code: func splitEmailTemplateFile(content string) (subject, body string, err error) {
  	if len(content) == 0 {
  		return "", "", fmt.Errorf("empty file")
  	}
  
  	parts := strings.SplitN(content, "\n", 3)
  	switch {
  	case len(parts) < 3:
  		return "", "", fmt.Errorf("less than three lines")
  
  	case len(strings.TrimSpace(parts[1])) > 0:
  		return "", "", fmt.Errorf("second line is not blank: %q", parts[1])
  
  	default:
  		return strings.TrimSpace(parts[0]), strings.TrimSpace(parts[2]), nil
  	}
  }
docs: // splitEmailTemplateFile splits an email template file into subject and body.
  // Does not validate their syntaxes.
  // See notify.proto for file format.