def load(self, requirements_file=None):
        """Load or reload requirements from a requirements.txt file.

        :param requirements_file: if not given, the filename used from
            initialization will be read again.
        """
        if requirements_file is None:
            requirements_file = self.filename
            if requirements_file is None:
                raise ValueError("no filename provided")
        elif isinstance(requirements_file, text_type):
            requirements_file = Path(requirements_file)
        self.clear()
        with requirements_file.open() as f:
            self.loads(f.read())

        if isinstance(requirements_file, (text_type, Path)):
            self.filename = requirements_file
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)