private function prepareAttributes($attributes = array())
    {
        if (!is_array($attributes)) {
            throw new InvalidArgumentException("[ImBundle] format attributes must be an array, recieved: " . var_export($attributes, true));
        }
        $result = "";
        foreach ($attributes as $key => $value) {
            if ($key === null || $key === "") {
                $result .= " " . $value;
            } else {
                $result .= " -" . $key;
                if ($value != "") {
                    $result .= " \"" . $value . "\"";
                }
            }
        }

        return $result;
    }