uo; argument specifies the event loop (as constructed by
make-event-loop in the (a-sync event-loop) module) with respect to
which the meeting will be held: it is an error if the meeting-send or
meeting-receive procedures are passed a different event loop as an
argument.  The &rsquo;loop&rsquo; argument is optional - if none is passed, or #f
is passed, then the default event loop will be chosen.
</p>
<p>Strictly speaking this procedure can be called in any native OS
thread, but since it carries out no synchr