code: def as_date(dat):
      
      LOGGER.debug('as_date(%s)', dat)
  
      return strict_rfc3339.timestamp_to_rfc3339_utcoffset(
          calendar.timegm(dat.timetuple()))
docs: Return the RFC3339 UTC string representation of the given date and time.
  
      Args:
          dat (:py:class:`datetime.date`): the object/type to be serialized.
  
      Raises:
          TypeError:
              when ``o`` is not an instance of ``datetime.date``.
  
      Returns:
          (str) JSON serializable type for the given object.