protected function arrayToLowercase($vars)
    {
        $result = array();

        foreach ($vars as $k => $v) {
            if (is_array($v)) {
                $result[strtolower($k)] = $this->arrayToLowercase($v);
            } else {
                $result[strtolower($k)] = strtolower($v);
            }
        }

        return $result;
    }