code: def test_astuple(self):
      dataset = dummy_dataset.DummyDataset(mode=self.mode, convert=True)
      view = dataset.astuple()
      self.assertIsInstance(view, chainer.dataset.TabularDataset)
      self.assertEqual(len(view), len(dataset))
      self.assertEqual(view.keys, dataset.keys)
      self.assertEqual(view.mode, tuple)
      self.assertEqual(
          view.get_examples(None, None),
          dataset.get_examples(None, None),
      )
      self.assertEqual(view.convert(view.fetch()), "converted")
  
file_path: chainer/tests/chainer_tests/dataset_tests/tabular_tests/test_asmode.py
imports: import unittest
  import chainer
  from chainer import testing
  from chainer_tests.dataset_tests.tabular_tests import dummy_dataset
label_desc: Use image node_id 1 for calling the TestAstuple obj's underlying member method code with example usage: obj.test_astuple() without return types