Returns a formatted list of all lessons, quizzes and modules attached to a single course.
$course_id (int) the course ID
$user_id (int) user ID
(string) List of all lessons connected to the course you passed
if(is_user_logged_in()){
$user_id = get_current_user_id();
$course_id = 47;
$lesson_list = wpc_get_single_course_progress_list($course_id, $user_id);
echo $lesson_list;
}