Change subject in woocommerce new order email

gistfile1.txt

/**
 * @snippet       Add Billing First_name to Email Receipt
 * @how-to        Watch tutorial @ https://businessbloomer.com/?p=19055
 * @sourcecode    https://businessbloomer.com/?p=19870
 * @author        Rodolfo Melogli
 * @testedwith    WooCommerce 2.5.2
 */
 
add_filter('woocommerce_email_subject_customer_processing_order', 'bbloomer_change_processing_email_subject', 10, 2);
 
function bbloomer_change_processing_email_subject( $subject, $order ) {
global $woocommerce;
$subject = $order->billing_first_name . ', Thanks for your order at ' . get_bloginfo( 'name', 'display' ) ;
return $subject;
}