Class only breaks super

[ForeverWintr]

@class_only
class a:
    @classmethod
    def f(cls):
        print('hi')


@class_only
class b(a):    
    @classmethod
    def f(cls):
        super().f()

b.f()

Traceback (most recent call last):
  Python Shell, prompt 13, line 1
  Python Shell, prompt 12, line 5
builtins.TypeError: super(type, obj): obj must be an instance or subtype of type

Not sure why yet.