Override wp_list_authors

I would like to know how to officially override the wp_list_authors core function in a plugin. I have copied over the entire function from the core and renamed the function as ma_list_authors and then added an add_action at the bottom of my plugin’s main file. However I dont see any changes (the change is simple, add a class of “members” to the li element). I know this seems trivial but what I’m trying to do first is prove that I can override a core function and then add the functionality im planning on doing. Any help would be nice. Thanks!