code: def observation(self, observation):
      return np.squeeze(observation, axis=-1)
  
imports: from collections import deque
  import gymnasium
  from gymnasium import spaces
  import numpy
  from typing import Union
  from ray.rllib.utils.annotations import PublicAPI
  from ray.rllib.utils.images import rgb2gray, resize
label_desc: Use image node_id 2 for calling the FrameStackTrajectoryView obj's underlying member method code with example usage: obj.observation(observation) and returns: np