text: #!/usr/bin/env python
  # pycodestyle.py - Check Python source code formatting, according to
  # PEP 8
  #
  # Copyright (C) 2006-2009 Johann C. Rocholl <johann@rocholl.net>
  # Copyright (C) 2009-2014 Florent Xicluna <florent.xicluna@gmail.com>
  # Copyright (C) 2014-2016 Ian Lee <ianlee1521@gmail.com>
  #
  # Permission is hereby granted, free of charge, to any person
  # obtaining a copy of this software and associated documentation files
  # (the "Software"), to deal in the Software without restriction,
  # including without limitation the rights to use, copy, modify, merge,
  # publish, distribute, sublicense, and/or sell copies of the Software,
  # and to permit persons to whom the Software is furnished to do so,
  # subject to the following conditions:
  #
  # The above copyright notice and this permission notice shall be
  # included in all copies or substantial portions of the Software.
  #
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  # BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  # ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  # SOFTWARE.
  
  r"""
  Check Python source code formatting, according to PEP 8.
  
  For usage and a list of options, try this:
  $ python pycodestyle.py -h
  
  This program and its regression test suite live here:
  https://github.com/pycqa/pycodestyle
  
  Groups of errors and warnings:
  E errors
  W warnings
  100 indentation
  200 whitespace
  300 blank lines
  400 imports
  500 line length
  600 deprecation
  700 statements
  900 syntax error
  """
  from __future__ import with_statement
  
  import inspect
  import keyword
  import os
  import re
  import sys
  import time
  import tokenize
  import warnings
  import bisect
  
  try:
      from functools import lru_cache
  except ImportError:
      def lru_cache(maxsize=128):  # noqa as it's a fake implementation.
          """Does not really need a real a lru_cache, it's just
          optimization, so let's just do nothing here. Python 3.2+ will
          just get better performances, time to upgrade?
          """
          return lambda function: function
  
  from fnmatch import fnmatch
  from optparse import OptionParser
  
  try:
      from configparser import RawConfigParser
      from io import TextIOWrapper
  except ImportError:
      from ConfigParser import RawConfigParser
  
  __version__ = '2.4.0'
  
  DEFAULT_EXCLUDE = '.svn,CVS,.bzr,.hg,.git,__pycache__,.tox'
  DEFAULT_IGNORE = 'E121,E123,E126,E226,E24,E704,W503,W504'
  try:
      if sys.platform == 'win32':
          USER_CONFIG = os.path.expanduser(r'~\.pycodestyle')
      else:
          USER_CONFIG = os.path.join(
              os.getenv('XDG_CONFIG_HOME') or os.path.expanduser('~/.config'),
              'pycodestyle'
          )
  except ImportError:
      USER_CONFIG = None
  
  PROJECT_CONFIG = ('setup.cfg', 'tox.ini')
  TESTSUITE_PATH = os.path.join(os.path.dirname(__file__), 'testsuite')
  MAX_LINE_LENGTH = 79
  # Number of blank lines between various code parts.
  BLANK_LINES_CONFIG = {
      # Top level class and function.
      'top_level': 2,
      # Methods and nested class and function.
      'method': 1,
  }
  MAX_DOC_LENGTH = 72
  REPORT_FORMAT = {
      'default': '%(path)s:%(row)d:%(col)d: %(code)s %(text)s',
      'pylint': '%(path)s:%(row)d: [%(code)s] %(text)s',
  }
  
  PyCF_ONLY_AST = 1024
  SINGLETONS = frozenset(['False', 'None', 'True'])
  KEYWORDS = frozenset(keyword.kwlist + ['print', 'async']) - SINGLETONS
  UNARY_OPERATORS = frozenset(['>>', '**', '*', '+', '-'])
  ARITHMETIC_OP = frozenset(['**', '*', '/', '//', '+', '-'])
  WS_OPTIONAL_OPERATORS = ARITHMETIC_OP.union(['^', '&', '|', '<<', '>>', '%'])
  # Warn for -> function annotation operator in py3.5+ (issue 803)
  FUNCTION_RETURN_ANNOTATION_OP = ['->'] if sys.version_info >= (3, 5) else []
  WS_NEEDED_OPERATORS = frozenset([
      '**=', '*=', '/=', '//=', '+=', '-=', '!=', '<>', '<', '>',
      '%=', '^=', '&=', '|=', '==', '<=', '>=', '<<=', '>>=', '='] +
      FUNCTION_RETURN_ANNOTATION_OP)
  WHITESPACE = frozenset(' \t')
  NEWLINE = frozenset([tokenize.NL, tokenize.NEWLINE])
  SKIP_TOKENS = NEWLINE.union([tokenize.INDENT, tokenize.DEDENT])
  # ERRORTOKEN is triggered by backticks in Python 3
  SKIP_COMMENTS = SKIP_TOKENS.union([tokenize.COMMENT, tokenize.ERRORTOKEN])
  BENCHMARK_KEYS = ['directories', 'files', 'logical lines', 'physical lines']
  
  INDENT_REGEX = re.compile(r'([ \t]*)')
  RAISE_COMMA_REGEX = re.compile(r'raise\s+\w+\s*,')
  RERAISE_COMMA_REGEX = re.compile(r'raise\s+\w+\s*,.*,\s*\w+\s*$')
  ERRORCODE_REGEX = re.compile(r'\b[A-Z]\d{3}\b')
  DOCSTRING_REGEX = re.compile(r'u?r?["\']')
  EXTRANEOUS_WHITESPACE_REGEX = re.compile(r'[\[({] | [\]}),;:]')
  WHITESPACE_AFTER_COMMA_REGEX = re.compile(r'[,;:]\s*(?:  |\t)')
  COMPARE_SINGLETON_REGEX = re.compile(r'(\bNone|\bFalse|\bTrue)?\s*([=!]=)'
                                       r'\s*(?(1)|(None|False|True))\b')
  COMPARE_NEGATIVE_REGEX = re.compile(r'\b(not)\s+[^][)(}{ ]+\s+(in|is)\s')
  COMPARE_TYPE_REGEX = re.compile(r'(?:[=!]=|is(?:\s+not)?)\s*type(?:s.\w+Type'
                                  r'|\s*\(\s*([^)]*[^ )])\s*\))')
  KEYWORD_REGEX = re.compile(r'(\s*)\b(?:%s)\b(\s*)' % r'|'.join(KEYWORDS))
  OPERATOR_REGEX = re.compile(r'(?:[^,\s])(\s*)(?:[-+*/|!<=>%&^]+)(\s*)')
  LAMBDA_REGEX = re.compile(r'\blambda\b')
  HUNK_REGEX = re.compile(r'^@@ -\d+(?:,\d+)? \+(\d+)(?:,(\d+))? @@.*$')
  STARTSWITH_DEF_REGEX = re.compile(r'^(async\s+def|def)\b')
  STARTSWITH_TOP_LEVEL_REGEX = re.compile(r'^(async\s+def\s+|def\s+|class\s+|@)')
  STARTSWITH_INDENT_STATEMENT_REGEX = re.compile(
      r'^\s*({0})\b'.format('|'.join(s.replace(' ', r'\s+') for s in (
          'def', 'async def',
          'for', 'async for',
          'if', 'elif', 'else',
          'try', 'except', 'finally',
          'with', 'async with',
          'class',
          'while',
      )))
  )
  DUNDER_REGEX = re.compile(r'^__([^\s]+)__ = ')
  
  _checks = {'physical_line': {}, 'logical_line': {}, 'tree': {}}
  
  
  def _get_parameters(function):
      if sys.version_info >= (3, 3):
          return [parameter.name
                  for parameter
                  in inspect.signature(function).parameters.values()
                  if parameter.kind == parameter.POSITIONAL_OR_KEYWORD]
      else:
          return inspect.getargspec(function)[0]
  
  
  def register_check(check, codes=None):
      """Register a new check object."""
      def _add_check(check, kind, codes, args):
          if check in _checks[kind]:
              _checks[kind][check][0].extend(codes or [])
          else:
              _checks[kind][check] = (codes or [''], args)
      if inspect.isfunction(check):
          args = _get_parameters(check)
          if args and args[0] in ('physical_line', 'logical_line'):
              if codes is None:
                  codes = ERRORCODE_REGEX.findall(check.__doc__ or '')
              _add_check(check, args[0], codes, args)
      elif inspect.isclass(check):
          if _get_parameters(check.__init__)[:2] == ['self', 'tree']:
              _add_check(check, 'tree', codes, None)
      return check
  
  
  ########################################################################
  # Plugins (check functions) for physical lines
  ########################################################################
  
  @register_check
  def tabs_or_spaces(physical_line, indent_char):
      r"""Never mix tabs and spaces.
  
      The most popular way of indenting Python is with spaces only.  The
      second-most popular way is with tabs only.  Code indented with a
      mixture of tabs and spaces should be converted to using spaces
      exclusively.  When invoking the Python command line interpreter with
      the -t option, it issues warnings about code that illegally mixes
      tabs and spaces.  When using -tt these warnings become errors.
      These options are highly recommended!
  
      Okay: if a == 0:\n        a = 1\n        b = 1
      E101: if a == 0:\n        a = 1\n\tb = 1
      """
      indent = INDENT_REGEX.match(physical_line).group(1)
      for offset, char in enumerate(indent):
          if char != indent_char:
              return offset, "E101 indentation contains mixed spaces and tabs\n____________________________________________"
  
  
  @register_check
  def tabs_obsolete(physical_line):
      r"""On new projects, spaces-only are strongly recommended over tabs.
  
      Okay: if True:\n    return
      W191: if True:\n\treturn
      """
      indent = INDENT_REGEX.match(physical_line).group(1)
      if '\t' in indent:
          return indent.index('\t'), "W191 indentation contains tabs\n____________________________________________"
  
  
  @register_check
  def trailing_whitespace(physical_line):
      r"""Trailing whitespace is superfluous.
  
      The warning returned varies on whether the line itself is blank,
      for easier filtering for those who want to indent their blank lines.
  
      Okay: spam(1)\n#
      W291: spam(1) \n#
      W293: class Foo(object):\n    \n    bang = 12
      """
      physical_line = physical_line.rstrip('\n')    # chr(10), newline
      physical_line = physical_line.rstrip('\r')    # chr(13), carriage return
      physical_line = physical_line.rstrip('\x0c')  # chr(12), form feed, ^L
      stripped = physical_line.rstrip(' \t\v')
      if physical_line != stripped:
          if stripped:
              return len(stripped), "W291 trailing whitespace\n____________________________________________"
          else:
              return 0, "W293 blank line contains whitespace\n____________________________________________"
  
  
  @register_check
  def trailing_blank_lines(physical_line, lines, line_number, total_lines):
      r"""Trailing blank lines are superfluous.
  
      Okay: spam(1)
      W391: spam(1)\n
  
      However the last line should end with a new line (warning W292).
      """
      if line_number == total_lines:
          stripped_last_line = physical_line.rstrip()
          if physical_line and not stripped_last_line:
              return 0, "W391 blank line at end of file\n____________________________________________"
          if stripped_last_line == physical_line:
              return len(lines[-1]), "W292 no newline at end of file\n____________________________________________"
  
  
  @register_check
  def maximum_line_length(physical_line, max_line_length, multiline,
                          line_number, noqa):
      r"""Limit all lines to a maximum of 79 characters.
  
