public function orderByItemId($item_id)
    {
        if (!($item_id = (int) $item_id)) {
            return null; // Not possible.
        }
        $WpDb  = $this->s::wpDb(); // DB instance.
        $table = $WpDb->prefix.'woocommerce_order_items';

        $sql = /* Get the order ID for this item. */ '
            SELECT `order_id` FROM `'.esc_sql($table).'`
             WHERE `order_item_id` = %s LIMIT 1';
        $sql = $WpDb->prepare($sql, $item_id); // Prepare.

        if (!($order_id = (int) $WpDb->get_var($sql))) {
            return null; // Not possible; can't get order ID.
        } elseif (!($post_type = get_post_type($order_id))) {
            debug(0, $this->c::issue(vars(), 'Unable to acquire order post type.'));
            return null; // Not possible; can't get post type.
        }
        switch ($post_type) { // Based on post type.
            case 'shop_subscription':
                $subscription_id = $order_id; // It's a subscription ID.
                if (($WC_Subscription = wcs_get_subscription($subscription_id))) {
                    return $WC_Subscription;
                }
                return null; // Not possible.

            case 'shop_order':
            default: // Any other order type.
                if (($WC_Order = wc_get_order($order_id))) {
                    return $WC_Order;
                }
                return null; // Not possible.
        }
    }