 
 protocol DetailViewControllerDelegate {
     func detailViewController(_ controller: DetailViewController, didSelectZone zone: Zone?)
+    func detailViewController(_ controller: DetailViewController, didChangeLicensePlateNumber licensePlate: String?)
 }

            self.licensePlateLabel?.text = self.licensePlateNumber ?? "-"
        }
    }
    
    var selectedZone: Zone? = nil {
        didSet {

        // If identifier is "licensePlateNumberChanged", then we can obtain the new license plate number from the VC
        if segue.identifier == "licensePlateNumberChanged", let licenseVC = segue.source as? CarLicenseViewController {
            self.licensePlateNumber = licenseVC.licensePlateNumber
            self.delegate?.detailViewController(self, didChangeLicensePlateNumber: licenseVC.licensePlateNumber)
        }
    }
    
