code: def test_set_keys_single_index(self):
      self.dataset.keys = 0
      self.assertEqual(self.dataset.keys, "item0")
      self.assertEqual(self.dataset[1], "item0(1)")
  
imports: import numpy
  import unittest
  from chainercv.chainer_experimental.datasets.sliceable import GetterDataset
  from chainercv.utils import testing
label_desc: Use image node_id 5 for calling the TestGetterDataset obj's underlying member method code with example usage: obj.test_set_keys_single_index() without return types