Can every method be overridden in Python?

What does Child().run() return?

class Parent:
    def run(self):
        return self.__secret() + " " + self.visible()
    def __secret(self):
        return "parent-secret"
    def visible(self):
        return "parent-visible"

class Child(Parent):
    def __secret(self):
        return "child-secret"
    def visible(self):
        return "child-visible"