我如何获取内置方法的签名? 例如: dict().get(k)
>> a = dict().get
>> a
<built-in method get of dict object at 0x1003aafd0>
>> a.__doc__
'D.get(k[,d]) -> D[k] if k in D, else d. d defaults to None.'
>> import inspect
>> inspect.getargspec(a)
TypeError: <built-in method get of dict object at 0x100377250> is not a Python function
我希望看到的结果是这样的>> a.some_function()
('key', 'default'=None)