      There are still many devices around that are limited to 80 character
      lines; plus, limiting windows to 80 characters makes it possible to
      have several windows side-by-side.  The default wrapping on such
      devices looks ugly.  Therefore, please limit all lines to a maximum
      of 79 characters. For flowing long blocks of text (docstrings or
      comments), limiting the length to 72 characters is recommended.
  
      Reports error E501.
      """
      line = physical_line.rstrip()
      length = len(line)
      if length > max_line_length and not noqa:
          # Special case: ignore long shebang lines.
          if line_number == 1 and line.startswith('#!'):
              return
          # Special case for long URLs in multi-line docstrings or
          # comments, but still report the error when the 72 first chars
          # are whitespaces.
          chunks = line.split()
          if ((len(chunks) == 1 and multiline) or
              (len(chunks) == 2 and chunks[0] == '#')) and \
                  len(line) - len(chunks[-1]) < max_line_length - 7:
              return
          if hasattr(line, 'decode'):   # Python 2
              # The line could contain multi-byte characters
              try:
                  length = len(line.decode('utf-8'))
              except UnicodeError:
                  pass
          if length > max_line_length:
              return (max_line_length, "E501 line too long\n____________________________________________"
                      "(%d > %d characters)" % (length, max_line_length))
  
  
  ########################################################################
  # Plugins (check functions) for logical lines
  ########################################################################
  
  
  @register_check
  def blank_lines(logical_line, blank_lines, indent_level, line_number,
                  blank_before, previous_logical,
                  previous_unindented_logical_line, previous_indent_level,
                  lines):
      r"""Separate top-level function and class definitions with two blank
      lines.
  
      Method definitions inside a class are separated by a single blank
      line.
  
      Extra blank lines may be used (sparingly) to separate groups of
      related functions.  Blank lines may be omitted between a bunch of
      related one-liners (e.g. a set of dummy implementations).
  
      Use blank lines in functions, sparingly, to indicate logical
      sections.
  
      Okay: def a():\n    pass\n\n\ndef b():\n    pass
      Okay: def a():\n    pass\n\n\nasync def b():\n    pass
      Okay: def a():\n    pass\n\n\n# Foo\n# Bar\n\ndef b():\n    pass
      Okay: default = 1\nfoo = 1
      Okay: classify = 1\nfoo = 1
  
      E301: class Foo:\n    b = 0\n    def bar():\n        pass
      E302: def a():\n    pass\n\ndef b(n):\n    pass
      E302: def a():\n    pass\n\nasync def b(n):\n    pass
      E303: def a():\n    pass\n\n\n\ndef b(n):\n    pass
      E303: def a():\n\n\n\n    pass
      E304: @decorator\n\ndef a():\n    pass
      E305: def a():\n    pass\na()
      E306: def a():\n    def b():\n        pass\n    def c():\n        pass
      """  # noqa
      top_level_lines = BLANK_LINES_CONFIG['top_level']
      method_lines = BLANK_LINES_CONFIG['method']
  
      if line_number < top_level_lines + 1 and not previous_logical:
          return  # Don't expect blank lines before the first line
      if previous_logical.startswith('@'):
          if blank_lines:
              yield 0, "E304 blank lines found after function decorator\n____________________________________________"
      elif (blank_lines > top_level_lines or
              (indent_level and blank_lines == method_lines + 1)
            ):
          yield 0, "E303 too many blank lines (%d)\n____________________________________________" % blank_lines
      elif STARTSWITH_TOP_LEVEL_REGEX.match(logical_line):
          if indent_level:
              if not (blank_before == method_lines or
                      previous_indent_level < indent_level or
                      DOCSTRING_REGEX.match(previous_logical)
                      ):
                  ancestor_level = indent_level
                  nested = False
                  # Search backwards for a def ancestor or tree root
                  # (top level).
                  for line in lines[line_number - top_level_lines::-1]:
                      if line.strip() and expand_indent(line) < ancestor_level:
                          ancestor_level = expand_indent(line)
                          nested = line.lstrip().startswith('def ')
                          if nested or ancestor_level == 0:
                              break
                  if nested:
                      yield 0, "E306 expected %s blank line before a \n____________________________________________" \
                          "nested definition, found 0" % (method_lines,)
                  else:
                      yield 0, "E301 expected %s blank line, found 0\n____________________________________________" % (
                          method_lines,)
          elif blank_before != top_level_lines:
              yield 0, "E302 expected %s blank lines, found %d\n____________________________________________" % (
                  top_level_lines, blank_before)
      elif (logical_line and
              not indent_level and
              blank_before != top_level_lines and
              previous_unindented_logical_line.startswith(('def ', 'class '))
            ):
          yield 0, "E305 expected %s blank lines after " \
              "class or function definition, found %d\n____________________________________________" % (
                  top_level_lines, blank_before)
  
  
  @register_check
  def extraneous_whitespace(logical_line):
      r"""Avoid extraneous whitespace.
  
      Avoid extraneous whitespace in these situations:
      - Immediately inside parentheses, brackets or braces.
      - Immediately before a comma, semicolon, or colon.
  
      Okay: spam(ham[1], {eggs: 2})
      E201: spam( ham[1], {eggs: 2})
      E201: spam(ham[ 1], {eggs: 2})
      E201: spam(ham[1], { eggs: 2})
      E202: spam(ham[1], {eggs: 2} )
      E202: spam(ham[1 ], {eggs: 2})
      E202: spam(ham[1], {eggs: 2 })
  
      E203: if x == 4: print x, y; x, y = y , x
      E203: if x == 4: print x, y ; x, y = y, x
      E203: if x == 4 : print x, y; x, y = y, x
      """
      line = logical_line
      for match in EXTRANEOUS_WHITESPACE_REGEX.finditer(line):
          text = match.group()
          char = text.strip()
          found = match.start()
          if text == char + ' ':
              # assert char in '([{'
              yield found + 1, "E201 whitespace after '%s'\n____________________________________________" % char
          elif line[found - 1] != ',':
              code = ('E202' if char in '}])' else 'E203')  # if char in ',;:'
              yield found, "%s whitespace before '%s'\n____________________________________________" % (code, char)
  
  
  @register_check
  def whitespace_around_keywords(logical_line):
      r"""Avoid extraneous whitespace around keywords.
  
      Okay: True and False
      E271: True and  False
      E272: True  and False
      E273: True and\tFalse
      E274: True\tand False
      """
      for match in KEYWORD_REGEX.finditer(logical_line):
          before, after = match.groups()
  
          if '\t' in before:
              yield match.start(1), "E274 tab before keyword\n____________________________________________"
          elif len(before) > 1:
              yield match.start(1), "E272 multiple spaces before keyword\n____________________________________________"
  
          if '\t' in after:
              yield match.start(2), "E273 tab after keyword\n____________________________________________"
          elif len(after) > 1:
              yield match.start(2), "E271 multiple spaces after keyword\n____________________________________________"
  
  
  @register_check
  def missing_whitespace_after_import_keyword(logical_line):
      r"""Multiple imports in form from x import (a, b, c) should have
      space between import statement and parenthesised name list.
  
      Okay: from foo import (bar, baz)
      E275: from foo import(bar, baz)
      E275: from importable.module import(bar, baz)
      """
      line = logical_line
      indicator = ' import('
      if line.startswith('from '):
          found = line.find(indicator)
          if -1 < found:
              pos = found + len(indicator) - 1
              yield pos, "E275 missing whitespace after keyword\n____________________________________________"
  
  
  @register_check
  def missing_whitespace(logical_line):
      r"""Each comma, semicolon or colon should be followed by whitespace.
  
      Okay: [a, b]
      Okay: (3,)
      Okay: a[1:4]
      Okay: a[:4]
      Okay: a[1:]
      Okay: a[1:4:2]
      E231: ['a','b']
      E231: foo(bar,baz)
      E231: [{'a':'b'}]
      """
      line = logical_line
      for index in range(len(line) - 1):
          char = line[index]
          if char in ',;:' and line[index + 1] not in WHITESPACE:
              before = line[:index]
              if char == ':' and before.count('[') > before.count(']') and \
                      before.rfind('{') < before.rfind('['):
                  continue  # Slice syntax, no space required
              if char == ',' and line[index + 1] == ')':
                  continue  # Allow tuple with only one element: (3,)
              yield index, "E231 missing whitespace after '%s'\n____________________________________________" % char
  
  
  @register_check
  def indentation(logical_line, previous_logical, indent_char,
                  indent_level, previous_indent_level):
      r"""Use 4 spaces per indentation level.
  
      For really old code that you don't want to mess up, you can continue
      to use 8-space tabs.
  
      Okay: a = 1
      Okay: if a == 0:\n    a = 1
      E111:   a = 1
      E114:   # a = 1
  
      Okay: for item in items:\n    pass
      E112: for item in items:\npass
      E115: for item in items:\n# Hi\n    pass
  
      Okay: a = 1\nb = 2
      E113: a = 1\n    b = 2
      E116: a = 1\n    # b = 2
      """
      c = 0 if logical_line else 3
      tmpl = "E11%d %s\n____________________________________________" if logical_line else "E11%d %s (comment)\n____________________________________________"
      if indent_level % 4:
          yield 0, tmpl % (1 + c, "indentation is not a multiple of four")
      indent_expect = previous_logical.endswith(':')
      if indent_expect and indent_level <= previous_indent_level:
          yield 0, tmpl % (2 + c, "expected an indented block")
      elif not indent_expect and indent_level > previous_indent_level:
          yield 0, tmpl % (3 + c, "unexpected indentation")
  
  
  @register_check
  def continued_indentation(logical_line, tokens, indent_level, hang_closing,
                            indent_char, noqa, verbose):
      r"""Continuation lines indentation.
  
      Continuation lines should align wrapped elements either vertically
      using Python's implicit line joining inside parentheses, brackets
      and braces, or using a hanging indent.
  
      When using a hanging indent these considerations should be applied:
      - there should be no arguments on the first line, and
      - further indentation should be used to clearly distinguish itself
        as a continuation line.
  
