// now let us make a blackmarket trading interface that uses multiple
   servers to verify that the point of sale interface never goes down
   class blackmarket_point_of_sale_interface : public amazon_seller
   {
   public:
     template<class... ParamTypes>
     blackmarket_point_of_sale_interface(ParamTypes ... params):
     : amazon_seller(params...)
     {
       std::cout << "Welcome to the Criminal Market.  We have outsourced
   to Amazon.  Good luck with their sort-by-cheapest button that was
   replaced by a honeypot half a decade ago." << std::endl;
     }
   };