gotiation with the
server.  Example values are "http/1.1" or "h2".  The selected protocol
can be obtained via <a href="dart-io/SecureSocket/selectedProtocol.html">SecureSocket.selectedProtocol</a>.</p>
<p>The argument <code>timeout</code> is used to specify the maximum allowed time to wait
for a connection to be established. If <code>timeout</code> is longer than the system
level timeout duration, a timeout may occur sooner than specified in
<code>timeout</code>. On timeout, a <a href="dart-io/SocketExcepti