docs: def generate_lifetime_subparser(subparsers):
      """Adds a sub-command parser to `subparsers` to make a lifetime report."""
      parser = subparsers.add_parser(
          'lifetime', description=constants.LIFETIME_DESCRIPTION,
          epilog=constants.LIFETIME_EPILOG, formatter_class=ParagraphFormatter,
          help=constants.LIFETIME_HELP)
      parser.set_defaults(func=lifetime_report)
      utils.add_tokenizer_argument(parser)
      utils.add_common_arguments(parser)
      utils.add_query_arguments(parser)
      parser.add_argument('results', help=constants.LIFETIME_RESULTS_HELP,
                          metavar='RESULTS')
      parser.add_argument('label', help=constants.LIFETIME_LABEL_HELP,
                          metavar='LABEL')
      parser.add_argument('output', help=constants.REPORT_OUTPUT_HELP,
                          metavar='OUTPUT')