anchor.diff:  
   let alt-ergo-parsers = ocamlPackages.buildDunePackage rec {
     pname = "alt-ergo-parsers";
  -  inherit version src useDune2;
  +  inherit version src;
     configureFlags = [ pname ];
     nativeBuildInputs = [ which ocamlPackages.menhir ];
     propagatedBuildInputs = [ alt-ergo-lib ] ++ (with ocamlPackages; [ camlzip psmt2-frontend ]);
  
positive.code: 
  ocamlPackages.buildDunePackage {
  
    inherit pname version src useDune2;
  
    configureFlags = [ pname ];
  
  
negative.code: { fetchFromGitHub, fetchpatch, lib, which, ocamlPackages }:
  
  let
    pname = "alt-ergo";
  