public double GetBasePremiumFor(Vehicle vehicle)
        {
            CheckIfVehicleTypeExist(vehicle);

            return _basePremiums[vehicle.GetType()];
        }
 public void CheckIfVehicleTypeExist(Vehicle vehicle)
 {
     if (!_basePremiums.Keys.Contains(vehicle.GetType()))
         throw new VehicleTypeNotExistException();
 }