code: def test_tag(self):
      self.assertEqual(
          "a/histogram_summary", self.histogram("a", []).value[0].tag
      )
      self.assertEqual(
          "a/b/histogram_summary",
          self.histogram("a/b", []).value[0].tag,
      )
  
imports: import glob
  import os
  import numpy
  import tensorflow
  from tensorboard.compat import tf2
  from tensorboard.compat.proto import summary_pb2
  from tensorboard.plugins.histogram import metadata
  from tensorboard.plugins.histogram import summary
  from tensorboard.util import tensor_util
label_desc: Use image node_id 2 for calling the SummaryV1PbTest obj's underlying member method code with example usage: obj.test_tag() without return types