class InMemoryBookingRepository:
    def __init__(self) -> None:
        self._lock = threading.RLock()
        self.technicians = {...}  # hardcoded cleaners
        self._bookings: list[Booking] = []

    def list_bookings(self) -> list[Booking]:
        with self._lock:
            return list(self._bookings)

    def create_booking(self, option, details, price) -> Booking:
        # check overlap in Python, then append to self._bookings
        ...