anchor.diff:  { darkMode ? false, stdenv, fetchurl, dpkg, makeWrapper , alsaLib, atk, cairo,
   cups, curl, dbus, expat, fontconfig, freetype, glib , gnome2, gtk3, gdk_pixbuf,
   libappindicator-gtk3, libnotify, libxcb, nspr, nss, pango , systemd, xorg,
  -at-spi2-atk }:
  +at-spi2-atk, libuuid }:
   
   let
   
  -  version = "3.4.0";
  +  version = "3.4.2";
   
     rpath = stdenv.lib.makeLibraryPath [
       alsaLib
  
positive.code:     if stdenv.hostPlatform.system == "x86_64-linux" then
        fetchurl {
          url = "https://downloads.slack-edge.com/linux_releases/slack-desktop-${version}-amd64.deb";
          sha256 = "0ld53gg0dbfpi79lz2sx5br29mlhwkfcypzf3iya4cm75a33hyw5";
        }
      else
        throw "Slack is not supported on ${stdenv.hostPlatform.system}";
  
negative.code:     nss
      stdenv.cc.cc
      systemd
      libuuid
  
      xorg.libxkbfile
      xorg.libX11
  