// range should be CNC (i pointing at N, j at C after sublist)
svoid surroundTokenRangeWithRoundBrackets(LS tok, IntRange r) {
  if (r != null) surroundTokenRangeWithRoundBrackets(tok, r.start, r.end);
}

svoid surroundTokenRangeWithRoundBrackets(LS tok, int i, int j) {
  tokAppend(tok, i & ~1, "(");
  tokPrepend(tok, incIfOdd(j-1), ")");
}