code: def _add_replay_buffer_and_policy(
      self,
      policy_id: PolicyID,
      policy_spec: PolicySpec,
      config: AlgorithmConfigDict,
  ):
      assert self.replay_actor is None
      assert len(self.policy_actors) == 0
  
      actual_policy_class = get_tf_eager_cls_if_necessary(
          policy_spec.policy_class, config
      )
  
      if isinstance(config, AlgorithmConfig):
          config = config.to_dict()
  
      colocated = create_colocated_actors(
          actor_specs=[
              (self.replay_actor_class, self.replay_actor_args, {}, 1),
          ]
          + [
              (
                  ray.remote(
                      num_cpus=1,
                      num_gpus=self.num_gpus_per_policy
                      if not config["_fake_gpus"]
                      else 0,
                  )(actual_policy_class),
                  # Policy c'tor args.
                  (
                      policy_spec.observation_space,
                      policy_spec.action_space,
                      config,
                  ),
                  # Policy c'tor kwargs={}.
                  {},
                  # Count=1,
                  1,
              )
          ],
          node=None,
      )  # None
  
      self.replay_actor = colocated[0][0]
      self.policy_actors[policy_id] = colocated[1][0]
      self.has_replay_buffer = True
  
      return self.policy_actors[policy_id]
  
imports: import math
  from typing import Any, Dict, List, Optional, Type
  import ray
  from ray.actor import ActorHandle
  from ray.rllib.algorithms.algorithm import Algorithm
  from ray.rllib.algorithms.algorithm_config import AlgorithmConfig
  from ray.rllib.policy.policy import PolicySpec
  from ray.rllib.utils.actors import create_colocated_actors
  from ray.rllib.utils.tf_utils import get_tf_eager_cls_if_necessary
  from ray.rllib.utils.typing import AlgorithmConfigDict, PolicyID
label_desc: Use image node_id 3 for calling the _Shard obj's underlying member method code with example usage: obj._add_replay_buffer_and_policy(policy_id, policy_spec, config) and returns: self