anchor.diff:        "${key}=${value'}";
     };
   
  +  themeType = types.submodule {
  +    options = {
  +      package = mkOption {
  +        type = types.package;
  +        example = literalExample "pkgs.gnome3.adwaita-icon-theme";
  +        description = "Package providing the theme.";
  +      };
  +
  +      name = mkOption {
  +        type = types.str;
  +        example = "Adwaita";
  +        description = "The name of the theme within the package.";
  +      };
  +
  +      size = mkOption {
  +        type = types.str;
  +        default = "32x32";
  +        example = "16x16";
  +        description = "The desired icon size.";
  +      };
  +    };
  +  };
  +
  +  hicolorTheme = {
  +    package = pkgs.hicolor_icon_theme;
  +    name = "hicolor";
  +    size = "32x32";
  +  };
  +
   in
   
   {
  
positive.code:         home.file.".local/share/dbus-1/services/org.knopwob.dunst.service".source =
            "${pkgs.dunst}/share/dbus-1/services/org.knopwob.dunst.service";
  
          systemd.user.services.dunst = {
            Unit = {
              Description = "Dunst notification daemon";
  
negative.code:   options = {
      services.dunst = {
        enable = mkEnableOption "the dunst notification daemon";
  
        iconTheme = mkOption {
          type = themeType;
          default = hicolorTheme;
          description = "Set the icon theme.";
        };
  
        settings = mkOption {
          type = types.attrsOf types.attrs;
  