presto-spi/src/main/java/io/prestosql/spi/block/RunLengthEncodedBlock.java/RunLengthEncodedBlock/getRegion
class RunLengthEncodedBlock:    @Override
    public Block getRegion(int positionOffset, int length)
    {
        checkValidRegion(positionCount, positionOffset, length);
        return new RunLengthEncodedBlock(value, length);
    }