def on_nav(
        self, nav: Navigation, /, *, config: MkDocsConfig, files: Files
    ) -> Navigation | None:
        """
        The `nav` event is called after the site navigation is created and can
        be used to alter the site navigation.

        Args:
            nav: global navigation object
            config: global configuration object
            files: global files collection

        Returns:
            global navigation object
        """
        return nav

        The `nav` event is called after the site navigation is created and can
        be used to alter the site navigation.

        Args:
            nav: global navigation object
            config: global configuration object
            files: global files collection

        Returns:
            global navigation object
        
mkdocs/plugins.py