code: func parseLiteralSource(source string) (keyName, value string, err error) {
  	items := strings.Split(source, "=")
  	if len(items) != 2 {
  		return "", "", fmt.Errorf("invalid literal source %v, expected key=value", source)
  	}
  
  	return items[0], items[1], nil
  }
docs: // parseLiteralSource parses the source key=val pair