code: def add_lun(self, luns):
          
          curr_lun_ids, curr_smp_names = self._get_current_names()
          luns = normalize_lun(luns, self._cli)
          new_ids, new_smps = convert_lun(luns)
          if new_ids:
              curr_lun_ids.extend(new_ids)
          if new_smps:
              curr_smp_names.extend(new_smps)
          return self.modify(lun_ids=curr_lun_ids, smp_names=curr_smp_names)
docs: A wrapper for modify method.
  
          .. note:: This API only append luns to existing luns.