code: def is_holiday(self, day, extra_holidays=None):
          
          day = cleaned_date(day)
  
          if extra_holidays:
              extra_holidays = tuple(map(cleaned_date, extra_holidays))
  
          if extra_holidays and day in extra_holidays:
              return True
  
          return day in self.holidays_set(day.year)
docs: Return True if it's an holiday.
          In addition to the regular holidays, you can add exceptions.
  
          By providing ``extra_holidays``, you'll state that these dates **are**
          holidays, even if not in the regular calendar holidays (or weekends).