(PECL weakref >= 0.1.0) Checks whether the object referenced still exists

(PECL weakref >= 0.2.0) Advances to the next map element

(PECL apc >= 3.1.1) Get current item public

(PHP 4 >= 4.3.0, PHP 5, PHP 7) Gets the current include_path configuration option

(PHP 4, PHP 5, PHP 7) Set/get the various assert flags

(PHP 4, PHP 5, PHP 7) Gets the value of an environment variable

(PECL apcu >= 5.1.0) Atomically fetch or generate a cache entry

(PECL apc >= 3.1.1) Increase a stored number

(PECL runkit >= 0.7.0) Runkit Sandbox Class -- PHP Virtual Machine

(PHP 5 >= 5.2.0, PHP 7) Returns the peak of memory allocated by PHP