner(object):
         # Therefore we restrict aliases to numbers and ASCII letters.
         start_mark = self.reader.get_mark()
         indicator = self.reader.peek()
-        if indicator == u'*':
+        if indicator == '*':
             name = 'alias'
         else:
             name = 'anchor'
@@ -998,19 +1028,23 @@ class Scanner(object):
             ch = self.reader.peek(length)
         if not length:
             raise ScannerError(
-                "while scanning an %s" % name, start_mark,
-                "expected alphabetic or numeric character, but found %r"
-                % utf8(ch), self.reader.get_mark())
+                'while scanning an %s' % name,
+                start_mark,
+                'expected alphabetic or numeric character, but found %r' % utf8(ch),
+                self.reader.get_mark(),
+            )
         value = self.reader.prefix(length)
         self.reader.forward(length)
         # ch1 = ch
         # ch = self.reader.peek()   # no need to peek, ch is already set
         # assert ch1 == ch
-        if ch not in u'\0 \t\r\n\x85\u2028\u2029?:,[]{}%@`':
+        if ch not in '\0 \t\r\n\x85\u2028\u2029?:,[]{}%@`':
             raise ScannerError(
-                "while scanning an %s" % name, start_mark,
-                "expected alphabetic or numeric character, but found %r"
-                % utf8(ch), self.reader.get_mark())
+                'while scanning an %s' % name,
+                start_mark,
+                'expected alphabetic or numeric character, but found %r' % utf8(ch),
+                self.reader.get_mark(),
+            )
         end_mark = self.reader.get_mark()
         return TokenClass(value, start_mark, end_mark)
 
@@ -1019,41 +1053,46 @@ class Scanner(object):
         # See the specification for details.
         start_mark = self.reader.get_mark()
         ch = self.reader.peek(1)
-        if ch == u'<':
+        if ch == '<':
             handle = None
             self.reader.forward(2)
             suffix = self.scan_tag_uri('tag', start_mark)
-            if self.reader.peek() != u'>':
+            if self.reader.peek() != '>':
                 raise ScannerError(
-                    "while parsing a tag", start_mark,
+                    'while parsing a tag',
+                    start_mark,
                     "expected '>', but found %r" % utf8(self.reader.peek()),
-                    self.reader.get_mark())
+                    self.reader.get_mark(),
+                )
             self.reader.forward()
         elif ch in _THE_END_SPACE_TAB:
             handle = None
-            suffix = u'!'
+            suffix = '!'
             self.reader.forward()
         else:
             length = 1
             use_handle = False
-            while ch not in u'\0 \r\n\x85\u2028\u2029':
-                if ch == u'!':
+            while ch not in '\0 \r\n\x85\u2028\u2029':
+                if ch == '!':
                     use_handle = True
                     break
                 length += 1
                 ch = self.reader.peek(length)
-            handle = u'!'
+            handle = '!'
             if use_handle:
                 handle = self.scan_tag_handle('tag', start_mark)
             else:
-                handle = u'!'
+                handle = '!'
                 self.reader.forward()
             suffix = self.scan_tag_uri('tag', start_mark)
         ch = self.reader.peek()
-        if ch not in u'\0 \r\n\x85\u2028\u2029':
-            raise ScannerError("while scanning a tag", start_mark,
-                               "expected ' ', but found %r" % utf8(ch),
-                               self.reader.get_mark())
+        if ch not in '\0 \r\n\x85\u2028\u2029':
+            raise ScannerError(
+                'while scanning a tag',
+                start_mark,
+                "expected ' ', but found %r" % utf8(ch),
+                self.reader.get_mark(),
+            )
         value = (handle, suffix)
         end_mark = self.reader.get_mark()
         return TagToken(value, start_mark, end_mark)
@@ -1078,11 +1117,13 @@ class Scanner(object):
         min_indent = self.indent + 1
         if increment is None:
             # no increment and top level, min_indent could be 0
-            if min_indent < 1 and \
-               (style not in '|>' or (
-                   self.scanner_processing_version == (1, 1)) and
-                   getattr(self.loader,
-                           'top_level_block_style_scalar_no_indent_error_1_1', False)):
+            if min_indent < 1 and (
+                style not in '|>'
+                or (self.scanner_processing_version == (1, 1))
+                and getattr(
+                    self.loader, 'top_level_block_style_scalar_no_indent_error_1_1', False
+                )
+            ):
                 min_indent = 1
             breaks, max_indent, end_mark = self.scan_block_scalar_indentation()
             indent = max(min_indent, max_indent)
@@ -1091,12 +1132,12 @@ class Scanner(object):
                 min_indent = 1
             indent = min_indent + increment - 1
             breaks, end_mark = self.scan_block_scalar_breaks(indent)
-        line_break = u''
+        line_break = ""
 
         # Scan the inner part of the block scalar.
-        while self.reader.column == indent and self.reader.peek() != u'\0':
+        while self.reader.column == indent and self.reader.peek() != '\0':
             chunks.extend(breaks)
-            leading_non_space = self.reader.peek() not in u' \t'
+            leading_non_space = self.reader.peek() not in ' \t'
             length = 0
             while self.reader.peek(length) not in _THE_END:
                 length += 1
@@ -1109,16 +1150,20 @@ class Scanner(object):
                 # end of document/start_new_document
                 if self.check_document_start() or self.check_document_end():
                     break
-            if self.reader.column == indent and self.reader.peek() != u'\0':
+            if self.reader.column == indent and self.reader.peek() != '\0':
 
                 # Unfortunately, folding rules are ambiguous.
                 #
                 # This is the folding according to the specification:
 
-                if folded and line_break == u'\n'   \
-                        and leading_non_space and self.reader.peek() not in u' \t':
+                if (
+                    folded
+                    and line_break == '\n'
+                    and leading_non_space
+                    and self.reader.peek() not in ' \t'
+                ):
                     if not breaks:
-                        chunks.append(u' ')
+                        chunks.append(' ')
                 else:
                     chunks.append(line_break)
 
@@ -1147,7 +1192,7 @@ class Scanner(object):
             trailing.extend(breaks)
 
         # We are done.
-        token = ScalarToken(u''.join(chunks), False, start_mark, end_mark, style)
+        token = ScalarToken("".join(chunks), False, start_mark, end_mark, style)
         if len(trailing) > 0:
             # print('trailing 1', trailing)  # XXXXX
             # Eat whitespaces and comments until we reach the next token.
@@ -1159,8 +1204,7 @@ class Scanner(object):
             # Keep track of the trailing whitespace and following comments
             # as a comment token, if isn't all included in the actual value.
             comment_end_mark = self.reader.get_mark()
-            comment = CommentToken(''.join(trailing), end_mark,
-                                   comment_end_mark)
+            comment = CommentToken("".join(trailing), end_mark, comment_end_mark)
             token.add_post_comment(comment)
         return token
 
@@ -1170,59 +1214,66 @@ class Scanner(object):
         chomping = None
         increment = None
         ch = self.reader.peek()
-        if ch in u'+-':
+        if ch in '+-':
             if ch == '+':
                 chomping = True
             else:
                 chomping = False
             self.reader.forward()
             ch = self.reader.peek()
-            if ch in u'0123456789':
+            if ch in '0123456789':
                 increment = int(ch)
                 if increment == 0:
                     raise ScannerError(
-                        "while scanning a block scalar", start_mark,
-                        "expected indentation indicator in the range 1-9, "
-                        "but found 0", self.reader.get_mark())
+                        'while scanning a block scalar',
+                        start_mark,
+                        'expected indentation indicator in the range 1-9, ' 'but found 0',
+                        self.reader.get_mark(),
+                    )
                 self.reader.forward()
-        elif ch in u'0123456789':
+        elif ch in '0123456789':
             increment = int(ch)
             if increment == 0:
                 raise ScannerError(
-                    "while scanning a block scalar", start_mark,
-                    "expected indentation indicator in the range 1-9, "
-                    "but found 0",
-                    self.reader.get_mark())
+                    'while scanning a block scalar',
+                    start_mark,
+                    'expected indentation indicator in the range 1-9, ' 'but found 0',
+                    self.reader.get_mark(),
+                )
             self.reader.forward()
             ch = self.reader.peek()
-            if ch in u'+-':
+            if ch in '+-':
                 if ch == '+':
                     chomping = True
                 else:
                     chomping = False
                 self.reader.forward()
         ch = self.reader.peek()
-        if ch not in u'\0 \r\n\x85\u2028\u2029':
+        if ch not in '\0 \r\n\x85\u2028\u2029':
             raise ScannerError(
-                "while scanning a block scalar", start_mark,
-                "expected chomping or indentation indicators, but found %r"
-                % utf8(ch), self.reader.get_mark())
+                'while scanning a block scalar',
+                start_mark,
+                'expected chomping or indentation indicators, but found %r' % utf8(ch),
+                self.reader.get_mark(),
+            )
         return chomping, increment
 
