docs: def _call_custom_creator(self, config):
          """
          Call a custom driver creator.
  
          :param config: The driver configuration
          :type config: dict
  
          :rtype: Repository
          """
          creator = self._custom_creators[config['driver']](config)
  
          if isinstance(creator, Store):
              creator = self.repository(creator)
  
          if not isinstance(creator, Repository):
              raise RuntimeError('Custom creator should return a Repository instance.')
  
          return creator