class_docstr: Simple class for frame-stacking observations.
class_docstr_tok: ["Simple","class","for","frame-stacking","observations","."]
code: def __init__(self, num_frames: int, flatten: bool = False):
      self._num_frames = num_frames
      self._flatten = flatten
      self.reset()
  
file_path: acme/acme/wrappers/frame_stacking.py
imports: import collections
  from acme import types
  from acme.wrappers import base
  import dm_env
  from dm_env import specs
  import numpy
  import tree
label_desc: Use image node_id 1 to create a new FrameStacker object  with example: obj = FrameStacker(num_frames, flatten)