public ParityDependentScheduleSubject(
     SubjectInstance numeratorSubjectInstance,
     SubjectInstance denominatorSubjectInstance,
     int order,
     DayOfWeek weekday,
     Guid groupId
     ) : base(order, weekday, groupId)
 {
     ParitySubjectInstanceId    = numeratorSubjectInstance?.Id;
     NotParitySubjectInstanceId = denominatorSubjectInstance?.Id;
 }
 public ParityIndependentScheduleSubject(SubjectInstance subject, int order, DayOfWeek weekday, Guid groupId)
     : base(order, weekday, groupId)
 {
     SubjectId = subject.Id;
 }