static <A> int smartIndexOfNot(L<A> l, A sub) {
  ret smartIndexOfNot(l, sub, 0);
}

static <A> int smartIndexOfNot(L<A> l, A sub, int start) {
  int i = start, n = l(l);
  while (i < n && eq(l.get(i), sub))
    ++i;
  ret i;
}