class my_super:
    def __init__(self, thisclass=None, target=None):
        self._thisclass = thisclass
        self._target = target


    def _get_mro(self):
        if issubclass(type, type(self._target)):
            return self._target.__mro__ #第二个参数是类型
        else:
            return self._target.__class__.__mro__ #第二个参数是实例


    def _get_function(self, name):
        mro = self._get_mro()
        if not self._thisclass in mro:
            return None

        index = mro.index(self._thisclass) + 1
        while index < len(mro):
            cls = mro[index]
            if hasattr(cls, name):
                attr = cls.__dict__[name]
                #不要用getattr，因为我们这里需要获取未绑定的函数
                #如果使用getattr, 并且获取的是classmethod
                #会直接将cls绑定到该函数上
                #attr = getattr(cls, name)
                if callable(attr) or isinstance(attr, classmethod):
                    return attr
            index += 1
        return None

    def __getattr__(self, name):
        func = self._get_function(name)
        if not func is None:
            if issubclass(type, type(self._target)):
                return func.__get__(None, self._target)
            else:
                return func.__get__(self._target, None)