code: func (msg *Message) SetReplyTo(replyTo string) error {
  	if !(msg.Type() == "request" || msg.Type() == "direct_request") {
  		return fmt.Errorf("custom reply to targets can only be set for requests")
  	}
  
  	msg.replyTo = replyTo
  
  	return nil
  }
docs: // SetReplyTo sets the NATS target where replies to this message should go