code: def __init__(self, train_iter, optimizer, bprop_len, device):
      super(BPTTUpdater, self).__init__(
          train_iter, optimizer, device=device
      )
      self.bprop_len = bprop_len
  
imports: from __future__ import division
  import argparse
  import sys
  import numpy
  import chainer
  import chainer.functions
  import chainer.links
  from chainer import training
  from chainer.training import extensions
  import chainerx
label_desc: Use image node_id 1 to create a new BPTTUpdater object from inherited base classes: training.updaters with example: obj = BPTTUpdater(train_iter, optimizer, bprop_len, device)