anchor.diff:          return this;
       }
   
  +    /// By default EventEmitters will print a warning if more than 10 listeners are added for a particular event.
  +    /// This is a useful default which helps finding memory leaks.
  +    /// Obviously not all Emitters should be limited to 10. This function allows that to be increased. Set to zero for unlimited.
  +    /// Returns emitter, so calls can be chained.
       EventEmitter setMaxListeners(int listenersCount) {
           _maxListeners = listenersCount;
   
           return this;
       }
   
  +    /// Returns a list of listeners for the specified event.
       List listeners(event) {
           List result = [];
           if (_listeners.containsKey(event)) {
  
positive.code:         return result;
      }
  
      bool emit(event, [List params = const []]) {
          var eventType = event is EventInterface ? event.runtimeType : event;
          bool handlersFound = false;
  
negative.code:         return this;
      }
  
      /// Removes all listeners, or those of the specified event.
      /// It's not a good idea to remove listeners that were added elsewhere in the code, especially when it's on an emitter that you didn't create
      /// Returns emitter, so calls can be chained.
      EventEmitter removeAllListeners([event]) {
          if (event == null) {
              _listeners.forEach((eventName, List handlers) {
  