class_docstr: Fix RecSim environment's observation space
  
  In RecSim's observation spaces, the "doc" field is a dictionary keyed by
  document IDs. Those IDs are changing every step, thus generating a
  different observation space in each time. This causes issues for RLlib
  because it expects the observation space to remain the same across steps.
  
  This environment wrapper fixes that by reindexing the documents by their
  positions in the list.
code: def observation(self, obs):
      new_obs = OrderedDict()
      new_obs["user"] = obs["user"]
      new_obs["doc"] = {
          str(k): v for k, (_, v) in enumerate(obs["doc"].items())
      }
      new_obs["response"] = obs["response"]
      new_obs = convert_element_to_space_type(
          new_obs, self._sampled_obs
      )
      return new_obs
  
imports: from collections import OrderedDict
  import gymnasium
  from gymnasium.spaces import Dict, Discrete, MultiDiscrete
  from gymnasium.wrappers import EnvCompatibility
  import numpy
  from recsim.document import AbstractDocumentSampler
  from recsim.simulator import environment, recsim_gym
  from recsim.user import AbstractUserModel, AbstractResponse
  from typing import Callable, List, Optional, Type
  from ray.rllib.env.env_context import EnvContext
  from ray.rllib.utils.error import UnsupportedSpaceException
  from ray.rllib.utils.gym import convert_old_gym_space_to_gymnasium_space
  from ray.rllib.utils.spaces.space_utils import convert_element_to_space_type
label_desc: Use image node_id 2 for calling the RecSimObservationSpaceWrapper obj's underlying member method code with example usage: obj.observation(obs) and returns: new_obs