Add a shortcode to show the currently active PMPro affiliate code

my_pmpro_show_affiliate_code_shortcode.php

<?php
/**
 * Add a shortcode to show the currently active PMPro affiliate code
 *
 * Use shortcode: [show_affiliate_code]
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */

function my_pmpro_show_affiliate_code() {
	$code = $_COOKIE['pmpro_affiliate'] ?? '';
	return $code;
}
add_shortcode( 'show_affiliate_code', 'my_pmpro_show_affiliate_code' );