code: def _shutdownBatchSystem(self):
          
          assert self._batchSystem is not None
  
          startTime = time.time()
          logger.debug('Shutting down batch system ...')
          self._batchSystem.shutdown()
          logger.debug('... finished shutting down the batch system in %s seconds.'
                       % (time.time() - startTime))
docs: Shuts down current batch system if it has been created.