code: def testItemsAndKeys(self):
      r = reservoir.Reservoir(42)
      r.AddItem("foo", 4)
      r.AddItem("bar", 9)
      r.AddItem("foo", 19)
      self.assertCountEqual(r.Keys(), ["foo", "bar"])
      self.assertEqual(r.Items("foo"), [4, 19])
      self.assertEqual(r.Items("bar"), [9])
  
imports: import tensorflow
  from tensorboard.backend.event_processing import reservoir
label_desc: Use image node_id 3 for calling the ReservoirTest obj's underlying member method code with example usage: obj.testItemsAndKeys() without return types