public Car Add(Car car) {
car.Id = _nextId;
_carsDictionary.TryAdd(car.Id, car);
_nextId++;
return car;
}
public bool TryUpdate(Car car) {
Car oldCar;
if (_carsDictionary.TryGetValue(car.Id, out oldCar)) {
return _carsDictionary.TryUpdate(car.Id, car, oldCar);
}
return false;
}