Offer URL

        :return:
            Offer URL (string).

def offer_url(self):
        """Offer URL

        :return:
            Offer URL (string).
        """
        return "{0}{1}/?tag={2}".format(
            AMAZON_ASSOCIATES_BASE_URL.format(domain=DOMAINS[self.region]),
            self.asin,
            self.aws_associate_tag)