public function setChecksum($mixed)
    {
        if (is_string($mixed)) {
            $data = [strtolower($mixed)];

            if (strpos($data[0], ',')) {
                $data = explode(',', $mixed);
            }

            $this->checksum = $data;
        } elseif ($mixed === true) {
            $this->checksum = ['md5'];
        }
    }