random between to php function

I have 2 php functions on a webpage, I would like to run one of those 2 functions randomly, I know how to do it with divs or html using php, but not how to run a php function randomly. I want to use php and not Javascripy

here are my 2 functions :

<?php get_template_part('module_sidebar_1'); ?>
<?php get_template_part('module_sidebar_2'); ?>

can anybody help me with this ?

thanks