// optional S bla;
// => S bla() { ret getOpt(this, "bla"); }
//    void bla(S bla) { setOpt(this, "bla", bla); }
svoid tok_optionalFields(LS tok) {
  for (int i : jfindAll_reverse(tok, "optional <id>")) {
    int iSemicolon = tok_endOfStatement(tok, i)-1;
    S var = tok.get(iSemicolon-2);
    S type = joinSubList(tok, i+2, iSemicolon-3);
    tokReplace_reTok(tok, i, iSemicolon+1,
      "public \*type*/ \*var*/() { ret (\*type*/ getOpt(this, \*quote(var)*/); }\n" +
      "public void var(\*type*/ var) { setOpt(this, \*quote(var)*/, \*var*/); }");
  }
}