code: def step(self, action):
      ob, reward, done, info = self.env.step(action)
      self.frames.append(ob)
      return self._get_ob(), reward, done, info
  
imports: import numpy
  import os
  from collections import deque
  import gym
  from gym import spaces
  import cv2
  from .wrappers import TimeLimit
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