class Timeslot:
    def __init__(self, ut_start, duration):
        self.ut_start = ut_start
        self.duration = duration

    @property
    def ut_end(self):
        return self.ut_start + self.duration

    @ut_end.setter
    def ut_end(self, value):
        self.duration = self.value - self.start


class Calendar:
    def create_reservation(self, ut_start, duration, maneuver):
        if not self.timeslot_is_free(ut_start, duration):
            raise
        pass

    def timeslot_is_free(self, ut_start: int, duration: int) -> bool:
        pass

    def next_free_timeslot(self, from_ut, duration=None) -> int:
        pass

    def get_reservation(self, ut_at) -> Timeslot:
        pass

    def delete_reservation(self, ut_at, priority):
        reservation = self.get_re(ut_at)
        if priority <= reservation.priority:
            raise