Add cancelled level's ID to Changed Membership Level trigger data if a membership is being cancelled

my_pmproz_after_change_membership_level_data.php

<?php
/**
 * Add cancelled level's ID to Changed Membership Level trigger data
 * if a membership is being cancelled
 *
 * 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_pmproz_after_change_membership_level_data( $data, $level_id, $user_id, $cancel_level ) {
  if ( ! empty( $cancel_level) ) {
	$data['cancelled_level_id'] = $cancel_level;	
  }

  return $data;
}
add_filter( 'pmproz_after_change_membership_level_data', 'my_pmproz_after_change_membership_level_data', 10, 4 );