Contao\Validator::isUuid PHP Method

    public static function isUuid($varValue)
    {
        return static::isBinaryUuid($varValue) || static::isStringUuid($varValue);
    }

 /**
  * @return string
  */
 public function generate()
 {
     if (TL_MODE == 'BE') {
         $objTemplate = new BackendTemplate('be_wildcard');
         $objTemplate->wildcard = '### LOGO MODULE ###';
         return $objTemplate->parse();
     }
     if ($this->singleSRC == '') {
         return '';
     }
     $objFile = FilesModel::findByUuid($this->singleSRC);
     if ($objFile === null) {
         if (!Validator::isUuid($this->singleSRC)) {
             return '<p class="error">' . $GLOBALS['TL_LANG']['ERR']['version2format'] . '</p>';
         }
         return '';
     }
     if (!is_file(TL_ROOT . '/' . $objFile->path)) {
         return '';
     }
     $this->singleSRC = $objFile->path;
     return parent::generate();
 }