anchor.diff:    src = fetchurl {
       urls = tarballUrls version;
       hashOutput = false;
  -    sha256 = "4e248e02c50404ea5c5fc29027d26600f895a9eae7ea5ef851be2c8587abc148";
  +    sha256 = "be3ba62e883185b6ee8475edae97d7197d701d6b9ad9c3d2df53697110c1bfd8";
     };
   
     nativeBuildInputs = [
  
positive.code:   passthru = {
      srcVerification = fetchurl rec {
        failEarly = true;
        urls = tarballUrls "5.18.10";
        pgpsigUrls = map (n: "${n}.sig") urls;
        pgpKeyFingerprint = "44A0 88E2 95C3 A722 C450  590E C9EF 76DE B74E E762";
        inherit (src) outputHashAlgo;
        outputHash = "4e248e02c50404ea5c5fc29027d26600f895a9eae7ea5ef851be2c8587abc148";
      };
    };
  
  
negative.code: }:
  
  let
    version = "5.18.12";
  
    tarballUrls = version: [
      "mirror://gnu/autogen/rel${version}/autogen-${version}.tar.xz"
  