old_contents: from notebook.utils import url_path_join
  from tornado import ioloop
  
  from nbresuse.api import ApiHandler
  from nbresuse.config import ResourceUseDisplay
  from nbresuse.metrics import PSUtilMetricsLoader
  from nbresuse.prometheus import PrometheusHandler
  
  
  def _jupyter_server_extension_paths():
      """
      Set up the server extension for collecting metrics
      """
      return [{"module": "nbresuse"}]
  
  
  def _jupyter_nbextension_paths():
      """
      Set up the notebook extension for displaying metrics
      """
      return [
          {
              "section": "notebook",
              "dest": "nbresuse",
              "src": "static",
              "require": "nbresuse/main",
          }
      ]
  
  
  def load_jupyter_server_extension(nbapp):
      """
      Called during notebook start
      """
      resuseconfig = ResourceUseDisplay(parent=nbapp)
      nbapp.web_app.settings["nbresuse_display_config"] = resuseconfig
      route_pattern = url_path_join(nbapp.web_app.settings['base_url'], '/api/nbresuse/v1')
      nbapp.web_app.add_handlers('.*', [(route_pattern, ApiHandler)])
      callback = ioloop.PeriodicCallback(
          PrometheusHandler(PSUtilMetricsLoader(nbapp)), 1000
      )
      callback.start()
new_contents: from notebook.utils import url_path_join
  from tornado import ioloop
  
  from nbresuse.api import ApiHandler
  from nbresuse.config import ResourceUseDisplay
  from nbresuse.metrics import PSUtilMetricsLoader
  from nbresuse.prometheus import PrometheusHandler
  
  
  def _jupyter_server_extension_paths():
      """
      Set up the server extension for collecting metrics
      """
      return [{"module": "nbresuse"}]
  
  
  def _jupyter_nbextension_paths():
      """
      Set up the notebook extension for displaying metrics
      """
      return [
          {
              "section": "notebook",
              "dest": "nbresuse",
              "src": "static",
              "require": "nbresuse/main",
          }
      ]
  
  
  def load_jupyter_server_extension(nbapp):
      """
      Called during notebook start
      """
      resuseconfig = ResourceUseDisplay(parent=nbapp)
      nbapp.web_app.settings["nbresuse_display_config"] = resuseconfig
      base_url = nbapp.web_app.settings["base_url"]
      nbapp.web_app.add_handlers(
          ".*",
          [
              (url_path_join(base_url, "/api/nbresuse/v1"), ApiHandler),
              (url_path_join(base_url, "/metrics"), ApiHandler),
          ],
      )
      callback = ioloop.PeriodicCallback(
          PrometheusHandler(PSUtilMetricsLoader(nbapp)), 1000
      )
      callback.start()
  
subject: Add back the /metrics endpoint