      Okay: a = (\n)
      E123: a = (\n    )
  
      Okay: a = (\n    42)
      E121: a = (\n   42)
      E122: a = (\n42)
      E123: a = (\n    42\n    )
      E124: a = (24,\n     42\n)
      E125: if (\n    b):\n    pass
      E126: a = (\n        42)
      E127: a = (24,\n      42)
      E128: a = (24,\n    42)
      E129: if (a or\n    b):\n    pass
      E131: a = (\n    42\n 24)
      """
      first_row = tokens[0][2][0]
      nrows = 1 + tokens[-1][2][0] - first_row
      if noqa or nrows == 1:
          return
  
      # indent_next tells us whether the next block is indented; assuming
      # that it is indented by 4 spaces, then we should not allow 4-space
      # indents on the final continuation line; in turn, some other
      # indents are allowed to have an extra 4 spaces.
      indent_next = logical_line.endswith(':')
  
      row = depth = 0
      valid_hangs = (4,) if indent_char != '\t' else (4, 8)
      # remember how many brackets were opened on each line
      parens = [0] * nrows
      # relative indents of physical lines
      rel_indent = [0] * nrows
      # for each depth, collect a list of opening rows
      open_rows = [[0]]
      # for each depth, memorize the hanging indentation
      hangs = [None]
      # visual indents
      indent_chances = {}
      last_indent = tokens[0][2]
      visual_indent = None
      last_token_multiline = False
      # for each depth, memorize the visual indent column
      indent = [last_indent[1]]
      if verbose >= 3:
          print(">>> " + tokens[0][4].rstrip())
  
      for token_type, text, start, end, line in tokens:
  
          newline = row < start[0] - first_row
          if newline:
              row = start[0] - first_row
              newline = not last_token_multiline and token_type not in NEWLINE
  
          if newline:
              # this is the beginning of a continuation line.
              last_indent = start
              if verbose >= 3:
                  print("... " + line.rstrip())
  
              # record the initial indent.
              rel_indent[row] = expand_indent(line) - indent_level
  
              # identify closing bracket
              close_bracket = (token_type == tokenize.OP and text in ']})')
  
              # is the indent relative to an opening bracket line?
              for open_row in reversed(open_rows[depth]):
                  hang = rel_indent[row] - rel_indent[open_row]
                  hanging_indent = hang in valid_hangs
                  if hanging_indent:
                      break
              if hangs[depth]:
                  hanging_indent = (hang == hangs[depth])
              # is there any chance of visual indent?
              visual_indent = (not close_bracket and hang > 0 and
                               indent_chances.get(start[1]))
  
              if close_bracket and indent[depth]:
                  # closing bracket for visual indent
                  if start[1] != indent[depth]:
                      yield (start, "E124 closing bracket does not match "
                             "visual indentation\n____________________________________________")
              elif close_bracket and not hang:
                  # closing bracket matches indentation of opening
                  # bracket's line
                  if hang_closing:
                      yield start, "E133 closing bracket is missing indentation\n____________________________________________"
              elif indent[depth] and start[1] < indent[depth]:
                  if visual_indent is not True:
                      # visual indent is broken
                      yield (start, "E128 continuation line "
                             "under-indented for visual indent\n____________________________________________")
              elif hanging_indent or (indent_next and rel_indent[row] == 8):
                  # hanging indent is verified
                  if close_bracket and not hang_closing:
                      yield (start, "E123 closing bracket does not match "
                             "indentation of opening bracket's line\n____________________________________________")
                  hangs[depth] = hang
              elif visual_indent is True:
                  # visual indent is verified
                  indent[depth] = start[1]
              elif visual_indent in (text, str):
                  # ignore token lined up with matching one from a
                  # previous line
                  pass
              else:
                  # indent is broken
                  if hang <= 0:
                      error = "E122", "missing indentation or outdented\n____________________________________________"
                  elif indent[depth]:
                      error = "E127", "over-indented for visual indent\n____________________________________________"
                  elif not close_bracket and hangs[depth]:
                      error = "E131", "unaligned for hanging indent\n____________________________________________"
                  else:
                      hangs[depth] = hang
                      if hang > 4:
                          error = "E126", "over-indented for hanging indent\n____________________________________________"
                      else:
                          error = "E121", "under-indented for hanging indent"
                  yield start, "%s continuation line %s\n____________________________________________" % error
  
          # look for visual indenting
          if (parens[row] and
                  token_type not in (tokenize.NL, tokenize.COMMENT) and
                  not indent[depth]):
              indent[depth] = start[1]
              indent_chances[start[1]] = True
              if verbose >= 4:
                  print("bracket depth %s indent to %s\n____________________________________________" % (depth, start[1]))
          # deal with implicit string concatenation
          elif (token_type in (tokenize.STRING, tokenize.COMMENT) or
                text in ('u', 'ur', 'b', 'br')):
              indent_chances[start[1]] = str
          # special case for the "if" statement because len("if (") == 4
          elif not indent_chances and not row and not depth and text == 'if':
              indent_chances[end[1] + 1] = True
          elif text == ':' and line[end[1]:].isspace():
              open_rows[depth].append(row)
  
          # keep track of bracket depth
          if token_type == tokenize.OP:
              if text in '([{':
                  depth += 1
                  indent.append(0)
                  hangs.append(None)
                  if len(open_rows) == depth:
                      open_rows.append([])
                  open_rows[depth].append(row)
                  parens[row] += 1
                  if verbose >= 4:
                      print("bracket depth %s seen, col %s, visual min = %s" %
                            (depth, start[1], indent[depth]))
              elif text in ')]}' and depth > 0:
                  # parent indents should not be more than this one
                  prev_indent = indent.pop() or last_indent[1]
                  hangs.pop()
                  for d in range(depth):
                      if indent[d] > prev_indent:
                          indent[d] = 0
                  for ind in list(indent_chances):
                      if ind >= prev_indent:
                          del indent_chances[ind]
                  del open_rows[depth + 1:]
                  depth -= 1
                  if depth:
                      indent_chances[indent[depth]] = True
                  for idx in range(row, -1, -1):
                      if parens[idx]:
                          parens[idx] -= 1
                          break
              assert len(indent) == depth + 1
              if start[1] not in indent_chances:
                  # allow lining up tokens
                  indent_chances[start[1]] = text
  
          last_token_multiline = (start[0] != end[0])
          if last_token_multiline:
              rel_indent[end[0] - first_row] = rel_indent[row]
  
      if indent_next and expand_indent(line) == indent_level + 4:
          pos = (start[0], indent[0] + 4)
          if visual_indent:
              code = "E129 visually indented line\n____________________________________________"
          else:
              code = "E125 continuation line"
          yield pos, "%s with same indent as next logical line\n____________________________________________" % code
  
  
  @register_check
  def whitespace_before_parameters(logical_line, tokens):
      r"""Avoid extraneous whitespace.
  
      Avoid extraneous whitespace in the following situations:
      - before the open parenthesis that starts the argument list of a
        function call.
      - before the open parenthesis that starts an indexing or slicing.
  
      Okay: spam(1)
      E211: spam (1)
  
      Okay: dict['key'] = list[index]
      E211: dict ['key'] = list[index]
      E211: dict['key'] = list [index]
      """
      prev_type, prev_text, __, prev_end, __ = tokens[0]
      for index in range(1, len(tokens)):
          token_type, text, start, end, __ = tokens[index]
          if (token_type == tokenize.OP and
              text in '([' and
              start != prev_end and
              (prev_type == tokenize.NAME or prev_text in '}])') and
              # Syntax "class A (B):" is allowed, but avoid it
              (index < 2 or tokens[index - 2][1] != 'class') and
                  # Allow "return (a.foo for a in range(5))"
                  not keyword.iskeyword(prev_text)):
              yield prev_end, "E211 whitespace before '%s'\n____________________________________________" % text
          prev_type = token_type
          prev_text = text
          prev_end = end
  
  
  @register_check
  def whitespace_around_operator(logical_line):
      r"""Avoid extraneous whitespace around an operator.
  
      Okay: a = 12 + 3
      E221: a = 4  + 5
      E222: a = 4 +  5
      E223: a = 4\t+ 5
      E224: a = 4 +\t5
      """
      for match in OPERATOR_REGEX.finditer(logical_line):
          before, after = match.groups()
  
          if '\t' in before:
              yield match.start(1), "E223 tab before operator\n____________________________________________"
          elif len(before) > 1:
              yield match.start(1), "E221 multiple spaces before operator\n____________________________________________"
  
          if '\t' in after:
              yield match.start(2), "E224 tab after operator\n____________________________________________"
          elif len(after) > 1:
              yield match.start(2), "E222 multiple spaces after operator\n____________________________________________"
  
  
  @register_check
  def missing_whitespace_around_operator(logical_line, tokens):
      r"""Surround operators with a single space on either side.
  
      - Always surround these binary operators with a single space on
        either side: assignment (=), augmented assignment (+=, -= etc.),
        comparisons (==, <, >, !=, <=, >=, in, not in, is, is not),
        Booleans (and, or, not).
  
      - If operators with different priorities are used, consider adding
        whitespace around the operators with the lowest priorities.
  
      Okay: i = i + 1
      Okay: submitted += 1
      Okay: x = x * 2 - 1
      Okay: hypot2 = x * x + y * y
      Okay: c = (a + b) * (a - b)
      Okay: foo(bar, key='word', *args, **kwargs)
      Okay: alpha[:-i]
  
      E225: i=i+1
      E225: submitted +=1
      E225: x = x /2 - 1
      E225: z = x **y
      E226: c = (a+b) * (a-b)
      E226: hypot2 = x*x + y*y
      E227: c = a|b
      E228: msg = fmt%(errno, errmsg)
      """
      parens = 0
      need_space = False
      prev_type = tokenize.OP
      prev_text = prev_end = None
      for token_type, text, start, end, line in tokens:
          if token_type in SKIP_COMMENTS:
              continue
          if text in ('(', 'lambda'):
              parens += 1
          elif text == ')':
              parens -= 1
          if need_space:
              if start != prev_end:
                  # Found a (probably) needed space
                  if need_space is not True and not need_space[1]:
                      yield (need_space[0],
                             "E225 missing whitespace around operator\n____________________________________________")
                  need_space = False
              elif text == '>' and prev_text in ('<', '-'):
                  # Tolerate the "<>" operator, even if running Python 3
                  # Deal with Python 3's annotated return value "->"
                  pass
              else:
                  if need_space is True or need_space[1]:
                      # A needed trailing space was not found
                      yield prev_end, "E225 missing whitespace around operator"
                  elif prev_text != '**':
                      code, optype = 'E226', 'arithmetic'
                      if prev_text == '%':
                          code, optype = 'E228', 'modulo'
                      elif prev_text not in ARITHMETIC_OP:
                          code, optype = 'E227', 'bitwise or shift'
                      yield (need_space[0], "%s missing whitespace "
                             "around %s operator\n____________________________________________" % (code, optype))
                  need_space = False
          elif token_type == tokenize.OP and prev_end is not None:
              if text == '=' and parens:
                  # Allow keyword args or defaults: foo(bar=None).
                  pass
              elif text in WS_NEEDED_OPERATORS:
                  need_space = True
              elif text in UNARY_OPERATORS:
                  # Check if the operator is used as a binary operator
                  # Allow unary operators: -123, -x, +1.
                  # Allow argument unpacking: foo(*args, **kwargs).
                  if (prev_text in '}])' if prev_type == tokenize.OP
                          else prev_text not in KEYWORDS):
                      need_space = None
              elif text in WS_OPTIONAL_OPERATORS:
                  need_space = None
  
              if need_space is None:
                  # Surrounding space is optional, but ensure that
                  # trailing space matches opening space
                  need_space = (prev_end, start != prev_end)
              elif need_space and start == prev_end:
                  # A needed opening space was not found
                  yield prev_end, "E225 missing whitespace around operator\n____________________________________________"
                  need_space = False
          prev_type = token_type
          prev_text = text
          prev_end = end
  
  
  @register_check
  def whitespace_around_comma(logical_line):
      r"""Avoid extraneous whitespace after a comma or a colon.
  
      Note: these checks are disabled by default
  
      Okay: a = (1, 2)
      E241: a = (1,  2)
      E242: a = (1,\t2)
      """
      line = logical_line
      for m in WHITESPACE_AFTER_COMMA_REGEX.finditer(line):
          found = m.start() + 1
          if '\t' in m.group():
              yield found, "E242 tab after '%s'\n____________________________________________" % m.group()[0]
          else:
              yield found, "E241 multiple spaces after '%s'\n____________________________________________" % m.group()[0]
  
  
  @register_check
  def whitespace_around_named_parameter_equals(logical_line, tokens):
      r"""Don't use spaces around the '=' sign in function arguments.
  
      Don't use spaces around the '=' sign when used to indicate a
      keyword argument or a default parameter value, except when
      using a type annotation.
  