     def scan_block_scalar_ignored_line(self, start_mark):
         # type: (Any) -> Any
         # See the specification for details.
-        while self.reader.peek() == u' ':
+        while self.reader.peek() == ' ':
             self.reader.forward()
-        if self.reader.peek() == u'#':
+        if self.reader.peek() == '#':
             while self.reader.peek() not in _THE_END:
                 self.reader.forward()
         ch = self.reader.peek()
         if ch not in _THE_END:
             raise ScannerError(
-                "while scanning a block scalar", start_mark,
-                "expected a comment or a line break, but found %r"
-                % utf8(ch), self.reader.get_mark())
+                'while scanning a block scalar',
+                start_mark,
+                'expected a comment or a line break, but found %r' % utf8(ch),
+                self.reader.get_mark(),
+            )
         self.scan_line_break()
 
     def scan_block_scalar_indentation(self):
@@ -1231,8 +1282,8 @@ class Scanner(object):
         chunks = []
         max_indent = 0
         end_mark = self.reader.get_mark()
-        while self.reader.peek() in u' \r\n\x85\u2028\u2029':
-            if self.reader.peek() != u' ':
+        while self.reader.peek() in ' \r\n\x85\u2028\u2029':
+            if self.reader.peek() != ' ':
                 chunks.append(self.scan_line_break())
                 end_mark = self.reader.get_mark()
             else:
@@ -1246,12 +1297,12 @@ class Scanner(object):
         # See the specification for details.
         chunks = []
         end_mark = self.reader.get_mark()
-        while self.reader.column < indent and self.reader.peek() == u' ':
+        while self.reader.column < indent and self.reader.peek() == ' ':
             self.reader.forward()
-        while self.reader.peek() in u'\r\n\x85\u2028\u2029':
+        while self.reader.peek() in '\r\n\x85\u2028\u2029':
             chunks.append(self.scan_line_break())
             end_mark = self.reader.get_mark()
-            while self.reader.column < indent and self.reader.peek() == u' ':
+            while self.reader.column < indent and self.reader.peek() == ' ':
                 self.reader.forward()
         return chunks, end_mark
 
@@ -1277,35 +1328,30 @@ class Scanner(object):
             chunks.extend(self.scan_flow_scalar_non_spaces(double, start_mark))
         self.reader.forward()
         end_mark = self.reader.get_mark()
-        return ScalarToken(u''.join(chunks), False, start_mark, end_mark,
-                           style)
+        return ScalarToken("".join(chunks), False, start_mark, end_mark, style)
 
     ESCAPE_REPLACEMENTS = {
-        u'0': u'\0',
-        u'a': u'\x07',
-        u'b': u'\x08',
-        u't': u'\x09',
-        u'\t': u'\x09',
-        u'n': u'\x0A',
-        u'v': u'\x0B',
-        u'f': u'\x0C',
-        u'r': u'\x0D',
-        u'e': u'\x1B',
-        u' ': u'\x20',
-        u'\"': u'\"',
-        u'/': u'/',  # as per http://www.json.org/
-        u'\\': u'\\',
-        u'N': u'\x85',
-        u'_': u'\xA0',
-        u'L': u'\u2028',
-        u'P': u'\u2029',
+        '0': '\0',
+        'a': '\x07',
+        'b': '\x08',
+        't': '\x09',
+        '\t': '\x09',
+        'n': '\x0A',
+        'v': '\x0B',
+        'f': '\x0C',
+        'r': '\x0D',
+        'e': '\x1B',
+        ' ': '\x20',
+        '"': '"',
+        '/': '/',  # as per http://www.json.org/
+        '\\': '\\',
+        'N': '\x85',
+        '_': '\xA0',
+        'L': '\u2028',
+        'P': '\u2029',
     }
 
-    ESCAPE_CODES = {
-        u'x': 2,
-        u'u': 4,
-        u'U': 8,
-    }
+    ESCAPE_CODES = {'x': 2, 'u': 4, 'U': 8}
 
     def scan_flow_scalar_non_spaces(self, double, start_mark):
         # type: (Any, Any) -> Any
@@ -1313,19 +1359,19 @@ class Scanner(object):
         chunks = []  # type: List[Any]
         while True:
             length = 0
-            while self.reader.peek(length) not in u'\'\"\\\0 \t\r\n\x85\u2028\u2029':
+            while self.reader.peek(length) not in '\'"\\\0 \t\r\n\x85\u2028\u2029':
                 length += 1
             if length != 0:
                 chunks.append(self.reader.prefix(length))
                 self.reader.forward(length)
             ch = self.reader.peek()
-            if not double and ch == u'\'' and self.reader.peek(1) == u'\'':
-                chunks.append(u'\'')
+            if not double and ch == "'" and self.reader.peek(1) == "'":
+                chunks.append("'")
                 self.reader.forward(2)
-            elif (double and ch == u'\'') or (not double and ch in u'\"\\'):
+            elif (double and ch == "'") or (not double and ch in '"\\'):
                 chunks.append(ch)
                 self.reader.forward()
-            elif double and ch == u'\\':
+            elif double and ch == '\\':
                 self.reader.forward()
                 ch = self.reader.peek()
                 if ch in self.ESCAPE_REPLACEMENTS:
@@ -1335,25 +1381,27 @@ class Scanner(object):
                     length = self.ESCAPE_CODES[ch]
                     self.reader.forward()
                     for k in range(length):
-                        if self.reader.peek(k) not in u'0123456789ABCDEFabcdef':
+                        if self.reader.peek(k) not in '0123456789ABCDEFabcdef':
                             raise ScannerError(
-                                "while scanning a double-quoted scalar",
+                                'while scanning a double-quoted scalar',
                                 start_mark,
-                                "expected escape sequence of %d hexdecimal "
-                                "numbers, but found %r" %
-                                (length, utf8(self.reader.peek(k))), self.reader.get_mark())
+                                'expected escape sequence of %d hexdecimal '
+                                'numbers, but found %r' % (length, utf8(self.reader.peek(k))),
+                                self.reader.get_mark(),
+                            )
                     code = int(self.reader.prefix(length), 16)
                     chunks.append(unichr(code))
                     self.reader.forward(length)
-                elif ch in u'\r\n\x85\u2028\u2029':
+                elif ch in '\r\n\x85\u2028\u2029':
                     self.scan_line_break()
-                    chunks.extend(self.scan_flow_scalar_breaks(
-                        double, start_mark))
+                    chunks.extend(self.scan_flow_scalar_breaks(double, start_mark))
                 else:
                     raise ScannerError(
-                        "while scanning a double-quoted scalar", start_mark,
-                        "found unknown escape character %r" % utf8(ch),
-                        self.reader.get_mark())
+                        'while scanning a double-quoted scalar',
+                        start_mark,
+                        'found unknown escape character %r' % utf8(ch),
+                        self.reader.get_mark(),
+                    )
             else:
                 return chunks
 
