(PHP 5, PHP 7) Check whether the inner iterator has a valid next element

(PHP 5 >= 5.2.0, PHP 7) Get flags used public

(PHP 5, PHP 7) Check whether the current element is valid

(PHP 5, PHP 7) Move the iterator forward public

(PHP 5, PHP 7) Returns the inner iterator public

(PHP 5 >= 5.2.0, PHP 7) The offsetExists purpose

(PHP 5 >= 5.2.0, PHP 7) The offsetGet purpose