code: func (m *Messenger) CallToActionsSetting(state string, actions []CallToActionsItem) error {
  	d := CallToActionsSetting{
  		SettingType:   "call_to_actions",
  		ThreadState:   state,
  		CallToActions: actions,
  	}
  
  	data, err := json.Marshal(d)
  	if err != nil {
  		return err
  	}
  
  	req, err := http.NewRequest("POST", SendSettingsURL, bytes.NewBuffer(data))
  	if err != nil {
  		return err
  	}
  
  	req.Header.Set("Content-Type", "application/json")
  	req.URL.RawQuery = "access_token=" + m.token
  
  	client := &http.Client{}
  
  	resp, err := client.Do(req)
  	if err != nil {
  		return err
  	}
  	defer resp.Body.Close()
  
  	return checkFacebookError(resp.Body)
  }
docs: // CallToActionsSetting sends settings for Get Started or Persistent Menu