presto-redis/src/main/java/io/prestosql/plugin/redis/RedisConnector.java/RedisConnector/beginTransaction
class RedisConnector:    @Override
    public ConnectorTransactionHandle beginTransaction(IsolationLevel isolationLevel, boolean readOnly)
    {
        checkConnectorSupports(READ_COMMITTED, isolationLevel);
        return RedisTransactionHandle.INSTANCE;
    }