      Okay: def complex(real, imag=0.0):
      Okay: return magic(r=real, i=imag)
      Okay: boolean(a == b)
      Okay: boolean(a != b)
      Okay: boolean(a <= b)
      Okay: boolean(a >= b)
      Okay: def foo(arg: int = 42):
      Okay: async def foo(arg: int = 42):
  
      E251: def complex(real, imag = 0.0):
      E251: return magic(r = real, i = imag)
      E252: def complex(real, image: float=0.0):
      """
      parens = 0
      no_space = False
      require_space = False
      prev_end = None
      annotated_func_arg = False
      in_def = bool(STARTSWITH_DEF_REGEX.match(logical_line))
  
      message = "E251 unexpected spaces around keyword / parameter equals\n____________________________________________"
      missing_message = "E252 missing whitespace around parameter equals\n____________________________________________"
  
      for token_type, text, start, end, line in tokens:
          if token_type == tokenize.NL:
              continue
          if no_space:
              no_space = False
              if start != prev_end:
                  yield (prev_end, message)
          if require_space:
              require_space = False
              if start == prev_end:
                  yield (prev_end, missing_message)
          if token_type == tokenize.OP:
              if text in '([':
                  parens += 1
              elif text in ')]':
                  parens -= 1
              elif in_def and text == ':' and parens == 1:
                  annotated_func_arg = True
              elif parens == 1 and text == ',':
                  annotated_func_arg = False
              elif parens and text == '=':
                  if annotated_func_arg and parens == 1:
                      require_space = True
                      if start == prev_end:
                          yield (prev_end, missing_message)
                  else:
                      no_space = True
                      if start != prev_end:
                          yield (prev_end, message)
              if not parens:
                  annotated_func_arg = False
  
          prev_end = end
  
  
  @register_check
  def whitespace_before_comment(logical_line, tokens):
      r"""Separate inline comments by at least two spaces.
  
      An inline comment is a comment on the same line as a statement.
      Inline comments should be separated by at least two spaces from the
      statement. They should start with a # and a single space.
  
      Each line of a block comment starts with a # and a single space
      (unless it is indented text inside the comment).
  
      Okay: x = x + 1  # Increment x
      Okay: x = x + 1    # Increment x
      Okay: # Block comment
      E261: x = x + 1 # Increment x
      E262: x = x + 1  #Increment x
      E262: x = x + 1  #  Increment x
      E265: #Block comment
      E266: ### Block comment
      """
      prev_end = (0, 0)
      for token_type, text, start, end, line in tokens:
          if token_type == tokenize.COMMENT:
              inline_comment = line[:start[1]].strip()
              if inline_comment:
                  if prev_end[0] == start[0] and start[1] < prev_end[1] + 2:
                      yield (prev_end,
                             "E261 at least two spaces before inline comment\n____________________________________________")
              symbol, sp, comment = text.partition(' ')
              bad_prefix = symbol not in '#:' and (symbol.lstrip('#')[:1] or '#')
              if inline_comment:
                  if bad_prefix or comment[:1] in WHITESPACE:
                      yield start, "E262 inline comment should start with '# '\n____________________________________________"
              elif bad_prefix and (bad_prefix != '!' or start[0] > 1):
                  if bad_prefix != '#':
                      yield start, "E265 block comment should start with '# '\n____________________________________________"
                  elif comment:
                      yield start, "E266 too many leading '#' for block comment\n____________________________________________"
          elif token_type != tokenize.NL:
              prev_end = end
  
  
  @register_check
  def imports_on_separate_lines(logical_line):
      r"""Place imports on separate lines.
  
      Okay: import os\nimport sys
      E401: import sys, os
  
      Okay: from subprocess import Popen, PIPE
      Okay: from myclas import MyClass
      Okay: from foo.bar.yourclass import YourClass
      Okay: import myclass
      Okay: import foo.bar.yourclass
      """
      line = logical_line
      if line.startswith('import '):
          found = line.find(',')
          if -1 < found and ';' not in line[:found]:
              yield found, "E401 multiple imports on one line\n____________________________________________"
  
  
  @register_check
  def module_imports_on_top_of_file(
          logical_line, indent_level, checker_state, noqa):
      r"""Place imports at the top of the file.
  
      Always put imports at the top of the file, just after any module
      comments and docstrings, and before module globals and constants.
  
      Okay: import os
      Okay: # this is a comment\nimport os
      Okay: '''this is a module docstring'''\nimport os
      Okay: r'''this is a module docstring'''\nimport os
      Okay:
      try:\n\timport x\nexcept ImportError:\n\tpass\nelse:\n\tpass\nimport y
      Okay:
      try:\n\timport x\nexcept ImportError:\n\tpass\nfinally:\n\tpass\nimport y
      E402: a=1\nimport os
      E402: 'One string'\n"Two string"\nimport os
      E402: a=1\nfrom sys import x
  
      Okay: if x:\n    import os
      """  # noqa
      def is_string_literal(line):
          if line[0] in 'uUbB':
              line = line[1:]
          if line and line[0] in 'rR':
              line = line[1:]
          return line and (line[0] == '"' or line[0] == "'")
  
      allowed_try_keywords = ('try', 'except', 'else', 'finally')
  
      if indent_level:  # Allow imports in conditional statement/function
          return
      if not logical_line:  # Allow empty lines or comments
          return
      if noqa:
          return
      line = logical_line
      if line.startswith('import ') or line.startswith('from '):
          if checker_state.get('seen_non_imports', False):
              yield 0, "E402 module level import not at top of file\n____________________________________________"
      elif re.match(DUNDER_REGEX, line):
          return
      elif any(line.startswith(kw) for kw in allowed_try_keywords):
          # Allow try, except, else, finally keywords intermixed with
          # imports in order to support conditional importing
          return
      elif is_string_literal(line):
          # The first literal is a docstring, allow it. Otherwise, report
          # error.
          if checker_state.get('seen_docstring', False):
              checker_state['seen_non_imports'] = True
          else:
              checker_state['seen_docstring'] = True
      else:
          checker_state['seen_non_imports'] = True
  
  
  @register_check
  def compound_statements(logical_line):
      r"""Compound statements (on the same line) are generally
      discouraged.
  
      While sometimes it's okay to put an if/for/while with a small body
      on the same line, never do this for multi-clause statements.
      Also avoid folding such long lines!
  
      Always use a def statement instead of an assignment statement that
      binds a lambda expression directly to a name.
  
      Okay: if foo == 'blah':\n    do_blah_thing()
      Okay: do_one()
      Okay: do_two()
      Okay: do_three()
  
      E701: if foo == 'blah': do_blah_thing()
      E701: for x in lst: total += x
      E701: while t < 10: t = delay()
      E701: if foo == 'blah': do_blah_thing()
      E701: else: do_non_blah_thing()
      E701: try: something()
      E701: finally: cleanup()
      E701: if foo == 'blah': one(); two(); three()
      E702: do_one(); do_two(); do_three()
      E703: do_four();  # useless semicolon
      E704: def f(x): return 2*x
      E731: f = lambda x: 2*x
      """
      line = logical_line
      last_char = len(line) - 1
      found = line.find(':')
      prev_found = 0
      counts = {char: 0 for char in '{}[]()'}
      while -1 < found < last_char:
          update_counts(line[prev_found:found], counts)
          if ((counts['{'] <= counts['}'] and   # {'a': 1} (dict)
               counts['['] <= counts[']'] and   # [1:2] (slice)
               counts['('] <= counts[')'])):    # (annotation)
              lambda_kw = LAMBDA_REGEX.search(line, 0, found)
              if lambda_kw:
                  before = line[:lambda_kw.start()].rstrip()
                  if before[-1:] == '=' and isidentifier(before[:-1].strip()):
                      yield 0, ("E731 do not assign a lambda expression, use a "
                                "def\n____________________________________________")
                  break
              if STARTSWITH_DEF_REGEX.match(line):
                  yield 0, "E704 multiple statements on one line (def)\n____________________________________________"
              elif STARTSWITH_INDENT_STATEMENT_REGEX.match(line):
                  yield found, "E701 multiple statements on one line (colon)\n____________________________________________"
          prev_found = found
          found = line.find(':', found + 1)
      found = line.find(';')
      while -1 < found:
          if found < last_char:
              yield found, "E702 multiple statements on one line (semicolon)\n____________________________________________"
          else:
              yield found, "E703 statement ends with a semicolon\n____________________________________________"
          found = line.find(';', found + 1)
  
  
  @register_check
  def explicit_line_join(logical_line, tokens):
      r"""Avoid explicit line join between brackets.
  
      The preferred way of wrapping long lines is by using Python's
      implied line continuation inside parentheses, brackets and braces.
      Long lines can be broken over multiple lines by wrapping expressions
      in parentheses.  These should be used in preference to using a
      backslash for line continuation.
  
      E502: aaa = [123, \\n       123]
      E502: aaa = ("bbb " \\n       "ccc")
  
      Okay: aaa = [123,\n       123]
      Okay: aaa = ("bbb "\n       "ccc")
      Okay: aaa = "bbb " \\n    "ccc"
      Okay: aaa = 123  # \\
      """
      prev_start = prev_end = parens = 0
      comment = False
      backslash = None
      for token_type, text, start, end, line in tokens:
          if token_type == tokenize.COMMENT:
              comment = True
          if start[0] != prev_start and parens and backslash and not comment:
              yield backslash, "E502 the backslash is redundant between brackets\n____________________________________________"
          if end[0] != prev_end:
              if line.rstrip('\r\n').endswith('\\'):
                  backslash = (end[0], len(line.splitlines()[-1]) - 1)
              else:
                  backslash = None
              prev_start = prev_end = end[0]
          else:
              prev_start = start[0]
          if token_type == tokenize.OP:
              if text in '([{':
                  parens += 1
              elif text in ')]}':
                  parens -= 1
  
  
  def _is_binary_operator(token_type, text):
      is_op_token = token_type == tokenize.OP
      is_conjunction = text in ['and', 'or']
      # NOTE(sigmavirus24): Previously the not_a_symbol check was executed
      # conditionally. Since it is now *always* executed, text may be
      # None. In that case we get a TypeError for `text not in str`.
      not_a_symbol = text and text not in "()[]{},:.;@=%~"
      # The % character is strictly speaking a binary operator, but the
      # common usage seems to be to put it next to the format parameters,
      # after a line break.
      return ((is_op_token or is_conjunction) and not_a_symbol)
  
  
  def _break_around_binary_operators(tokens):
      """Private function to reduce duplication.
  
      This factors out the shared details between
      :func:`break_before_binary_operator` and
      :func:`break_after_binary_operator`.
      """
      line_break = False
      unary_context = True
      # Previous non-newline token types and text
      previous_token_type = None
      previous_text = None
      for token_type, text, start, end, line in tokens:
          if token_type == tokenize.COMMENT:
              continue
          if ('\n' in text or '\r' in text) and token_type != tokenize.STRING:
              line_break = True
          else:
              yield (token_type, text, previous_token_type, previous_text,
                     line_break, unary_context, start)
              unary_context = text in '([{,;'
              line_break = False
              previous_token_type = token_type
              previous_text = text
  
  
  @register_check
  def break_before_binary_operator(logical_line, tokens):
      r"""
      Avoid breaks before binary operators.
  
      The preferred place to break around a binary operator is after the
      operator, not before it.
  
