// If String keyed, then MapBlockHelper.exec() would have
// filled in the Strings into ncs[ncol] already
//
public void map(Chunk chks[], NewChunk ncs[]) {
long start = chks[0].start();
NewChunk nclabel = isRstr ? ncs[ncs.length - 1] : null;
deblockify(MapBlockHelper.exec(bmf, blockify(chks), start, labels, nclabel, k, r), ncs);
// assert chks[i]._len == ncs[j]._len
}
}