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: Initialization method.
  
  Args:
      runtime_group: The group where the workers will be started.
      dbname: The name of the mongodb instance.
      poll_interval: The poll interval of the hyperopt worker.
  
  Raises.
      ValueError: In case dbname is empty.
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code: def __init__(
      self,
      runtime_group: RuntimeGroup,
      dbname: str,
      poll_interval: float,
  ):
      """Initialization method.
  
      Args:
          runtime_group: The group where the workers will be started.
          dbname: The name of the mongodb instance.
          poll_interval: The poll interval of the hyperopt worker.
  
      Raises.
          ValueError: In case dbname is empty.
      """
      super().__init__(runtime_group)
      self._ports = None
  
      if not dbname:
          raise ValueError("dbname must not be empty")
      self._dbname = dbname
  
      if not poll_interval:
          raise ValueError("poll_interval must not be empty")
      self._poll_interval = poll_interval
  
      self.log.debug("RoundRobinLauncher initialized.")
  
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 1 to create a new RoundRobinLauncher object from inherited base classes: WorkerLauncher with example: obj = RoundRobinLauncher(runtime_group, dbname, poll_interval)