using System;

​

public class StringTransformer {

    public string Author {

        get;

        set;

    }

    public StringTransformer(string author) {

        this.Author = author;

    }

    public virtual string Transform(string s) {

        return s;

    }

}

​

public class BillsTransformer : StringTransformer {

    public BillsTransformer() : base("bill") {

    }

    public override string Transform(string s) {

        string t = "";

        for (int i = s.Length-1; i >= 0; i--) {

            t += s[i];

        }

        return t;

    }

}

​

public class jacobTransformer : StringTransformer {

    public jacobTransformer() : base("jacob") {     

    }

    public override string Transform(string s) {

        s = s.ToUpper() + " bing bong";

        return s;

    }

}

public class Program

{

    public static void Main()

    {

        StringTransformer basic = new StringTransformer("shepherd");

        BillsTransformer btrans = new BillsTransformer();

        jacobTransformer jtrans = new jacobTransformer();

        string result = jtrans.Transform(btrans.Transform(basic.Transform("cheese")));

        result = jtrans.Transform(result);

        Console.WriteLine(result);

    }

}