anchor.diff:  
     buildInputs = [
       sqlite pkgconfig xapian glib gmime texinfo emacs guile libsoup icu
  -    autoreconfHook
  -    gtk3 webkitgtk24x ];
  +    autoreconfHook ] ++ stdenv.lib.optionals withMug [ gtk3 webkitgtk24x ];
   
     preBuild = ''
       # Fix mu4e-builddir (set it to $out)
  
positive.code:   '';
  
    # Install mug and msg2pdf
    postInstall = ''
      cp -v toys/msg2pdf/msg2pdf $out/bin/
      cp -v toys/mug/mug $out/bin/
    '';
  
negative.code: { fetchurl, stdenv, sqlite, pkgconfig, autoreconfHook
  , xapian, glib, gmime, texinfo , emacs, guile
  , gtk3, webkitgtk24x, libsoup, icu
  , withMug ? stdenv.isLinux }:
  
  stdenv.mkDerivation rec {
    version = "0.9.18";
  