anchor.diff:      lib.optional stdenv.isLinux (lib.getDev pcsclite)
       ++ lib.optional stdenv.isDarwin (darwin.apple_sdk.frameworks.PCSC);
   
  -  nativeBuildInputs = [ makeWrapper pkg-config ];
  +  nativeBuildInputs = lib.optionals stdenv.isLinux [ pkg-config ];
   
     postPatch = lib.optionalString stdenv.isLinux ''
       substituteInPlace main.go --replace 'notify-send' ${libnotify}/bin/notify-send
  
positive.code: { stdenv, lib, fetchFromGitHub, buildGoModule, libnotify, makeWrapper, pcsclite, pkg-config, darwin }:
  
  buildGoModule rec {
    pname = "yubikey-agent";
  
negative.code:   doCheck = false;
  
    subPackages = [ "." ];
  
    ldflags = [ "-s" "-w" "-X main.Version=${version}" ];
  
    postInstall = lib.optionalString stdenv.isLinux ''
      mkdir -p $out/lib/systemd/user
  