docs: public static int advance(Iterator<?> iterator, int numberToAdvance) {
      checkNotNull(iterator);
      checkArgument(numberToAdvance >= 0, "numberToAdvance must be nonnegative");
  
      int i;
      for (i = 0; i < numberToAdvance && iterator.hasNext(); i++) {
        iterator.next();
      }
      return i;
    }