- # build both_ones and different such that:
- # * if both_ones is set, then both_ones[i] and different[i] are both
- # ones in order to set the carry bit out.
- # * if different is set, then both_ones[i] and different[i] are both
- # zeros in order to clear the carry bit out.
- # * otherwise exactly one of both_ones[i] and different[i] are set and
+ # build `both_ones` and `different` such that:
+ # for every bit index `i`:
+ # * if `both_ones[i]` is set, then both addends bits at index `i` are
+ # set in order to set the carry bit out, since `cin + 1 + 1` always
+ # has a carry out.
+ # * if `different[i]` is set, then both addends bits at index `i` are
+ # zeros in order to clear the carry bit out, since `cin + 0 + 0`
+ # never has a carry out.
+ # * otherwise exactly one of the addends bits at index `i` is set and