protected function _setPermission(string $pointer, string $mode): void
    {
        $this->permissions[$pointer] = $mode;
        $pointer_with_special_graph = '/^g:([a-f0-9\-]+):$/i';
        if(preg_match($pointer_with_special_graph, $pointer, $matches)) {
            $this->permissions_with_graph[] = $matches[1];
        }
    }