code: def get_sunset_time(self, timeformat='unix'):
          
          if self._sunset_time is None:
              return None
          return timeformatutils.timeformat(self._sunset_time, timeformat)
docs: Returns the GMT time of sunset
  
          :param timeformat: the format for the time value. May be:
              '*unix*' (default) for UNIX time or '*iso*' for ISO8601-formatted
              string in the format ``YYYY-MM-DD HH:MM:SS+00``
          :type timeformat: str
          :returns: an int or a str or None
          :raises: ValueError