anchor.diff:  
       buildInputs = [ xar cpio python pbzx ];
   
  -    phases = [ "unpackPhase" "installPhase" "fixupPhase" ];
       outputs = [ "out" "dev" "man" ];
   
       unpackPhase = ''
  
positive.code:   libs = {
      xpc = stdenv.mkDerivation {
        name   = "apple-lib-xpc";
        phases = [ "installPhase" "fixupPhase" ];
  
        installPhase = ''
          mkdir -p $out/include
  
negative.code:   framework = name: deps: stdenv.mkDerivation {
      name = "apple-framework-${name}";
  
      dontUnpack = true;
  
      # because we copy files from the system
      preferLocalBuild = true;
  