Python MRO logging

class Meta(type):
    def mro(self):
        print("! Computing MRO")
        return super().mro()

class Foo:
    x = 'foo'

class Bar:
    x = 'bar'

print("Defining Baz")

class Baz(Foo, metaclass=Meta):
    pass

print("Instantiating Baz")
b = Baz()
print("Accessing attribute")
b.x
print("Changing Baz's bases")
Baz.__bases__ = (Bar,)
print("Accessing attribute")
b.x