动物—> 哺乳动物 ---->猫
继承的关系

class Animals():
    def breathe(self):
        print('breathing')
    def move(self):
        print('moving')
    def eat(self):
        print("eating food")

class Mammals(Animals):
    def breastfeed(self):
        print("breastfeed")
class Cats(Mammals):
    def __init__(self,spots):
        self.spots =spots
    def catch_mouse(self):
        print("catch mouse")
kitty =Cats(10)
print(kitty.spots)
kitty.eat()
kitty.breastfeed()