@@ -1362,22 +1410,25 @@ class Scanner(object):
         # See the specification for details.
         chunks = []
         length = 0
-        while self.reader.peek(length) in u' \t':
+        while self.reader.peek(length) in ' \t':
             length += 1
         whitespaces = self.reader.prefix(length)
         self.reader.forward(length)
         ch = self.reader.peek()
-        if ch == u'\0':
+        if ch == '\0':
             raise ScannerError(
-                "while scanning a quoted scalar", start_mark,
-                "found unexpected end of stream", self.reader.get_mark())
-        elif ch in u'\r\n\x85\u2028\u2029':
+                'while scanning a quoted scalar',
+                start_mark,
+                'found unexpected end of stream',
+                self.reader.get_mark(),
+            )
+        elif ch in '\r\n\x85\u2028\u2029':
             line_break = self.scan_line_break()
             breaks = self.scan_flow_scalar_breaks(double, start_mark)
-            if line_break != u'\n':
+            if line_break != '\n':
                 chunks.append(line_break)
             elif not breaks:
-                chunks.append(u' ')
+                chunks.append(' ')
             chunks.extend(breaks)
         else:
             chunks.append(whitespaces)
@@ -1391,15 +1442,18 @@ class Scanner(object):
             # Instead of checking indentation, we check for document
             # separators.
             prefix = self.reader.prefix(3)
-            if (prefix == u'---' or prefix == u'...')   \
-                    and self.reader.peek(3) in _THE_END_SPACE_TAB:
-                raise ScannerError("while scanning a quoted scalar",
-                                   start_mark,
-                                   "found unexpected document separator",
-                                   self.reader.get_mark())
-            while self.reader.peek() in u' \t':
+            if (prefix == '---' or prefix == '...') and self.reader.peek(
+                3
+            ) in _THE_END_SPACE_TAB:
+                raise ScannerError(
+                    'while scanning a quoted scalar',
+                    start_mark,
+                    'found unexpected document separator',
+                    self.reader.get_mark(),
+                )
+            while self.reader.peek() in ' \t':
                 self.reader.forward()
-            if self.reader.peek() in u'\r\n\x85\u2028\u2029':
+            if self.reader.peek() in '\r\n\x85\u2028\u2029':
                 chunks.append(self.scan_line_break())
             else:
                 return chunks
@@ -1422,31 +1476,41 @@ class Scanner(object):
         spaces = []  # type: List[Any]
         while True:
             length = 0
-            if self.reader.peek() == u'#':
+            if self.reader.peek() == '#':
                 break
             while True:
                 ch = self.reader.peek(length)
-                if (ch == u':' and
-                   self.reader.peek(length + 1) not in _THE_END_SPACE_TAB):
+                if ch == ':' and self.reader.peek(length + 1) not in _THE_END_SPACE_TAB:
                     pass
-                elif (ch == u'?' and self.scanner_processing_version != (1, 1)):
+                elif ch == '?' and self.scanner_processing_version != (1, 1):
                     pass
-                elif (ch in _THE_END_SPACE_TAB or
-                      (not self.flow_level and ch == u':' and
-                          self.reader.peek(length + 1) in _THE_END_SPACE_TAB) or
-                      (self.flow_level and ch in u',:?[]{}')):
+                elif (
+                    ch in _THE_END_SPACE_TAB
+                    or (
+                        not self.flow_level
+                        and ch == ':'
+                        and self.reader.peek(length + 1) in _THE_END_SPACE_TAB
+                    )
+                    or (self.flow_level and ch in ',:?[]{}')
+                ):
                     break
                 length += 1
             # It's not clear what we should do with ':' in the flow context.
-            if (self.flow_level and ch == u':' and
-               self.reader.peek(length + 1) not in u'\0 \t\r\n\x85\u2028\u2029,[]{}'):
+            if (
+                self.flow_level
+                and ch == ':'
+                and self.reader.peek(length + 1) not in '\0 \t\r\n\x85\u2028\u2029,[]{}'
+            ):
                 self.reader.forward(length)
                 raise ScannerError(
-                    "while scanning a plain scalar", start_mark,
-                    "found unexpected ':'", self.reader.get_mark(),
-                    "Please check "
-                    "http://pyyaml.org/wiki/YAMLColonInFlowContext "
-                    "for details.")
+                    'while scanning a plain scalar',
+                    start_mark,
+                    "found unexpected ':'",
+                    self.reader.get_mark(),
+                    'Please check '
+                    'http://pyyaml.org/wiki/YAMLColonInFlowContext '
+                    'for details.',
+                )
             if length == 0:
                 break
             self.allow_simple_key = False
@@ -1455,14 +1519,17 @@ class Scanner(object):
             self.reader.forward(length)
             end_mark = self.reader.get_mark()
             spaces = self.scan_plain_spaces(indent, start_mark)
-            if not spaces or self.reader.peek() == u'#' \
-                    or (not self.flow_level and self.reader.column < indent):
+            if (
+                not spaces
+                or self.reader.peek() == '#'
+                or (not self.flow_level and self.reader.column < indent)
+            ):
                 break
 
-        token = ScalarToken(u''.join(chunks), True, start_mark, end_mark)
+        token = ScalarToken("".join(chunks), True, start_mark, end_mark)
         if spaces and spaces[0] == '\n':
             # Create a comment token to preserve the trailing line breaks.
-            comment = CommentToken(''.join(spaces) + '\n', start_mark, end_mark)
+            comment = CommentToken("".join(spaces) + '\n', start_mark, end_mark)
             token.add_post_comment(comment)
         return token
 
@@ -1473,32 +1540,34 @@ class Scanner(object):
         # We just forbid them completely. Do not use tabs in YAML!
         chunks = []
         length = 0
-        while self.reader.peek(length) in u' ':
+        while self.reader.peek(length) in ' ':
             length += 1
         whitespaces = self.reader.prefix(length)
         self.reader.forward(length)
         ch = self.reader.peek()
-        if ch in u'\r\n\x85\u2028\u2029':
+        if ch in '\r\n\x85\u2028\u2029':
             line_break = self.scan_line_break()
             self.allow_simple_key = True
             prefix = self.reader.prefix(3)
-            if (prefix == u'---' or prefix == u'...')   \
-                    and self.reader.peek(3) in _THE_END_SPACE_TAB:
+            if (prefix == '---' or prefix == '...') and self.reader.peek(
+                3
+            ) in _THE_END_SPACE_TAB:
                 return
             breaks = []
-            while self.reader.peek() in u' \r\n\x85\u2028\u2029':
+            while self.reader.peek() in ' \r\n\x85\u2028\u2029':
                 if self.reader.peek() == ' ':
                     self.reader.forward()
                 else:
                     breaks.append(self.scan_line_break())
                     prefix = self.reader.prefix(3)
-                    if (prefix == u'---' or prefix == u'...')   \
-                       and self.reader.peek(3) in _THE_END_SPACE_TAB:
+                    if (prefix == '---' or prefix == '...') and self.reader.peek(
+                        3
+                    ) in _THE_END_SPACE_TAB:
                         return
-            if line_break != u'\n':
+            if line_break != '\n':
                 chunks.append(line_break)
             elif not breaks:
-                chunks.append(u' ')
+                chunks.append(' ')
             chunks.extend(breaks)
         elif whitespaces:
             chunks.append(whitespaces)
@@ -1510,23 +1579,27 @@ class Scanner(object):
         # For some strange reasons, the specification does not allow '_' in
         # tag handles. I have allowed it anyway.
         ch = self.reader.peek()
-        if ch != u'!':
-            raise ScannerError("while scanning a %s" % name, start_mark,
-                               "expected '!', but found %r" % utf8(ch),
-                               self.reader.get_mark())
+        if ch != '!':
+            raise ScannerError(
+                'while scanning a %s' % name,
+                start_mark,
+                "expected '!', but found %r" % utf8(ch),
+                self.reader.get_mark(),
+            )
         length = 1
         ch = self.reader.peek(length)
-        if ch != u' ':
-            while u'0' <= ch <= u'9' or u'A' <= ch <= u'Z' \
-                  or u'a' <= ch <= u'z' \
-                  or ch in u'-_':
+        if ch != ' ':
+            while '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z' or ch in '-_':
                 length += 1
                 ch = self.reader.peek(length)
-            if ch != u'!':
+            if ch != '!':
                 self.reader.forward(length)
-                raise ScannerError("while scanning a %s" % name, start_mark,
-                                   "expected '!', but found %r" % utf8(ch),
-                                   self.reader.get_mark())
+                raise ScannerError(
+                    'while scanning a %s' % name,
+                    start_mark,
+                    "expected '!', but found %r" % utf8(ch),
+                    self.reader.get_mark(),
+                )
             length += 1
         value = self.reader.prefix(length)
         self.reader.forward(length)
@@ -1539,9 +1612,13 @@ class Scanner(object):
         chunks = []
         length = 0
         ch = self.reader.peek(length)
-        while u'0' <= ch <= u'9' or u'A' <= ch <= u'Z' or u'a' <= ch <= u'z'    \
-                or ch in u'-;/?:@&=+$,_.!~*\'()[]%':
-            if ch == u'%':
+        while (
+            '0' <= ch <= '9'
+            or 'A' <= ch <= 'Z'
+            or 'a' <= ch <= 'z'
+            or ch in "-;/?:@&=+$,_.!~*'()[]%"
+        ):
+            if ch == '%':
                 chunks.append(self.reader.prefix(length))
                 self.reader.forward(length)
                 length = 0
@@ -1554,25 +1631,30 @@ class Scanner(object):
             self.reader.forward(length)
             length = 0
         if not chunks:
-            raise ScannerError("while parsing a %s" % name, start_mark,
-                               "expected URI, but found %r" % utf8(ch),
-                               self.reader.get_mark())
-        return u''.join(chunks)
+            raise ScannerError(
+                'while parsing a %s' % name,
+                start_mark,
+                'expected URI, but found %r' % utf8(ch),
+                self.reader.get_mark(),
+            )
+        return "".join(chunks)
 
