public override Task OnDisconnected(bool stopCalled)
        {
            Debug.Print($"User disconnected {Context.User.Identity.Name}");

            var userId = Context.User.Identity.GetUserId();

            hubService.Disconnect(userId, () => {
                Clients.Clients(hubService.GetOnlineIds()).notifyOnline(userId, false);
            });

            return(base.OnDisconnected(stopCalled));
        }