public static function get_previous_evaluation_file($modelid, $timesplittingid) {
        $fs = get_file_storage();
        // Evaluation data is always labelled.
        $filepath = '/timesplitting/' . \core_analytics\analysis::clean_time_splitting_id($timesplittingid) . '/';
        return $fs->get_file(\context_system::instance()->id, 'analytics', self::LABELLED_FILEAREA, $modelid,
            $filepath, self::EVALUATION_FILENAME);
    }