start method
      
void
start()
      
     
    
    
Implementation
void start() async {
  _ws = await WebSocket.connect(url, protocols: ['echo-protocol']);
  _ws!.listen((data) {
    onWebSocketRequest(data);
  });
}void start() async {
  _ws = await WebSocket.connect(url, protocols: ['echo-protocol']);
  _ws!.listen((data) {
    onWebSocketRequest(data);
  });
}