anchor.diff:  
   
     pg8000 = buildPythonPackage rec {
  -    name = "pg8000-1.9.14";
  +    name = "pg8000-1.10.1";
   
       src = pkgs.fetchurl {
         url = "http://pypi.python.org/packages/source/p/pg8000/${name}.tar.gz";
  -      sha256 = "1vandvfaf1m3a1fbc7nbm6syfqr9bazhzsnmai0jpjkbmb349izs";
  +      md5 = "173275fd76628b0e0cbed70ed9ce9eb9";
       };
   
       propagatedBuildInputs = with self; [ pytz ];
  
positive.code: 
  
    pyramid_tm = buildPythonPackage rec {
      name = "pyramid_tm-0.7";
  
      src = pkgs.fetchurl {
        url = "http://pypi.python.org/packages/source/p/pyramid_tm/${name}.tar.gz";
        md5 = "6dc917d262c69366630c542bd21859a3";
      };
  
      # tests are failing in version 0.7 but are fixed in trunk
  
negative.code: 
  
    mccabe = buildPythonPackage (rec {
      name = "mccabe-0.3";
  
      src = pkgs.fetchurl {
        url = "http://pypi.python.org/packages/source/m/mccabe/${name}.tar.gz";
        md5 = "81640948ff226f8c12b3277059489157";
      };
  
      meta = {
        description = "McCabe checker, plugin for flake8";
  