code: func (inbox *Inbox) New(user *User, text string) error {
  	insta := inbox.inst
  	to, err := prepareRecipients(user.ID)
  	if err != nil {
  		return err
  	}
  
  	data := insta.prepareDataQuery(
  		map[string]interface{}{
  			"recipient_users": to,
  			"client_context":  generateUUID(),
  			"thread_ids":      `["0"]`,
  			"action":          "send_item",
  			"text":            text,
  		},
  	)
  	_, err = insta.sendRequest(
  		&reqOptions{
  			Connection: "keep-alive",
  			Endpoint:   urlInboxSend,
  			Query:      data,
  			IsPost:     true,
  		},
  	)
  	return err
  }
docs: // New initialises a new conversation with a user, for further messages you should use Conversation.Send
  //
  // See example: examples/inbox/newconversation.go