anchor.diff:    };
     guiPreview = mkGui {
       stable = false;
  -    sha256Hash = "1a64c314v7mbaiipyap2skqgf69pyp1ld58cn2g3d89w2zrhf5q7";
  +    sha256Hash = "0p4g5hszys68ijzsi2rb89j1rpg04wlqlzzrl92npvqqf2i0jdf8";
     };
   
     serverStable = mkServer {
  
positive.code:   };
    serverPreview = mkServer {
      stable = false;
      sha256Hash = "1jlz8a34q3s1sz9r6swh3jnlp96602axnvh1byywry5fb9ga8mfy";
    };
  }
  
negative.code: 
  let
    stableVersion = "2.1.15";
    previewVersion = "2.2.0a5";
    addVersion = args:
      let version = if args.stable then stableVersion else previewVersion;
          branch = if args.stable then "stable" else "preview";
  