static S tok_dropAllCurlyBrackets(S s) {
  ret join(tok_dropAllCurlyBrackets(javaTok(s)));
}

static L<S> tok_dropAllCurlyBrackets(L<S> tok) {
  new L<S> out;
  for (int i = 0; i < l(tok); i++) {
    S t = tok.get(i);
    if (eqOneOf(t, "{", "}"))
      tokAppend(out, l(out)-1, tok.get(++i)); // merge N tokens
    else
      out.add(t);
  }
  ret out;
}