class_docstr: Concrete WorkerLauncher implementation for launching hyperopt workers in a round robin manner.
  
  See the `WorkerLauncher` documentation to get a list of the inherited methods and attributes.
docstr: Launch a single worker instance in a `Runtime` in the `RuntimeGroup`.
docstr_tok: ["Launch","a","single","worker","instance","in","a","`","Runtime","`","in","the","`","RuntimeGroup","`","."]
code: def _launch_single_worker(
      self, host: str, worker_index: int, master_port: int, debug: bool
  ) -> None:
      """Launch a single worker instance in a `Runtime` in the `RuntimeGroup`."""
      # 2. Start the worker on this port
      task = RuntimeTask("launch-hyperopt-worker-" + str(worker_index))
      task.run_command(
          self._get_launch_command(
              master_port, self._dbname, self._poll_interval
          )
      )
      self._group.execute_task(
          task, host, omit_on_join=True, debug=debug
      )
  
imports: import os
  import time
  from typing import List, Optional, Union
  from lazycluster import Runtime, RuntimeGroup, RuntimeTask, _utils
  from lazycluster.cluster import MasterLauncher, MasterWorkerCluster, WorkerLauncher
  from lazycluster.cluster.exceptions import MasterStartError
  from lazycluster.exceptions import PortInUseError
  from lazycluster.utils import Environment
label_desc: Use image node_id 3 for calling the RoundRobinLauncher obj's underlying member method code with example usage: obj._launch_single_worker(host, worker_index, master_port, debug) without return types