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 step(self, action: types.NestedArray) -> dm_env.TimeStep:
      timestep = self._environment.step(action)
      new_timestep = self._augment_observation(
          action, timestep.reward, timestep
      )
      return new_timestep
  
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 2 for calling the ObservationActionRewardWrapper obj's underlying member method code with example usage: obj.step(action) and returns: new_timestep