code: def shift_christmas_boxing_days(self, year):
          
          christmas = date(year, 12, 25)
          boxing_day = date(year, 12, 26)
          boxing_day_label = "{} Shift".format(self.boxing_day_label)
          results = []
          if christmas.weekday() in self.get_weekend_days():
              shift = self.find_following_working_day(christmas)
              results.append((shift, "Christmas Shift"))
              results.append((shift + timedelta(days=1), boxing_day_label))
          elif boxing_day.weekday() in self.get_weekend_days():
              shift = self.find_following_working_day(boxing_day)
              results.append((shift, boxing_day_label))
          return results
docs: When Christmas and/or Boxing Day falls on a weekend, it is rolled
              forward to the next weekday.