rgument, or if none is passed (or #f is passed), on the default event
loop.
</p>
<p>A port can be made non-blocking with this:
</p>
<div class="example">
<pre class="example">(fcntl [port] F_SETFL (logior O_NONBLOCK
                      (fcntl [port] F_GETFL)))
</pre></div>

<p>For reasons of efficiency, this procedure by-passes the port&rsquo;s output
buffer and sends the output to the underlying file descriptor
directly.  This means that it is most convenient for use with
unbuffered ports.  However, wher