static void Main(string[] args) { Mediator mediator = new Mediator(); Teacher alikaan = new Teacher(mediator) { Name = "Ali Kaan" }; mediator.Teacher = alikaan; Student kivanc = new Student(mediator) { Name = "Kıvanç" }; Student merve = new Student(mediator) { Name = "Merve" }; mediator.Students = new List <Student> { merve, kivanc }; alikaan.SendNewImageUrl("slide1.jpg"); merve.SendQuestion("is it true?"); alikaan.AnswerQuestion("yes, it is true.", merve); Console.ReadLine(); }