public function trim($log)
    {
        $period = new \DateTime('-7 day');
        if ($log === 'change') {
            $this->changeRepository->trimLog($period);
        } elseif ($log === 'system') {
            $this->systemRepository->trimLog($period);
        } else {
            throw new \UnexpectedValueException("Invalid log type requested: $log");
        }
    }