docstr: Clear buffer and re-fill by duplicating the first observation.
docstr_tok: ["Clear","buffer","and","re-fill","by","duplicating","the","first","observation","."]
code: def reset(self):
      """Clear buffer and re-fill by duplicating the first observation."""
      ob = self.env.reset()
      for _ in range(self.k - 1):
          self.frames.append(np.zeros_like(ob))
      self.frames.append(ob)
      return self.observation()
  
imports: import gym
  import numpy
  from collections import deque
  from gym import spaces
label_desc: Use image node_id 2 for calling the FrameStack obj's underlying member method code with example usage: obj.reset() and returns: self