docs: def toggle_item(self, item, test_func, field_name=None):
          """
          Toggles the section based on test_func.
  
          test_func takes an item and returns a boolean. If it returns True, the
          item will be added to the given section. It will be removed from the
          section otherwise.
  
          Intended for use with items of settings.ARMSTRONG_SECTION_ITEM_MODEL.
          Behavior on other items is undefined.
          """
          if test_func(item):
              self.add_item(item, field_name)
              return True
          else:
              self.remove_item(item, field_name)
              return False