though 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).
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 t