anchor.diff:  
   class Clock{
   
  -  int startAt;
  +  int startPomodoroAt, startBreakAt;
     String durationBreak, durationPomodoro;
     String counter;
     Stopwatch watch = new Stopwatch();
     Timer timer;
   
     Clock(){
  -    startAt = (25*60);
  -    durationBreak = prettyPrintTime(5*60);
  -    durationPomodoro = prettyPrintTime(25*60);
  +    startPomodoroAt = (25*60);
  +    startBreakAt = (5*60);
  +    durationBreak = prettyPrintTime(startBreakAt);
  +    durationPomodoro = prettyPrintTime(startPomodoroAt);
       counter= prettyPrintTime(25*60);
     }
     
  
positive.code:   void setDurationPomodoro(string duration){
      var value = int.parse(duration, onError: (source) => null);
      if (value != null){
        startAt = value*60;
        durationPomodoro = prettyPrintTime(startAt);
        counter = durationPomodoro;
      }
    }
  
negative.code:   }
  
    void updateTimeRemaining(Timer _) {
      var s  = startPomodoroAt - watch.elapsedMilliseconds~/1000;
      
      if( s < 0){ 
        stop();
  