Add 'col' class to Genesis footer widgets

<?php
/*
Plugin Name: Add class to Genesis footer widgets
Plugin URI: https://www.damiencarbery.com
Description: Add a 'col' class to Genesis footer widgets - asked in Genesis WordPress Facebook group.
Author: Damien Carbery
Version: 0.1
*/

add_filter( 'genesis_attr_footer-widget-area', 'dcwd_genesis_attributes_footer_widget_area', 20, 3 );
function dcwd_genesis_attributes_footer_widget_area( $attributes, $context, $args ) {
    //error_log( "Attributes: " . var_export( $attributes, true ) );
    //error_log( "Context: " . var_export( $context, true ) );
    //error_log( "Args: " . var_export( $args, true ) );

    $attributes['class'] .= ' col';

    return $attributes;
}