Updates the data structures to add an appointment

def _addappt(self, iden, appt):
        '''
        Updates the data structures to add an appointment
        '''
        if appt.nexttime:
            heapq.heappush(self.apptheap, appt)
        self.appts[iden] = appt
        if self.apptheap and self.apptheap[0] is appt:
            self._wake_event.set()