public async Task LookupFriendshipAsync(IUserModel user)
        {
            IFriendshipModel model = StorageService.GetCachedFriendship(user.ScreenName);

            if (model == null)
            {
                var option = Const.GetDictionary();
                option.Add(Const.USER_ID, user.Id);
                var friendships = await tokens.Friendships.LookupAsync(option);

                if (friendships != null && friendships.Count != 0)
                {
                    model = new FriendshipModel(friendships[0]);
                }
            }
            if (model == null)
            {
                return;
            }

            var connections = model.Connections.Select(c => c.ToLower()).ToList();

            user.IsFollowing  = connections.Contains(Const.FOLLOWING);
            user.IsFollowedBy = connections.Contains(Const.FOLLOWED_BY);

            StorageService.AddOrUpdateCachedFriendship(model);
        }