 port. If <code>address</code> is not specified, the operating
system will attempt to listen on all addresses. Once binding is
complete, a <code>'listening'</code> event is emitted and the optional <code>callback</code>
function is called.</p>
<p>The <code>options</code> object may contain a <code>fd</code> property. When a <code>fd</code> greater
than <code>0</code> is set, it will wrap around an existing socket with the given
file descriptor. In this case, the properties of <code>port</code> and <code>add