anchor.diff:  
       postInstall = ''
         wrapProgram $out/bin/alot \
  -        --prefix LD_LIBRARY_PATH : ${pkgs.notmuch}/lib:${pkgs.file511}/lib
  +        --prefix LD_LIBRARY_PATH : ${pkgs.notmuch}/lib:${pkgs.file511}/lib:${pkgs.gpgme}/lib
       '';
   
       meta = {
  
positive.code:       description = "A concurrent networking library for Python";
      };
    };
  
  
    flask = buildPythonPackage {
  
negative.code: 
  
    urwid = buildPythonPackage (rec {
      name = "urwid-1.0.2";
  
      doCheck = false;
  
      src = fetchurl {
        url = "http://excess.org/urwid/${name}.tar.gz";
        md5 = "00542bbd15fae7ea60b02a7570edee2b";
      };
  
      meta = {
  