code: def test_iter(self):
      it = iter(self.dataset)
      for i in six.moves.range(len(self.dataset)):
          self.assertEqual(
              next(it),
              (
                  "item0({:d})".format(i),
                  "item1({:d})".format(i),
                  "item2({:d})".format(i),
              ),
          )
      with self.assertRaises(StopIteration):
          next(it)
  
imports: import numpy
  import six
  import unittest
  from chainercv.chainer_experimental.datasets.sliceable import SliceableDataset
  from chainercv.utils import testing
label_desc: Use image node_id 18 for calling the TestSliceableDataset obj's underlying member method code with example usage: obj.test_iter() without return types