public function hasItem($sku, $requireAll = false)
    {
        if (is_array($sku)) {
            foreach ($sku as $skuSingle) {
                $hasItem = $this->hasItem($skuSingle);

                if ($hasItem && !$requireAll) {
                    return true;
                } elseif (!$hasItem && $requireAll) {
                    return false;
                }
            }

            // If we've made it this far and $requireAll is FALSE, then NONE of the roles were found
            // If we've made it this far and $requireAll is TRUE, then ALL of the roles were found.
            // Return the value of $requireAll;
            return $requireAll;
        } else {
            foreach ($this->items as $item) {
                if ($item->sku == $sku) {
                    return true;
                }
            }
        }

        return false;
    }