anchor.diff:      this._points = pointsComputer.points;
       this._importantPoints = importantPointsComputer.importantPoints;
       this._pointDensity = pointDensityComputer.pointDensity;
  -    
  -    pointStream = new StreamController.broadcast( sync: true);
  -    LengthUpFlatDownComputer lengthUpFlatDownComputer = new LengthUpFlatDownComputer(pointStream.stream);
  -    
  -    for (var iter = rawData.points.iterator; iter.moveNext();) {
  -      pointStream.add(iter.current) ;
  -    }
  -    pointStream.close();
  -    
       this._inclinationUp = lengthUpFlatDownComputer.inclinationUp;
       this._inclinationDown = lengthUpFlatDownComputer.inclinationDown;
       this._lengthUp = lengthUpFlatDownComputer.lengthUp ;
  
positive.code:   num get difficulty => _difficulty ;
   
    num get pointDensity => _pointDensity ;
  }
  
  
negative.code:     PointsComputer pointsComputer = new PointsComputer(pointStream.stream);
      ImportantPointsComputer importantPointsComputer = new ImportantPointsComputer(pointStream.stream); 
      PointDensityComputer pointDensityComputer = new PointDensityComputer(pointStream.stream);
      LengthUpFlatDownComputer lengthUpFlatDownComputer = new LengthUpFlatDownComputer(pointStream.stream);
      
      for (var iter = rawData.points.iterator; iter.moveNext();) {
        pointStream.add(iter.current) ;
  