private function init($fileName)
 {
     if (!file_exists($fileName)) {
         throw InvalidArgumentException::fileNotExists($fileName);
     }
     $this->fileName = $fileName;
 }
 public function __construct($fileName)
 {
     if (!file_exists($fileName)) {
         throw InvalidArgumentException::fileNotExists($fileName);
     }
     $this->fileName = $fileName;
 }