def load(self, filename, create_if_missing=True):
        filename = Path(filename)
        if not filename.exists() and create_if_missing:
            self.load_pip_requirements()
            with filename.open("w") as f:
                f.write(yaml.dump(self.serialized, default_flow_style=False,
                                  encoding=None))
            self.filename = filename
            return self.save(filename)
        with filename.open() as f:
            for group, requirements in yaml.load(f.read()).items():
                for requirement in requirements:
                    self[group].add(Requirement.coerce(requirement))
        self.filename = filename
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)