static L<S> tok_groupRoundBrackets(S s) {
  ret tok_groupRoundBrackets(javaTok(s));
}
  
static L<S> tok_groupRoundBrackets(L<S> tok) {
  while true {
    int i = tok.lastIndexOf("(");
    if (i < 0) ret tok;
    int j = indexOf(tok, ")", i);
    if (j < 0) ret tok;
    tok.set(i, join(subList(tok, i, j+1)));
    tok.subList(i+1, j+1).clear();
    assertTrue(odd(l(tok)));
  }
}