public void Add(TimetableStretch timetableStretch)
{
if (timetableStretch == null)
{
throw new ArgumentNullException(nameof(timetableStretch));
}
if (TimetableStretches.Contains(timetableStretch))
{
return;
}
TimetableStretches.Add(timetableStretch);
}
public TimetableStretch TimetableStretch(string number) => TimetableStretches.Single(t => t.Number == number);
