(PHP 5 >= 5.1.0, PHP 7) The key() method public
(PHP 5 >= 5.1.0, PHP 7) The next() method
(PHP 5 >= 5.1.0, PHP 7) The rewind() method
(PHP 5 >= 5.1.0, PHP 7) The valid() method
(PHP 5 >= 5.1.0, PHP 7) The current() method