static void Main(string[] args) { RubberDuck rubberDuck = new RubberDuck(); rubberDuck.disPlay(); rubberDuck.PerformFly(); BlackDuck blackDuck = new BlackDuck(); blackDuck.disPlay(); blackDuck.PerformFly(); blackDuck.setFlyBehavior(new FlyWithRocket()); blackDuck.PerformFly(); }