h supplies the &rsquo;await&rsquo; and &rsquo;resume&rsquo; arguments).
It will normally be necessary to call event-loop-block! before
invoking this procedure.
</p>
<p>This procedure must (like the a-sync procedure) be called in the same
thread as that in which the event loop runs.  As mentioned above, the
generator itself will run in its own thread.
</p>
<p>As the worker thread calls event-post!, it might be subject to
throttling by the event loop concerned.  See the documentation on the
make-event-loop pr