+extern zend_bool php_pq_callback_is_enabled(php_pq_callback_t *cb);
+extern void php_pq_callback_disable(php_pq_callback_t *cb TSRMLS_DC);
+extern void php_pq_callback_recurse_ex(php_pq_callback_t *old, php_pq_callback_t *new TSRMLS_DC);
+extern zend_bool php_pq_callback_is_recurrent(php_pq_callback_t *cb);