public static function parse($answer)
    {
        if ( ! is_array($answer)) {
            return;
        }

        foreach ($answer as $key => $value) {
            $parsed = is_array($value) ? self::parse($value) : self::process($value);

            if ( ! empty($parsed)) {
                $answer[$key] = $parsed;
            } else {
                unset($answer[$key]);
            }
        }

        return $answer;
    }