code: def test_image_data(self):
      self._write_image("run1", "images/tagA", 1, None)
      self._multiplexer.Reload()
  
      # Get the blob_key manually.
      image_id = self._get_image_blob_key(
          "run1", "images/tagA", step=0, sample=0
      )
      (data, content_type) = self._plugin._image_data_impl(
          context.RequestContext(), image_id
      )
  
      self.assertIsInstance(data, bytes)
      self.assertEqual(content_type, "image/png")
      self.assertGreater(len(data), 0)
  
imports: import argparse
  import collections.abc
  import os.path
  import tensorflow.compat.v1
  import tensorflow.compat.v2
  from tensorboard import context
  from tensorboard.backend.event_processing import data_provider
  from tensorboard.backend.event_processing import plugin_event_multiplexer
  from tensorboard.data import provider
  from tensorboard.plugins import base_plugin
  from tensorboard.plugins.image import metadata
  from tensorboard.plugins.metrics import metrics_plugin
label_desc: Use image node_id 22 for calling the MetricsPluginTest obj's underlying member method code with example usage: obj.test_image_data() without return types