How to use the pympress.util.set_screensaver function in pympress

def save_and_quit(self, *args):
        """ Save configuration and exit the main loop.
        """
        self.scribbler.disable_scribbling()
        self.medias.hide_all()

        extras.FileWatcher.stop_daemon()
        self.doc.cleanup_media_files()

        self.config.update_layout('notes' if self.notes_mode else 'plain',
                                  self.p_central.get_children()[0], self.pane_handle_pos)

        if bool(self.c_win.get_window().get_state() & Gdk.WindowState.FULLSCREEN):
            util.set_screensaver(False, self.c_win.get_window())

        self.config.save_config()
        Gtk.main_quit()

def on_window_state_event(self, widget, event):
        """ Track whether the preview window is maximized.

        Args:
            widget (:class:`~Gtk.Widget`):  the widget in which the event occurred
            event (:class:`~Gtk.Event`):  the event that occurred

        Returns:
            `bool`: whether the event was consumed.
        """
        if widget.get_name() == self.c_win.get_name():
            fullscreen = (Gdk.WindowState.FULLSCREEN & event.new_window_state) != 0
            util.set_screensaver(fullscreen, self.c_win.get_window())
        return False

            GLib.idle_add(lambda: util.set_screensaver(True, self.c_win.get_window()))