class_docstr: Array-like object that lazily concat multiple frames.
  
  This object ensures that common frames between the observations are only
  stored once.  It exists purely to optimize memory usage which can be huge
  for DQN's 1M frames replay buffers.
  
  This object should only be converted to numpy array before being passed to
  the model.
  
  You'd not believe how complex the previous solution was.
code: def __array__(self, dtype=None):
      out = np.concatenate(self._frames, axis=self.stack_axis)
      if dtype is not None:
          out = out.astype(dtype)
      return out
  
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 LazyFrames obj's underlying member method code with example usage: obj.__array__(dtype) and returns: out