using System;

​

public interface IIf1 { }

​

public class Cl1 : IIf1 { }

public class Program

{

    public static void Method1<T>() where T : class { Console.WriteLine(typeof(T)); }

    public static void Main()

    {

        Console.WriteLine("Hello World");

        IIf1 inst1 = new Cl1();

        Method1<IIf1>();

    }

}