anchor.diff:      overrides = self: super: with self; {
         backports_ssl_match_hostname = self.backports_ssl_match_hostname_3_4_0_2;
   
  +      flask = super.flask.overridePythonAttrs (oldAttrs: rec {
  +        version = "0.12.4";
  +        src = oldAttrs.src.override {
  +          inherit version;
  +          sha256 = "2ea22336f6d388b4b242bc3abf8a01244a8aa3e236e7407469ef78c16ba355dd";
  +        };
  +      });
  +
         tornado = buildPythonPackage rec {
  -        name = "tornado-${version}";
  +        pname = "tornado";
           version = "4.0.2";
   
           propagatedBuildInputs = [ backports_ssl_match_hostname certifi ];
   
  -        src = fetchurl {
  -          url = "mirror://pypi/t/tornado/${name}.tar.gz";
  +        src = fetchPypi {
  +          inherit pname version;
             sha256 = "1yhvn8i05lp3b1953majg48i8pqsyj45h34aiv59hrfvxcj5234h";
           };
         };
   
         flask_login = buildPythonPackage rec {
  -        name = "Flask-Login-${version}";
  +        pname = "Flask-Login";
           version = "0.2.2";
   
  -        src = fetchurl {
  -          url = "mirror://pypi/F/Flask-Login/${name}.tar.gz";
  +        src = fetchPypi {
  +          inherit pname version;
             sha256 = "09ygn0r3i3jz065a5psng6bhlsqm78msnly4z6x39bs48r5ww17p";
           };
   
           propagatedBuildInputs = [ flask ];
  -        buildInputs = [ nose ];
  +        checkInputs = [ nose ];
   
           # No tests included
           doCheck = false;
  
positive.code:       jinja2 = buildPythonPackage rec {
          pname = "Jinja2";
          version = "2.8.1";
          name = "${pname}-${version}";
  
          src = fetchurl {
            url = "mirror://pypi/J/Jinja2/${name}.tar.gz";
            sha256 = "14aqmhkc9rw5w0v311jhixdm6ym8vsm29dhyxyrjfqxljwx1yd1m";
          };
  
  
negative.code:       -e 's,PyYAML>=[^"]*,PyYAML,g' \
        -e 's,scandir>=[^"]*,scandir,g' \
        -e 's,werkzeug>=[^"]*,werkzeug,g' \
        -e 's,psutil==[^"]*,psutil,g' \
        -e 's,requests>=[^"]*,requests,g' \
        -e 's,future>=[^"]*,future,g' \
        -e 's,pyserial>=[^"]*,pyserial,g' \
  