anchor.diff:              && ((pre_ins ? 1 : 0) + (pre_del ? 1 : 0) + (post_ins ? 1 : 0)
                   + (post_del ? 1 : 0)) == 3))) {
             // Duplicate record.
  -          diffs.insertRange(equalities.last, 1,
  +          diffs.insert(equalities.last,
                               new Diff(DIFF_DELETE, lastequality));
             // Change second copy to insert.
             diffs[equalities.last + 1].operation = DIFF_INSERT;
  
positive.code:     final prefix = text.substring(max(0, patch.start2 - padding),
          patch.start2);
      if (!prefix.isEmpty) {
        patch.diffs.insertRange(0, 1, new Diff(DIFF_EQUAL, prefix));
      }
      // Add the suffix.
      final suffix = text.substring(patch.start2 + patch.length1,
  
negative.code:             && (lastequality.length <= max(length_insertions2,
                                                  length_deletions2))) {
            // Duplicate record.
            diffs.insert(equalities.last,
                              new Diff(DIFF_DELETE, lastequality));
            // Change second copy to insert.
            diffs[equalities.last + 1].operation = DIFF_INSERT;
  