public void RemoveLike(ApplicationUser user)
{
// 1. check lecture
var like = Likes.SingleOrDefault(l => l.UserId == user.Id);
if (like == null)
{
throw new NotFoundException("like not found");
}
// 2. remove like
var likeList = Likes.ToList();
likeList.Remove(like);
Likes = likeList;
}
