code: def test_index(self):
      server = self.load_server(
          [
              self._RUN_WITH_LEGACY_SCALARS,
              self._RUN_WITH_SCALARS,
              self._RUN_WITH_HISTOGRAM,
          ]
      )
      response = server.get("/data/plugin/scalars/tags")
      self.assertEqual(200, response.status_code)
      self.assertEqual(
          "application/json", response.headers["Content-Type"]
      )
      self.assertEqual(
          {
              self._RUN_WITH_LEGACY_SCALARS: {
                  self._LEGACY_SCALAR_TAG: {
                      "displayName": self._LEGACY_SCALAR_TAG,
                      "description": "",
                  },
              },
              self._RUN_WITH_SCALARS: {
                  "%s/scalar_summary"
                  % self._SCALAR_TAG: {
                      "displayName": self._DISPLAY_NAME,
                      "description": self._HTML_DESCRIPTION,
                  },
              },
              # _RUN_WITH_HISTOGRAM omitted: No scalar data.
          },
          json.loads(response.get_data()),
      )
  
imports: import csv
  import io
  import json
  import os.path
  import tensorflow
  from werkzeug import test
  from werkzeug import wrappers
  from tensorboard.backend import application
  from tensorboard.backend.event_processing import data_provider
  from tensorboard.backend.event_processing import plugin_event_multiplexer
  from tensorboard.backend.event_processing import tag_types
  from tensorboard.plugins import base_plugin
  from tensorboard.plugins.scalar import scalars_plugin
  from tensorboard.plugins.scalar import summary
  from tensorboard.util import test_util
label_desc: Use image node_id 4 for calling the ScalarsPluginTest obj's underlying member method code with example usage: obj.test_index() without return types