code: def setUp(self):
      self.concatenated_dataset = ConcatenatedDataset(*self.datasets)
      self.expected_dataset = [
          sample for dataset in self.datasets for sample in dataset
      ]
  
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 1 for calling the TestConcatenatedDataset obj's underlying member method code with example usage: obj.setUp() without return types