code: def _augment_observation(self, ob, reward, cumulative_reward):
      Expand observation array with additional information header (top rows).
  
      Args:
        ob: observation
        reward: reward to be included in header.
        cumulative_reward: total cumulated reward to be included in header.
  
      Returns:
        Expanded observation array.
      """
      img = PIL_Image().new("RGB",
                            (ob.shape[1], self.HEADER_HEIGHT,))
      draw = PIL_ImageDraw().Draw(img)
      draw.text(
          (1, 0), "c:{:3}, r:{:3}".format(int(cumulative_reward), int(reward)),
          fill=(255, 0, 0)
      )
      draw.text(
          (1, 15), "fc:{:3}".format(int(self._frame_counter)),
          fill=(255, 0, 0)
      )
      header = np.asarray(img)
      del img
      header.setflags(write=1)
      # Top row color indicates if WAIT MODE is on.
      if self._wait:
        pixel_fill = (0, 255, 0)
      else:
        pixel_fill = (255, 0, 0)
      header[0, :, :] = pixel_fill
      return np.concatenate([header, ob], axis=0)
docs: Expand observation array with additional information header (top rows).
  
      Args:
        ob: observation
        reward: reward to be included in header.
        cumulative_reward: total cumulated reward to be included in header.
  
      Returns:
        Expanded observation array.