Add images to WooCommerce emails

wc-add-images-order-email-table.php

// Edit order items table template defaults
function sww_add_wc_order_email_images( $table, $order ) {
  
	ob_start();
	
	$template = $plain_text ? 'emails/plain/email-order-items.php' : 'emails/email-order-items.php';
	wc_get_template( $template, array(
		'order'                 => $order,
		'items'                 => $order->get_items(),
		'show_download_links'   => $show_download_links,
		'show_sku'              => $show_sku,
		'show_purchase_note'    => $show_purchase_note,
		'show_image'            => true,
		'image_size'            => $image_size
	) );
   
	return ob_get_clean();
}
add_filter( 'woocommerce_email_order_items_table', 'sww_add_wc_order_email_images', 10, 2 );

where add this code?