static void Main(string[] args)
{
Console.WriteLine("Welcome to Duck App");
Console.WriteLine("-------------------");
Console.WriteLine("Mallard Duck.");
Duck mallard = new MallardDuck();
//this call the mallardDuck's inherited fly and quack method which the delegates the object's Behvior.
mallard.Fly();
mallard.Quack();
Console.WriteLine("-------------------");
Console.WriteLine("Mallard Duck with setting dynamic behaviour");
//setting the behavior dynamically
Duck dynamicMallard = new MallardDuck();
dynamicMallard.SetFly(new FlyWithWings());
dynamicMallard.Fly();
dynamicMallard.SetQuack(new Quack());
dynamicMallard.Quack();
Console.ReadKey();
}