code: def test_get_example_by_keys(self):
      example = self.dataset.get_example_by_keys(1, (1, 2, 3))
      self.assertEqual(example, ("item1(1)", "item2(1)", "item3(1)"))
      self.assertEqual(self.dataset.count, 2)
  
imports: import numpy
  import unittest
  from chainercv.chainer_experimental.datasets.sliceable import GetterDataset
  from chainercv.utils import testing
label_desc: Use image node_id 3 for calling the TestGetterDataset obj's underlying member method code with example usage: obj.test_get_example_by_keys() without return types