code: def date(self):
          
          instant_date = date_by_instant_cache.get(self)
          if instant_date is None:
              date_by_instant_cache[self] = instant_date = datetime.date(*self)
          return instant_date
docs: Convert instant to a date.
  
          >>> instant(2014).date
          datetime.date(2014, 1, 1)
          >>> instant('2014-2').date
          datetime.date(2014, 2, 1)
          >>> instant('2014-2-3').date
          datetime.date(2014, 2, 3)