anchor.diff:  
     nativeBuildInputs = [
       meson ninja pkgconfig gettext docbook_xsl docbook_xsl_ns docbook_xml_dtd_42 perl wrapGAppsHook glibcLocales
  -    sassc desktop-file-utils libxslt.bin
  +    sassc desktop-file-utils libxslt.bin python3
     ];
     buildInputs = [
       systemd caribou
  
positive.code: { fetchurl, fetchpatch, substituteAll, stdenv, meson, ninja, pkgconfig, gnome3, json-glib, libcroco, gettext, libsecret
  , python3Packages, libsoup, polkit, clutter, networkmanager, docbook_xsl , docbook_xsl_ns, at-spi2-core
  , libstartup_notification, telepathy-glib, telepathy-logger, libXtst, unzip, glibcLocales, shared-mime-info
  , libgweather, libcanberra-gtk3, librsvg, geoclue2, perl, docbook_xml_dtd_42, desktop-file-utils
  , libpulseaudio, libical, gobject-introspection, gstreamer, wrapGAppsHook, libxslt, gcr, caribou
  
negative.code: # http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/gnome-base/gnome-shell/gnome-shell-3.10.2.1.ebuild?revision=1.3&view=markup
  
  let
    pythonEnv = python3.withPackages ( ps: with ps; [ pygobject3 ] );
  
  in stdenv.mkDerivation rec {
    name = "gnome-shell-${version}";
  