PHPML\Exception\DatasetException::missingFolder PHP Method

    public static function missingFolder($path)
    {
        return new self(sprintf('Dataset root folder "%s" missing.', $path));
    }

 /**
  * @param string $rootPath
  *
  * @throws DatasetException
  */
 public function __construct(string $rootPath)
 {
     if (!is_dir($rootPath)) {
         throw DatasetException::missingFolder($rootPath);
     }
     $this->scanRootPath($rootPath);
 }