anchor.diff:      if( s < 0){ 
         updateState();
         setCounter();
  +      addToHistory();
         reset();
         return; 
       }
       counter = prettyPrintTime(s);
  +  }
  +
  +  void addToHistory(){
  +    switch(currentState){
  +      case ClockState.pomodoro:
  +        times.add("rest");
  +        break;
  +      case ClockState.rest:
  +        times.add("pomodoro");
  +        break;
  +    }
     }
   
     void setDurationPomodoro(string duration){
  
positive.code:     counter= prettyPrintTime(25*60);
      currentState = ClockState.pomodoro;
      currentDuration = startPomodoroAt;
    }
    
    void start() {
  
negative.code:   String counter;
    Stopwatch watch = new Stopwatch();
    Timer timer;
    List<String> times;
  
    ClockState currentState;
  
  