anchor.diff:      rev = version;
       sha256 = "0hglj1p0753w2isds01h90knraxa42d2jghr35dpwf9g8a1sm9d3";
     };
  -
  -  useDune2 = true;
   in
   
   let alt-ergo-lib = ocamlPackages.buildDunePackage rec {
     pname = "alt-ergo-lib";
  -  inherit version src useDune2;
  +  inherit version src;
     configureFlags = [ pname ];
     nativeBuildInputs = [ which ];
     buildInputs = with ocamlPackages; [ dune-configurator ];
  
positive.code: 
  ocamlPackages.buildDunePackage {
  
    inherit pname version src useDune2;
  
    configureFlags = [ pname ];
  
  
negative.code: 
  let alt-ergo-parsers = ocamlPackages.buildDunePackage rec {
    pname = "alt-ergo-parsers";
    inherit version src;
    configureFlags = [ pname ];
    nativeBuildInputs = [ which ocamlPackages.menhir ];
    propagatedBuildInputs = [ alt-ergo-lib ] ++ (with ocamlPackages; [ camlzip psmt2-frontend ]);
  