ssCallback, errorCallback, notifyCallback)</code> – regardless of when the promise was or
will be resolved or rejected, <code>then</code> calls one of the success or error callbacks asynchronously
as soon as the result is available. The callbacks are called with a single argument: the result
or rejection reason. Additionally, the notify callback may be called zero or more times to
provide a progress indication, before the promise is resolved or rejected.</p>
<p>This method <em>returns a new promise</em> w