/// <summary>
 /// Called from observer constructor. Detaches it from _observers list.
 /// </summary>
 public static void Detach(MonoBehaviourFoolObserver observer)
 {
     if (_observers.Contains(observer))
     {
         _observers.Remove(observer);
     }
 }
 /// <summary>
 /// Called from observer constructor. Attaches it to _observers list.
 /// </summary>
 public static void Attach(MonoBehaviourFoolObserver observer)
 {
     _observers.Add(observer);
 }