public function add_associations($unused = null) {

        if ($unused !== null) {
            debugging('Illegal argument used in blog_entry->add_associations()', DEBUG_DEVELOPER);
        }

        $this->remove_associations();

        if (!empty($this->courseassoc)) {
            $this->add_association($this->courseassoc);
        }

        if (!empty($this->modassoc)) {
            $this->add_association($this->modassoc);
        }
    }