class_docstr: Simple class for frame-stacking observations.
class_docstr_tok: ["Simple","class","for","frame-stacking","observations","."]
code: def reset(self):
      self._stack = collections.deque(maxlen=self._num_frames)
  
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 3 for calling the FrameStacker obj's underlying member method code with example usage: obj.reset() without return types