code: def test_step(self):
      data = np.array(1, np.float32, ndmin=3)
      event = self.audio_event("a", data, 44100, step=333)
      self.assertEqual(333, event.step)
  
imports: import glob
  import os
  import numpy
  import tensorflow
  from tensorboard.compat import tf2
  from tensorboard.plugins.audio import metadata
  from tensorboard.plugins.audio import summary
  from tensorboard.util import tensor_util
label_desc: Use image node_id 5 for calling the SummaryV2OpTest obj's underlying member method code with example usage: obj.test_step() without return types