code: def _preprocess_batch(batch):
      shape = batch["prev_n_obs"].shape
      obs = batch["prev_n_obs"].reshape((shape[0], shape[1] * shape[2]))
      batch[SampleBatch.OBS] = obs
      return batch
  
imports: from ray.rllib.core.rl_module.rl_module import RLModuleConfig
  from ray.rllib.policy.sample_batch import SampleBatch
  from ray.rllib.algorithms.ppo.ppo_rl_module import PPORLModule
  from ray.rllib.algorithms.ppo.torch.ppo_torch_rl_module import PPOTorchRLModule
  from ray.rllib.algorithms.ppo.tf.ppo_tf_rl_module import PPOTfRLModule
  from ray.rllib.policy.view_requirement import ViewRequirement
  from ray.rllib.utils.framework import try_import_tf, try_import_torch
  import gymnasium
label_desc: Use image node_id 1 for calling the TorchFrameStackingCartPoleRLM obj's underlying member method code with example usage: obj._preprocess_batch(batch) and returns: batch