Usage example:<?phpclass AdultFilter extends \FilterIterator{ public function accept() { $person = $this->current(); if (18 <= $person[1]) { return true; } return false; }}$persons = new \ArrayIterator([ ['John', 27], ['Jack', 15], ['Jeff', 54],]);$adults = new AdultFilter($persons);foreach ($adults as $adult) { var_dump($adult);}