anchor.diff:  { lib
   , stdenv
   , fetchFromGitHub
  -, fetchurl
   , buildPackages
   , cmake
   , glib
  
positive.code: 
  stdenv.mkDerivation rec {
    pname = "libical";
    version = "3.0.15";
  
    outputs = [ "out" "dev" ]; # "devdoc" ];
  
  
negative.code:     owner = "libical";
      repo = "libical";
      rev = "v${version}";
      sha256 = "sha256-3D/0leI3LLKDFOXkKSrmMamLoaXdi/2Z4iPUXqgwtg8=";
    };
  
    strictDeps = true;
  