code: def __call__(self, batch, device):
      self.args.append({"batch": batch, "device": device})
      return next(self.iterator)
  
imports: import unittest
  import numpy
  import chainer
  from chainer import backend
  from chainer.backends import _cpu
  from chainer import dataset
  from chainer import iterators
  from chainer import testing
  from chainer.training import extensions
label_desc: Use image node_id 2 for calling the DummyConverter obj's underlying member method code with example usage: obj.__call__(batch, device) and returns: next