def METHOD_NAME(self):
    first, last = _to_first_and_last_day_of_the_week(isoweek=1, isoyear=2019)
    self.assertEqual(first.day, 31)
    self.assertEqual(first.month, 12)
    self.assertEqual(first.year, 2018)
    self.assertEqual(last.day, 7)
    self.assertEqual(last.month, 1)
    self.assertEqual(last.year, 2019)