return sealETag(key, md5sumcurr)
	}
	return fn
}

// compressOpts are the options for writing compressed data.
var compressOpts []s2.WriterOption

func init() {
	if runtime.GOARCH == "amd64" {
		// On amd64 we have assembly and can use stronger compression.
		compressOpts = append(compressOpts, s2.WriterBetterCompression())
	}
}