类的继承

class Base():
    def play(self):
        print('--base--')
class A(Base):
    def play(self):
        # super().play()
        print('--A--')
class B(Base):
    def play(self):
        super().play()
        print('--B--')
class C(Base):
    def play(self):
        super().play()
        print('--C--')
class D(A,B,C):
    def play(self):
        super().play()   #打印A  判断A是否有super().play()
                         #如果有没有 结束
                         #如果有打印B 依次类推
        print('--D--')
d=D()
d.play()