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