docstr: Use APEX-DQN's training iteration function.
docstr_tok: ["Use","APEX-DQN","'s","training","iteration","function","."]
code: def training_step(self) -> ResultDict:
      """Use APEX-DQN's training iteration function."""
      return ApexDQN.training_step(self)
  
file_path: ray/rllib_contrib/apex_ddpg/src/rllib_apex_ddpg/apex_ddpg/apex_ddpg.py
imports: from typing import Optional
  from ray.rllib.algorithms.algorithm_config import AlgorithmConfig, NotProvided
  from ray.rllib.algorithms.apex_dqn.apex_dqn import ApexDQN
  from ray.rllib.algorithms.ddpg.ddpg import DDPG, DDPGConfig
  from ray.rllib.utils.annotations import override
  from ray.rllib.utils.deprecation import DEPRECATED_VALUE
  from ray.rllib.utils.typing import ResultDict
label_desc: Use image node_id 3 for calling the ApexDDPG obj's underlying member method code with example usage: obj.training_step() and returns: ApexDQN