def __repr__(self):
        return "<Requirement(package={package}, version='{version}')>".format(
            package=self.package, version=self.version)
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)