anchor.diff:    
     int _maxFloor;
     Elevator _elevator;
  +  var start;
     
     // Incoming calls
     List<Call> _calls = new List();
  
positive.code:   
  }
  
  Future<bool> log(HttpRequest req) {
    _stack.add("!!! Filtered request: ${req.uri.path}/${req.uri.query} !!!");
    return new Future.value(true);
  }
  
  
  /**
  
negative.code:     req.response..writeln(response)..close();
    }
    
    Future<bool> log(HttpRequest req) {
      start = new DateTime.now();
      return new Future.value(true);
    }
  
    
    ///
    /// A new incoming call
    /// 
  