     def scan_uri_escapes(self, name, start_mark):
         # type: (Any, Any) -> Any
         # See the specification for details.
         code_bytes = []  # type: List[Any]
         mark = self.reader.get_mark()
-        while self.reader.peek() == u'%':
+        while self.reader.peek() == '%':
             self.reader.forward()
             for k in range(2):
-                if self.reader.peek(k) not in u'0123456789ABCDEFabcdef':
+                if self.reader.peek(k) not in '0123456789ABCDEFabcdef':
                     raise ScannerError(
-                        "while scanning a %s" % name, start_mark,
-                        "expected URI escape sequence of 2 hexdecimal numbers,"
-                        " but found %r"
-                        % utf8(self.reader.peek(k)), self.reader.get_mark())
+                        'while scanning a %s' % name,
+                        start_mark,
+                        'expected URI escape sequence of 2 hexdecimal numbers,'
+                        ' but found %r' % utf8(self.reader.peek(k)),
+                        self.reader.get_mark(),
+                    )
             if PY3:
                 code_bytes.append(int(self.reader.prefix(2), 16))
             else:
@@ -1582,10 +1664,11 @@ class Scanner(object):
             if PY3:
                 value = bytes(code_bytes).decode('utf-8')
             else:
-                value = unicode(b''.join(code_bytes), 'utf-8')  # type: ignore
+                # fmt: off
+                value = unicode(b"".join(code_bytes), 'utf-8')  # type: ignore
+                # fmt: on
         except UnicodeDecodeError as exc:
-            raise ScannerError("while scanning a %s" % name, start_mark,
-                               str(exc), mark)
+            raise ScannerError('while scanning a %s' % name, start_mark, str(exc), mark)
         return value
 
     def scan_line_break(self):
@@ -1599,16 +1682,16 @@ class Scanner(object):
         #   '\u2029     :   '\u2029'
         #   default     :   ''
         ch = self.reader.peek()
-        if ch in u'\r\n\x85':
-            if self.reader.prefix(2) == u'\r\n':
+        if ch in '\r\n\x85':
+            if self.reader.prefix(2) == '\r\n':
                 self.reader.forward(2)
             else:
                 self.reader.forward()
-            return u'\n'
-        elif ch in u'\u2028\u2029':
+            return '\n'
+        elif ch in '\u2028\u2029':
             self.reader.forward()
             return ch
-        return u''
+        return ""
 
 
 class RoundTripScanner(Scanner):
@@ -1673,11 +1756,15 @@ class RoundTripScanner(Scanner):
             # scalar, value token. FlowXEndToken, otherwise
             # hidden streamtokens could get them (leave them and they will be
             # pre comments for the next map/seq
-            if len(self.tokens) > 1 and \
-               isinstance(self.tokens[0], (ScalarToken, ValueToken,
-                                           FlowSequenceEndToken, FlowMappingEndToken, )) and \
-               isinstance(self.tokens[1], CommentToken) and \
-               self.tokens[0].end_mark.line == self.tokens[1].start_mark.line:
+            if (
+                len(self.tokens) > 1
+                and isinstance(
+                    self.tokens[0],
+                    (ScalarToken, ValueToken, FlowSequenceEndToken, FlowMappingEndToken),
+                )
+                and isinstance(self.tokens[1], CommentToken)
+                and self.tokens[0].end_mark.line == self.tokens[1].start_mark.line
+            ):
                 self.tokens_taken += 1
                 self.tokens[0].add_post_comment(self.tokens.pop(1))
             self.tokens_taken += 1
@@ -1687,7 +1774,7 @@ class RoundTripScanner(Scanner):
     def fetch_comment(self, comment):
         # type: (Any) -> None
         value, start_mark, end_mark = comment
-        while value and value[-1] == u' ':
+        while value and value[-1] == ' ':
             # empty line within indented key context
             # no need to update end-mark, that is not used
             value = value[:-1]
@@ -1716,20 +1803,20 @@ class RoundTripScanner(Scanner):
         # `unwind_indent` before issuing BLOCK-END.
         # Scanners for block, flow, and plain scalars need to be modified.
 
-        if self.reader.index == 0 and self.reader.peek() == u'\uFEFF':
+        if self.reader.index == 0 and self.reader.peek() == '\uFEFF':
             self.reader.forward()
         found = False
         while not found:
-            while self.reader.peek() == u' ':
+            while self.reader.peek() == ' ':
                 self.reader.forward()
             ch = self.reader.peek()
-            if ch == u'#':
+            if ch == '#':
                 start_mark = self.reader.get_mark()
                 comment = ch
                 self.reader.forward()
                 while ch not in _THE_END:
                     ch = self.reader.peek()
-                    if ch == u'\0':  # don't gobble the end-of-stream character
+                    if ch == '\0':  # don't gobble the end-of-stream character
                         break
                     comment += ch
                     self.reader.forward()
@@ -1747,9 +1834,9 @@ class RoundTripScanner(Scanner):
                 if not self.flow_level:
                     self.allow_simple_key = True
                 ch = self.reader.peek()
-                if ch == '\n':    # empty toplevel lines
+                if ch == '\n':  # empty toplevel lines
                     start_mark = self.reader.get_mark()
-                    comment = ''
+                    comment = ""
                     while ch:
                         ch = self.scan_line_break(empty_line=True)
                         comment += ch
@@ -1773,19 +1860,20 @@ class RoundTripScanner(Scanner):
         #   '\u2029     :   '\u2029'
         #   default     :   ''
         ch = self.reader.peek()  # type: Text
-        if ch in u'\r\n\x85':
-            if self.reader.prefix(2) == u'\r\n':
+        if ch in '\r\n\x85':
+            if self.reader.prefix(2) == '\r\n':
                 self.reader.forward(2)
             else:
                 self.reader.forward()
-            return u'\n'
-        elif ch in u'\u2028\u2029':
+            return '\n'
+        elif ch in '\u2028\u2029':
             self.reader.forward()
             return ch
         elif empty_line and ch in '\t ':
             self.reader.forward()
             return ch
-        return u''
+        return ""
+
 
 # try:
 #     import psyco
diff --git a/serializer.py b/serializer.py
index c88539d..b2b26bf 100644
--- a/serializer.py
+++ b/serializer.py
@@ -7,13 +7,18 @@ from ruamel.yaml.compat import nprint, DBG_NODE, dbg, string_types
 from ruamel.yaml.util import RegExp
 
 from ruamel.yaml.events import (
-    StreamStartEvent, StreamEndEvent, MappingStartEvent, MappingEndEvent,
-    SequenceStartEvent, SequenceEndEvent, AliasEvent, ScalarEvent,
-    DocumentStartEvent, DocumentEndEvent,
-)
-from ruamel.yaml.nodes import (
-    MappingNode, ScalarNode, SequenceNode,
+    StreamStartEvent,
+    StreamEndEvent,
+    MappingStartEvent,
+    MappingEndEvent,
+    SequenceStartEvent,
+    SequenceEndEvent,
+    AliasEvent,
+    ScalarEvent,
+    DocumentStartEvent,
+    DocumentEndEvent,
 )
+from ruamel.yaml.nodes import MappingNode, ScalarNode, SequenceNode
 
 if False:  # MYPY
     from typing import Any, Dict, Union, Text  # NOQA
@@ -32,9 +37,16 @@ class Serializer(object):
     ANCHOR_TEMPLATE = u'id%03d'
     ANCHOR_RE = RegExp(u'id(?!000$)\\d{3,}')
 
-    def __init__(self, encoding=None, explicit_start=None, explicit_end=None,
-                 version=None, tags=None, dumper=None):
-        # type: (Any, bool, bool, VersionType, Any, Any) -> None
+    def __init__(
+        self,
+        encoding=None,
+        explicit_start=None,
+        explicit_end=None,
+        version=None,
+        tags=None,
+        dumper=None,
+    ):
+        # type: (Any, Union[None, bool], Union[None, bool], Union[None, VersionType], Any, Any) -> None  # NOQA
         self.dumper = dumper
         if self.dumper is not None:
             self.dumper._serializer = self
@@ -56,15 +68,15 @@ class Serializer(object):
     def emitter(self):
         # type: () -> Any
         if hasattr(self.dumper, 'typ'):
-            return self.dumper.emitter  # type: ignore
-        return self.dumper._emitter  # type: ignore
+            return self.dumper.emitter
+        return self.dumper._emitter
 
