L (logior O_NONBLOCK
                      (fcntl [port] F_GETFL)))
</pre></div>

<p>This procedure must (like the a-sync procedure) be called in the same
thread as that in which the event loop runs.
</p>
<p>Exceptions may propagate out of this procedure if they arise while
setting up (that is, before the first call to &rsquo;await&rsquo; is made), which
shouldn&rsquo;t happen unless memory is exhausted.  With versions of this
library before 0.13, any exceptions because of read errors or
conversion errors w