anchor.diff:  }:
   
   let
  -  version = "1.6.36";
  +  version = "1.6.37";
   in
   stdenv.mkDerivation rec {
     name = "libpng-${version}";
  
positive.code:   src = fetchurl {
      url = "mirror://sourceforge/libpng/libpng16/${version}/${name}.tar.xz";
      hashOutput = false;
      sha256 = "eceb924c1fa6b79172fdfd008d335f0e59172a86a66481e09d4089df872aa319";
    };
  
    buildInputs = [
  
negative.code:   patches = [
      (fetchurl {
        url = "mirror://sourceforge/libpng-apng/libpng16/${version}/${name}-apng.patch.gz";
        sha256 = "823bb2d1f09dc7dae4f91ff56d6c22b4b533e912cbd6c64e8762255e411100b6";
      })
    ];
  
  