code: def test_cityscapes_dataset(self):
      indices = np.random.permutation(np.arange(len(self.dataset)))
      for i in indices[:10]:
          img = self.dataset[i]
          assert_is_image(img, color=True)
  
imports: import numpy
  import os
  import shutil
  import tempfile
  import unittest
  from chainer import testing
  from chainer.testing import attr
  from chainercv.datasets.cityscapes.cityscapes_utils import cityscapes_labels
  from chainercv.datasets import CityscapesSemanticSegmentationDataset
  from chainercv.datasets import CityscapesTestImageDataset
  from chainercv.utils import assert_is_semantic_segmentation_dataset
  from chainercv.utils.testing.assertions.assert_is_image import assert_is_image
  from chainercv.utils import write_image
label_desc: Use image node_id 3 for calling the TestCityscapesTestImageDataset obj's underlying member method code with example usage: obj.test_cityscapes_dataset() without return types