sbool tok_doubleFor_v2_debug;

static void tok_doubleFor_v2(L<S> tok) {

  for (int i : reversed(indexesOf(tok, "for"))) {

    if (neq(get(tok, i+2), "(")) continue;

    int argsFrom = i+4;

    // move loop label to proper place

    if (eqGet(tok, i-2, ":") && isIdentifier(get(tok, i-4))) i -= 4;

    int iColon = indexOfAny(tok, argsFrom, ":", ")");

    if (neq(get(tok, iColon), ":")) continue;

    if (tok_doubleFor_v2_debug) print("have colon");

    tok_typesAndNamesOfParams_keepModifiers.set(true);

    L<Pair<S>> args = tok_typesAndNamesOfParams(subList(tok, argsFrom-1, iColon-1));

    if (l(args) != 2) continue; // simple for or a three-argument for (out of this world!)

    // S a, b => S a, S b

    if (eq(second(args).a, "?")) second(args).a = first(args).a;

    if (tok_doubleFor_v2_debug) print("have 2 args: " + sfu(args));

    int iClosing = tok_findEndOfForExpression(tok, iColon+2);

    if (iClosing < 0) continue;

    if (tok_doubleFor_v2_debug) print("have closing");

    S exp = trimJoinSubList(tok, iColon+2, iClosing-1);

    if (tok_doubleFor_v2_debug) print("Expression: " + exp);

    int iCurly = iClosing+2;

    if (neq(get(tok, iCurly), "{")) fail("please use { with double for");

    int iCurlyEnd = findEndOfStatement(tok, iCurly)-1;

    if (iCurlyEnd < 0) continue;

    if (tok_doubleFor_v2_debug) print("have curly end");

    // complicated expression? evaluate to variable first

    if (!isIdentifier(exp)) {

      S expVar = makeVar();

      S mapType = tok_toNonPrimitiveTypes("Map<" + first(args).a + ", " + second(args).a + ">");

      tokPrepend(tok, i, "{ final " + mapType + " " + expVar + " = " + exp + "; ");

      tokAppend(tok, iCurlyEnd, "}");

      replaceTokens(tok, iColon+2, iClosing-1, expVar);

      exp = expVar;

    }

    tokAppend(tok, iColon, " keys(");

    tokPrepend(tok, iClosing, ")");

    replaceTokens(tok, argsFrom, iColon-1, joinPairWithSpace(first(args)));

    tokAppend(tok, iCurly, " " + joinPairWithSpace(second(args)) + " =" + exp + ".get(" + first(args).b + "); ");

    reTok(tok, i, iCurlyEnd+1);

  }

}