docstr: Stack one channel (channel keyword) from previous frames
docstr_tok: ["Stack","one","channel","(","channel","keyword",")","from","previous","frames"]
code: def __init__(self, env, k, channel=1):
      """
      Stack one channel (channel keyword) from previous frames
      """
      gym.Wrapper.__init__(self, env)
      shp = env.observation_space.shape
      self.channel = channel
      self.observation_space = gym.spaces.Box(
          low=0,
          high=255,
          shape=(shp[0], shp[1], shp[2] + k - 1),
          dtype=env.observation_space.dtype,
      )
      self.k = k
      self.frames = deque([], maxlen=k)
      shp = env.observation_space.shape
  
imports: from collections import deque
  import cv2
  from .atari_wrappers import WarpFrame, ClipRewardEnv, FrameStack, ScaledFloatFrame
  from .wrappers import TimeLimit
  import numpy
  import gym
label_desc: Use image node_id 1 to create a new PartialFrameStack object from inherited base classes: gym with example: obj = PartialFrameStack(env, k, channel)