     @property
     def resolver(self):
         # type: () -> Any
         if hasattr(self.dumper, 'typ'):
-            self.dumper.resolver  # type: ignore
-        return self.dumper._resolver  # type: ignore
+            self.dumper.resolver
+        return self.dumper._resolver
 
     def open(self):
         # type: () -> None
@@ -72,14 +84,14 @@ class Serializer(object):
             self.emitter.emit(StreamStartEvent(encoding=self.use_encoding))
             self.closed = False
         elif self.closed:
-            raise SerializerError("serializer is closed")
+            raise SerializerError('serializer is closed')
         else:
-            raise SerializerError("serializer is already opened")
+            raise SerializerError('serializer is already opened')
 
     def close(self):
         # type: () -> None
         if self.closed is None:
-            raise SerializerError("serializer is not opened")
+            raise SerializerError('serializer is not opened')
         elif not self.closed:
             self.emitter.emit(StreamEndEvent())
             self.closed = True
@@ -93,12 +105,14 @@ class Serializer(object):
             nprint('Serializing nodes')
             node.dump()
         if self.closed is None:
-            raise SerializerError("serializer is not opened")
+            raise SerializerError('serializer is not opened')
         elif self.closed:
-            raise SerializerError("serializer is closed")
-        self.emitter.emit(DocumentStartEvent(explicit=self.use_explicit_start,
-                                             version=self.use_version,
-                                             tags=self.use_tags))
+            raise SerializerError('serializer is closed')
+        self.emitter.emit(
+            DocumentStartEvent(
+                explicit=self.use_explicit_start, version=self.use_version, tags=self.use_tags
+            )
+        )
         self.anchor_node(node)
         self.serialize_node(node, None, None)
         self.emitter.emit(DocumentEndEvent(explicit=self.use_explicit_end))
@@ -151,12 +165,23 @@ class Serializer(object):
                 # if not equal quoting is necessary for strings
                 detected_tag = self.resolver.resolve(ScalarNode, node.value, (True, False))
                 default_tag = self.resolver.resolve(ScalarNode, node.value, (False, True))
-                implicit = ((node.tag == detected_tag), (node.tag == default_tag),
-                            node.tag.startswith('tag:yaml.org,2002:'))
-                self.emitter.emit(ScalarEvent(alias, node.tag, implicit, node.value,
-                                              style=node.style, comment=node.comment))
+                implicit = (
+                    (node.tag == detected_tag),
+                    (node.tag == default_tag),
+                    node.tag.startswith('tag:yaml.org,2002:'),
+                )
+                self.emitter.emit(
+                    ScalarEvent(
+                        alias,
+                        node.tag,
+                        implicit,
+                        node.value,
+                        style=node.style,
+                        comment=node.comment,
+                    )
+                )
             elif isinstance(node, SequenceNode):
-                implicit = (node.tag == self.resolver.resolve(SequenceNode, node.value, True))
+                implicit = node.tag == self.resolver.resolve(SequenceNode, node.value, True)
                 comment = node.comment
                 end_comment = None
                 seq_comment = None
@@ -168,16 +193,22 @@ class Serializer(object):
                     end_comment = comment[2]
                 else:
                     end_comment = None
-                self.emitter.emit(SequenceStartEvent(alias, node.tag, implicit,
-                                                     flow_style=node.flow_style,
-                                                     comment=node.comment))
+                self.emitter.emit(
+                    SequenceStartEvent(
+                        alias,
+                        node.tag,
+                        implicit,
+                        flow_style=node.flow_style,
+                        comment=node.comment,
+                    )
+                )
                 index = 0
                 for item in node.value:
                     self.serialize_node(item, node, index)
                     index += 1
                 self.emitter.emit(SequenceEndEvent(comment=[seq_comment, end_comment]))
             elif isinstance(node, MappingNode):
-                implicit = (node.tag == self.resolver.resolve(MappingNode, node.value, True))
+                implicit = node.tag == self.resolver.resolve(MappingNode, node.value, True)
                 comment = node.comment
                 end_comment = None
                 map_comment = None
@@ -187,9 +218,15 @@ class Serializer(object):
                         # comment[0] = None
                 if comment and len(comment) > 2:
                     end_comment = comment[2]
-                self.emitter.emit(MappingStartEvent(alias, node.tag, implicit,
-                                                    flow_style=node.flow_style,
-                                                    comment=node.comment))
+                self.emitter.emit(
+                    MappingStartEvent(
+                        alias,
+                        node.tag,
+                        implicit,
+                        flow_style=node.flow_style,
+                        comment=node.comment,
+                    )
+                )
                 for key, value in node.value:
                     self.serialize_node(key, node, None)
                     self.serialize_node(value, node, key)
diff --git a/setup.py b/setup.py
index c0d00cf..4eb777c 100644
--- a/setup.py
+++ b/setup.py
@@ -9,14 +9,15 @@ import sys
 import os
 import datetime
 import traceback
-sys.path = [path for path in sys.path if path not in [os.getcwd(), '']]
-import platform          # NOQA
-from _ast import *       # NOQA
-from ast import parse    # NOQA
+
+sys.path = [path for path in sys.path if path not in [os.getcwd(), ""]]
+import platform  # NOQA
+from _ast import *  # NOQA
+from ast import parse  # NOQA
 
 from setuptools import setup, Extension, Distribution  # NOQA
-from setuptools.command import install_lib             # NOQA
-from setuptools.command.sdist import sdist as _sdist   # NOQA
+from setuptools.command import install_lib  # NOQA
+from setuptools.command.sdist import sdist as _sdist  # NOQA
 
 
 if __name__ != '__main__':
@@ -29,33 +30,41 @@ full_package_name = None
 if __name__ != '__main__':
     raise NotImplementedError('should never include setup.py')
 
-if sys.version_info < (3, ):
+if sys.version_info < (3,):
     string_type = basestring
 else:
     string_type = str
 
 
 if sys.version_info < (3, 4):
-    class Bytes():
+
+    class Bytes:
         pass
 
     class NameConstant:
         pass
 
-if sys.version_info < (3, ):
+
+if sys.version_info < (3,):
     open_kw = dict()
 else:
     open_kw = dict(encoding='utf-8')
 
 
 if sys.version_info < (2, 7) or platform.python_implementation() == 'Jython':
-    class Set():
+
+    class Set:
         pass
 
-if os.environ.get('DVDEBUG', '') == '':
+
+if os.environ.get('DVDEBUG', "") == "":
+
     def debug(*args, **kw):
         pass
+
+
 else:
+
     def debug(*args, **kw):
         with open(os.environ['DVDEBUG'], 'a') as fp:
             kw1 = kw.copy()
@@ -70,6 +79,9 @@ def literal_eval(node_or_string):
     expression.  The string or node provided may only consist of the following
     Python literal structures: strings, bytes, numbers, tuples, lists, dicts,
     sets, booleans, and None.
+
+    Even when passing in Unicode, the resulting Str types parsed are 'str' in Python 2.
+    I don't now how to set 'unicode_literals' on parse -> Str is explicitly converted.
     """
     _safe_names = {'None': None, 'True': True, 'False': False}
     if isinstance(node_or_string, string_type):
@@ -77,10 +89,14 @@ def literal_eval(node_or_string):
     if isinstance(node_or_string, Expression):
         node_or_string = node_or_string.body
     else:
-        raise TypeError("only string or AST nodes supported")
+        raise TypeError('only string or AST nodes supported')
 
     def _convert(node):
-        if isinstance(node, (Str, Bytes)):
+        if isinstance(node, Str):
+            if sys.version_info < (3,) and not isinstance(node.s, unicode):
+                return node.s.decode('utf-8')
+            return node.s
+        elif isinstance(node, Bytes):
             return node.s
         elif isinstance(node, Num):
             return node.n
@@ -91,25 +107,28 @@ def literal_eval(node_or_string):
         elif isinstance(node, Set):
             return set(map(_convert, node.elts))
         elif isinstance(node, Dict):
-            return dict((_convert(k), _convert(v)) for k, v
-                        in zip(node.keys, node.values))
+            return dict((_convert(k), _convert(v)) for k, v in zip(node.keys, node.values))
         elif isinstance(node, NameConstant):
             return node.value
         elif sys.version_info < (3, 4) and isinstance(node, Name):
             if node.id in _safe_names:
                 return _safe_names[node.id]
-        elif isinstance(node, UnaryOp) and \
-             isinstance(node.op, (UAdd, USub)) and \
-             isinstance(node.operand, (Num, UnaryOp, BinOp)):  # NOQA
+        elif (
+            isinstance(node, UnaryOp)
+            and isinstance(node.op, (UAdd, USub))
+            and isinstance(node.operand, (Num, UnaryOp, BinOp))
+        ):  # NOQA
             operand = _convert(node.operand)
             if isinstance(node.op, UAdd):
-                return + operand
+                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)):  # NOQA
+                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))
+        ):  # NOQA
             left = _convert(node.left)
             right = _convert(node.right)
             if isinstance(node.op, Add):
@@ -133,6 +152,7 @@ def literal_eval(node_or_string):
         err.text = repr(node)
         err.node = node
         raise err
+
     return _convert(node_or_string)
 
