//constructor-2
 // GoldUser goldUser = new GoldUser(userName,magazine);
 public GoldUser(string userName, Magazine magazine)
 {
     this.userName = userName;
     this.magazine = magazine;
     magazine.AddSubscriber(this);
 }
 public void SetMagazine(Magazine magazine)
 {
     this.magazine = magazine;
     magazine.AddSubscriber(this);
 }
        //private Magazine magazine; inherited from User class
        // private string userName;  inherited from User class
        #endregion


        #region constructor
        //constructor-1
        // GoldUser goldUser = new GoldUser(magazine); UserName eksik
        public GoldUser(Magazine magazine)
        {
            this.magazine = magazine;
            magazine.AddSubscriber(this);
            this.userName = "";
        }