class_docstr: A memory backend which transfers the experiences from the rollout to the training worker using Redis Pub/Sub in
  Coach when distributed mode is used.
docstr: :param agent: The agent in use.
docstr_tok: [":","param","agent",":","The","agent","in","use","."]
code: def subscribe(self, agent):
      """
      :param agent: The agent in use.
      """
      redis_sub = RedisSub(
          redis_address=self.params.redis_address,
          redis_port=self.params.redis_port,
          channel=self.params.channel,
      )
      return redis_sub
  
imports: import redis
  import pickle
  import uuid
  import time
  from rl_coach.memories.backend.memory import MemoryBackend, MemoryBackendParameters
  from rl_coach.core_types import Transition, Episode, EnvironmentSteps, EnvironmentEpisodes
  from rl_coach.logger import screen
label_desc: Use image node_id 8 for calling the RedisPubSubBackend obj's underlying member method code with example usage: obj.subscribe(agent) and returns: redis_sub