obj_property.py

class Foo:
    x = None

    def __init__(self):
        self.x = set()

        setattr(self, 'x', set())

    @classmethod
    def x(cls):
        print(Foo.x)
        return True

    def what(self):
        print(Foo.x)


print(Foo.x)
a = Foo()
print(a.x)
print(Foo.x)
a.what()

'''
<bound method Foo.x of <class '__main__.Foo'>>
set()
<bound method Foo.x of <class '__main__.Foo'>>
<bound method Foo.x of <class '__main__.Foo'>>
'''