anchor.diff:  
       var isThrottling = false;
       var buffer;
  -    void handleNewEvent(x) {
  +    void handleNewValue(x) {
         // if this is the first item then push it
         if (!isThrottling) {
           _tryAdd(controller, x);
  
positive.code: 
      var maximum;
  
      void handleNewEvent(x) => _tryRun(() {
        if (maximum == null || compare(maximum, x) < 0) {
          maximum = x;
        }
      }, onError);
  
      input.listen(handleNewEvent,
                   onError : onError,
                   onDone  : () {
                     if (!completer.isCompleted) completer.complete(maximum);
  
negative.code:       }, onError);
      }
  
      stream1.listen((x) => handleNewValue(buffer1, buffer2, x),
                     onError : onError,
                     onDone  : () => _tryClose(controller));
      stream2.listen((x) => handleNewValue(buffer2, buffer1, x),
                     onError : onError,
                     onDone  : () => _tryClose(controller));
  
  