code: def build_lv_grids(self):
          
  
          for mv_grid_district in self.mv_grid_districts():
              for load_area in mv_grid_district.lv_load_areas():
                  if not load_area.is_aggregated:
                      for lv_grid_district in load_area.lv_grid_districts():
  
                          lv_grid_district.lv_grid.build_grid()
                  else:
                      logger.info(
                          '{} is of type aggregated. No grid is created.'.format(repr(load_area)))
  
          logger.info('=====> LV model grids created')
docs: Builds LV grids for every non-aggregated LA in every MV grid
          district using model grids.