public static function pageHas(string $name, ?string $page = null): bool
    {
        if ($page === null) {
            $page = $_SERVER['PHP_SELF'];
        }
        return self::has($name, $page);
    }
public static function pageHas(string $name, ?string $page = null): bool
    {
        if ($page === null) {
            $page = $_SERVER['PHP_SELF'];
        }
        return self::has($name, $page);
    }
public static function pageHas ( string $ name , ? string $ page = null ) : bool { if ( $ page === null ) { $ page = $ _SERVER [ 'PHP_SELF' ] ; } return self :: has ( $ name , $ page ) ; }
Check if session-variable exists by page-filename.

@param string $name
@param string $page Default null which means current page PHP_SELF.
@return bool
Check if session - variable exists by page - filename .