def CheckHashes(self, hashes, unused_external=True):
    hash_map = {}
    for hsh in hashes:
      if hsh.HasField("sha1"):
        hash_urn = self.PATH.Add(str(hsh.sha1))
        logging.info("Checking URN %s", str(hash_urn))
        hash_map[hash_urn] = hsh

    for metadata in aff4.FACTORY.Stat(list(hash_map), token=self.token):
      yield metadata["urn"], hash_map[metadata["urn"]]
Method for itemizing all the versions of a particular object
dataset/ETHPy150Open google/grr/grr/lib/aff4_objects/filestore.py/NSRLFileStore.CheckHashes--crossover with--dataset/ETHPy150Open ooici/pyon/pyon/datastore/postgresql/base_store.py/PostgresDataStore.list_object_revisions