void OnItemSelected(object sender, SelectedItemChangedEventArgs e)
{
var employee = e.SelectedItem as Employee;
var employeePage = new EmployeePage();
employeePage.BindingContext = employee;
Navigation.PushAsync(employeePage);
}
void OnAddItemClicked(object sender, EventArgs e)
{
var employee = new Employee();
var employeePage = new EmployeePage(true);
employeePage.BindingContext = employee;
Navigation.PushAsync(employeePage);
}