Recently, I am learning argparse module, Argument error occurred below the code
import argparse import sys class ExecuteShell(object): def create(self, args): """aaaaaaa""" print('aaaaaaa') return args def list(self, args): """ccccccc""" print('ccccccc') return args def delete(self, args): """ddddddd""" print('ddddddd') return args class TestShell(object): def get_base_parser(self): parser = argparse.ArgumentParser() parser.add_argument('-h', '--help', action='store_true', help=argparse.SUPPRESS) parser.add_argument('-c', action='store', dest='create_value', help='create a file') parser.add_argument('-d', action='store', dest='delete_value', help='delete a file') parser.add_argument('-l', action='store', dest='list_value', help='list a dir') return parser def _find_actions(self, subparsers, actions_module): for attr in (action for action in dir(actions_module) if not action.startswith('__')): callback = getattr(actions_module, attr) desc = callback.__doc__ or '' subparser = subparsers.add_parser(attr, description=desc) subparser.add_argument('-h', '--help', action='help', help=argparse.SUPPRESS) self.subcommands[attr] = subparser subparser.set_defaults(func=callback) def main(self, args): parser = self.get_base_parser() (options, args) = parser.parse_known_args(args) subparsers = parser.add_subparsers(metavar='<subcommand>') a = ExecuteShell() self.subcommands = {} subcommand_parser = self._find_actions(subparsers, a) if __name__ == "__main__": a = TestShell() a.main(sys.argv[1:]) Why do I get this error and how can I fix it?