async void onAddBtnClicked(object sender, EventArgs e)
{
Estudiante newEstudiante = new Estudiante();
var nextPage = new EstudiantesCreateUpdatePage(asignaturaUid, true);
nextPage.BindingContext = newEstudiante;
await Navigation.PushAsync(nextPage);
}
async public void OnEdit(object sender, EventArgs e)
{
var menuItem = ((MenuItem)sender);
Estudiante estudiante = menuItem.CommandParameter as Estudiante;
var nextPage = new EstudiantesCreateUpdatePage(asignaturaUid, false);
nextPage.BindingContext = estudiante;
await Navigation.PushAsync(nextPage);
}