Cannot figure out how to overwrite files in child theme

The catch-base theme wraps every function in an if statement to make it easy to modify if necessary.

Example….

if (! function_exists('function_name')) { 
    /* some code */
}

So what I ended up doing was adding this to my functions.php file in the child theme and it overwrote the function and the extra divs that I added showed up!

function function_name() {
    /* some modified code */
}