code: def xd(self):
          
          if self._xd is None:
              # download files if the user requests
              if None not in (self.download_start_datetime, self.download_end_datetime):
                  self._download()
  
              self._xd = super(ERAtoGSSHA, self).xd
              self._xd.lsm.lon_to_180 = True
          return self._xd
docs: get xarray dataset file handle to LSM files