code: func (up *Unsubscribe) String() string {
  	var topics []string
  
  	for _, t := range up.Topics {
  		topics = append(topics, fmt.Sprintf("%q", t))
  	}
  
  	return fmt.Sprintf("<Unsubscribe Topics=[%s]>",
  		strings.Join(topics, ", "))
  }
docs: // String returns a string representation of the packet.