def test__area_code(self):
phone = PhoneNumber('')
self.assertEqual(phone.area_code(), '')
phone.npa = '519'
self.assertEqual(phone.area_code(), '519')
def test__area_code(self):
phone = PhoneNumber('')
self.assertEqual(phone.area_code(), '')
phone.npa = '519'
self.assertEqual(phone.area_code(), '519')
