public Calendar RetrieveCalendar(PersonGroup personGroup, DoorGroup doorGroup)
 {
     try {
         return calendars[new Tuple<PersonGroup, DoorGroup>(personGroup, doorGroup)];
     } catch (KeyNotFoundException e) {
         Calendar c = new Calendar(DateTime.Now.Year);
         calendars[new Tuple<PersonGroup, DoorGroup>(personGroup, doorGroup)] = c;
         return c;
     }
 }
 public void SaveCalendar(PersonGroup personGroup, DoorGroup doorGroup, Calendar cal)
 {
     calendars[new Tuple<PersonGroup, DoorGroup>(personGroup, doorGroup)] = cal;
 }
 internal void SaveCalendar(PersonGroup personGroup, DoorGroup doorGroup, Calendar cal)
 {
     DBCalendarInterface.Instance.SaveCalendar(personGroup, doorGroup, cal);
 }