n the default event loop if no
&rsquo;loop&rsquo; argument is provided or if #f is provided as the &rsquo;loop&rsquo;
argument.  &rsquo;proc&rsquo; should be a procedure taking a single argument,
namely the value yielded by the generator.
</p>
<p>This procedure 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 will normally be necessary to call event-loop-block! on &rsquo;loop&rsquo; (or
on the default event