func handleClassification(request: VNRequest, error: Error?) {
        guard let observations = request.results as? [VNClassificationObservation]
            else { fatalError("unexpected result type from VNCoreMLRequest") }
        guard let best = observations.first
            else { fatalError("can't get best result") }

        DispatchQueue.main.async {
            self.classificationLabel.text = "Classification: \"\(best.identifier)\" Confidence: \(best.confidence)"
        }
    }