loopReplacer method
Implementation
String loopReplacer(match, s, e, snippet) {
  String string = '';
  int start = int.parse(s);
  int end = int.parse(e);
  for (int i = start; i < end; i++) {
    snippet = snippet
      ..replaceAll(RegExp(r"\[\s*i\s*\]"), '[ $i ]')
      ..replaceAll(RegExp(r"UNROLLED_LOOP_INDEX"), i);
    string += snippet;
  }
  return string;
}