Fatal error: Uncaught Error: Call to undefined function Cornerstone\API\Prefabs\add_action() in /home/waterengineering/public_html/wp-content/plugins/cornerstone/includes/integration/Api/ApiTesterPrefab.php:9 Stack trace: #0 {main} thrown in /home/waterengineering/public_html/wp-content/plugins/cornerstone/includes/integration/Api/ApiTesterPrefab.php on line 9