anchor.diff:    src = fetchurl {
       url = "mirror://gnome/sources/pango/${versionMajor}/${name}.tar.xz";
       hashOutput = false;
  -    sha256 = "517645c00c4554e82c0631e836659504d3fd3699c564c633fccfdfd37574e278";
  +    sha256 = "9faea6535312fe4436b93047cf7a04af544eb52a079179bd3a33821aacce7e16";
     };
   
     nativeBuildInputs = [
  
positive.code: , xorg
  }:
  
  assert xorg != null ->
    xorg.libX11 != null
    && xorg.libXft != null
    && xorg.libXrender != null;
  
  let
  
negative.code:     optionalString;
  
    versionMajor = "1.40";
    versionMinor = "9";
    version = "${versionMajor}.${versionMinor}";
  in
  stdenv.mkDerivation rec {
  