docs: def apply_config_defaults(parser, args, root):
      """Update the parser's defaults from either the arguments' config_arg or
      the config files given in config_files(root)."""
      if root is None:
          try:
              from pep8radius.vcs import VersionControl
              root = VersionControl.which().root_dir()
          except NotImplementedError:
              pass  # don't update local, could be using as module
  
      config = SafeConfigParser()
      config.read(args.global_config)
      if root and not args.ignore_local_config:
          config.read(local_config_files(root))
  
      try:
          defaults = dict((k.lstrip('-').replace('-', '_'), v)
                          for k, v in config.items("pep8"))
          parser.set_defaults(**defaults)
      except NoSectionError:
          pass  # just do nothing, potentially this could raise ?
      return parser