anchor.diff:  
     src = fetchurl {
       urls = tarballUrls version;
  -    multihash = "QmZW6enUX5jA8JNCK72oQnCiaG4FEPuCHoC84yg12WyDqA";
  +    multihash = "QmPWcjgfiucBtkhxoWqJjHcKDXuj7QTmj5qnrCRfxgBJXj";
       hashOutput = false;
  -    sha256 = "94fb70890143e3c6549f265cee93ec064c80a84c42ad0f23e85ee1fd6540a871";
  +    sha256 = "aafee193ffb8fe0c82d4afef6ef91972cbaf5feea100edc2f262750611b4be1f";
     };
   
     buildInputs = [
  
positive.code:     zlib
    ];
  
    propagatedBuildInputs = [
      findXMLCatalogs
    ];
  
    configureFlags = [
      "--with-icu=${icu}"
      "--with-readline=${readline}"
      "--with-zlib=${zlib}"
      "--with-lzma=${xz}"
    ];
  
    passthru = {
      srcVerification = fetchurl rec {
        failEarly = true;
        urls = tarballUrls "2.9.9";
        inherit (src) outputHashAlgo;
        outputHash = "94fb70890143e3c6549f265cee93ec064c80a84c42ad0f23e85ee1fd6540a871";
        fullOpts = {
          pgpsigUrls = map (n: "${n}.asc") urls;
          pgpKeyFingerprint = "C744 15BA 7C9C 7F78 F02E  1DC3 4606 B8A5 DE95 BC1F";
  
negative.code: }:
  
  let
    version = "2.9.10";
  
    tarballUrls = version: [
      "http://xmlsoft.org/sources/libxml2-${version}.tar.gz"
  