anchor.diff:    passthru = {
       srcVerification = fetchurl rec {
         failEarly = true;
  -      urls = tarballUrls "2.0.12";
  +      urls = tarballUrls "2.0.13";
         pgpsigUrls = map (n: "${n}.sig") urls;
  -      pgpKeyFingerprint = "FF47 8FB2 64DE 32EC 2967  25A3 DDC0 F535 8812 F8F2";
  +      pgpKeyFingerprints = [
  +        "FF47 8FB2 64DE 32EC 2967  25A3 DDC0 F535 8812 F8F2"
  +        "3CE4 6455 8A84 FDC6 9DB4  0CFB 090B 1199 3D9A EBB5"
  +      ];
         inherit (src) outputHashAlgo;
  -      outputHash = "de8187736f9b260f2fa776ed39b52cb74dd389ccf7039c042f0606270196b7e9";
  +      outputHash = "3744f2addc282a0de627aaef048f062982b44564d54ac31ff5217972529ed88b";
       };
     };
   
  
positive.code: }:
  
  let
    version = "2.0.12";
  
    tarballUrls = version: [
      "mirror://gnu/guile/guile-${version}.tar.xz"
  
negative.code:   src = fetchurl {
      urls = tarballUrls version;
      hashOutput = false;
      sha256 = "3744f2addc282a0de627aaef048f062982b44564d54ac31ff5217972529ed88b";
    };
  
    nativeBuildInputs = [
  