public function set($value) {
        if (empty($this->grade->id)) {
            if (empty($value)) {
                return false;
            }

            $gradeitem = $this->grade->grade_item;

            // Fill in arbitrary grade to be excluded.
            $gradeitem->update_final_grade(
                $this->grade->userid, null, 'singleview', null, FORMAT_MOODLE
            );

            $gradeparams = array(
                'userid' => $this->grade->userid,
                'itemid' => $this->grade->itemid
            );

            $this->grade = grade_grade::fetch($gradeparams);
            $this->grade->grade_item = $gradeitem;
        }

        $state = $value == 0 ? false : true;

        $this->grade->set_excluded($state);

        $this->grade->grade_item->get_parent_category()->force_regrading();
        return false;
    }