code: def item_related_name(self):
          
          if not hasattr(self, '_item_related_name'):
              many_to_many_rels = \
                  get_section_many_to_many_relations(self.__class__)
              if len(many_to_many_rels) != 1:
                  self._item_related_name = None
              else:
                  self._item_related_name = many_to_many_rels[0].field.name
          return self._item_related_name
docs: The ManyToMany field on the item class pointing to this class.
  
          If there is more than one field, this value will be None.