@abc.abstractmethod
  def add_identifier(self, ident):
    pass
Restore entity map handler.
dataset/ETHPy150Open scottrice/Ice/ice/persistence/backing_store.py/BackingStore.add_identifier--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/ext/datastore_admin/backup_handler.py/RestoreEntity.map