anchor.diff:    patches = [
       (fetchurl {
         url = "mirror://sourceforge/libpng-apng/libpng16/${version}/${name}-apng.patch.gz";
  -      sha256 = "a6b79f1027bde510b215042c4375a3e2f9103113393269a5c261048e8d7a30c9";
  +      sha256 = "e661944e54574a3f26927ac9eb7e2788f3a2675545a19735b83fbb9adcb544c1";
       })
     ];
   
  
positive.code: }:
  
  let
    version = "1.6.32";
  in
  stdenv.mkDerivation rec {
    name = "libpng-${version}";
  
negative.code:   src = fetchurl {
      url = "mirror://sourceforge/libpng/libpng16/${version}/${name}.tar.xz";
      hashOutput = false;
      sha256 = "2f1e960d92ce3b3abd03d06dfec9637dfbd22febf107a536b44f7a47c60659f6";
    };
  
    buildInputs = [
  