public function clone(string $id, string $name): ?string
  {
    if ( \bbn\str::is_uid($id) && ($id_menu = $this->add(['text' => $name])) ){
      if ( ($bits = $this->pref->get_full_bits($id)) && !$this->_clone($id_menu, $bits) ){
        return null;
      }
      return $id_menu;
    }
    return null;
  }