public void withdraw_notification (string id)
Withdraws a notification that was sent with send_notification.
This call does nothing if a notification with
id doesn't exist or the notification was never sent.
This function works even for notifications sent in previous executions of this application, as long
id is the same as it was for
the sent notification.
Note that notifications are dismissed when the user clicks on one of the buttons in a notification or triggers its default action, so there is no need to explicitly withdraw the notification in that case.
id of a previously sent notification