def METHOD_NAME(parent_subparsers):
    parser = parent_subparsers.add_parser("index", help=__doc__)
    parser.add_argument('--sequences', '-s', required=True, help="sequences in FASTA or VCF formats. Augur will summarize the content of FASTA sequences and only report the names of strains found in a given VCF.")
    parser.add_argument('--output', '-o', help="tab-delimited file containing the number of bases per sequence in the given file. Output columns include strain, length, and counts for A, C, G, T, N, other valid IUPAC characters, ambiguous characters ('?' and '-'), and other invalid characters.", required=True)
    parser.add_argument('--verbose', '-v', action="store_true", help="print index statistics to stdout")
    return parser