public void Add(TrackStretch stretch) {
     if (stretch == null) throw new ArgumentNullException(nameof(stretch));
     if (_stretches.Any() && stretch.End.Station.Equals(_stretches.Last().Start.Station)) {
         _stretches.Insert(0, stretch);
     } else {
         _stretches.Add(stretch);
     }
 }
 public TrackStretchCoordinator(TrackStretch stretch) {
     Stretch = stretch;
 }