@classmethod
def add_args(cls, parser):
    """adds arguments according to NAME and FLAG"""
    parser.add_argument('-{}'.format(cls.FLAG.lower()), action='store_true',
        default=False, help='output in {}'.format(cls.NAME))
    parser.add_argument('-{}'.format(cls.FLAG.upper()), action='store_true',
        default=False, help='force input as {}'.format(cls.NAME))
    return parser
