private IDisposable Subscribe(object handler, MethodInfo method, IHubConnection connection)
        {
            var args        = method.GetParameters().Select(p => p.ParameterType).ToArray();
            var state       = new HandlerState(method, handler);
            var handlerFunc = HandlerForMethod(method);

            return(connection.On(method.Name, args, handlerFunc, state));
        }