code: def step(self, action):
      ob, reward, done, info = self.env.step(action)
      self.frames.append(ob)
      return self.observation(), reward, done, info
  
imports: import gym
  import numpy
  from collections import deque
  from gym import spaces
label_desc: Use image node_id 3 for calling the FrameStack obj's underlying member method code with example usage: obj.step(action) and returns: self,  reward,  done,  info