anchor.diff:  , enableRST ? true
   , enableSpelling ? true, gtkspell ? null
   , enableNotifications ? false
  -, enableLaTeX ? false, texLive ? null
   }:
   
   assert enableJingle -> farstream != null && gst_plugins_bad != null
  
positive.code: assert enableRST -> pythonPackages.docutils != null;
  assert enableSpelling -> gtkspell != null;
  assert enableNotifications -> pythonPackages.notify != null;
  assert enableLaTeX -> texLive != null;
  
  with stdenv.lib;
  
  
negative.code:   '' + optionalString enableSpelling ''
      sed -i -e 's|=.*find_lib.*|= "${gtkspell}/lib/libgtkspell.so"|'   \
        src/gtkspell.py
    '';
  
    buildInputs = [
  