code: func (r Notification) GetRequiredPreferences() (resp []datatypes.Notification_Preference, err error) {
  	err = r.Session.DoRequest("SoftLayer_Notification", "getRequiredPreferences", nil, &r.Options, &resp)
  	return
  }
docs: // Retrieve The required preferences related to the notification. While configurable, the subscriber does not have the option whether to use the preference.