code: def load_jupyter_server_extension(app):  # pragma: no cover
      """Use Jupytext's contents manager"""
      if hasattr(app.contents_manager_class, "formats"):
          app.log.info(
              "[Jupytext Server Extension] NotebookApp.contents_manager_class is "
              "(a subclass of) jupytext.TextFileContentsManager already - OK"
          )
          return
  
      # The server extension call is too late!
      # The contents manager was set at NotebookApp.init_configurables
  
      # Let's change the contents manager class
      base_class = app.contents_manager_class
      if "async" in base_class.__name__.lower():
          app.log.warning(
              "[Jupytext Server Extension] Async contents managers like {} "
              "are not supported at the moment "
              "(https://github.com/mwouts/jupytext/issues/1020). "
              "We will derive a contents manager from LargeFileManager instead.".format(
                  base_class.__name__
              )
          )
          from jupyter_server.services.contents.largefilemanager import (  # noqa
              LargeFileManager,
          )
  
          base_class = LargeFileManager
  
      app.log.info(
          "[Jupytext Server Extension] Deriving a JupytextContentsManager "
          "from {}".format(base_class.__name__)
      )
      app.contents_manager_class = (
          build_jupytext_contents_manager_class(base_class)
      )
  
      try:
          # And rerun selected init steps from https://github.com/jupyter/notebook/blob/
          # 132f27306522b32fa667a6b208034cb7a04025c9/notebook/notebookapp.py#L1634-L1638
  
          # app.init_configurables()
          app.contents_manager = app.contents_manager_class(
              parent=app, log=app.log
          )
          app.session_manager.contents_manager = app.contents_manager
  
          # app.init_components()
          # app.init_webapp()
          app.web_app.settings[
              "contents_manager"
          ] = app.contents_manager
  
          # app.init_terminals()
          # app.init_signal()
  
      except Exception:
          app.log.error(
              """[Jupytext Server Extension] An error occurred. Please deactivate the server extension with
      jupyter serverextension disable jupytext
  and configure the contents manager manually by adding
      c.NotebookApp.contents_manager_class = "jupytext.TextFileContentsManager"
  to your .jupyter/jupyter_notebook_config.py file.
  """
          )
          raise
  
label_desc: Use image node_id 1 for calling a global function with example usage: load_jupyter_server_extension(app) without return types