def METHOD_NAME(self, parser):
    super().METHOD_NAME(parser)
    parser.add_argument(
        '--channel',
        action='store',
        dest='channel',
        type=str,
        choices=('listed', 'unlisted'),
        help=(
            'Only select add-ons who have either listed or unlisted '
            'versions. Add-ons that have both will be returned too.'
        ),
    )