using System;

public class Program

{

    public static void Main()

    {

        invokeApi(url => "Hello World!");       

    }

    public static void invokeApi(Func<IUriBuilder, string> func)

    {

        var url = new UriBuilder();

        Console.WriteLine(func(url));

    }

}

​

public interface IUriBuilder

{

    string Build();

}

​

public class UriBuilder : IUriBuilder

{

    public string Build() { return "Whatever"; }

}

​

​