public static function get_labels_by_courses($courseids = array()) {

        $warnings = array();
        $returnedlabels = array();

        $params = array(
            'courseids' => $courseids,
        );
        $params = self::validate_parameters(self::get_labels_by_courses_parameters(), $params);

        $mycourses = array();
        if (empty($params['courseids'])) {
            $mycourses = enrol_get_my_courses();
            $params['courseids'] = array_keys($mycourses);
        }

        // Ensure there are courseids to loop through.
        if (!empty($params['courseids'])) {

            list($courses, $warnings) = external_util::validate_courses($params['courseids'], $mycourses);

            // Get the labels in this course, this function checks users visibility permissions.
            // We can avoid then additional validate_context calls.
            $labels = get_all_instances_in_courses("label", $courses);
            foreach ($labels as $label) {
                $context = context_module::instance($label->coursemodule);
                // Entry to return.
                $label->name = external_format_string($label->name, $context->id);

                list($label->intro, $label->introformat) = external_format_text($label->intro,
                                                                $label->introformat, $context->id, 'mod_label', 'intro', null);
                $label->introfiles = external_util::get_area_files($context->id, 'mod_label', 'intro', false, false);

                $returnedlabels[] = $label;
            }
        }

        $result = array(
            'labels' => $returnedlabels,
            'warnings' => $warnings
        );
        return $result;
    }