code: def check_workers(self):
          '''Kill workers that have been pending for a while and check if all workers
          are alive. '''
          if time.time() - self._worker_alive_time > 5:
              self._worker_alive_time = time.time()
              # join processes if they are now gone, it should not do anything bad
              # if the process is still running
              [worker.join() for worker in self._workers if not worker.is_alive()]
              self._workers = [
                  worker for worker in self._workers if worker.is_alive()
              ]
              if len(self._workers) < self._num_workers:
                  raise ProcessKilled('One of the workers has been killed.'f check_workers(self):
          '''Kill workers that have been pending for a while and check if all workers
          are alive. '''
          if time.time() - self._worker_alive_time > 5:
              self._worker_alive_time = time.time()
              # join processes if they are now gone, it should not do anything bad
              # if the process is still running
              [worker.join() for worker in self._workers if not worker.is_alive()]
              self._workers = [
                  worker for worker in self._workers if worker.is_alive()
              ]
              if len(self._workers) < self._num_workers:
                  raise ProcessKilled('One of the workers has been killed.')
docs: Kill workers that have been pending for a while and check if all workers
          are alive.