cli.py 文件源码

def __init__(self, option_strings, dest, nargs=None, const=None, default=None, type=None, choices=None,
                 required=False, help=None, metavar=None):
        if not option_strings:
            raise ValueError('at least one option argument must be supplied')
        if nargs == 0:
            raise ValueError('nargs for option-values actions must be > 0')
        if const is not None and nargs != argparse.OPTIONAL:
            raise ValueError('nargs must be %r to supply const' % argparse.OPTIONAL)
        super().__init__(option_strings, dest, nargs, const, default, type, choices, required, help, metavar)