import argparse as arg
import inspect


def sum(num1, num2):
    print(num1)
    print(num2)
    print('SUM:', num1 + num2)


if __name__ == '__main__':

    parser = arg.ArgumentParser()
    subparsers = parser.add_subparsers(help='sum sub-comand help')

    # SUM
    sum_parser = subparsers.add_parser('sum')
    sum_parser.add_argument('-num1', type=int)
    sum_parser.add_argument('-num2', type=int)
    sum_parser.set_defaults(func=sum)

    args = parser.parse_args()
    arg_spec = inspect.getargspec(args.func)
    if arg_spec.keywords:
        # convert args to a dictionary
        args_for_func = vars(args)
    else:
        # get a subset of the dictionary containing just the arguments of func
        args_for_func = {k:getattr(args, k) for k in arg_spec.args}

    args.func(**args_for_func)