# File lib/amazon/search/exchange/marketplace.rb, line 156
          def listing_search(seller_id, listing_id, weight=HEAVY, &block)
            url = "/onca/xml3?t=%s&MarketplaceSearch=listing-id&f=xml" +
                  "&type=%s&dev-t=%s&listing-id=%s&seller-id=%s"
            type = weight ? 'heavy' : 'lite'

            search(url % [@id, type, @token, listing_id, seller_id], &block)
          end