docs: def generate_align_subparser(subparsers):
      """Adds a sub-command parser to `subparsers` to generate aligned
      sequences from a set of results."""
      parser = subparsers.add_parser(
          'align', description=constants.ALIGN_DESCRIPTION,
          epilog=constants.ALIGN_EPILOG,
          formatter_class=ParagraphFormatter, help=constants.ALIGN_HELP)
      parser.set_defaults(func=align_results)
      utils.add_common_arguments(parser)
      parser.add_argument('-m', '--minimum', default=20,
                          help=constants.ALIGN_MINIMUM_SIZE_HELP, type=int)
      utils.add_corpus_arguments(parser)
      parser.add_argument('output', help=constants.ALIGN_OUTPUT_HELP,
                          metavar='OUTPUT')
      parser.add_argument('results', help=constants.RESULTS_RESULTS_HELP,
                          metavar='RESULTS')