code: func (e *Error) Error() string {
  	message := strings.TrimRight(e.err.Error(), "\n ")
  	if strings.Contains(message, "\n") {
  		message = fmt.Sprintf("%s:\n  %s", e.class.String(),
  			strings.Replace(message, "\n", "\n  ", -1))
  	} else {
  		message = fmt.Sprintf("%s: %s", e.class.String(), message)
  	}
  	if stack := e.Stack(); stack != "" {
  		message = fmt.Sprintf(
  			"%s\n\"%s\" backtrace:\n%s", message, e.class, stack)
  	}
  	if exits := e.Exits(); exits != "" {
  		message = fmt.Sprintf(
  			"%s\n\"%s\" exits:\n%s", message, e.class, exits)
  	}
  	return message
  }
docs: // Error conforms to the error interface. Error will return the backtrace if
  // it was captured and any recorded exits.