public static string Method1(
            this string data,
            Method1Func Handler1 = null,
            string n             = null
            )
        {
            if (n == null)
            {
                Console.WriteLine("n is null");
            }
            else
            {
                Console.WriteLine("n is not null");
            }

            Console.WriteLine("Method1: " + data);

            if (Handler1 != null)
            {
                var y = Handler1(data + " from clr");

                Console.WriteLine("y: " + y);
            }

            return("!");
        }
        public static string Method1(
            this string data,
            Method1Func Handler1 = null,
            string n = null
        )
        {
            if (n == null)
                Console.WriteLine("n is null");
            else
                Console.WriteLine("n is not null");

            Console.WriteLine("Method1: " + data);

            if (Handler1 != null)
            {
                var y = Handler1(data + " from clr");

                Console.WriteLine("y: " + y);
            }

            return "!";
        }