      W503: (width == 0\n + height == 0)
      W503: (width == 0\n and height == 0)
      W503: var = (1\n       & ~2)
      W503: var = (1\n       / -2)
      W503: var = (1\n       + -1\n       + -2)
  
      Okay: foo(\n    -x)
      Okay: foo(x\n    [])
      Okay: x = '''\n''' + ''
      Okay: foo(x,\n    -y)
      Okay: foo(x,  # comment\n    -y)
      """
      for context in _break_around_binary_operators(tokens):
          (token_type, text, previous_token_type, previous_text,
           line_break, unary_context, start) = context
          if (_is_binary_operator(token_type, text) and line_break and
                  not unary_context and
                  not _is_binary_operator(previous_token_type,
                                          previous_text)):
              yield start, "W503 line break before binary operator\n____________________________________________"
  
  
  @register_check
  def break_after_binary_operator(logical_line, tokens):
      r"""
      Avoid breaks after binary operators.
  
      The preferred place to break around a binary operator is before the
      operator, not after it.
  
      W504: (width == 0 +\n height == 0)
      W504: (width == 0 and\n height == 0)
      W504: var = (1 &\n       ~2)
  
      Okay: foo(\n    -x)
      Okay: foo(x\n    [])
      Okay: x = '''\n''' + ''
      Okay: x = '' + '''\n'''
      Okay: foo(x,\n    -y)
      Okay: foo(x,  # comment\n    -y)
  
      The following should be W504 but unary_context is tricky with these
      Okay: var = (1 /\n       -2)
      Okay: var = (1 +\n       -1 +\n       -2)
      """
      prev_start = None
      for context in _break_around_binary_operators(tokens):
          (token_type, text, previous_token_type, previous_text,
           line_break, unary_context, start) = context
          if (_is_binary_operator(previous_token_type, previous_text) and
                  line_break and
                  not unary_context and
                  not _is_binary_operator(token_type, text)):
              yield prev_start, "W504 line break after binary operator\n____________________________________________"
          prev_start = start
  
  
  @register_check
  def comparison_to_singleton(logical_line, noqa):
      r"""Comparison to singletons should use "is" or "is not".
  
      Comparisons to singletons like None should always be done
      with "is" or "is not", never the equality operators.
  
      Okay: if arg is not None:
      E711: if arg != None:
      E711: if None == arg:
      E712: if arg == True:
      E712: if False == arg:
  
      Also, beware of writing if x when you really mean if x is not None
      -- e.g. when testing whether a variable or argument that defaults to
      None was set to some other value.  The other value might have a type
      (such as a container) that could be false in a boolean context!
      """
      match = not noqa and COMPARE_SINGLETON_REGEX.search(logical_line)
      if match:
          singleton = match.group(1) or match.group(3)
          same = (match.group(2) == '==')
  
          msg = "'if cond is %s:'" % (('' if same else 'not ') + singleton)
          if singleton in ('None',):
              code = 'E711'
          else:
              code = 'E712'
              nonzero = ((singleton == 'True' and same) or
                         (singleton == 'False' and not same))
              msg += " or 'if %scond:'" % ('' if nonzero else 'not ')
          yield match.start(2), ("%s comparison to %s should be %s\n____________________________________________" %
                                 (code, singleton, msg))
  
  
  @register_check
  def comparison_negative(logical_line):
      r"""Negative comparison should be done using "not in" and "is not".
  
      Okay: if x not in y:\n    pass
      Okay: assert (X in Y or X is Z)
      Okay: if not (X in Y):\n    pass
      Okay: zz = x is not y
      E713: Z = not X in Y
      E713: if not X.B in Y:\n    pass
      E714: if not X is Y:\n    pass
      E714: Z = not X.B is Y
      """
      match = COMPARE_NEGATIVE_REGEX.search(logical_line)
      if match:
          pos = match.start(1)
          if match.group(2) == 'in':
              yield pos, "E713 test for membership should be 'not in'\n____________________________________________"
          else:
              yield pos, "E714 test for object identity should be 'is not'\n____________________________________________"
  
  
  @register_check
  def comparison_type(logical_line, noqa):
      r"""Object type comparisons should always use isinstance().
  
      Do not compare types directly.
  
      Okay: if isinstance(obj, int):
      E721: if type(obj) is type(1):
  
      When checking if an object is a string, keep in mind that it might
      be a unicode string too! In Python 2.3, str and unicode have a
      common base class, basestring, so you can do:
  
      Okay: if isinstance(obj, basestring):
      Okay: if type(a1) is type(b1):
      """
      match = COMPARE_TYPE_REGEX.search(logical_line)
      if match and not noqa:
          inst = match.group(1)
          if inst and isidentifier(inst) and inst not in SINGLETONS:
              return  # Allow comparison for types which are not obvious
          yield match.start(), "E721 do not compare types, use 'isinstance()'\n____________________________________________"
  
  
  @register_check
  def bare_except(logical_line, noqa):
      r"""When catching exceptions, mention specific exceptions when
      possible.
  
      Okay: except Exception:
      Okay: except BaseException:
      E722: except:
      """
      if noqa:
          return
  
      regex = re.compile(r"except\s*:")
      match = regex.match(logical_line)
      if match:
          yield match.start(), "E722 do not use bare 'except'\n____________________________________________"
  
  
  @register_check
  def ambiguous_identifier(logical_line, tokens):
      r"""Never use the characters 'l', 'O', or 'I' as variable names.
  
      In some fonts, these characters are indistinguishable from the
      numerals one and zero. When tempted to use 'l', use 'L' instead.
  
      Okay: L = 0
      Okay: o = 123
      Okay: i = 42
      E741: l = 0
      E741: O = 123
      E741: I = 42
  
      Variables can be bound in several other contexts, including class
      and function definitions, 'global' and 'nonlocal' statements,
      exception handlers, and 'with' statements.
  
      Okay: except AttributeError as o:
      Okay: with lock as L:
      E741: except AttributeError as O:
      E741: with lock as l:
      E741: global I
      E741: nonlocal l
      E742: class I(object):
      E743: def l(x):
      """
      idents_to_avoid = ('l', 'O', 'I')
      prev_type, prev_text, prev_start, prev_end, __ = tokens[0]
      for token_type, text, start, end, line in tokens[1:]:
          ident = pos = None
          # identifiers on the lhs of an assignment operator
          if token_type == tokenize.OP and '=' in text:
              if prev_text in idents_to_avoid:
                  ident = prev_text
                  pos = prev_start
          # identifiers bound to values with 'as', 'global', or 'nonlocal'
          if prev_text in ('as', 'global', 'nonlocal'):
              if text in idents_to_avoid:
                  ident = text
                  pos = start
          if prev_text == 'class':
              if text in idents_to_avoid:
                  yield start, "E742 ambiguous class definition '%s'\n____________________________________________" % text
          if prev_text == 'def':
              if text in idents_to_avoid:
                  yield start, "E743 ambiguous function definition '%s'\n____________________________________________" % text
          if ident:
              yield pos, "E741 ambiguous variable name '%s'\n____________________________________________" % ident
          prev_text = text
          prev_start = start
  
  
  @register_check
  def python_3000_has_key(logical_line, noqa):
      r"""The {}.has_key() method is removed in Python 3: use the 'in'
      operator.
  
      Okay: if "alph" in d:\n    print d["alph"]
      W601: assert d.has_key('alph')
      """
      pos = logical_line.find('.has_key(')
      if pos > -1 and not noqa:
          yield pos, "W601 .has_key() is deprecated, use 'in'\n____________________________________________"
  
  
  @register_check
  def python_3000_raise_comma(logical_line):
      r"""When raising an exception, use "raise ValueError('message')".
  
      The older form is removed in Python 3.
  
      Okay: raise DummyError("Message")
      W602: raise DummyError, "Message"
      """
      match = RAISE_COMMA_REGEX.match(logical_line)
      if match and not RERAISE_COMMA_REGEX.match(logical_line):
          yield match.end() - 1, "W602 deprecated form of raising exception\n____________________________________________"
  
  
  @register_check
  def python_3000_not_equal(logical_line):
      r"""New code should always use != instead of <>.
  
      The older syntax is removed in Python 3.
  
      Okay: if a != 'no':
      W603: if a <> 'no':
      """
      pos = logical_line.find('<>')
      if pos > -1:
          yield pos, "W603 '<>' is deprecated, use '!='\n____________________________________________"
  
  
  @register_check
  def python_3000_backticks(logical_line):
      r"""Use repr() instead of backticks in Python 3.
  
      Okay: val = repr(1 + 2)
      W604: val = `1 + 2`
      """
      pos = logical_line.find('`')
      if pos > -1:
          yield pos, "W604 backticks are deprecated, use 'repr()'\n____________________________________________"
  
  
  @register_check
  def python_3000_invalid_escape_sequence(logical_line, tokens):
      r"""Invalid escape sequences are deprecated in Python 3.6.
  
      Okay: regex = r'\.png$'
      W605: regex = '\.png$'
      """
      # https://docs.python.org/3/reference/lexical_analysis.html#string-and-bytes-literals
      valid = [
          '\n',
          '\\',
          '\'',
          '"',
          'a',
          'b',
          'f',
          'n',
          'r',
          't',
          'v',
          '0', '1', '2', '3', '4', '5', '6', '7',
          'x',
  
          # Escape sequences only recognized in string literals
          'N',
          'u',
          'U',
      ]
  
      for token_type, text, start, end, line in tokens:
          if token_type == tokenize.STRING:
              start_line, start_col = start
              quote = text[-3:] if text[-3:] in ('"""', "'''") else text[-1]
              # Extract string modifiers (e.g. u or r)
              quote_pos = text.index(quote)
              prefix = text[:quote_pos].lower()
              start = quote_pos + len(quote)
              string = text[start:-len(quote)]
  
              if 'r' not in prefix:
                  pos = string.find('\\')
                  while pos >= 0:
                      pos += 1
                      if string[pos] not in valid:
                          line = start_line + string.count('\n', 0, pos)
                          if line == start_line:
                              col = start_col + len(prefix) + len(quote) + pos
                          else:
                              col = pos - string.rfind('\n', 0, pos) - 1
                          yield (
                              (line, col - 1),
                              "W605 invalid escape sequence '\\%s'\n____________________________________________" %
                              string[pos],
                          )
                      pos = string.find('\\', pos + 1)
  
  
  @register_check
  def python_3000_async_await_keywords(logical_line, tokens):
      """'async' and 'await' are reserved keywords starting at Python 3.7.
  
      W606: async = 42
      W606: await = 42
      Okay: async def read(db):\n    data = await db.fetch('SELECT ...')
      """
      # The Python tokenize library before Python 3.5 recognizes
      # async/await as a NAME token. Therefore, use a state machine to
      # look for the possible async/await constructs as defined by the
      # Python grammar:
      # https://docs.python.org/3/reference/grammar.html
  
      state = None
      for token_type, text, start, end, line in tokens:
          error = False
  
          if state is None:
              if token_type == tokenize.NAME:
                  if text == 'async':
                      state = ('async_stmt', start)
                  elif text == 'await':
                      state = ('await', start)
          elif state[0] == 'async_stmt':
              if token_type == tokenize.NAME and text in ('def', 'with', 'for'):
                  # One of funcdef, with_stmt, or for_stmt. Return to
                  # looking for async/await names.
                  state = None
              else:
                  error = True
          elif state[0] == 'await':
              if token_type == tokenize.NAME:
                  # An await expression. Return to looking for async/await
                  # names.
                  state = None
              else:
                  error = True
  
          if error:
              yield (
                  state[1],
                  "W606 'async' and 'await' are reserved keywords starting with "
                  "Python 3.7",
              )
              state = None
  
      # Last token
      if state is not None:
          yield (
              state[1],
              "W606 'async' and 'await' are reserved keywords starting with "
              "Python 3.7",
          )
  
  
  ########################################################################
  @register_check
  def maximum_doc_length(logical_line, max_doc_length, noqa, tokens):
      r"""Limit all doc lines to a maximum of 72 characters.
  
