docs: def synchronizer_class(self):
          """ returns synchronizer class """
          if not self.synchronizer_path or self.synchronizer_path == 'None' or not self.layer:
              return False
          # ensure data is up to date
          if (self._synchronizer_class is not None and self._synchronizer_class.__name__ not in self.synchronizer_path):
              self._synchronizer = None
              self._synchronizer_class = None
          # import synchronizer class only if not imported already
          if not self._synchronizer_class:
              self._synchronizer_class = import_by_path(self.synchronizer_path)
          return self._synchronizer_class