public MainViewModel(IContactService contactService
     , ICreateContacts contactCreator)
 {
     _contactService = contactService;
     _contactCreator = contactCreator;
     CreateDesignTimeData();
     CreateCommands();
 }
 public MainViewModel(IContactService contactService
                      , ICreateContacts contactCreator)
 {
     _contactService = contactService;
     _contactCreator = contactCreator;
     CreateDesignTimeData();
     CreateCommands();
 }