求助，这里cls是None吗？

本人小白，请帮忙看下这段代码，我想问下，最后d.__doc__执行的结果为什么没有打印"旺财"呢？self是__doc__，obj是d，cls应该没有传入吧，所以应该满足"cls is None"这个条件吧？是我理解有问题吗？请大神指教！

class MethodType:
    def __init__(self,func,obj):
        self.__func__=func
        self.__self__=obj
    def __call__(self,*args,**kwargs):
        func=self.__func__
        obj=self.__self__
        print("小白")
        return func(obj,*args,**kwargs)

   
class ClassMethod:
    def __init__(self,f):
        self.f=f
    def __get__(self,obj,cls=None):
        if cls is None:
            print("旺财")
            cls=type(obj)
        if hasattr(type(self.f),'__get__'):
            print(f"来福，type(self.f)->{type(self.f)}")
            return self.f.__get__(cls,cls)
        return MethodType(self.f,cls)

   
class D:
    @ClassMethod
    @property
    def __doc__(cls):
        return f"I love FishC.--from class {cls.__name__}"

d=D()
d.__doc__
来福，type(self.f)-><class 'property'>
'I love FishC.--from class D'