public override void AddObject(AbstractObject obj)
 {
     if (!this._mediators.Contains(obj))
     {
         this._mediators.Add(obj);
     }
 }
 public override void Send(string message, AbstractObject obj)
 {
     foreach (AbstractObject item in this._mediators)
     {
         if (obj == item)
             continue;
         item.Notify(message);
     }
 }
 public abstract void Send(String message, AbstractObject obj);
 public abstract void AddObject(AbstractObject obj);