有没有办法引用自定义类对象作为它的属性/方法之一？

class Engine:
    def __init__(self, horsepower):
        self.horsepower = horsepower

    def start(self):
        print("Engine started.")

    def stop(self):
        print("Engine stopped.")

class Car:
    def __init__(self, make, model, engine):
        self.make = make
        self.model = model
        self.engine = engine

    def start(self):
        print(f"{self.make} {self.model} started.")
        self.engine.start()

    def stop(self):
        print(f"{self.make} {self.model} stopped.")
        self.engine.stop()

# 创建一个Engine实例
engine = Engine(200)

# 创建一个Car实例，并将Engine实例作为其属性
car = Car("Tesla", "Model S", engine)

# 调用Car实例的方法，间接调用Engine实例的方法
car.start()
car.stop()