acter).  &rsquo;proc&rsquo;
should be a procedure taking a string as its only argument.
</p>
<p>The event loop will not be blocked by this procedure even if only
individual characters or part characters are available at any one time
(although if &rsquo;port&rsquo; references a socket, it should be non-blocking for
this to be guaranteed).  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), and this procedure i