docs: def xd(self):
          """get xarray dataset file handle to LSM files"""
          if self._xd is None:
              path_to_lsm_files = path.join(self.lsm_input_folder_path,
                                            self.lsm_search_card)
              self._xd = super(NWMtoGSSHA, self).xd
              self._xd.lsm.coords_projected = True
          return self._xd