      For flowing long blocks of text (docstrings or comments), limiting
      the length to 72 characters is recommended.
  
      Reports warning W505
      """
      if max_doc_length is None or noqa:
          return
  
      prev_token = None
      skip_lines = set()
      # Skip lines that
      for token_type, text, start, end, line in tokens:
          if token_type not in SKIP_COMMENTS.union([tokenize.STRING]):
              skip_lines.add(line)
  
      for token_type, text, start, end, line in tokens:
          # Skip lines that aren't pure strings
          if token_type == tokenize.STRING and skip_lines:
              continue
          if token_type in (tokenize.STRING, tokenize.COMMENT):
              # Only check comment-only lines
              if prev_token is None or prev_token in SKIP_TOKENS:
                  lines = line.splitlines()
                  for line_num, physical_line in enumerate(lines):
                      if hasattr(physical_line, 'decode'):  # Python 2
                          # The line could contain multi-byte characters
                          try:
                              physical_line = physical_line.decode('utf-8')
                          except UnicodeError:
                              pass
                      if start[0] + line_num == 1 and line.startswith('#!'):
                          return
                      length = len(physical_line)
                      chunks = physical_line.split()
                      if token_type == tokenize.COMMENT:
                          if (len(chunks) == 2 and
                                  length - len(chunks[-1]) < MAX_DOC_LENGTH):
                              continue
                      if len(chunks) == 1 and line_num + 1 < len(lines):
                          if (len(chunks) == 1 and
                                  length - len(chunks[-1]) < MAX_DOC_LENGTH):
                              continue
                      if length > max_doc_length:
                          doc_error = (start[0] + line_num, max_doc_length)
                          yield (doc_error, "W505 doc line too long "
                                            "(%d > %d characters)\n____________________________________________"
                                 % (length, max_doc_length))
          prev_token = token_type
  
  
  ########################################################################
  # Helper functions
  ########################################################################
  
  
  if sys.version_info < (3,):
      # Python 2: implicit encoding.
      def readlines(filename):
          """Read the source code."""
          with open(filename, 'rU') as f:
              return f.readlines()
      isidentifier = re.compile(r'[a-zA-Z_]\w*$').match
      stdin_get_value = sys.stdin.read
  else:
      # Python 3
      def readlines(filename):
          """Read the source code."""
          try:
              with open(filename, 'rb') as f:
                  (coding, lines) = tokenize.detect_encoding(f.readline)
                  f = TextIOWrapper(f, coding, line_buffering=True)
                  return [line.decode(coding) for line in lines] + f.readlines()
          except (LookupError, SyntaxError, UnicodeError):
              # Fall back if file encoding is improperly declared
              with open(filename, encoding='latin-1') as f:
                  return f.readlines()
      isidentifier = str.isidentifier
  
      def stdin_get_value():
          """Read the value from stdin."""
          return TextIOWrapper(sys.stdin.buffer, errors='ignore').read()
  
  noqa = lru_cache(512)(re.compile(r'# no(?:qa|pep8)\b', re.I).search)
  
  
  def expand_indent(line):
      r"""Return the amount of indentation.
  
      Tabs are expanded to the next multiple of 8.
  
      >>> expand_indent('    ')
      4
      >>> expand_indent('\t')
      8
      >>> expand_indent('       \t')
      8
      >>> expand_indent('        \t')
      16
      """
      if '\t' not in line:
          return len(line) - len(line.lstrip())
      result = 0
      for char in line:
          if char == '\t':
              result = result // 8 * 8 + 8
          elif char == ' ':
              result += 1
          else:
              break
      return result
  
  
  def mute_string(text):
      """Replace contents with 'xxx' to prevent syntax matching.
  
      >>> mute_string('"abc"')
      '"xxx"'
      >>> mute_string("'''abc'''")
      "'''xxx'''"
      >>> mute_string("r'abc'")
      "r'xxx'"
      """
      # String modifiers (e.g. u or r)
      start = text.index(text[-1]) + 1
      end = len(text) - 1
      # Triple quotes
      if text[-3:] in ('"""', "'''"):
          start += 2
          end -= 2
      return text[:start] + 'x' * (end - start) + text[end:]
  
  
  def parse_udiff(diff, patterns=None, parent='.'):
      """Return a dictionary of matching lines."""
      # For each file of the diff, the entry key is the filename,
      # and the value is a set of row numbers to consider.
      rv = {}
      path = nrows = None
      for line in diff.splitlines():
          if nrows:
              if line[:1] != '-':
                  nrows -= 1
              continue
          if line[:3] == '@@ ':
              hunk_match = HUNK_REGEX.match(line)
              (row, nrows) = [int(g or '1') for g in hunk_match.groups()]
              rv[path].update(range(row, row + nrows))
          elif line[:3] == '+++':
              path = line[4:].split('\t', 1)[0]
              # Git diff will use (i)ndex, (w)ork tree, (c)ommit and
              # (o)bject instead of a/b/c/d as prefixes for patches
              if path[:2] in ('b/', 'w/', 'i/'):
                  path = path[2:]
              rv[path] = set()
      return {
          os.path.join(parent, filepath): rows
          for (filepath, rows) in rv.items()
          if rows and filename_match(filepath, patterns)
      }
  
  
  def normalize_paths(value, parent=os.curdir):
      """Parse a comma-separated list of paths.
  
      Return a list of absolute paths.
      """
      if not value:
          return []
      if isinstance(value, list):
          return value
      paths = []
      for path in value.split(','):
          path = path.strip()
          if '/' in path:
              path = os.path.abspath(os.path.join(parent, path))
          paths.append(path.rstrip('/'))
      return paths
  
  
  def filename_match(filename, patterns, default=True):
      """Check if patterns contains a pattern that matches filename.
  
      If patterns is unspecified, this always returns True.
      """
      if not patterns:
          return default
      return any(fnmatch(filename, pattern) for pattern in patterns)
  
  
  def update_counts(s, counts):
      r"""Adds one to the counts of each appearance of characters in s,
          for characters in counts"""
      for char in s:
          if char in counts:
              counts[char] += 1
  
  
  def _is_eol_token(token):
      return token[0] in NEWLINE or token[4][token[3][1]:].lstrip() == '\\\n'
  
  
  ########################################################################
  # Framework to run all checks
  ########################################################################
  
  
  class Checker(object):
      """Load a Python source file, tokenize it, check coding style."""
  
      def __init__(self, filename=None, lines=None,
                   options=None, report=None, **kwargs):
          if options is None:
              options = StyleGuide(kwargs).options
          else:
              assert not kwargs
          self._io_error = None
          self._physical_checks = options.physical_checks
          self._logical_checks = options.logical_checks
          self._ast_checks = options.ast_checks
          self.max_line_length = options.max_line_length
          self.max_doc_length = options.max_doc_length
          self.multiline = False  # in a multiline string?
          self.hang_closing = options.hang_closing
          self.verbose = options.verbose
          self.filename = filename
          # Dictionary where a checker can store its custom state.
          self._checker_states = {}
          if filename is None:
              self.filename = 'stdin'
              self.lines = lines or []
          elif filename == '-':
              self.filename = 'stdin'
              self.lines = stdin_get_value().splitlines(True)
          elif lines is None:
              try:
                  self.lines = readlines(filename)
              except IOError:
                  (exc_type, exc) = sys.exc_info()[:2]
                  self._io_error = '%s: %s' % (exc_type.__name__, exc)
                  self.lines = []
          else:
              self.lines = lines
          if self.lines:
              ord0 = ord(self.lines[0][0])
              if ord0 in (0xef, 0xfeff):  # Strip the UTF-8 BOM
                  if ord0 == 0xfeff:
                      self.lines[0] = self.lines[0][1:]
                  elif self.lines[0][:3] == '\xef\xbb\xbf':
                      self.lines[0] = self.lines[0][3:]
          self.report = report or options.report
          self.report_error = self.report.error
          self.noqa = False
  
      def report_invalid_syntax(self):
          """Check if the syntax is valid."""
          (exc_type, exc) = sys.exc_info()[:2]
          if len(exc.args) > 1:
              offset = exc.args[1]
              if len(offset) > 2:
                  offset = offset[1:3]
          else:
              offset = (1, 0)
          self.report_error(offset[0], offset[1] or 0,
                            'E901 %s: %s' % (exc_type.__name__, exc.args[0]),
                            self.report_invalid_syntax)
  
      def readline(self):
          """Get the next line from the input buffer."""
          if self.line_number >= self.total_lines:
              return ''
          line = self.lines[self.line_number]
          self.line_number += 1
          if self.indent_char is None and line[:1] in WHITESPACE:
              self.indent_char = line[0]
          return line
  
      def run_check(self, check, argument_names):
          """Run a check plugin."""
          arguments = []
          for name in argument_names:
              arguments.append(getattr(self, name))
          return check(*arguments)
  
      def init_checker_state(self, name, argument_names):
          """Prepare custom state for the specific checker plugin."""
          if 'checker_state' in argument_names:
              self.checker_state = self._checker_states.setdefault(name, {})
  
      def check_physical(self, line):
          """Run all physical checks on a raw input line."""
          self.physical_line = line
          for name, check, argument_names in self._physical_checks:
              self.init_checker_state(name, argument_names)
              result = self.run_check(check, argument_names)
              if result is not None:
                  (offset, text) = result
                  self.report_error(self.line_number, offset, text, check)
                  if text[:4] == 'E101':
                      self.indent_char = line[0]
  
      def build_tokens_line(self):
          """Build a logical line from tokens."""
          logical = []
          comments = []
          length = 0
          prev_row = prev_col = mapping = None
          for token_type, text, start, end, line in self.tokens:
              if token_type in SKIP_TOKENS:
                  continue
              if not mapping:
                  mapping = [(0, start)]
              if token_type == tokenize.COMMENT:
                  comments.append(text)
                  continue
              if token_type == tokenize.STRING:
                  text = mute_string(text)
              if prev_row:
                  (start_row, start_col) = start
                  if prev_row != start_row:    # different row
                      prev_text = self.lines[prev_row - 1][prev_col - 1]
                      if prev_text == ',' or (prev_text not in '{[(' and
                                              text not in '}])'):
                          text = ' ' + text
                  elif prev_col != start_col:  # different column
                      text = line[prev_col:start_col] + text
              logical.append(text)
              length += len(text)
              mapping.append((length, end))
              (prev_row, prev_col) = end
          self.logical_line = ''.join(logical)
          self.noqa = comments and noqa(''.join(comments))
          return mapping
  
      def check_logical(self):
          """Build a line from tokens and run all logical checks on it."""
          self.report.increment_logical_line()
          mapping = self.build_tokens_line()
          if not mapping:
              return
  
