public void AddSubUser()
        {
            // Create a new subuser for account_id = 1

            try {
                var voximplant = new VoximplantAPI();

                var result = voximplant.AddSubUser(
                    "John_McClane",
                    "pssw0rd"
                    ).Result;

                Console.WriteLine($"Response: {result.ToString()}");
            } catch (Exception e) {
                Console.WriteLine($"Error: {e.Message}");
            }
        }