php abstract class extends normal class code example

Example: php abstract class constant

abstract class Hello {
    const CONSTANT_1 = 'abstract'; // Make Abstract
    const CONSTANT_2 = 'abstract'; // Make Abstract
    const CONSTANT_3 = 'Hello World'; // Normal Constant
    function __construct() {
        Enforcer::__add(__CLASS__, get_called_class());
    }
}