anchor.diff:      '';
   
       preBuild = ''
  -      ln -s ${pkgs.z3} Binaries/z3
  +      ln -s ${z3} Binaries/z3
       '';
   
       buildInputs = [ Boogie ];
  
positive.code:     # Boogie as an input is not enough. Boogie libraries need to be at the same
      # place as Dafny ones. Same for "*.dll.mdb". No idea why or how to fix.
      postFixup = ''
        for lib in ${Boogie}/lib/dotnet/${Boogie.baseName}/*.dll{,.mdb}; do
          ln -s $lib $out/lib/dotnet/${baseName}/
        done
        # We generate our own executable scripts
  
negative.code: 
    Boogie = buildDotnetPackage rec {
      baseName = "Boogie";
      version = "2.4.1";
      name = "${baseName}-${version}";
  
      src = fetchFromGitHub {
        owner = "boogie-org";
        repo = "boogie";
        rev = "v${version}";
        sha256 = "13f6ifkh6gpy4bvx5zhgwmk3wd5rfxzl9wxwfhcj1c90fdrhwh1b";
      };
  
      # emulate `nuget restore Source/Boogie.sln`
  