def generate_ngrams_subparser(subparsers):
    """Adds a sub-command parser to `subparsers` to add n-grams data
    to the data store."""
    parser = subparsers.add_parser(
        'ngrams', description=constants.NGRAMS_DESCRIPTION,
        epilog=constants.NGRAMS_EPILOG, formatter_class=ParagraphFormatter,
        help=constants.NGRAMS_HELP)
    parser.set_defaults(func=generate_ngrams)
    utils.add_common_arguments(parser)
    parser.add_argument('-c', '--catalogue', dest='catalogue',
                        help=constants.NGRAMS_CATALOGUE_HELP,
                        metavar='CATALOGUE')
    utils.add_db_arguments(parser)
    utils.add_corpus_arguments(parser)
    parser.add_argument('min_size', help=constants.NGRAMS_MINIMUM_HELP,
                        metavar='MINIMUM', type=int)
    parser.add_argument('max_size', help=constants.NGRAMS_MAXIMUM_HELP,
                        metavar='MAXIMUM', type=int)
Adds a sub-command parser to `subparsers` to add n-grams data
    to the data store.