startup add.cs

            // Register LUIS recognizer
            services.AddSingleton<AppointmentBookingRecognizer>();

            // Register the AppointmentBookingDialog
            services.AddSingleton<AppointmentBookingDialog>();

            // The MainDialog that will be run by the bot.
            services.AddSingleton<MainDialog>();

            // Create the bot as a transient. In this case the ASP Controller is expecting an IBot.
            services.AddTransient<IBot, DialogAndWelcomeBot<MainDialog>>();

            // Create the Twilio Adapter
            services.AddSingleton<TwilioAdapter, TwilioAdapterWithErrorHandler>();