ided or #f is provided as the &rsquo;loop&rsquo; argument.
This procedure calls &rsquo;await&rsquo; and will return the thunk&rsquo;s return value.
It is intended to be called within a waitable procedure invoked by
a-sync (which supplies the &rsquo;await&rsquo; and &rsquo;resume&rsquo; arguments).  It is the
single-threaded corollary of await-task-in-thread!.  This means that
(unlike with await-task-in-thread!) while &rsquo;thunk&rsquo; is running other
events in the event loop will not make progress, so bl