public static function get(string $fileName) : array
    {
        if (isset(self::$files[$fileName]) === false) {
            if (($content = file_get_contents($fileName)) === false) {
                throw new FileNotReadable('file "' . $fileName . '" can\'t be read');
            }
            $content = (string) $content; // re: https://github.com/phpstan/phpstan/issues/647
            try {
                $content = Yaml::parse($content);
            } catch (ParseException $e) {
                throw new FileNotParsable('file "' . $fileName . '" can\'t be parsed');
            }
            self::$files[$fileName] = $content;
        }

        return self::$files[$fileName];
    }