public static void iterator()
        {
            var tasks = new Tasks();
            var iterator = tasks.GetIterator();
            var item = "";

            tasks[0] = "Wake up";
            tasks[1] = "Take a shower";
            tasks[2] = "Take a bus";
            tasks[3] = "Work";
            tasks[4] = "Have lunch";
            tasks[5] = "Go home";

            item = iterator.FirstItem;

            while (!iterator.IsDone)
            {
                Console.WriteLine(item);
                item = iterator.NextItem;
            }
        }