docs: def _create_executor(self, handler, args, cpus_per_worker=1):
          """Return a new :class:`.Executor` instance."""
          if self._args.parallel > 0:
              workers = self._args.parallel
          else:
              try:
                  workers = mp.cpu_count() // cpus_per_worker
              except NotImplementedError:
                  workers = 1
  
          if workers != 1:
              logger.info('Using {} parallel worker processes...'.format(
                  workers))
              executor = ProcessPoolExecutor(
                  processes=workers, handler_init=handler, handler_args=args)
          else:
              logger.info('Using single worker...')
              executor = SequentialExecutor(
                  handler_init=handler, handler_args=args)
  
          return executor