class_docstr: A wrapper that puts the previous action and reward into the observation.
class_docstr_tok: ["A","wrapper","that","puts","the","previous","action","and","reward","into","the","observation","."]
code: def observation_spec(self):
      return OAR(
          observation=self._environment.observation_spec(),
          action=self.action_spec(),
          reward=self.reward_spec(),
      )
  
file_path: acme/acme/wrappers/observation_action_reward.py
imports: from typing import NamedTuple
  from acme import types
  from acme.wrappers import base
  import dm_env
  import tree
label_desc: Use image node_id 4 for calling the ObservationActionRewardWrapper obj's underlying member method code with example usage: obj.observation_spec() and returns: OAR