code: def observation(self, frame):
      frame = cv2.cvtColor(frame, cv2.COLOR_RGB2GRAY)
      frame = cv2.resize(
          frame, (self.width, self.height), interpolation=cv2.INTER_AREA
      )
      return frame.reshape(self.observation_space.low.shape)
  
imports: from collections import deque
  import gym
  import numpy
  from gym import spaces
  import chainerrl
label_desc: Use image node_id 2 for calling the WarpFrame obj's underlying member method code with example usage: obj.observation(frame) and returns: frame