code: def set_model(self, model):
          
          self._model = model
          for c in self.childItems:
              c.set_model(model)
docs: Set the model the item belongs to
  
          A TreeItem can only belong to one model.
  
          :param model: the model the item belongs to
          :type model: :class:`Treemodel`
          :returns: None
          :rtype: None
          :raises: None