          mapping_offsets = [offset for offset, _ in mapping]
          (start_row, start_col) = mapping[0][1]
          start_line = self.lines[start_row - 1]
          self.indent_level = expand_indent(start_line[:start_col])
          if self.blank_before < self.blank_lines:
              self.blank_before = self.blank_lines
          if self.verbose >= 2:
              print(self.logical_line[:80].rstrip())
          for name, check, argument_names in self._logical_checks:
              if self.verbose >= 4:
                  print('   ' + name)
              self.init_checker_state(name, argument_names)
              for offset, text in self.run_check(check, argument_names) or ():
                  if not isinstance(offset, tuple):
                      # As mappings are ordered, bisecting is a fast way
                      # to find a given offset in them.
                      token_offset, pos = mapping[bisect.bisect_left(
                          mapping_offsets, offset)]
                      offset = (pos[0], pos[1] + offset - token_offset)
                  self.report_error(offset[0], offset[1], text, check)
          if self.logical_line:
              self.previous_indent_level = self.indent_level
              self.previous_logical = self.logical_line
              if not self.indent_level:
                  self.previous_unindented_logical_line = self.logical_line
          self.blank_lines = 0
          self.tokens = []
  
      def check_ast(self):
          """Build the file's AST and run all AST checks."""
          try:
              tree = compile(''.join(self.lines), '', 'exec', PyCF_ONLY_AST)
          except (ValueError, SyntaxError, TypeError):
              return self.report_invalid_syntax()
          for name, cls, __ in self._ast_checks:
              checker = cls(tree, self.filename)
              for lineno, offset, text, check in checker.run():
                  if not self.lines or not noqa(self.lines[lineno - 1]):
                      self.report_error(lineno, offset, text, check)
  
      def generate_tokens(self):
          """Tokenize file, run physical line checks and yield tokens."""
          if self._io_error:
              self.report_error(1, 0, 'E902 %s' % self._io_error, readlines)
          tokengen = tokenize.generate_tokens(self.readline)
          try:
              for token in tokengen:
                  if token[2][0] > self.total_lines:
                      return
                  self.noqa = token[4] and noqa(token[4])
                  self.maybe_check_physical(token)
                  yield token
          except (SyntaxError, tokenize.TokenError):
              self.report_invalid_syntax()
  
      def maybe_check_physical(self, token):
          """If appropriate for token, check current physical line(s)."""
          # Called after every token, but act only on end of line.
          if _is_eol_token(token):
              # Obviously, a newline token ends a single physical line.
              self.check_physical(token[4])
          elif token[0] == tokenize.STRING and '\n' in token[1]:
              # Less obviously, a string that contains newlines is a
              # multiline string, either triple-quoted or with internal
              # newlines backslash-escaped. Check every physical line in
              # the string *except* for the last one: its newline is
              # outside of the multiline string, so we consider it a
              # regular physical line, and will check it like any other
              # physical line.
              #
              # Subtleties:
              # - we don't *completely* ignore the last line; if it
              #   contains the magical "# noqa" comment, we disable all
              #   physical checks for the entire multiline string
              # - have to wind self.line_number back because initially it
              #   points to the last line of the string, and we want
              #   check_physical() to give accurate feedback
              if noqa(token[4]):
                  return
              self.multiline = True
              self.line_number = token[2][0]
              _, src, (_, offset), _, _ = token
              src = self.lines[self.line_number - 1][:offset] + src
              for line in src.split('\n')[:-1]:
                  self.check_physical(line + '\n')
                  self.line_number += 1
              self.multiline = False
  
      def check_all(self, expected=None, line_offset=0):
          """Run all checks on the input file."""
          self.report.init_file(self.filename, self.lines, expected, line_offset)
          self.total_lines = len(self.lines)
          if self._ast_checks:
              self.check_ast()
          self.line_number = 0
          self.indent_char = None
          self.indent_level = self.previous_indent_level = 0
          self.previous_logical = ''
          self.previous_unindented_logical_line = ''
          self.tokens = []
          self.blank_lines = self.blank_before = 0
          parens = 0
          for token in self.generate_tokens():
              self.tokens.append(token)
              token_type, text = token[0:2]
              if self.verbose >= 3:
                  if token[2][0] == token[3][0]:
                      pos = '[%s:%s]' % (token[2][1] or '', token[3][1])
                  else:
                      pos = 'l.%s' % token[3][0]
                  print('l.%s\t%s\t%s\t%r' %
                        (token[2][0], pos, tokenize.tok_name[token[0]], text))
              if token_type == tokenize.OP:
                  if text in '([{':
                      parens += 1
                  elif text in '}])':
                      parens -= 1
              elif not parens:
                  if token_type in NEWLINE:
                      if token_type == tokenize.NEWLINE:
                          self.check_logical()
                          self.blank_before = 0
                      elif len(self.tokens) == 1:
                          # The physical line contains only this token.
                          self.blank_lines += 1
                          del self.tokens[0]
                      else:
                          self.check_logical()
          if self.tokens:
              self.check_physical(self.lines[-1])
              self.check_logical()
          return self.report.get_file_results()
  
  
  class BaseReport(object):
      """Collect the results of the checks."""
  
      print_filename = False
  
      def __init__(self, options):
          self._benchmark_keys = options.benchmark_keys
          self._ignore_code = options.ignore_code
          # Results
          self.elapsed = 0
          self.total_errors = 0
          self.counters = dict.fromkeys(self._benchmark_keys, 0)
          self.messages = {}
  
      def start(self):
          """Start the timer."""
          self._start_time = time.time()
  
      def stop(self):
          """Stop the timer."""
          self.elapsed = time.time() - self._start_time
  
      def init_file(self, filename, lines, expected, line_offset):
          """Signal a new file."""
          self.filename = filename
          self.lines = lines
          self.expected = expected or ()
          self.line_offset = line_offset
          self.file_errors = 0
          self.counters['files'] += 1
          self.counters['physical lines'] += len(lines)
  
      def increment_logical_line(self):
          """Signal a new logical line."""
          self.counters['logical lines'] += 1
  
      def error(self, line_number, offset, text, check):
          """Report an error, according to options."""
          code = text[:4]
          if self._ignore_code(code):
              return
          if code in self.counters:
              self.counters[code] += 1
          else:
              self.counters[code] = 1
              self.messages[code] = text[5:]
          # Don't care about expected errors or warnings
          if code in self.expected:
              return
          if self.print_filename and not self.file_errors:
              print(self.filename)
          self.file_errors += 1
          self.total_errors += 1
          return code
  
      def get_file_results(self):
          """Return the count of errors and warnings for this file."""
          return self.file_errors
  
      def get_count(self, prefix=''):
          """Return the total count of errors and warnings."""
          return sum(self.counters[key]
                     for key in self.messages if key.startswith(prefix))
  
      def get_statistics(self, prefix=''):
          """Get statistics for message codes that start with the prefix.
  
          prefix='' matches all errors and warnings
          prefix='E' matches all errors
          prefix='W' matches all warnings
          prefix='E4' matches all errors that have to do with imports
          """
          return ['%-7s %s %s' % (self.counters[key], key, self.messages[key])
                  for key in sorted(self.messages) if key.startswith(prefix)]
  
      def print_statistics(self, prefix=''):
          """Print overall statistics (number of errors and warnings)."""
          for line in self.get_statistics(prefix):
              print(line)
  
      def print_benchmark(self):
          """Print benchmark numbers."""
          print('%-7.2f %s' % (self.elapsed, 'seconds elapsed'))
          if self.elapsed:
              for key in self._benchmark_keys:
                  print('%-7d %s per second (%d total)' %
                        (self.counters[key] / self.elapsed, key,
                         self.counters[key]))
  
  
  class FileReport(BaseReport):
      """Collect the results of the checks and print the filenames."""
  
      print_filename = True
  
  
  class StandardReport(BaseReport):
      """Collect and print the results of the checks."""
  
      def __init__(self, options):
          super(StandardReport, self).__init__(options)
          self._fmt = REPORT_FORMAT.get(options.format.lower(),
                                        options.format)
          self._repeat = options.repeat
          self._show_source = options.show_source
          self._show_pep8 = options.show_pep8
  
      def init_file(self, filename, lines, expected, line_offset):
          """Signal a new file."""
          self._deferred_print = []
          return super(StandardReport, self).init_file(
              filename, lines, expected, line_offset)
  
      def error(self, line_number, offset, text, check):
          """Report an error, according to options."""
          code = super(StandardReport, self).error(line_number, offset,
                                                   text, check)
          if code and (self.counters[code] == 1 or self._repeat):
              self._deferred_print.append(
                  (line_number, offset, code, text[5:], check.__doc__))
          return code
  
      def get_file_results(self):
          """Print results and return the overall count for this file."""
          self._deferred_print.sort()
          for line_number, offset, code, text, doc in self._deferred_print:
              print(self._fmt % {
                  'path': self.filename,
                  'row': self.line_offset + line_number, 'col': offset + 1,
                  'code': code, 'text': text,
              })
              if self._show_source:
                  if line_number > len(self.lines):
                      line = ''
                  else:
                      line = self.lines[line_number - 1]
                  print(line.rstrip())
                  print(re.sub(r'\S', ' ', line[:offset]) + '^')
              if self._show_pep8 and doc:
                  print('    ' + doc.strip())
  
              # stdout is block buffered when not stdout.isatty().
              # line can be broken where buffer boundary since other
              # processes write to same file.
              # flush() after print() to avoid buffer boundary.
              # Typical buffer size is 8192. line written safely when
              # len(line) < 8192.
              sys.stdout.flush()
          return self.file_errors
  
  
  class DiffReport(StandardReport):
      """Collect and print the results for the changed lines only."""
  
      def __init__(self, options):
          super(DiffReport, self).__init__(options)
          self._selected = options.selected_lines
  
      def error(self, line_number, offset, text, check):
          if line_number not in self._selected[self.filename]:
              return
          return super(DiffReport, self).error(line_number, offset, text, check)
  
  
  class StyleGuide(object):
      """Initialize a PEP-8 instance with few options."""
  
      def __init__(self, *args, **kwargs):
          # build options from the command line
          self.checker_class = kwargs.pop('checker_class', Checker)
          parse_argv = kwargs.pop('parse_argv', False)
          config_file = kwargs.pop('config_file', False)
          parser = kwargs.pop('parser', None)
          # build options from dict
          options_dict = dict(*args, **kwargs)
          arglist = None if parse_argv else options_dict.get('paths', None)
          verbose = options_dict.get('verbose', None)
          options, self.paths = process_options(
              arglist, parse_argv, config_file, parser, verbose)
          if options_dict:
              options.__dict__.update(options_dict)
              if 'paths' in options_dict:
                  self.paths = options_dict['paths']
  
          self.runner = self.input_file
          self.options = options
  
          if not options.reporter:
              options.reporter = BaseReport if options.quiet else StandardReport
  
          options.select = tuple(options.select or ())
          if not (options.select or options.ignore or
                  options.testsuite or options.doctest) and DEFAULT_IGNORE:
              # The default choice: ignore controversial checks
              options.ignore = tuple(DEFAULT_IGNORE.split(','))
          else:
              # Ignore all checks which are not explicitly selected
              options.ignore = ('',) if options.select else tuple(options.ignore)
          options.benchmark_keys = BENCHMARK_KEYS[:]
          options.ignore_code = self.ignore_code
          options.physical_checks = self.get_checks('physical_line')
          options.logical_checks = self.get_checks('logical_line')
          options.ast_checks = self.get_checks('tree')
          self.init_report()
  
      def init_report(self, reporter=None):
          """Initialize the report instance."""
          self.options.report = (reporter or self.options.reporter)(self.options)
          return self.options.report
  
      def check_files(self, paths=None):
          """Run all checks on the paths."""
          if paths is None:
              paths = self.paths
          report = self.options.report
          runner = self.runner
          report.start()
          try:
              for path in paths:
                  if os.path.isdir(path):
                      self.input_dir(path)
                  elif not self.excluded(path):
                      runner(path)
          except KeyboardInterrupt:
              print('... stopped')
          report.stop()
          return report
  
      def input_file(self, filename, lines=None, expected=None, line_offset=0):
          """Run all checks on a Python source file."""
          if self.options.verbose:
              print('checking %s' % filename)
          fchecker = self.checker_class(
              filename, lines=lines, options=self.options)
          return fchecker.check_all(expected=expected, line_offset=line_offset)
  
      def input_dir(self, dirname):
          """Check all files in this directory and all subdirectories."""
          dirname = dirname.rstrip('/')
          if self.excluded(dirname):
              return 0
          counters = self.options.report.counters
          verbose = self.options.verbose
          filepatterns = self.options.filename
          runner = self.runner
          for root, dirs, files in os.walk(dirname):
              if verbose:
                  print('directory ' + root)
              counters['directories'] += 1
              for subdir in sorted(dirs):
                  if self.excluded(subdir, root):
                      dirs.remove(subdir)
              for filename in sorted(files):
                  # contain a pattern that matches?
                  if ((filename_match(filename, filepatterns) and
                       not self.excluded(filename, root))):
                      runner(os.path.join(root, filename))
  
      def excluded(self, filename, parent=None):
          """Check if the file should be excluded.
  
