def register_updated_key(self, app_id, current_txid, target_txid, entity_key):
    if self.needs_connection or not self.handle.connected:
      self.reestablish_connection()

    vtxpath = self.get_valid_transaction_path(app_id, entity_key)

    try:
      if self.run_with_retry(self.handle.exists, vtxpath):
        # Update the transaction ID for entity if there is valid transaction.
        self.run_with_retry(self.handle.set_async, vtxpath, str(target_txid))
      else:
        # Store the updated key info into the current transaction node.
        value = PATH_SEPARATOR.join([urllib.quote_plus(entity_key),
          str(target_txid)])
        txpath = self.get_transaction_path(app_id, current_txid)

        if self.run_with_retry(self.handle.exists, txpath):
          self.handle.create_async(PATH_SEPARATOR.join([txpath,
            TX_UPDATEDKEY_PREFIX]), value=str(value), acl=ZOO_ACL_OPEN,
            ephemeral=False, sequence=True, makepath=False)
        else:
          raise ZKTransactionException("Transaction {0} is not valid.".format(
            current_txid))
    except kazoo.exceptions.KazooException as kazoo_exception:
      logging.exception(kazoo_exception)
      self.reestablish_connection()
      raise ZKInternalException("Couldn't register updated key for app " \
        "{0}, current txid {1}, target txid {2}, entity_key {3}".format(app_id,
        current_txid, target_txid, entity_key))

    return True
Text expression.  Get the value at a given key.  Note that the
dataset/ETHPy150Open AppScale/appscale/AppDB/zkappscale/zktransaction.py/ZKTransaction.register_updated_key--crossover with--dataset/ETHPy150Open RoseOu/flasky/venv/lib/python2.7/site-packages/sqlalchemy/dialects/postgresql/hstore.py/HSTORE.comparator_factory.__getitem__