/**
  * Add data for our newly-added custom columns.
  * @access public
  * @since  1.0.0
  * @param  string $column_name
  * @param  int $id
  * @return void
  */
 public function add_column_data($column_name, $id)
 {
     global $wpdb, $post;
     switch ($column_name) {
         case 'id':
             echo $id;
             break;
         case 'lesson-course':
             $lesson_course_id = get_post_meta($id, '_lesson_course', true);
             if (0 < absint($lesson_course_id)) {
                 echo '<a href="' . esc_url(get_edit_post_link(absint($lesson_course_id))) . '" title="' . esc_attr(sprintf(__('Edit %s', 'woothemes-sensei'), get_the_title(absint($lesson_course_id)))) . '">' . get_the_title(absint($lesson_course_id)) . '</a>';
             }
             // End If Statement
             break;
         case 'lesson-prerequisite':
             $lesson_prerequisite_id = get_post_meta($id, '_lesson_prerequisite', true);
             if (0 < absint($lesson_prerequisite_id)) {
                 echo '<a href="' . esc_url(get_edit_post_link(absint($lesson_prerequisite_id))) . '" title="' . esc_attr(sprintf(__('Edit %s', 'woothemes-sensei'), get_the_title(absint($lesson_prerequisite_id)))) . '">' . get_the_title(absint($lesson_prerequisite_id)) . '</a>';
             }
             // End If Statement
             break;
         case 'lesson-modules':
             //echo '<ul>';
             $modules = new Sensei_Core_Modules();
             $module = $modules->get_lesson_module($id);
             if ($module) {
                 echo substr($module->name, 0, 50) . '...';
             }
             //echo '</ul>';
             break;
         default:
             break;
     }
     // End Switch Statement
 }