protected static synchronized void saveModel() {
   try {
     seal(Model.getInstance(), SEALED_MODEL_FILE_NAME, sealer);
   } catch (IOException | CEEncryptionErrorException ex) {
     Logger.getLogger(ViewerController.class.getName()).log(Level.SEVERE, null, ex);
   }
 }
 protected static final synchronized void seal(Model modelIn, String fileName, SealObject sealerIn)
     throws IOException, CEEncryptionErrorException {
   seal(modelIn, new File(fileName), sealerIn);
 }