class GreatGrandParent(object):
    pass


class GrandParent(GreatGrandParent):

    def on_start(self):
        print('the ONLY class that has on_start')


class Parent(GrandParent):
    pass


class Child(Parent):

    def on_start(self):
        super(Child, self).on_start()
Python Multiple Inheritance: call super on all