protected function _call($fieldData, $controller, $method, $passing, $arguments)
    {
        // If data to be passed to the method isn't an array, put it in array format.
        $fieldData = array($fieldData, $arguments);
            
        // Call custom controller->method and pass the data to it.
        $result = call_user_func_array(array($controller, $method), $fieldData);

        // If the returned result meets expections, pass test (return false) otherwise return message.
        return $result == $passing ? true : false;
    }