public static void DeletePeople()
        {
            DeleteByQueryResult result = client.Delete <Person>(p => p.PersonID.Exists());

            WriteLine($"Delete all people. Ok: {result.Ok}");
        }
        public static void DeleteBooks()
        {
            DeleteByQueryResult result = client.Delete <Book>(b => b.Id.Exists());

            WriteLine($"Delete all books. Ok: {result.Ok}");
        }