@classmethod
def _load_jupyter_server_extension(cls, serverapp):
    """Initialize and configure this extension, then add the extension's
        settings and handlers to the server's web application.
        """
    try:
        extension = serverapp._enabled_extensions[cls.extension_name]
    except KeyError:
        extension = cls()
        extension.link_to_serverapp(serverapp)
    extension.initialize()
    return extension
