anchor.diff:    elemental_demo = buildDemo rec {
       name = "ue4demos-elemental_demo";
       src = fetchurl {
  -      url = "http://ue4linux.raxxy.com/elemental_demo.zip";
  +      urls = urls "elemental_demo.zip";
         sha256 = "1v4jdsy8jvv8wgc8dx17q17xigfrya5q0nfdzw4md7fzm3bg9z0v";
       };
     };
  
positive.code:   shooter_game = buildDemo rec {
      name = "ue4demos-shooter_game";
      src = fetchurl {
        url = "http://ue4linux.raxxy.com/shooter_game.zip";
        sha256 = "1bk32k349iqbqk8x8jffnqq0pjiqmvrvv675xxmlvkkr8qrlhz98";
      };
    };
  
negative.code:   vehicle_game = buildDemo rec {
      name = "ue4demos-vehicle_game";
      src = fetchurl {
        urls = urls "vehicle_game.zip";
        sha256 = "03dlacf1iv7sgn7pl3sx9r6243wy8fsi2kd858syfm9slg0190bs";
      };
    };
  