using System;

public class Program

{

    interface ISth

    {

        void Doo();

    }

    class ASth : ISth

    {

        public void Doo() {}

    }

    public static void Main()

    {

        var it = typeof(ISth);

        var at = typeof(ASth);

        Console.WriteLine(it.IsInstanceOfType(at));

        Console.WriteLine(it.IsAssignableFrom(at));

​

    }

}