static <A> CloseableIterableIterator<A> filterCloseableIterator(final CloseableIterableIterator<A> it, final F1<A, Bool> f) {
  if (it == null) null;
  ret (CloseableIterableIterator) iteratorFromFunction_withEndMarker_f0_autoCloseable(func -> O {
    while (it.hasNext()) {
      A a = it.next();
      if (callF(f, a))
        ret a;
    }
    ret endMarker();
  }, it);
}

static <A> CloseableIterableIterator<A> filterCloseableIterator(final F1<A, Bool> f, final CloseableIterableIterator<A> it) {
  ret filterCloseableIterator(it, f);
}

Began life as a copy of #1015351