In this example, we have three classes: Engine, Car, and Person. The Engine class has a method start() that simply outputs a message to the console indicating that the engine has started. The Car class has a private member engine of type Engine, and a method start() that calls the start() method of the engine member and then outputs a message indicating that the car has started. The Person class has a private member car of type Car, and a method drive() that calls the start() method of the car member and then outputs a message indicating that the person is driving the car.
This demonstrates a composition relationship between the classes, where Person is composed of a Car, which is composed of an Engine. The Person class owns a Car object, which owns an Engine object. When the Person object is created and its drive() method is called, it starts the Car object, which in turn starts the Engine object, and then outputs a message indicating that the person is driving the car.