anchor.diff:        -e 's,werkzeug>=[^"]*,werkzeug,g' \
         -e 's,psutil>=[^"]*,psutil,g' \
         -e 's,requests>=[^"]*,requests,g' \
  +      -e 's,future>=[^"]*,future,g' \
         setup.py
     '';
   
  
positive.code:     semantic-version flask_principal werkzeug flaskbabel tornado
      psutil pyserial flask_login netaddr markdown sockjs-tornado
      pylru pyyaml sarge feedparser netifaces click websocket_client
      scandir chainmap future
    ];
  
    buildInputs = with pythonPackages; [ nose mock ddt ];
  
negative.code: 
  in pythonPackages.buildPythonApplication rec {
    name = "OctoPrint-${version}";
    version = "1.3.4";
  
    src = fetchFromGitHub {
      owner = "foosel";
      repo = "OctoPrint";
      rev = version;
      sha256 = "06l8khbq3waaaa4cqpv6056w1ziylkfgzlb28v30i1h234rlkknq";
    };
  
    # We need old Tornado
  