code: def test_slice_keys_single_tuple_index(self):
      dataset = self.dataset.slice[:, self.iterable((1,))]
      self.assertIsInstance(dataset, SliceableDataset)
      self.assertEqual(len(dataset), len(self.dataset))
      self.assertEqual(dataset.keys, ("item1",))
      self.assertEqual(dataset[2], ("item1(2)",))
  
imports: import numpy
  import six
  import unittest
  from chainercv.chainer_experimental.datasets.sliceable import SliceableDataset
  from chainercv.utils import testing
label_desc: Use image node_id 6 for calling the TestSliceableDataset obj's underlying member method code with example usage: obj.test_slice_keys_single_tuple_index() without return types