def _get_key_value(self, key, value, pair):
        if pair:
            key, value = pair.popitem()
        return key, value
This returns valid transaction id for the entity key.
dataset/ETHPy150Open espeed/bulbs/bulbs/neo4jserver/index.py/Index._get_key_value--crossover with--dataset/ETHPy150Open AppScale/appscale/AppDB/zkappscale/zktransaction.py/ZKTransaction.get_valid_transaction_id