anchor.diff:  
   stdenv.mkDerivation rec {
     pname = "libical";
  -  version = "3.0.15";
  +  version = "3.0.16";
   
     outputs = [ "out" "dev" ]; # "devdoc" ];
   
  
positive.code: { lib
  , stdenv
  , fetchFromGitHub
  , fetchurl
  , buildPackages
  , cmake
  , glib
  
negative.code:     owner = "libical";
      repo = "libical";
      rev = "v${version}";
      sha256 = "sha256-3D/0leI3LLKDFOXkKSrmMamLoaXdi/2Z4iPUXqgwtg8=";
    };
  
    strictDeps = true;
  