class_docstr: Buffer consecutive k observations and stack them on a new last axis.
  The output observation has shape `original_shape + (k, )`.
class_docstr_tok: ["Buffer","consecutive","k","observations","and","stack","them","on","a","new","last","axis",".","The","output","observation","has","shape","`","original_shape","+","(","k",",",")","`","."]
code: def __init__(self, env, k):
      gym.Wrapper.__init__(self, env)
      self.k = k
      self.frames = deque([], maxlen=k)
  
imports: import numpy
  from collections import deque
  import gym
label_desc: Use image node_id 1 to create a new FrameStack object from inherited base classes: gym with example: obj = FrameStack(env, k)