How to create a lib function without modifying the core functions

I wanted to create a filter function same as isAdmin for a different role. Is there any way that we can duplicate the engine/lib/users.php in mod/some_theme/engine/lib/users.php as we do for views. 

Beginning Developers

Beginning Developers

This space is for newcomers, who wish to build a new plugin or to customize an existing one to their liking