led within a waitable
procedure invoked by a-sync (which supplies the &rsquo;await&rsquo; and &rsquo;resume&rsquo;
arguments).  This procedure is implemented using a-sync-read-watch!.
The watch will not end until end-of-file or an exceptional condition
(&rsquo;excpt) is reached, which would cause this procedure to end and
return an end-of-file object or #f respectively, or until the escape
continuation is invoked, in which case the value passed to the escape
continuation will be returned.
</p>
<p>A port can