public function export($pretty=false)
    {
        $tmp = new \stdClass();
        if ( $this->home != false ) $tmp->home = $this->home;
        if ( $this->left != false ) $tmp->left = $this->left->menu;
        if ( $this->right != false ) $tmp->right = $this->right->menu;
        if ( $pretty ) {
            return json_encode($tmp, JSON_PRETTY_PRINT);
        } else {
            return json_encode($tmp);
        }
    }