public async void Adicionar(Professor professor)
{
if (ValidarProfessor(professor))
{
if (await ProfessorRepositorio.PostProfessorSqlAzureAsync(professor))
{
await App.Current.MainPage.Navigation.PopAsync();
}
else
{
await App.Current.MainPage.DisplayAlert("Erro", "Erro ao adicionar professor!", "OK");
}
}
}