class_docstr: Simple replay buffer that operates over batches.
code: def __len__(self):
      return len(self.replay_batches)
  
file_path: ray/python/ray/rllib/execution/replay_ops.py
imports: from typing import Optional
  import random
  from ray.rllib.utils.replay_buffers.replay_buffer import warn_replay_capacity
  from ray.rllib.utils.typing import SampleBatchType
label_desc: Use image node_id 4 for calling the SimpleReplayBuffer obj's underlying member method code with example usage: obj.__len__() and returns: len