          Check if 'options.exclude' contains a pattern matching filename.
          """
          if not self.options.exclude:
              return False
          basename = os.path.basename(filename)
          if filename_match(basename, self.options.exclude):
              return True
          if parent:
              filename = os.path.join(parent, filename)
          filename = os.path.abspath(filename)
          return filename_match(filename, self.options.exclude)
  
      def ignore_code(self, code):
          """Check if the error code should be ignored.
  
          If 'options.select' contains a prefix of the error code,
          return False.  Else, if 'options.ignore' contains a prefix of
          the error code, return True.
          """
          if len(code) < 4 and any(s.startswith(code)
                                   for s in self.options.select):
              return False
          return (code.startswith(self.options.ignore) and
                  not code.startswith(self.options.select))
  
      def get_checks(self, argument_name):
          """Get all the checks for this category.
  
          Find all globally visible functions where the first argument
          name starts with argument_name and which contain selected tests.
          """
          checks = []
          for check, attrs in _checks[argument_name].items():
              (codes, args) = attrs
              if any(not (code and self.ignore_code(code)) for code in codes):
                  checks.append((check.__name__, check, args))
          return sorted(checks)
  
  
  def get_parser(prog='pycodestyle', version=__version__):
      """Create the parser for the program."""
      parser = OptionParser(prog=prog, version=version,
                            usage="%prog [options] input ...")
      parser.config_options = [
          'exclude', 'filename', 'select', 'ignore', 'max-line-length',
          'max-doc-length', 'hang-closing', 'count', 'format', 'quiet',
          'show-pep8', 'show-source', 'statistics', 'verbose']
      parser.add_option('-v', '--verbose', default=0, action='count',
                        help="print status messages, or debug with -vv")
      parser.add_option('-q', '--quiet', default=0, action='count',
                        help="report only file names, or nothing with -qq")
      parser.add_option('-r', '--repeat', default=True, action='store_true',
                        help="(obsolete) show all occurrences of the same error")
      parser.add_option('--first', action='store_false', dest='repeat',
                        help="show first occurrence of each error")
      parser.add_option('--exclude', metavar='patterns', default=DEFAULT_EXCLUDE,
                        help="exclude files or directories which match these "
                             "comma separated patterns (default: %default)")
      parser.add_option('--filename', metavar='patterns', default='*.py',
                        help="when parsing directories, only check filenames "
                             "matching these comma separated patterns "
                             "(default: %default)")
      parser.add_option('--select', metavar='errors', default='',
                        help="select errors and warnings (e.g. E,W6)")
      parser.add_option('--ignore', metavar='errors', default='',
                        help="skip errors and warnings (e.g. E4,W) "
                             "(default: %s)" % DEFAULT_IGNORE)
      parser.add_option('--show-source', action='store_true',
                        help="show source code for each error")
      parser.add_option('--show-pep8', action='store_true',
                        help="show text of PEP 8 for each error "
                             "(implies --first)")
      parser.add_option('--statistics', action='store_true',
                        help="count errors and warnings")
      parser.add_option('--count', action='store_true',
                        help="print total number of errors and warnings "
                             "to standard error and set exit code to 1 if "
                             "total is not null")
      parser.add_option('--max-line-length', type='int', metavar='n',
                        default=MAX_LINE_LENGTH,
                        help="set maximum allowed line length "
                             "(default: %default)")
      parser.add_option('--max-doc-length', type='int', metavar='n',
                        default=None,
                        help="set maximum allowed doc line length and perform "
                             "these checks (unchecked if not set)")
      parser.add_option('--hang-closing', action='store_true',
                        help="hang closing bracket instead of matching "
                             "indentation of opening bracket's line")
      parser.add_option('--format', metavar='format', default='default',
                        help="set the error format [default|pylint|<custom>]")
      parser.add_option('--diff', action='store_true',
                        help="report changes only within line number ranges in "
                             "the unified diff received on STDIN")
      group = parser.add_option_group("Testing Options")
      if os.path.exists(TESTSUITE_PATH):
          group.add_option('--testsuite', metavar='dir',
                           help="run regression tests from dir")
          group.add_option('--doctest', action='store_true',
                           help="run doctest on myself")
      group.add_option('--benchmark', action='store_true',
                       help="measure processing speed")
      return parser
  
  
  def read_config(options, args, arglist, parser):
      """Read and parse configurations.
  
      If a config file is specified on the command line with the
      "--config" option, then only it is used for configuration.
  
      Otherwise, the user configuration (~/.config/pycodestyle) and any
      local configurations in the current directory or above will be
      merged together (in that order) using the read method of
      ConfigParser.
      """
      config = RawConfigParser()
  
      cli_conf = options.config
  
      local_dir = os.curdir
  
      if USER_CONFIG and os.path.isfile(USER_CONFIG):
          if options.verbose:
              print('user configuration: %s' % USER_CONFIG)
          config.read(USER_CONFIG)
  
      parent = tail = args and os.path.abspath(os.path.commonprefix(args))
      while tail:
          if config.read(os.path.join(parent, fn) for fn in PROJECT_CONFIG):
              local_dir = parent
              if options.verbose:
                  print('local configuration: in %s' % parent)
              break
          (parent, tail) = os.path.split(parent)
  
      if cli_conf and os.path.isfile(cli_conf):
          if options.verbose:
              print('cli configuration: %s' % cli_conf)
          config.read(cli_conf)
  
      pycodestyle_section = None
      if config.has_section(parser.prog):
          pycodestyle_section = parser.prog
      elif config.has_section('pep8'):
          pycodestyle_section = 'pep8'  # Deprecated
          warnings.warn('[pep8] section is deprecated. Use [pycodestyle].')
  
      if pycodestyle_section:
          option_list = {o.dest: o.type or o.action for o in parser.option_list}
  
          # First, read the default values
          (new_options, __) = parser.parse_args([])
  
          # Second, parse the configuration
          for opt in config.options(pycodestyle_section):
              if opt.replace('_', '-') not in parser.config_options:
                  print("  unknown option '%s' ignored" % opt)
                  continue
              if options.verbose > 1:
                  print("  %s = %s" % (opt,
                                       config.get(pycodestyle_section, opt)))
              normalized_opt = opt.replace('-', '_')
              opt_type = option_list[normalized_opt]
              if opt_type in ('int', 'count'):
                  value = config.getint(pycodestyle_section, opt)
              elif opt_type in ('store_true', 'store_false'):
                  value = config.getboolean(pycodestyle_section, opt)
              else:
                  value = config.get(pycodestyle_section, opt)
                  if normalized_opt == 'exclude':
                      value = normalize_paths(value, local_dir)
              setattr(new_options, normalized_opt, value)
  
          # Third, overwrite with the command-line options
          (options, __) = parser.parse_args(arglist, values=new_options)
      options.doctest = options.testsuite = False
      return options
  
  
  def process_options(arglist=None, parse_argv=False, config_file=None,
                      parser=None, verbose=None):
      """Process options passed either via arglist or command line args.
  
      Passing in the ``config_file`` parameter allows other tools, such as
      flake8 to specify their own options to be processed in pycodestyle.
      """
      if not parser:
          parser = get_parser()
      if not parser.has_option('--config'):
          group = parser.add_option_group("Configuration", description=(
              "The project options are read from the [%s] section of the "
              "tox.ini file or the setup.cfg file located in any parent folder "
              "of the path(s) being processed.  Allowed options are: %s." %
              (parser.prog, ', '.join(parser.config_options))))
          group.add_option('--config', metavar='path', default=config_file,
                           help="user config file location")
      # Don't read the command line if the module is used as a library.
      if not arglist and not parse_argv:
          arglist = []
      # If parse_argv is True and arglist is None, arguments are
      # parsed from the command line (sys.argv)
      (options, args) = parser.parse_args(arglist)
      options.reporter = None
  
      # If explicitly specified verbosity, override any `-v` CLI flag
      if verbose is not None:
          options.verbose = verbose
  
      if options.ensure_value('testsuite', False):
          args.append(options.testsuite)
      elif not options.ensure_value('doctest', False):
          if parse_argv and not args:
              if options.diff or any(os.path.exists(name)
                                     for name in PROJECT_CONFIG):
                  args = ['.']
              else:
                  parser.error('input not specified')
          options = read_config(options, args, arglist, parser)
          options.reporter = parse_argv and options.quiet == 1 and FileReport
  
      options.filename = _parse_multi_options(options.filename)
      options.exclude = normalize_paths(options.exclude)
      options.select = _parse_multi_options(options.select)
      options.ignore = _parse_multi_options(options.ignore)
  
      if options.diff:
          options.reporter = DiffReport
          stdin = stdin_get_value()
          options.selected_lines = parse_udiff(stdin, options.filename, args[0])
          args = sorted(options.selected_lines)
  
      return options, args
  
  
  def _parse_multi_options(options, split_token=','):
      r"""Split and strip and discard empties.
  
      Turns the following:
  
      A,
      B,
  
      into ["A", "B"]
      """
      if options:
          return [o.strip() for o in options.split(split_token) if o.strip()]
      else:
          return options
  
  
  def _main():
      """Parse options and run checks on Python source."""
      import signal
  
      # Handle "Broken pipe" gracefully
      try:
          signal.signal(signal.SIGPIPE, lambda signum, frame: sys.exit(1))
      except AttributeError:
          pass    # not supported on Windows
  
      style_guide = StyleGuide(parse_argv=True)
      options = style_guide.options
  
      if options.doctest or options.testsuite:
          from testsuite.support import run_tests
          report = run_tests(style_guide)
      else:
          report = style_guide.check_files()
  
      if options.statistics:
          report.print_statistics()
  
      if options.benchmark:
          report.print_benchmark()
  
      if options.testsuite and not options.quiet:
          report.print_results()
  
      if report.total_errors:
          if options.count:
              sys.stderr.write(str(report.total_errors) + '\n')
          sys.exit(1)
  
  
  if __name__ == '__main__':
      _main()
  