def coerce(cls, string):
        """Create a :class:`Requirement` object from a given package spec."""
        match = re.match(cls.spec_regex, string)
        if not match:
            raise InvalidRequirementSpecError("could not parse requirement")
        package = match.group(1)
        if all(match.group(2, 3)):
            version = "".join(match.group(2, 3))
        else:
            version = None
        return cls(package, version)
def ProcessCommandLineArgs(parser, args):
  # TODO(ariblue): Delete this flag entirely at some future data, when the
  # existence of such a flag has been long forgotten.
  if args.output_file:
    parser.error('This flag is deprecated. Please use --output-dir instead.')

  try:
    os.makedirs(args.output_dir)
  except OSError:
    # Do nothing if the output directory already exists. Existing files will
    # get overwritten.
    pass

  args.output_dir = os.path.expanduser(args.output_dir)