code: func fileChecksum(path string) (string, error) {
  	data, err := ioutil.ReadFile(path)
  	if err != nil {
  		return "", err
  	}
  	hash := sha1.New()
  	io.WriteString(hash, string(data))
  	return fmt.Sprintf("%x", hash.Sum(nil)), nil
  }
docs: // Returns SHA1 file checksum