code: def __getitem__(self, idx):
      if idx < 0 or idx >= self.length:
          raise KeyError()
      return self.data[(self.start + idx) % self.maxlen]
  
imports: from __future__ import absolute_import
  from collections import deque, namedtuple
  import warnings
  import random
  import numpy
label_desc: Use image node_id 3 for calling the RingBuffer obj's underlying member method code with example usage: obj.__getitem__(idx) and returns: self