public bool SetTrack(Track track, GuitarDifficulty difficulty = GuitarDifficulty.Unknown)
        {
            var ret = false;
            if (difficulty.IsUnknown())
                difficulty = this.CurrentDifficulty;

            if (track.IsFileTypePro())
            {
                ret = SetTrack6(track, difficulty);
            }
            else
            {
                ret = SetTrack5(track, difficulty);
            }
            return ret;
        }