public function col_grader(\stdClass $history) {
        if (empty($history->usermodified)) {
            // Not every row has a valid usermodified.
            return '';
        }

        $grader = new \stdClass();
        $grader = username_load_fields_from_object($grader, $history, 'grader');
        $name = fullname($grader);

        if ($this->download) {
            return $name;
        }

        $userid = $history->usermodified;
        $profileurl = new \moodle_url('/user/view.php', array('id' => $userid, 'course' => $this->courseid));

        return \html_writer::link($profileurl, $name);
    }