code: def testSizeZeroBucket(self):
      b = reservoir._ReservoirBucket(0)
      for i in range(20):
          b.AddItem(i)
          self.assertEqual(b.Items(), list(range(i + 1)))
      self.assertEqual(b._num_items_seen, 20)
  
imports: import tensorflow
  from tensorboard.backend.event_processing import reservoir
label_desc: Use image node_id 7 for calling the ReservoirBucketTest obj's underlying member method code with example usage: obj.testSizeZeroBucket() without return types