func parseIntHeader(bucket, object string, h http.Header, headerName string) (value int, err error) {
	stringInt := strings.TrimSpace(h.Get(headerName))
	if stringInt == "" {
		return
	}
	value, err = strconv.Atoi(stringInt)
	if err != nil {
		return 0, InvalidArgument{
			Bucket: bucket,
			Object: object,
			Err:    fmt.Errorf("Unable to parse %s, value should be an integer", headerName),
		}
	}
	return
}