presto-spi/src/main/java/io/prestosql/spi/Page.java/Page/prependColumn
class Page:    public Page prependColumn(Block column)
    {
        if (column.getPositionCount() != positionCount) {
            throw new IllegalArgumentException(format("Column does not have same position count (%s) as page (%s)", column.getPositionCount(), positionCount));
        }

        Block[] result = new Block[blocks.length + 1];
        result[0] = column;
        System.arraycopy(blocks, 0, result, 1, blocks.length);

        return new Page(positionCount, result);
    }