golang get file md5

func Md5File(filePath string) (string, error) {
    var returnMD5String string
    file, err := os.Open(filePath)
    if err != nil {
        return returnMD5String, err
    }
    defer file.Close()
    hash := md5.New()
    if _, err := io.Copy(hash, file); err != nil {
        return returnMD5String, err
    }
    hashInBytes := hash.Sum(nil)[:16]
    returnMD5String = hex.EncodeToString(hashInBytes)
    return returnMD5String, nil
}