 Promises, the <code>resource</code> object will have an
<code>isChainedPromise</code> property, set to <code>true</code> if the promise has a parent promise,
and <code>false</code> otherwise. For example, in the case of <code>b = a.then(handler)</code>, <code>a</code> is
considered a parent <code>Promise</code> of <code>b</code>. Here, <code>b</code> is considered a chained promise.</p>
<p>In some cases the resource object is reused for performance reasons, it is
thus not safe to use it as a key in a <code