Fatal error: Uncaught Error: Call to undefined function add_filter() in /home/tholic/training.stjohnkenya.org/wp-content/plugins/masterstudy-lms-learning-management-system/_core/lms/classes/guest_checkout.php:10 Stack trace: #0 /home/tholic/training.stjohnkenya.org/wp-content/plugins/masterstudy-lms-learning-management-system/_core/lms/classes/guest_checkout.php(6): STM_LMS_Guest_Checkout->__construct() #1 {main} thrown in /home/tholic/training.stjohnkenya.org/wp-content/plugins/masterstudy-lms-learning-management-system/_core/lms/classes/guest_checkout.php on line 10