Description:
------------
For over 2 years now, the below code doesn't work :

<?php
    $test = variant_pow(2, 5);
    echo '$test = ' . $test;
?>

The error is :

PHP Fatal error:  Call to undefined function variant_pow()

Test script:
---------------
<?php
    $test = variant_pow(2, 5);
    echo '$test = ' . $test;
?>

Expected result:
----------------
32

Actual result:
--------------
The website cannot display the page