/// <summary>
 /// Detaches the specified receiver.
 /// </summary>
 /// <param name="receiver">The receiver.</param>
 public static void Detach(IPlayRequestReceiver receiver)
 {
     _receivers.Remove(receiver);
 }
 /// <summary>
 /// Attaches the specified receiver.
 /// </summary>
 /// <param name="receiver">The receiver.</param>
 public static void Attach(IPlayRequestReceiver receiver)
 {
     _receivers.Add(receiver);
 }