code: def validate(self):
          
          # TODO: at the moment only required_languages is validated.
          # Maybe check other options as well?
          if self.required_languages:
              if isinstance(self.required_languages, (tuple, list)):
                  self._check_languages(self.required_languages)
              else:
                  self._check_languages(self.required_languages.keys(), extra=('default',))
                  for fieldnames in self.required_languages.values():
                      if any(f not in self.fields for f in fieldnames):
                          raise ImproperlyConfigured(
                              'Fieldname in required_languages which is not in fields option.')
docs: Perform options validation.