code: def _get_coordinates_for_dataset_key(self, dsid):
          
          coords = super(VIIRSSDRReader, self)._get_coordinates_for_dataset_key(dsid)
          for c_id in coords:
              c_info = self.ids[c_id]  # c_info['dataset_groups'] should be a list of 2 elements
              self._get_file_handlers(c_id)
              if len(c_info['dataset_groups']) == 1:  # filtering already done
                  continue
              try:
                  req_geo, rem_geo = self._get_req_rem_geo(c_info)
              except ValueError:  # DNB
                  continue
  
              # check the dataset file for the geolocation filename
              geo_filenames = self._load_from_geo_ref(dsid)
              if not geo_filenames:
                  c_info['dataset_groups'] = [rem_geo]
              else:
                  # concatenate all values
                  new_fhs = sum(self.create_filehandlers(geo_filenames).values(), [])
                  desired, other = split_desired_other(new_fhs, req_geo, rem_geo)
                  if desired:
                      c_info['dataset_groups'].remove(rem_geo)
                  else:
                      c_info['dataset_groups'].remove(req_geo)
  
          return coords
docs: Get the coordinate dataset keys for `dsid`.
  
          Wraps the base class method in order to load geolocation files
          from the geo reference attribute in the datasets file.