using System;

​

interface Foo {

    void method();

}

​

public class A: Foo {

    public void method() {

        Console.WriteLine("A implementation");

    }

}

​

public class B: A {

    public new void method() {

        Console.WriteLine("B implementation");

    }

}

​

​

public class Program

{

    public static void Main()

    {

        A b_as_a = new B();

        b_as_a.method();

​

    }

}