anchor.diff:      doxygen                   # (optional) api docs
       pythonPackages.sphinx     # (optional) documentation -> doc/INSTALL
       texinfo                   # (optional) documentation -> doc/INSTALL
  -  ] ++ optional withEmacs emacs;
  +  ] ++ lib.optional withEmacs emacs;
   
     buildInputs = [
       gnupg                     # undefined dependencies
  
positive.code:     mkdir -p test/test-databases
      ln -s ${test-database} test/test-databases/database-v1.tar.xz
    '';
    doCheck = !stdenv.hostPlatform.isDarwin && (versionAtLeast gmime.version "3.0.3");
    checkTarget = "test";
    checkInputs = [
      which dtach openssl bash
  
negative.code: 
    dontGzipMan = true; # already compressed
  
    passthru = {
      pythonSourceRoot = "${src.name}/bindings/python";
      inherit version;
    };
  
    meta = with lib; {
      description = "Mail indexer";
      homepage    = "https://notmuchmail.org/";
      license     = licenses.gpl3Plus;
  