code: def grid_model_params_ria(lvgd):
      
  
      # Choose retail/industrial and agricultural grid model
      model_params_ria = {}
      if ((lvgd.sector_count_retail +
               lvgd.sector_count_industrial > 0) or
              (lvgd.peak_load_retail +
                   lvgd.peak_load_industrial > 0)):
          model_params_ria['retail/industrial'] = select_grid_model_ria(
              lvgd, 'retail/industrial')
      else:
          model_params_ria['retail/industrial'] = None
  
      if ((lvgd.sector_count_agricultural > 0) or
              (lvgd.peak_load_agricultural > 0)):
          model_params_ria['agricultural'] = select_grid_model_ria(lvgd,
                                                                   'agricultural')
      else:
          model_params_ria['agricultural'] = None
  
      return model_params_ria
docs: Determine grid model parameters for LV grids of sectors
      retail/industrial and agricultural
      
      Parameters
      ----------
      lvgd : LVGridDistrictDing0
          Low-voltage grid district object
  
      Returns
      -------
      :obj:`dict`
          Structural description of (parts of) LV grid topology