Remove user role when users cancel in Paid Memberships Pro

my_pmpro_after_change_membership_level.php

/*
	Remove user role when users cancel.
*/
function my_pmpro_after_change_membership_level($level_id, $user_id)
{
	if(empty($level_id))
	{
		//If they are a subscriber, remove their role.
		$wp_user_object = new WP_User($user_id);
		if(in_array("subscriber", $wp_user_object->roles))
			$wp_user_object->set_role('');
	}
	else
	{
		//If they have no role, make them a subscriber.
		$wp_user_object = new WP_User($user_id);
		if(empty($wp_user_object->roles))
			$wp_user_object->set_role('subscriber');
	}
}
add_action("pmpro_after_change_membership_level", "my_pmpro_after_change_membership_level", 10, 2);