private boolean[] join0(ThreadContext context, ByteList sep, int max, ByteList result) {
        boolean t = false;
        boolean u = false;
        try {
            for(int i = begin; i < max; i++) {
                IRubyObject val = values[i];

                if(i > begin && sep != null) {
                    result.append(sep);
                }

                result.append(((RubyString)val).getByteList());
                if(val.isTaint()) {
                    t = true;
                }
                if(val.isUntrusted()) {
                    u = true;
                }
            }
        } catch (ArrayIndexOutOfBoundsException e) {
            concurrentModification();
            return new boolean[] {t,u};
        }
        return new boolean[]{t,u};
    }

    AFTER:
    private RubyString join0(RubyString sep, int max, RubyString result) {
        try {
            for(int i = begin; i < max; i++) {
                if (i > begin && sep != null) result.append(sep);
                result.append(values[i]);
            }
        } catch (ArrayIndexOutOfBoundsException e) {
            concurrentModification();
        }

        return result;
    }