def addListing(parser):
    """
    Add option to request the list of versions.
    """
    if hasattr(parser, 'add_option'):
        from .options_old import addListing
        return addListing(parser)
    parser.add_argument('-l', '--list', action='store_true', help=
        'list the available versions of the requested project and exit',
        default=False)
    parser.add_argument('--list-versions', action='store_true', dest='list',
        help='obsolete spelling of --list', default=False)
    parser.add_argument('-L', '--list-platforms', action='store_true', help
        =
        'list the available platforms for the requested project/version and exit'
        , default=False)
    return parser
