protected function define_table_columns() {
        // Define headers and columns.
        $cols = array(
            'name' => get_string('name', 'cohort'),
            'idnumber' => get_string('idnumber', 'cohort'),
        );

        if ($this->template->can_manage()) {
            $cols['actions'] = get_string('actions');
        }

        $this->define_columns(array_keys($cols));
        $this->define_headers(array_values($cols));
    }