/// <summary>
 /// Remove an observer from the list
 /// </summary>
 /// <param name="obs">Removed observer object</param>
 public void unregister(Observer obs)
 {
     if (this.observersList.Contains(obs))
     {
         this.observersList.RemoveAt(this.observersList.IndexOf(obs));
     }
 }
 /// <summary>
 /// Register a new observer
 /// </summary>
 /// <param name="obs">Observer object</param>
 public void register(Observer obs)
 {
     this.observersList.Add(obs);
 }
 /// <summary>
 /// Unregister the observer from the scenario
 /// </summary>
 /// <param name="obs">removed observer</param>
 public void unregisterObserver(ZRTSModel.Scenario.Observer obs)
 {
     scenario.unregister(obs);
 }