https://www.php.net/manual/uk/multipleiterator.containsiterator.php
PHP: MultipleIterator::containsIterator - Manual
Checks if an iterator is attached
phpmanual
https://www.php.net/manual/en/multipleiterator.containsiterator.php
PHP: MultipleIterator::containsIterator - Manual
Checks if an iterator is attached
phpmanual