public LaptopCheckinCheckoutViewModel(IRegionManager regionManager, ILaptopRepository repository, IEventAggregator eventAggregator)
{
this.regionManager = regionManager;
this.repository = repository;
this.users = repository.GetUsers();
this.checkinCheckoutCommand = new DelegateCommand <string>(CheckinCheckout);
this.eventAggregator = eventAggregator;
this.cancelCommand = new DelegateCommand(Cancel);
}