presto-main/src/main/java/io/prestosql/execution/buffer/ArbitraryOutputBuffer.java/ArbitraryOutputBuffer/enqueue
class ArbitraryOutputBuffer:    @Override
    public void enqueue(int partition, List<SerializedPage> pages)
    {
        checkState(partition == 0, "Expected partition number to be zero");
        enqueue(pages);
    }