public static async Task ConflictHandlingAsync()
{
// user 1
Tuple<BooksContext, Book> tuple1 = await PrepareUpdateAsync();
tuple1.Item2.Title = "updated from user 1";
// user 2
Tuple<BooksContext, Book> tuple2 = await PrepareUpdateAsync();
tuple2.Item2.Title = "updated from user 2";
// user 1
await UpdateAsync(tuple1.Item1, tuple1.Item2);
// user 2
await UpdateAsync(tuple2.Item1, tuple2.Item2);
tuple1.Item1.Dispose();
tuple2.Item1.Dispose();
await CheckUpdateAsync(tuple1.Item2.BookId);
}