Adding languages switcher in admin tool bar

Hi,
I would like to add Polylang language switcher in admin toolbar.
I added the corresponding code <?php pll_the_languages(); ?> in function.php, with admin_bar_menu function. So, it works but the languages are not added directly to the admin bar but before. So, the different languages appear before the admin bar and I would like for them to appear inside the admin bar.
There are some admin toolbar functions like add_node() or add_menu() that work when we specify an array but not when we add a function.
Do you have any idea on how I can add these languages inside the admin bar and not before?
Thanks.