public ILeanKitApi Subscribe(LeanKitAccountAuth auth, long boardId, Action <long, BoardChangedEventArgs, ILeanKitApi> notification)
        {
            if (notification == null)
            {
                throw new Exception("Must provide subscription notification function");
            }
            lock (BoardSubscriptions)
            {
                if (!BoardSubscriptions.ContainsKey(boardId))
                {
                    BoardSubscriptions[boardId] = new BoardSubscription(auth, boardId);
                }

                BoardSubscriptions[boardId].Notifications.Add(notification);

                return(BoardSubscriptions[boardId].LkClientApi);
            }
        }
        public ILeanKitApi Subscribe(ILeanKitAccountAuth auth, long boardId, int pollingFrequency, Action<long, BoardChangedEventArgs, ILeanKitApi> notification)
        {
            if (notification == null)
            {
                throw new Exception("Must provide subscription notification function");
            }
            lock (BoardSubscriptions)
            {
                if (!BoardSubscriptions.ContainsKey(boardId))
                {
	                BoardSubscriptions[boardId] = new BoardSubscription(auth, boardId, pollingFrequency);
                }
 
                BoardSubscriptions[boardId].Notifications.Add(notification);
                
                return BoardSubscriptions[boardId].LkClientApi;
            }
        }