private void addCustomer_Click(object sender, RoutedEventArgs e)
 {
     Customer customer = new Customer
     {
         FirstName = "Nate",
         LastName = "Haskell",
         Telephone = "8184348962",
         EmailAddress = "*****@*****.**"
     };
 }
 private void dataGrid_SelectionChanged(object sender, SelectionChangedEventArgs e)
 {
     currentlySelectedCustomer = (Customer)dataGrid.SelectedItem;
 }