private function merge(array $merged, array $array)
    {
        foreach ($array as $key => $value) {
            if (is_array($value) && isset ($merged[$key]) && is_array($merged[$key])) {
                $merged[$key] = $this->merge($merged[$key], $value);
            } else {
                $merged[$key] = $value;
            }
        }

        return $merged;
    }