anchor.diff:  
   python3.pkgs.buildPythonApplication rec {
     pname = "calibre-web";
  -  version = "0.6.17";
  +  version = "0.6.18";
   
     src = fetchFromGitHub {
       owner = "janeczku";
       repo = "calibre-web";
       rev = version;
  -    sha256 = "sha256-K2va9as+z00txpg/0fR89+kpMzpQSiSSIV489NDs8Bs=";
  +    sha256 = "sha256-KjmpFetNhNM5tL34e/Pn1i3hc86JZglubSMsHZWu198=";
     };
   
     propagatedBuildInputs = with python3Packages; [
  +    advocate
       backports_abc
       flask-babel
       flask_login
  
positive.code:     tornado
      unidecode
      Wand
    ];
  
    patches = [
  
negative.code:       --replace "cps = calibreweb:main" "calibre-web = calibreweb:main" \
        --replace "Flask>=1.0.2,<2.1.0" "Flask>=1.0.2" \
        --replace "Flask-Login>=0.3.2,<0.5.1" "Flask-Login>=0.3.2" \
        --replace "flask-wtf>=0.14.2,<1.1.0" "flask-wtf>=0.14.2" \
        --replace "lxml>=3.8.0,<4.9.0" "lxml>=3.8.0" \
        --replace "PyPDF3>=1.0.0,<1.0.7" "PyPDF3>=1.0.0" \
        --replace "requests>=2.11.1,<2.28.0" "requests" \
        --replace "unidecode>=0.04.19,<1.4.0" "unidecode>=0.04.19" \
        --replace "werkzeug<2.1.0" ""
    '';
  
    # Upstream repo doesn't provide any tests.
  