code: public void addListener (Telegraph listener, int msg) {
  		Array<Telegraph> listeners = msgListeners.get(msg);
  		if (listeners == null) {
  			// Associate an empty unordered array with the message code
  			listeners = new Array<Telegraph>(false, 16);
  			msgListeners.put(msg, listeners);
  		}
  		listeners.add(listener);
  
  		// Dispatch messages from registered providers
  		Array<TelegramProvider> providers = msgProviders.get(msg);
  		if (providers != null) {
  			for (int i = 0, n = providers.size; i < n; i++) {
  				TelegramProvider provider = providers.get(i);
  				Object info = provider.provideMessageInfo(msg, listener);
  				if (info != null) {
  					Telegraph sender = ClassReflection.isInstance(Telegraph.class, provider) ? (Telegraph)provider : null;
  					dispatchMessage(0, sender, listener, msg, info, false);
  				}
  			}
  		}
  	}
docs: Registers a listener for the specified message code. Messages without an explicit receiver are broadcasted to all its
  registered listeners.
  @param listener the listener to add
  @param msg the message code