code: def test_concatenated_dataset(self):
      self.assertEqual(
          len(self.concatenated_dataset), len(self.expected_dataset)
      )
  
      for i, expected in enumerate(self.expected_dataset):
          np.testing.assert_equal(
              self.concatenated_dataset[i], 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 2 for calling the TestConcatenatedDataset obj's underlying member method code with example usage: obj.test_concatenated_dataset() without return types