code: func MultipleErrors(prefix string, errs []error) string {
  	buf := &bytes.Buffer{}
  	for _, err := range errs {
  		fmt.Fprintf(buf, "%s%v\n", prefix, messageForError(err))
  	}
  	return buf.String()
  }
docs: // MultipleErrors returns a newline delimited string containing
  // the prefix and referenced errors in standard form.