private function updateTaxonomy($data)
 {
     $taxonomy = Taxonomy::find((int) $_POST['id']);
     $new_parent_id = (int) $data['taxonomy']['content-type-id'];
     if (!$new_parent_id) {
         $taxonomy->parent_id = null;
     } else {
         $taxonomy->parent_id = $new_parent_id;
     }
     try {
         $saved = $taxonomy->save();
         $this->content_types_admin_index();
     } catch (Exception $e) {
         return new WP_Error(500, "Could not update taxonomy");
     }
     return $saved;
 }