public async Task Close()
        {
            using (_webSocket)
            {
                foreach (var subscription in _subscriptions)
                {
                    subscription.Dispose();
                }
                _subscriptions.Clear();

                await _webSocket.CloseAsync();
            }
        }
        public async Task Close()
        {
            if (_webSocket != null)
            {
                foreach (var subscription in _subscriptions)
                {
                    subscription.Dispose();
                }
                _subscriptions.Clear();

                await _webSocket.CloseAsync();

                _webSocket.Dispose();
                _webSocket = null;
            }
        }