code: def test_concatenated_dataset_slice(self):
      concatenated_slice = self.concatenated_dataset[1:8:2]
      expected_slice = self.concatenated_dataset[1:8:2]
  
      self.assertEqual(len(concatenated_slice), len(expected_slice))
  
      for concatenated, expected in six.moves.zip(
          concatenated_slice, expected_slice
      ):
          np.testing.assert_equal(concatenated, expected)
  
file_path: chainer/tests/chainer_tests/datasets_tests/test_concatenated_dataset.py
imports: import unittest
  import numpy
  import six
  from chainer.datasets import ConcatenatedDataset
  from chainer import testing
label_desc: Use image node_id 3 for calling the TestConcatenatedDataset obj's underlying member method code with example usage: obj.test_concatenated_dataset_slice() without return types