__subclasses__未显示任何内容

class.__subclasses__()

class Animal:
    pass

class Mammal(Animal):
    pass

class Reptile(Animal):
    pass

class Dog(Mammal):
    pass

class Cat(Mammal):
    pass

class Snake(Reptile):
    pass

class Turtle(Reptile):
    pass

# 获取Animal类的所有子类
subclasses = Animal.__subclasses__()
for subclass in subclasses:
    print(subclass.__name__)

Mammal
Reptile