anchor.diff:  , libjpeg
   , libgsf
   , libexif
  +, libheif
   , ApplicationServices
   , python27
  -, libpng ? null
  +, libpng
   , fetchFromGitHub
   , fetchpatch
   , autoreconfHook
  
positive.code: 
  stdenv.mkDerivation rec {
    pname = "vips";
    version = "8.9.1";
  
    outputs = [ "bin" "out" "man" "dev" ];
  
  
negative.code:     libjpeg
      libgsf
      libexif
      libheif
      libpng
      python27
      libpng
      expat
  