Fatal error: Uncaught Error: Class "core_question\local\bank\column_base" not found in C:\xampp\htdocs\moodle\question\bank\statistics\classes\columns\discrimination_index.php:31 Stack trace: #0 {main} thrown in C:\xampp\htdocs\moodle\question\bank\statistics\classes\columns\discrimination_index.php on line 31