有条件地实例化正确的子类？

class Animal:
    def __init__(self, name):
        self.name = name

    def sound(self):
        pass

class Dog(Animal):
    def sound(self):
        return "Woof!"

class Cat(Animal):
    def sound(self):
        return "Meow!"

def create_animal(animal_type):
    if animal_type == "dog":
        return Dog("Buddy")
    elif animal_type == "cat":
        return Cat("Kitty")
    else:
        return None

# 根据条件实例化正确的子类
animal_type = input("请输入动物类型（dog/cat）：")
animal = create_animal(animal_type)
if animal:
    print(animal.sound())
else:
    print("无效的动物类型")