def yaml(self):
        return yaml.dump(self.serialized, default_flow_style=False,
                         encoding=None)
def _setup_drag(self, item):
    self._drag_and_drop_context.setup_drag(
      item.item_widget,
      self._get_drag_data,
      self._on_drag_data_received,
      [item],
      [item],
      self)