protected function initializeProductSuperAttribute(array $attr)
    {

        // load product/attribute ID
        $productId = $attr[MemberNames::PRODUCT_ID];
        $attributeId = $attr[MemberNames::ATTRIBUTE_ID];

        // query whether or not, the product super attribute already exists
        if ($entity = $this->loadProductSuperAttribute($productId, $attributeId)) {
            return $this->mergeEntity($entity, $attr);
        }

        // simply return the attributes
        return $attr;
    }