code: def test_assert_is_semantic_segmentation_dataset(self):
      if self.valid:
          assert_is_semantic_segmentation_dataset(self.dataset, 21)
      else:
          with self.assertRaises(AssertionError):
              assert_is_semantic_segmentation_dataset(self.dataset, 21)
  
imports: import numpy
  import unittest
  from chainer.dataset import DatasetMixin
  from chainercv.utils import assert_is_semantic_segmentation_dataset
  from chainercv.utils import testing
label_desc: Use image node_id 1 for calling the TestAssertIsSemanticSegmentationDataset obj's underlying member method code with example usage: obj.test_assert_is_semantic_segmentation_dataset() without return types