public override void FollowUser(string followerId, string followeeId)
        {
            UserIsFollowingDAO userIsFollowing = new UserIsFollowingDAO
            {
                FollowerId = followerId,
                FolloweeId = followeeId
            };

            _userIsFollowingDAO.Add(userIsFollowing);
        }
        public override void UnfollowUser(string followerId, string followeeId)
        {
            UserIsFollowingDAO userIsFollowing = _userIsFollowingDAO.Where(e => e.FollowerId == followerId && e.FolloweeId == followeeId).Single();

            _userIsFollowingDAO.Remove(userIsFollowing);
        }
        public override bool IsUserFollowing(string followerId, string followeeId)
        {
            UserIsFollowingDAO userIsFollowing = _userIsFollowingDAO.Where(e => e.FollowerId == followerId && e.FolloweeId == followeeId).SingleOrDefault();

            return(null != userIsFollowing ? true : false);
        }