 
@@ -145,23 +165,23 @@ def _package_data(fn):
         for line in fp.readlines():
             if sys.version_info < (3,):
                 line = line.decode('utf-8')
-            if line.startswith(u'_package_data'):
+            if line.startswith('_package_data'):
                 if 'dict(' in line:
                     parsing = 'python'
-                    lines.append(u'dict(\n')
-                elif line.endswith(u'= {\n'):
+                    lines.append('dict(\n')
+                elif line.endswith('= {\n'):
                     parsing = 'python'
-                    lines.append(u'{\n')
+                    lines.append('{\n')
                 else:
                     raise NotImplementedError
                 continue
             if not parsing:
                 continue
             if parsing == 'python':
-                if line.startswith(u')') or line.startswith(u'}'):
+                if line.startswith(')') or line.startswith('}'):
                     lines.append(line)
                     try:
-                        data = literal_eval(u''.join(lines))
+                        data = literal_eval("".join(lines))
                     except SyntaxError as e:
                         context = 2
                         from_line = e.lineno - (context + 1)
@@ -169,11 +189,16 @@ def _package_data(fn):
                         w = len(str(to_line))
                         for index, line in enumerate(lines):
                             if from_line <= index <= to_line:
-                                print(u"{0:{1}}: {2}".format(index, w, line).encode('utf-8'),
-                                      end=u'')
+                                print(
+                                    '{0:{1}}: {2}'.format(index, w, line).encode('utf-8'),
+                                    end="",
+                                )
                                 if index == e.lineno - 1:
-                                    print(u"{0:{1}}  {2}^--- {3}".format(
-                                        u' ', w, u' ' * e.offset, e.node))
+                                    print(
+                                        '{0:{1}}  {2}^--- {3}'.format(
+                                            ' ', w, ' ' * e.offset, e.node
+                                        )
+                                    )
                         raise
                     break
                 lines.append(line)
@@ -185,32 +210,29 @@ def _package_data(fn):
 # make sure you can run "python ../some/dir/setup.py install"
 pkg_data = _package_data(__file__.replace('setup.py', '__init__.py'))
 
-exclude_files = [
-    'setup.py',
-]
+exclude_files = ['setup.py']
 
 
 # # helper
 def _check_convert_version(tup):
     """Create a PEP 386 pseudo-format conformant string from tuple tup."""
     ret_val = str(tup[0])  # first is always digit
-    next_sep = "."  # separator for next extension, can be "" or "."
+    next_sep = '.'  # separator for next extension, can be "" or "."
     nr_digits = 0  # nr of adjacent digits in rest, to verify
     post_dev = False  # are we processig post/dev
     for x in tup[1:]:
         if isinstance(x, int):
             nr_digits += 1
             if nr_digits > 2:
-                raise ValueError("too many consecutive digits after " + ret_val)
+                raise ValueError('too many consecutive digits after ' + ret_val)
             ret_val += next_sep + str(x)
             next_sep = '.'
             continue
         first_letter = x[0].lower()
-        next_sep = ''
+        next_sep = ""
         if first_letter in 'abcr':
             if post_dev:
-                raise ValueError("release level specified after "
-                                 "post/dev: " + x)
+                raise ValueError('release level specified after ' 'post/dev: ' + x)
             nr_digits = 0
             ret_val += 'rc' if first_letter == 'r' else first_letter
         elif first_letter in 'pd':
@@ -232,8 +254,7 @@ version_str = _check_convert_version(version_info)
 class MyInstallLib(install_lib.install_lib):
     def install(self):
         fpp = pkg_data['full_package_name'].split('.')  # full package path
-        full_exclude_files = [os.path.join(*(fpp + [x]))
-                              for x in exclude_files]
+        full_exclude_files = [os.path.join(*(fpp + [x])) for x in exclude_files]
         alt_files = []
         outfiles = install_lib.install_lib.install(self)
         for x in outfiles:
@@ -263,7 +284,7 @@ class MySdist(_sdist):
 # try except so this doesn't bomb when you don't have wheel installed, implies
 # generation of wheels in ./dist
 try:
-    from wheel.bdist_wheel import bdist_wheel as _bdist_wheel   # NOQA
+    from wheel.bdist_wheel import bdist_wheel as _bdist_wheel  # NOQA
 
     class MyBdistWheel(_bdist_wheel):
         def initialize_options(self):
@@ -287,23 +308,25 @@ class InMemoryZipFile(object):
         except ImportError:
             from io import BytesIO as StringIO
         import zipfile
+
         self.zip_file = zipfile
         # Create the in-memory file-like object
         self._file_name = file_name
         self.in_memory_data = StringIO()
         # Create the in-memory zipfile
         self.in_memory_zip = self.zip_file.ZipFile(
-            self.in_memory_data, "w", self.zip_file.ZIP_DEFLATED, False)
+            self.in_memory_data, 'w', self.zip_file.ZIP_DEFLATED, False
+        )
         self.in_memory_zip.debug = 3
 
     def append(self, filename_in_zip, file_contents):
-        '''Appends a file with name filename_in_zip and contents of
-        file_contents to the in-memory zip.'''
+        """Appends a file with name filename_in_zip and contents of
+        file_contents to the in-memory zip."""
         self.in_memory_zip.writestr(filename_in_zip, file_contents)
-        return self   # so you can daisy-chain
+        return self  # so you can daisy-chain
 
     def write_to_file(self, filename):
-        '''Writes the in-memory zip to a file.'''
+        """Writes the in-memory zip to a file."""
         # Mark the files as having been created on Windows so that
         # Unix permissions are not inferred as 0000
         for zfile in self.in_memory_zip.filelist:
@@ -328,6 +351,7 @@ class InMemoryZipFile(object):
         """
         if pattern and isinstance(pattern, string_type):
             import re
+
             pattern = re.compile(pattern)
         if file_names:
             if not isinstance(file_names, list):
@@ -343,9 +367,12 @@ class InMemoryZipFile(object):
                     continue
                 self.append(l.filename, zf.read(l))
             if file_names:
-                raise IOError('[Errno 2] No such file{}: {}'.format(
-                    '' if len(file_names) == 1 else 's',
-                    ', '.join([repr(f) for f in file_names])))
+                raise IOError(
+                    '[Errno 2] No such file{}: {}'.format(
+                        "" if len(file_names) == 1 else 's',
+                        ', '.join([repr(f) for f in file_names]),
+                    )
+                )
 
 
 class NameSpacePackager(object):
@@ -359,8 +386,11 @@ class NameSpacePackager(object):
         self.command = None
         self.python_version()
         self._pkg = [None, None]  # required and pre-installable packages
-        if sys.argv[0] == 'setup.py' and sys.argv[1] == 'install' and \
-           '--single-version-externally-managed' not in sys.argv:
+        if (
+            sys.argv[0] == 'setup.py'
+            and sys.argv[1] == 'install'
+            and '--single-version-externally-managed' not in sys.argv
+        ):
             if os.environ.get('READTHEDOCS', None) == 'True':
                 os.system('pip install .')
                 sys.exit(0)
@@ -381,7 +411,7 @@ class NameSpacePackager(object):
             break
 
     def pn(self, s):
-        if sys.version_info < (3, ) and isinstance(s, unicode):
+        if sys.version_info < (3,) and isinstance(s, unicode):
             return s.encode('utf-8')
         return s
 
@@ -408,14 +438,15 @@ class NameSpacePackager(object):
                     if pd.get('nested', False):
                         continue
                     self._split.append(self.full_package_name + '.' + d)
-            if sys.version_info < (3, ):
-                self._split = [(y.encode('utf-8') if isinstance(y, unicode) else y)
-                               for y in self._split]
+            if sys.version_info < (3,):
+                self._split = [
+                    (y.encode('utf-8') if isinstance(y, unicode) else y) for y in self._split
+                ]
         return self._split
 
