多层继承

def solve():
    class Animal:
        def __init__(____):
            self.name = name
    class Mammal(____):
        def __init__(____):
            super().__init__(____)
            self.fur_color = fur_color
    class Dog(____):
        def __init__(____):
            super().__init__(____)
            self.breed = breed
    d = Dog(____)
    print(____)