code: def hold_worker(self, worker_id):
          
          c = self.command_client.run("HOLD_WORKER;{}".format(worker_id))
          logger.debug("Sent hold request to worker: {}".format(worker_id))
          return c
docs: Puts a worker on hold, preventing scheduling of additional tasks to it.
  
          This is called "hold" mostly because this only stops scheduling of tasks,
          and does not actually kill the worker.
  
          Parameters
          ----------
  
          worker_id : str
              Worker id to be put on hold