svoid lambdaMapLike gazelle_visit(IVF1<S> visitor, S input, O... _) {
  if (visitor == null) ret;
  
  // call visitor on whole input
  visitor.get(input);
  
  // tokenize input
  O tokenizer = optPar tokenizer(_, f javaTokWithBrackets);
  LS tok = callTokenizer(tokenizer, input);
  
  for (int i = 1; i < l(tok); i += 2) {
    S t = tok.get(i);
    if (tok_isRoundOrCurlyBracketed(t)) {
      S unBracketed = tok_deRoundOrCurlyBracket(t);
      gazelle_visit(visitor, unBracketed, _);
    }
  }
}