anchor.diff:    ///
     /// Returns a [Future] that completes with the event when it is broadcast to
     /// all listeners.
  -  Future broadcast(Event event);
  +  Future<Event> broadcast(Event event);
   
     /// Schedule a new event to be broadcast to all registered listeners after
     /// the provided [Duration]. If it is 0 or less, it behaves as [broadcast].
  
positive.code:     }
    }
  
    _addEvent(Event e) {
      e._timeStamp = new DateTime.now();
      _ctrl.add(e);
    }
  }
  
  
negative.code:   ///
    /// Returns a [Future] that completes with the event when it is broadcast to
    /// all listeners.
    Future<Event> broadcastDelayed(Duration delay, Event event);
  
    void begin();
  }
  