public function save_post($post_id)
 {
     $sidebar_id = $_POST['custom-sidebar-select'];
     if (isset($_POST['custom-sidebar'])) {
         $sidebar_id = Custom_Sidebars::get_sidebar_id($post_id);
     }
     update_post_meta($post_id, '_custom_sidebar', (bool) $_POST['custom-sidebar']);
     update_post_meta($post_id, '_custom_sidebar_id', sanitize_text_field($sidebar_id));
 }