anchor.diff:  }:
   
   let
  -  version = "1.6.32";
  +  version = "1.6.34";
   in
   stdenv.mkDerivation rec {
     name = "libpng-${version}";
  
positive.code:   src = fetchurl {
      url = "mirror://sourceforge/libpng/libpng16/${version}/${name}.tar.xz";
      hashOutput = false;
      sha256 = "c918c3113de74a692f0a1526ce881dc26067763eb3915c57ef3a0f7b6886f59b";
    };
  
    buildInputs = [
  
negative.code:   patches = [
      (fetchurl {
        url = "mirror://sourceforge/libpng-apng/libpng16/${version}/${name}-apng.patch.gz";
        sha256 = "e661944e54574a3f26927ac9eb7e2788f3a2675545a19735b83fbb9adcb544c1";
      })
    ];
  
  