code: def playback_trajectory(env, ep_dir):
      
  
      # first reload the model from the xml
      xml_path = os.path.join(ep_dir, "model.xml")
      with open(xml_path, "r") as f:
          env.reset_from_xml_string(f.read())
  
      state_paths = os.path.join(ep_dir, "state_*.npz")
  
      # read states back, load them one by one, and render
      t = 0
      for state_file in sorted(glob(state_paths)):
          print(state_file)
          dic = np.load(state_file)
          states = dic["states"]
          for state in states:
              env.sim.set_state_from_flattened(state)
              env.sim.forward()
              env.render()
              t += 1
              if t % 100 == 0:
                  print(t)
docs: Playback data from an episode.
  
      Args:
          ep_dir: The path to the directory containing data for an episode.