     @property
     def namespace_packages(self):
-        return self.split[:self.depth]
+        return self.split[: self.depth]
 
     def namespace_directories(self, depth=None):
         """return list of directories where the namespace should be created /
@@ -433,8 +464,10 @@ class NameSpacePackager(object):
     def package_dir(self):
         d = {
             # don't specify empty dir, clashes with package_data spec
-            self.full_package_name: '.',
+            self.full_package_name: '.'
         }
+        if 'extra_packages' in self._pkg_data:
+            return d
         if len(self.split) > 1:  # only if package namespace
             d[self.split[0]] = self.namespace_directories(1)[0]
         return d
@@ -448,8 +481,9 @@ class NameSpacePackager(object):
             for d in directories:
                 os.mkdir(d)
                 with open(os.path.join(d, '__init__.py'), 'w') as fp:
-                    fp.write('import pkg_resources\n'
-                             'pkg_resources.declare_namespace(__name__)\n')
+                    fp.write(
+                        'import pkg_resources\n' 'pkg_resources.declare_namespace(__name__)\n'
+                    )
 
     def python_version(self):
         supported = self._pkg_data.get('supported')
@@ -505,12 +539,10 @@ class NameSpacePackager(object):
                     if self.command == 'develop':
                         raise InstallationError(
                             'Cannot mix develop (pip install -e),\nwith '
-                            'non-develop installs for package name {0}'.format(
-                                fn))
+                            'non-develop installs for package name {0}'.format(fn)
+                        )
                 elif fn == prefix:
-                    raise InstallationError(
-                        'non directory package {0} in {1}'.format(
-                            fn, p))
+                    raise InstallationError('non directory package {0} in {1}'.format(fn, p))
                 for pre in [x + '.' for x in prefixes]:
                     if fn.startswith(pre):
                         break
@@ -519,7 +551,8 @@ class NameSpacePackager(object):
                 if fn.endswith('-link') and self.command == 'install':
                     raise InstallationError(
                         'Cannot mix non-develop with develop\n(pip install -e)'
-                        ' installs for package name {0}'.format(fn))
+                        ' installs for package name {0}'.format(fn)
+                    )
 
     def entry_points(self, script_name=None, package_name=None):
         """normally called without explicit script_name and package name
@@ -533,13 +566,15 @@ class NameSpacePackager(object):
         if the ep entry is a simple string without "=", that is assumed to be
         the name of the script.
         """
+
         def pckg_entry_point(name):
             return '{0}{1}:main'.format(
-                name,
-                '.__main__' if os.path.exists('__main__.py') else '',
+                name, '.__main__' if os.path.exists('__main__.py') else ""
             )
 
         ep = self._pkg_data.get('entry_points', True)
+        if isinstance(ep, dict):
+            return ep
         if ep is None:
             return None
         if ep not in [True, 1]:
@@ -553,9 +588,11 @@ class NameSpacePackager(object):
             package_name = self.full_package_name
         if not script_name:
             script_name = package_name.split('.')[-1]
-        return {'console_scripts': [
-            '{0} = {1}'.format(script_name, pckg_entry_point(package_name)),
-        ]}
+        return {
+            'console_scripts': [
+                '{0} = {1}'.format(script_name, pckg_entry_point(package_name))
+            ]
+        }
 
     @property
     def url(self):
@@ -567,11 +604,11 @@ class NameSpacePackager(object):
 
     @property
     def author(self):
-        return self._pkg_data['author']
+        return self._pkg_data['author']  # no get needs to be there
 
     @property
     def author_email(self):
-        return self._pkg_data['author_email']
+        return self._pkg_data['author_email']  # no get needs to be there
 
     @property
     def license(self):
@@ -580,7 +617,7 @@ class NameSpacePackager(object):
         if lic is None:
             # lic_fn = os.path.join(os.path.dirname(__file__), 'LICENSE')
             # assert os.path.exists(lic_fn)
-            return "MIT license"
+            return 'MIT license'
         return lic
 
     def has_mit_lic(self):
@@ -588,30 +625,40 @@ class NameSpacePackager(object):
 
     @property
     def description(self):
-        return self._pkg_data['description']
+        return self._pkg_data['description']  # no get needs to be there
 
     @property
     def status(self):
         # αβ
-        status = self._pkg_data.get('status', u'β').lower()
-        if status in [u'α', u'alpha']:
+        status = self._pkg_data.get('status', 'β').lower()
+        if status in ['α', 'alpha']:
             return (3, 'Alpha')
-        elif status in [u'β', u'beta']:
+        elif status in ['β', 'beta']:
             return (4, 'Beta')
-        elif u'stable' in status.lower():
+        elif 'stable' in status.lower():
             return (5, 'Production/Stable')
         raise NotImplementedError
 
     @property
     def classifiers(self):
-        return [
-            'Development Status :: {0} - {1}'.format(*self.status),
-            'Intended Audience :: Developers',
-            'License :: ' + ('OSI Approved :: MIT' if self.has_mit_lic()
-                             else 'Other/Proprietary') + ' License',
-            'Operating System :: OS Independent',
-            'Programming Language :: Python',
-        ] + [self.pn(x) for x in self._pkg_data.get('classifiers', [])]
+        """this needs more intelligence, probably splitting the classifiers from _pkg_data
+        and only adding defaults when no explicit entries were provided.
+        Add explicit Python versions in sync with tox.env generation based on python_requires?
+        """
+        return sorted(
+            set(
+                [
+                    'Development Status :: {0} - {1}'.format(*self.status),
+                    'Intended Audience :: Developers',
+                    'License :: '
+                    + ('OSI Approved :: MIT' if self.has_mit_lic() else 'Other/Proprietary')
+                    + ' License',
+                    'Operating System :: OS Independent',
+                    'Programming Language :: Python',
+                ]
+                + [self.pn(x) for x in self._pkg_data.get('classifiers', [])]
+            )
+        )
 
     @property
     def keywords(self):
@@ -649,7 +696,7 @@ class NameSpacePackager(object):
         # 'any' for all builds, 'py27' etc for specifics versions
         packages = ir.get('any', [])
         if isinstance(packages, string_type):
-            packages = packages.split()    # assume white space separated string
+            packages = packages.split()  # assume white space separated string
         if self.nested:
             # parent dir is also a package, make sure it is installed (need its .pth file)
             parent_pkg = self.full_package_name.rsplit('.', 1)[0]
@@ -659,7 +706,7 @@ class NameSpacePackager(object):
         if implementation == 'CPython':
             pyver = 'py{0}{1}'.format(*sys.version_info)
         elif implementation == 'PyPy':
-            pyver = 'pypy' if sys.version_info < (3, ) else 'pypy3'
+            pyver = 'pypy' if sys.version_info < (3,) else 'pypy3'
         elif implementation == 'Jython':
             pyver = 'jython'
         packages.extend(ir.get(pyver, []))
@@ -692,7 +739,7 @@ class NameSpacePackager(object):
             df.append('LICENSE')
         if not df:
             return None
-        return [('.', df), ]
+        return [('.', df)]
 
     @property
     def package_data(self):
@@ -702,9 +749,30 @@ class NameSpacePackager(object):
             df.append('LICENSE')
             # but don't install it
             exclude_files.append('LICENSE')
-        if not df:
-            return {}
-        return {self.full_package_name: df}
+        pd = self._pkg_data.get('package_data', {})
+        if df:
+            pd[self.full_package_name] = df
+        if sys.version_info < (3,):
+            # python2 doesn't seem to like unicode package names as keys
+            # maybe only when the packages themselves are non-unicode
+            for k in pd:
+                if isinstance(k, unicode):
+                    pd[str(k)] = pd.pop(k)
+            # for k in pd:
+            #     pd[k] = [e.encode('utf-8') for e in pd[k]]  # de-unicode
+        return pd
+
+    @property
+    def packages(self):
+        s = self.split
+        # fixed this in package_data, the keys there must be non-unicode for py27
+        # if sys.version_info < (3, 0):
+        #     s = [x.encode('utf-8') for x in self.split]
+        return s + self._pkg_data.get('extra_packages', [])
+
+    @property
+    def python_requires(self):
+        return self._pkg_data.get('python_requires', None)
 
     @property
     def ext_modules(self):
@@ -787,16 +855,13 @@ class NameSpacePackager(object):
                 distutils.sysconfig.customize_compiler(compiler)
                 # make sure you can reach header files because compile does change dir
                 compiler.add_include_dir(os.getcwd())
-                if sys.version_info < (3, ):
+                if sys.version_info < (3,):
                     tmp_dir = tmp_dir.encode('utf-8')
                 # used to be a different directory, not necessary
                 compile_out_dir = tmp_dir
                 try:
                     compiler.link_executable(
-                        compiler.compile(
-                            [file_name],
-                            output_dir=compile_out_dir,
-                        ),
+                        compiler.compile([file_name], output_dir=compile_out_dir),
                         bin_file_name,
                         output_dir=tmp_dir,
                         libraries=ext.libraries,
@@ -819,6 +884,10 @@ class NameSpacePackager(object):
                 shutil.rmtree(tmp_dir)
         return self._ext_modules
 
+    @property
+    def test_suite(self):
+        return self._pkg_data.get('test_suite')
+
     def wheel(self, kw, setup):
         """temporary add setup.cfg if creating a wheel to include LICENSE file
         https://bitbucket.org/pypa/wheel/issues/47
@@ -832,7 +901,7 @@ class NameSpacePackager(object):
             if os.path.exists('LICENSE'):
                 fp.write('[metadata]\nlicense-file = LICENSE\n')
             else:
-                print("\n\n>>>>>> LICENSE file not found <<<<<\n\n")
+                print('\n\n>>>>>> LICENSE file not found <<<<<\n\n')
             if self._pkg_data.get('universal'):
                 fp.write('[bdist_wheel]\nuniversal = 1\n')
         try:
@@ -851,6 +920,7 @@ def main():
         import wheel
         import distutils
         import setuptools
+
         print('python:    ', sys.version)
         print('setuptools:', setuptools.__version__)
         print('distutils: ', distutils.__version__)
@@ -862,10 +932,7 @@ def main():
     if pkg_data.get('tarfmt'):
         MySdist.tarfmt = pkg_data.get('tarfmt')
 
