code: def completed_work_items(self):
          "Iterable of `(work-item, result)`s for all completed items."
          completed = self._conn.execute(
              "SELECT * FROM work_items, results WHERE work_items.job_id == results.job_id"
          )
          return ((_row_to_work_item(result), _row_to_work_result(result))
                  for result in completedf completed_work_items(self):
          "Iterable of `(work-item, result)`s for all completed items."
          completed = self._conn.execute(
              "SELECT * FROM work_items, results WHERE work_items.job_id == results.job_id"
          )
          return ((_row_to_work_item(result), _row_to_work_result(result))
                  for result in completed)
docs: Iterable of `(work-item, result)`s for all completed items.