code: def _is_dst(dt):
          
          # we can't use `dt.timestamp()` here since it requires a `utcoffset`
          # and we don't want to get into a recursive loop
          localtime = time.localtime(time.mktime((
              dt.year,
              dt.month,
              dt.day,
              dt.hour,
              dt.minute,
              dt.second,
              dt.weekday(),
              0,              # day of the year
              -1              # dst
          )))
          return localtime.tm_isdst > 0
docs: Returns True if a given datetime object represents a time with
          DST shift.