anchor.diff:    ] ++ lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
       # provides ical-glib-src-generator that runs during build
       libical
  -  ] ++ lib.optionals introspectionSupport [
  +  ] ++ lib.optionals withIntrospection [
       gobject-introspection
       vala
     ] ++ lib.optionals stdenv.isDarwin [
  
positive.code:     sha256 = "sha256-gZ6IBjG5pNKJ+hWcTzXMP7yxL4he4LTklZGoC9vXra8=";
    };
  
    nativeBuildInputs = [
      cmake
      ninja
  
negative.code: , python3
  , tzdata
  , fixDarwinDylibNames
  , withIntrospection ? stdenv.buildPlatform == stdenv.hostPlatform
  , gobject-introspection
  , vala
  }:
  