code: def move_item_up(self, item):
          
          prev_iter = self._prev_iter_for(item)
          if prev_iter is not None:
              self.model.swap(prev_iter, self._iter_for(item))
docs: Move an item up in the list.
  
          Essentially swap it with the item above it.
  
          :param item: The item to be moved.