static void Main(string[] args)
        {
            Duck rubber = new RubberDuck();

            rubber.Display();
            rubber.PerformFly();
            rubber.SetFlyBehavior(new FlyRocketPowered());
            rubber.PerformFly();
            rubber.PerformQuack();
            rubber.SetQuackBehavior(new SqueakR());
            rubber.PerformQuack();
        }
        static void Main(string[] args)
        {
            Duck rubber = new RubberDuck();

            rubber.Display();
            rubber.PerformFly();
            rubber.FlyBehavior = FlyRocketPowered.Fly;
            rubber.PerformFly();
            rubber.PerformQuack();
            rubber.QuackBehavior = MuteQuackR.Quack;
            rubber.PerformQuack();
        }