/**
  * Gets the submitted locale. if the provided locale is not null, this will be used, else the
  * LocalizePanelForm will be checked.
  * @param string $locale
  * @return string Code of the submitted locale
  * @throws zibo\ZiboException when no locale is provided through an argument or the LocalizePanelForm
  */
 private function getSubmittedLocale($locale)
 {
     if ($locale !== null) {
         return $locale;
     }
     $form = new LocalizePanelForm();
     if ($form->isSubmitted()) {
         return $form->getLocaleCode();
     }
     throw new ZiboException('No locale provided and the LocalizePanelForm is not submitted');
 }