Fatal error: Uncaught Error: Class 'Date' not found in /opt/www/internett/php/PHP_Book/eksempler/ch12 - Date and Time/getisoweekofyear.php:3 Stack trace: #0 {main} thrown in /opt/www/internett/php/PHP_Book/eksempler/ch12 - Date and Time/getisoweekofyear.php on line 3