WebSocketSessionPair constructor
Two connected sessions, both with uri and with protocol as their
accepted sub-protocol.
Implementation
WebSocketSessionPair(Uri uri, {String? protocol}) {
server = _PairedSession(uri, protocol);
client = _PairedSession(uri, protocol);
(server as _PairedSession)._peer = client as _PairedSession;
(client as _PairedSession)._peer = server as _PairedSession;
}