message: refactor: format, clarify var name, highlight operation order
diff: @@ -69,7 +69,7 @@ void stripGeneInPlace(NucleotideSequence& seq) {
  // Find the first non-GAP nucleotide and replace GAPs in the corresponding codon with Ns, so that it's not getting stripped
  for (int i = 0; i < length; ++i) {
  if (at(seqSpan, i) != Nucleotide::GAP) {
  - const auto codonBegin = i - i % 3;
  + const auto codonBegin = i - (i % 3);
  invariant_greater_equal(codonBegin, 0);
  invariant_less(codonBegin + 2, length);
  @@ -79,14 +79,14 @@ void stripGeneInPlace(NucleotideSequence& seq) {
  }
  }
  - const auto& final_frame = length%3;
  // Find the last non-GAP nucleotide and replace GAPs in the corresponding codon with Ns, so that it's not getting stripped
  - // Do to insertions elsewhere in the sequence, the beginning of a codon is not necessarily
  + // NOTE: Due to insertions elsewhere in the sequence, the beginning of a codon is not necessarily
  // a position with i % 3 == 0. Assuming the 3' end of the gene is in frame, we use
  - // the frame a the end (final_frame) as the reference frame for the end of the gene
  + // the frame a the end (lastFrame) as the reference frame for the end of the gene
  + const auto& lastFrame = length % 3;
  for (int i = length - 1; i >= 0; --i) {
  if (at(seqSpan, i) != Nucleotide::GAP) {
  - const auto codonBegin = i - (i - final_frame) % 3;
  + const auto codonBegin = i - ((i - lastFrame) % 3);
  invariant_greater_equal(codonBegin, 0);
  invariant_less(codonBegin + 2, length);
  