code: def test_unary_callable_tuple(self):
      dataset = tabular.from_data(
          (("a", "b"), lambda i: (i * i, -i)), size=10
      )
  
      self.assertIsInstance(dataset, chainer.dataset.TabularDataset)
      self.assertEqual(len(dataset), 10)
      self.assertEqual(dataset.keys, ("a", "b"))
      self.assertEqual(dataset.mode, tuple)
  
      output = dataset.slice[[1, 3]].fetch()
      np.testing.assert_equal(output, ([1, 9], [-1, -3]))
      for out in output:
          self.assertIsInstance(out, list)
  
imports: import unittest
  import numpy
  import chainer
  from chainer.dataset import tabular
  from chainer import testing
label_desc: Use image node_id 6 for calling the TestFromData obj's underlying member method code with example usage: obj.test_unary_callable_tuple() without return types