public virtual void AppendCurveSets(List <FillCurveSet2d> paths)
 {
     if (CurrentSorter == null)
     {
         TargetScheduler.AppendCurveSets(paths);
         throw new Exception("TODO: need to update lastPoint...");
     }
     else
     {
         CurrentSorter.SpeedHint = this.SpeedHint;
         CurrentSorter.AppendCurveSets(paths);
     }
 }