anchor.diff:      ++ lib.optional stdenv.isDarwin [ Cocoa ];
   
     propagatedBuildInputs =
  -    [ cycler dateutil numpy pyparsing tornado freetype kiwisolver
  -      certifi libpng mock pytz pillow ]
  +    [ cycler dateutil numpy pyparsing tornado freetype qhull
  +      kiwisolver certifi libpng mock pytz pillow ]
       ++ lib.optionals enableGtk3 [ cairo pycairo gtk3 gobject-introspection pygobject3 ]
       ++ lib.optionals enableTk [ tcl tk tkinter libX11 ]
       ++ lib.optionals enableQt [ pyqt5 ];
  
positive.code: assert enableQt -> pyqt5 != null;
  
  buildPythonPackage rec {
    version = "3.3.4";
    pname = "matplotlib";
  
    disabled = !isPy3k;
  
    src = fetchPypi {
      inherit pname version;
      sha256 = "3e477db76c22929e4c6876c44f88d790aacdf3c3f8f3a90cb1975c0bf37825b0";
    };
  
    XDG_RUNTIME_DIR = "/tmp";
  
negative.code: { lib, stdenv, fetchPypi, writeText, python, buildPythonPackage, isPy3k, pycairo, backports_functools_lru_cache
  , which, cycler, dateutil, nose, numpy, pyparsing, sphinx, tornado, kiwisolver
  , freetype, qhull, libpng, pkg-config, mock, pytz, pygobject3, gobject-introspection
  , certifi, pillow
  , enableGhostscript ? true, ghostscript ? null, gtk3
  , enableGtk3 ? false, cairo
  