Fatal error: Uncaught Error: Class "PHP_UML_Metamodel_Classifier" not found in C:\xampp\htdocs\php\pear\PHP\UML\Metamodel\Datatype.php:26 Stack trace: #0 {main} thrown in C:\xampp\htdocs\php\pear\PHP\UML\Metamodel\Datatype.php on line 26