Description:
------------
Provide a function for returning all namespaces used in the current request to aid in autoloading. 

Reproduce code:
---------------
<?php
    use My\Namespace;
    use Other\Namespace;

    print_r(get_used_namespaces());
?>

Expected result:
----------------
Array(
    [0] = My\Namespace,
    [1] = Other\Namespace
)

Actual result:
--------------
No such function exists.