-    cmdclass = dict(
-        install_lib=MyInstallLib,
-        sdist=MySdist,
-    )
+    cmdclass = dict(install_lib=MyInstallLib, sdist=MySdist)
     if _bdist_wheel_available:
         MyBdistWheel.nsp = nsp
         cmdclass['bdist_wheel'] = MyBdistWheel
@@ -874,7 +941,8 @@ def main():
         name=nsp.full_package_name,
         namespace_packages=nsp.namespace_packages,
         version=version_str,
-        packages=nsp.split,
+        packages=nsp.packages,
+        python_requires=nsp.python_requires,
         url=nsp.url,
         author=nsp.author,
         author_email=nsp.author_email,
@@ -889,6 +957,7 @@ def main():
         keywords=nsp.keywords,
         package_data=nsp.package_data,
         ext_modules=nsp.ext_modules,
+        test_suite=nsp.test_suite,
     )
 
     if '--version' not in sys.argv and ('--verbose' in sys.argv or dump_kw in sys.argv):
@@ -912,6 +981,7 @@ def main():
         # until you match your/package/name for your.package.name
         for p in nsp.install_pre:
             import subprocess
+
             # search other source
             setup_path = os.path.join(*p.split('.') + ['setup.py'])
             try_dir = os.path.dirname(sys.executable)
diff --git a/timestamp.py b/timestamp.py
index 7035c0f..b87a348 100644
--- a/timestamp.py
+++ b/timestamp.py
@@ -20,7 +20,6 @@ class TimeStamp(datetime.datetime):
 
     def __deepcopy__(self, memo):
         # type: (Any) -> Any
-        ts = TimeStamp(self.year, self.month, self.day,
-                       self.hour, self.minute, self.second)
+        ts = TimeStamp(self.year, self.month, self.day, self.hour, self.minute, self.second)
         ts._yaml = copy.deepcopy(self._yaml)
         return ts
diff --git a/tokens.py b/tokens.py
index 94b1c10..54a8bd7 100644
--- a/tokens.py
+++ b/tokens.py
@@ -8,7 +8,7 @@ SHOWLINES = True
 
 
 class Token(object):
-    __slots__ = 'start_mark', 'end_mark', '_comment',
+    __slots__ = 'start_mark', 'end_mark', '_comment'
 
     def __init__(self, start_mark, end_mark):
         # type: (Any, Any) -> None
@@ -21,8 +21,7 @@ class Token(object):
         #               hasattr('self', key)]
         attributes = [key for key in self.__slots__ if not key.endswith('_mark')]
         attributes.sort()
-        arguments = u', '.join([u'%s=%r' % (key, getattr(self, key))
-                               for key in attributes])
+        arguments = u', '.join([u'%s=%r' % (key, getattr(self, key)) for key in attributes])
         if SHOWLINES:
             try:
                 arguments += u', line: ' + str(self.start_mark.line)
@@ -102,8 +101,9 @@ class Token(object):
 # class BOMToken(Token):
 #     id = '<byte order mark>'
 
+
 class DirectiveToken(Token):
-    __slots__ = 'name', 'value',
+    __slots__ = 'name', 'value'
     id = '<directive>'
 
     def __init__(self, name, value, start_mark, end_mark):
@@ -124,7 +124,7 @@ class DocumentEndToken(Token):
 
 
 class StreamStartToken(Token):
-    __slots__ = 'encoding',
+    __slots__ = ('encoding',)
     id = '<stream start>'
 
     def __init__(self, start_mark=None, end_mark=None, encoding=None):
@@ -198,7 +198,7 @@ class FlowEntryToken(Token):
 
 
 class AliasToken(Token):
-    __slots__ = 'value',
+    __slots__ = ('value',)
     id = '<alias>'
 
     def __init__(self, value, start_mark, end_mark):
@@ -208,7 +208,7 @@ class AliasToken(Token):
 
 
 class AnchorToken(Token):
-    __slots__ = 'value',
+    __slots__ = ('value',)
     id = '<anchor>'
 
     def __init__(self, value, start_mark, end_mark):
@@ -218,7 +218,7 @@ class AnchorToken(Token):
 
 
 class TagToken(Token):
-    __slots__ = 'value',
+    __slots__ = ('value',)
     id = '<tag>'
 
     def __init__(self, value, start_mark, end_mark):
@@ -228,7 +228,7 @@ class TagToken(Token):
 
 
 class ScalarToken(Token):
-    __slots__ = 'value', 'plain', 'style',
+    __slots__ = 'value', 'plain', 'style'
     id = '<scalar>'
 
     def __init__(self, value, plain, start_mark, end_mark, style=None):
@@ -240,7 +240,7 @@ class ScalarToken(Token):
 
 
 class CommentToken(Token):
-    __slots__ = 'value', 'pre_done',
+    __slots__ = 'value', 'pre_done'
     id = '<comment>'
 
     def __init__(self, value, start_mark, end_mark):
diff --git a/tox.ini b/tox.ini
index c09b65f..da5806b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,7 +7,6 @@ commands =
     /bin/bash -c 'pytest _test/test_*.py'
 deps =
     pytest
-    flake8==2.5.5
     ruamel.std.pathlib
 
 [testenv:py27m]
@@ -15,17 +14,24 @@ basepython = /opt/python/2.7.15m/bin/python
 
 [testenv:cs]
 basepython = python3.6
+deps =
+    flake8
+    flake8-bugbear;python_version>="3.5"
 commands =
-    flake8  --exclude ".tox,.#*,jabsy,jinja2,base,cmd,convert" {posargs}
+    flake8 []{posargs}
 
 [testenv:pep8]
 basepython = python3.6
+deps =
+    flake8
+    flake8-bugbear;python_version>="3.5"
 commands =
-    flake8  --exclude ".tox,.#*,jabsy,jinja2,base,cmd,convert" {posargs}
+    flake8 []{posargs}
 
 [flake8]
 show-source = True
 max-line-length = 95
+ignore = W503,F405,E203
 exclude = _test/lib,.hg,.git,.tox,dist,.cache,__pycache__,ruamel.zip2tar.egg-info
 
 [pytest]
diff --git a/util.py b/util.py
index e5e816f..2412888 100644
--- a/util.py
+++ b/util.py
@@ -26,20 +26,26 @@ class LazyEval(object):
     The sole additional attribute is the lazy_self function which holds the
     return value (or, prior to evaluation, func and arguments), in its closure.
     """
+
     def __init__(self, func, *args, **kwargs):
+        # type: (Any, Any, Any) -> None
         def lazy_self():
+            # type: () -> Any
             return_value = func(*args, **kwargs)
-            object.__setattr__(self, "lazy_self", lambda: return_value)
+            object.__setattr__(self, 'lazy_self', lambda: return_value)
             return return_value
-        object.__setattr__(self, "lazy_self", lazy_self)
+
+        object.__setattr__(self, 'lazy_self', lazy_self)
 
     def __getattribute__(self, name):
-        lazy_self = object.__getattribute__(self, "lazy_self")
-        if name == "lazy_self":
+        # type: (Any) -> Any
+        lazy_self = object.__getattribute__(self, 'lazy_self')
+        if name == 'lazy_self':
             return lazy_self
         return getattr(lazy_self(), name)
 
     def __setattr__(self, name, value):
+        # type: (Any, Any) -> None
         setattr(self.lazy_self(), name, value)
 
 
@@ -90,7 +96,7 @@ def load_yaml_guess_indent(stream, **kw):
             idx = l_s + 1
             while line[idx] == ' ':  # this will end as we rstripped
                 idx += 1
-            if line[idx] == '#':     # comment after -
+            if line[idx] == '#':  # comment after -
                 continue
             indent = idx - key_indent
             break
@@ -120,6 +126,7 @@ def configobj_walker(cfg):
     corresponding YAML output (including comments
     """
     from configobj import ConfigObj  # type: ignore
+
     assert isinstance(cfg, ConfigObj)
     for c in cfg.initial_comment:
         if c.strip():
@@ -135,6 +142,7 @@ def configobj_walker(cfg):
 def _walk_section(s, level=0):
     # type: (Any, int) -> Any
     from configobj import Section
+
     assert isinstance(s, Section)
     indent = u'  ' * level
     for name in s.scalars:
@@ -162,6 +170,7 @@ def _walk_section(s, level=0):
         for val in _walk_section(s[name], level=level + 1):
             yield val
 
+
 # def config_obj_2_rt_yaml(cfg):
 #     from .comments import CommentedMap, CommentedSeq
 #     from configobj import ConfigObj