presto-spi/src/main/java/io/prestosql/spi/block/RunLengthEncodedBlock.java/RunLengthEncodedBlock/copyPositions
class RunLengthEncodedBlock:    @Override
    public Block copyPositions(int[] positions, int offset, int length)
    {
        checkArrayRange(positions, offset, length);
        for (int i = offset; i < offset + length; i++) {
            checkValidPosition(positions[i], positionCount);
        }
        return new RunLengthEncodedBlock(value.copyRegion(0, 1), length);
    }