docs: def GetClientStates(self, client_list, client_chunk=50):
      """Take in a client list and return dicts with their age and hostname."""
      for client_group in collection.Batch(client_list, client_chunk):
        for fd in aff4.FACTORY.MultiOpen(
            client_group,
            mode="r",
            aff4_type=aff4_grr.VFSGRRClient,
            token=self.token):
          result = {}
          result["age"] = fd.Get(fd.Schema.PING)
          result["hostname"] = fd.Get(fd.Schema.HOSTNAME)
          yield (fd.urn, result)