public PrincipalViewModel(INavigator navigator, 
     IServicioDatos servicio, Session session) : 
     base(navigator, servicio, session)
 {
     var a = "";
    CmdNuevo=new Command(NuevoBloc);
 }
 public GeneralViewModel(INavigator navigator, 
     IServicioDatos servicio,Session session)
 {
     _navigator = navigator;
     _servicio = servicio;
     Session = session;
 }
        public LoginViewModel(INavigator navigator, 
            IServicioDatos servicio,Session session) :
            base(navigator, servicio,session)
        {
           cmdLogin=new Command(IniciarSesion);
            cmdAlta=new Command(NuevoUsuario);
			Titulo="Blocs";
        }
 public RegistroViewModel(INavigator navigator, IServicioDatos servicio, Session session) : base(navigator, servicio, session)
 {
     cmdRegistro=new Command(GuardarUsuario);
 }
        public NuevoBlocViewModel(INavigator navigator, IServicioDatos servicio, Session session) : base(navigator, servicio, session)
        {
            _bloc = new Bloc();
            CmdGuardar=new Command(Guardar);

        }