d in as an argument, or
if none is passed (or #f is passed), from the default event loop.  The
file argument may be a port or a file descriptor.  This is thread safe
- any thread may remove a watch.  A file descriptor and a port with
the same underlying file descriptor compare equal for the purposes of
removal.
</p>
<p>This procedure should not throw an exception unless memory is
exhausted.
</p></dd></dl>

<dl class="def">
<dt id="index-event_002dpost_0021"><span class="category">Scheme Procedure: </span><s