private static async Task <User> CreateUser(IDocumentClient client, string userId)
        {
            Console.WriteLine($">>> Create User {userId} <<<");

            User userDefinition = new User {
                Id = userId
            };
            ResourceResponse <User> result = await client.CreateUserAsync(MyDbDatabaseUri, userDefinition);

            User user = result.Resource;

            Console.WriteLine("Created new user");
            PrintUser(user);

            return(user);
        }