anchor.diff:  { stdenv, fetchurl, gettext, intltool, pkgconfig, python
   , avahi, bluez, boost, eigen, fftw, glib, glibmm, gtk, gtkmm, libjack2
   , ladspaH, librdf, libsndfile, lilv, lv2, serd, sord, sratom
  -,  zita-convolver, zita-resampler
  +, webkitgtk2, zita-convolver, zita-resampler
   , optimizationSupport ? false # Enable support for native CPU extensions
   }:
   
  
positive.code:   buildInputs = [
      avahi bluez boost eigen fftw glib glibmm gtk gtkmm libjack2
      ladspaH librdf libsndfile lilv lv2 serd sord sratom
      zita-convolver zita-resampler
    ];
  
    configureFlags = [
  
negative.code: 
  stdenv.mkDerivation rec {
    name = "guitarix-${version}";
    version = "0.34.0";
  
    src = fetchurl {
      url = "mirror://sourceforge/guitarix/guitarix2-${version}.tar.bz2";
      sha256 = "0pamaq8iybsaglq6y1m1rlmz4wgbs2r6m24bj7x4fwg4grjvzjl8";
    };
  
    nativeBuildInputs = [ gettext intltool pkgconfig python ];
  