code: def reset(self):
      ob = self.env.reset()
      for _ in range(self.k):
          self.frames.append(ob)
      return self._get_ob()
  
imports: import time
  import numpy
  from collections import deque
  import gym
  from gym import spaces
  from parl.env.compat_wrappers import CompatWrapper, is_gym_version_ge, V_NPRANDOM_CHANGED
  import cv2
label_desc: Use image node_id 2 for calling the FrameStack obj's underlying member method code with example usage: obj.reset() and returns: self