anchor.diff:  
   
     urwid = buildPythonPackage (rec {
  -    name = "urwid-1.2.1";
  +    name = "urwid-1.3.0";
   
       # multiple:  NameError: name 'evl' is not defined
       doCheck = false;
   
       src = pkgs.fetchurl {
         url = "https://pypi.python.org/packages/source/u/urwid/${name}.tar.gz";
  -      md5 = "6a05ada11b87e7b026b01fc5150855b0";
  +      md5 = "a989acd54f4ff1a554add464803a9175";
       };
   
       meta = {
  
positive.code: 
      src = pkgs.fetchurl {
        url = "http://pypi.python.org/packages/source/t/tweepy/${name}.tar.gz";
        sha256 = "0wcj5g21brcqr1g7m4by4rs72lfiib4scg19qynn2wz1x77jyrzp";
      };
  
      meta = {
  
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";
  