/**
* Just like the sendElement: method above,
* but allows you to receive a receipt that can later be used to verify the element has been sent.
*
* If you later want to check to see if the element has been sent:
*
* if ([receipt wait:0]) {
* // Element has been sent
* }
*
* If you later want to wait until the element has been sent:
*
* if ([receipt wait:-1]) {
* // Element was sent
* } else {
* // Element failed to send due to disconnection
* }
*
* It is important to understand what it means when [receipt wait:timeout] returns YES.
* It does NOT mean the server has received the element.
* It only means the data has been queued for sending in the underlying OS socket buffer.
*
* So at this point the OS will do everything in its capacity to send the data to the server,
* which generally means the server will eventually receive the data.
* Unless, of course, something horrible happens such as a network failure,
* or a system crash, or the server crashes, etc.
*
* Even if you close the xmpp stream after this point, the OS will still do everything it can to send the data.
**/
- (void)sendElement:(NSXMLElement *)element andGetReceipt:(XMPPElementReceipt **)receiptPtr;