class Base1:
    def f1(self):
        print('base1.f1')
    def f2(self):
        print('base1.f2')

class Base2:
    def f1(self):
        print('base2.f1')

    def f2(self):
        print('base2.f2')

    def f3(self):
        print('base2.f3')
        self.f1()

class Foo(Base1,Base2):

    def f0(self):
        print('foo.f0')
        self.f3()
# self是那个类的对象(实例),那么就从该类开始找(自己没有就找父类)
# 要始终记得self到底是谁的实例
obj = Foo()
obj.f0()