public AtmViewModel(Atm atm)
        {
            _atm = atm;
            _repository = new AtmRepository();
            _paymentGateway = new PaymentGateway();

            TakeMoneyCommand = new Command<decimal>(x => x > 0, TakeMoney);
        }
        public AtmViewModel(Atm atm, IAtmRepository repository, EventDispatcher eventDispatcher)
        {
            _atm = atm;
            _repository = repository;
            _eventDispatcher = eventDispatcher;
            _paymentGateway = new PaymentGateway();

            TakeMoneyCommand = new Command<decimal>(x => x > 0, TakeMoney);
        }