anchor.diff:      "mirror://gnu/mpfr/mpfr-${version}.tar.xz"
     ];
   
  -  version = "4.0.0";
  +  version = "4.0.1";
   
     inherit (stdenv.lib)
       flip
  
positive.code:   passthru = {
      srcVerification = fetchurl rec {
        failEarly = true;
        urls = tarballUrls "4.0.0";
        pgpsigUrls = map (n: "${n}.sig") urls;
        pgpKeyFingerprint = "07F3 DBBE CC1A 3960 5078  094D 980C 1976 98C3 739D";
        inherit (src) outputHashAlgo;
        outputHash = "fbe2cd1418b321f5c899ce4f0f0f4e73f5ecc7d02145b0e1fd096f5c3afb8a1d";
      };
    };
  
  
negative.code:   src = fetchurl {
      urls = tarballUrls version;
      hashOutput = false;
      sha256 = "67874a60826303ee2fb6affc6dc0ddd3e749e9bfcb4c8655e3953d0458a6e16e";
    };
  
    patches = flip mapAttrsToList patchSha256s (n: { multihash, sha256 }: fetchurl {
  