def __repr__(self):
        return "<Requirement(package={package}, version='{version}')>".format(
            package=self.package, version=self.version)
def _on_drag_data_received(self, dragged_item_index_str, destination_item):
    dragged_item = self._items[int(dragged_item_index_str)]
    self.reorder_item(dragged_item, self._get_item_position(destination_item))