anchor.diff:  
     @override
     void cancel() {
  +    onFinish();
  +
       if (!live)
         return;
       live = false;
  
positive.code:       return new Status();
      } else {
        if (supportsColor) {
          _status = new _AnsiStatus(message);
          return _status;
        } else {
          printStatus(message);
  
negative.code:   void stop({ bool showElapsedTime: true }) { }
    void cancel() { }
  }
  
  typedef void _FinishCallback();
  
  class StdoutLogger extends Logger {
    Status _status;
  