code: def _container_factory(self, **options):
          
          ac_dict = options.get("ac_dict", False)
          _dicts = [x for x in (options.get(o) for o in self.dict_options())
                    if x]
  
          if self.dict_options() and ac_dict and callable(ac_dict):
              return ac_dict  # Higher priority than ac_ordered.
          if _dicts and callable(_dicts[0]):
              return _dicts[0]
          if self.ordered() and options.get("ac_ordered", False):
              return anyconfig.compat.OrderedDict
  
          return dict
docs: The order of prirorities are ac_dict, backend specific dict class
          option, ac_ordered.
  
          :param options: Keyword options may contain 'ac_ordered'.
          :return: Factory (class or function) to make an container.