code: def testFillToSize(self):
      b = reservoir._ReservoirBucket(100)
      for i in range(100):
          b.AddItem(i)
      self.assertEqual(b.Items(), list(range(100)))
      self.assertEqual(b._num_items_seen, 100)
  
imports: import tensorflow
  from tensorboard.backend.event_processing import reservoir
label_desc: Use image node_id 2 for calling the ReservoirBucketTest obj's underlying member method code with example usage: obj.testFillToSize() without return types