(PHP 5 >= 5.1.0, PHP 7) Create an iterator from anything that is traversable

(PHP 5 >= 5.1.0, PHP 7) Get the current element value

(PHP 5 >= 5.1.0, PHP 7) Seeks to a position

(PHP 5 >= 5.1.0, PHP 7) Sets the iterator classname for the ArrayObject.

(PHP 5 >= 5.3.0, PHP 7) Check whether the heap contains more nodes

(PHP 5 >= 5.2.0, PHP 7) Sort the entries by keys using a user-defined comparison function

(PHP 5 >= 5.1.0, PHP 7) Seek to the given position

(PHP 5 >= 5.1.0, PHP 7) Return the current position

(PHP 5 >= 5.1.0, PHP 7) Get current key public

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