public void UpdateCerere()
        {
            if (SelectedCerere == null)
            {
                MessageBox.Show("You must select a cerere!", "Error", MessageBoxButton.OK);
            }
            else
            {
                var DetailViewModel = new CerereDetailViewModel(SelectedCerere);
                CerereMasterDetailView DetailPage = new CerereMasterDetailView(DetailViewModel);
                DetailPage.Show();
                DetailViewModel.CerereUpdated += (source, cerere) =>
                {
                    var cererevm = new CerereViewModel(cerere);

                    Cereri.ToList().ForEach(x =>
                    {
                        if (x.Id == cererevm.Id)
                        {
                            x = cererevm;
                        }
                    });
                    DetailPage.Close();
                };
            }
        }
        public void AddCerere()
        {
            var DetailViewModel = new CerereDetailViewModel(new CerereViewModel());
            CerereMasterDetailView DetailPage = new CerereMasterDetailView(DetailViewModel);

            DetailPage.Show();
            DetailViewModel.CerereAdded += (source, cerere) =>
            {
                Cereri.Add(new CerereViewModel(cerere));
                DetailPage.Close();
            };
        }