https://www.php.net/manual/zh/recursivefilteriterator.construct.php
PHP: RecursiveFilterIterator::__construct - Manual
Create a RecursiveFilterIterator from a RecursiveIterator
phpconstructmanual
https://www.php.net/manual/tr/recursivefilteriterator.getchildren.php
PHP: RecursiveFilterIterator::getChildren - Manual
Return the inner iterator's children contained in a RecursiveFilterIterator
phpgetchildrenmanual