using System;

​

​

interface IHaveASandwich{

    void Yummy();

}

​

class SimpleBag : IHaveASandwich{

    public virtual void Yummy(){

        Console.WriteLine("Yummy for SimpleBag");

    }

}

​

class SuperBag : SimpleBag{

    public override void Yummy(){

        Console.WriteLine("Yummy for SuperBag");

    }

}

​

static class BagEnhancer{   

    public static void Dummy(this IHaveASandwich bag){

        Console.WriteLine("Dummy for IHaveASandwich");

    }

    public static void Dummy(this SimpleBag bag){

        Console.WriteLine("Dummy for SimpleBag");

    }

    public static void Dummy(this SuperBag bag){

        Console.WriteLine("Dummy for SuperBag");

    }

}

public class Program

{

    public static void Main()

    {

        IHaveASandwich bag = new SuperBag();

        bag.Yummy();

        bag.Dummy();

    }

}