anchor.diff: -{ usePipenvShell ? false, sources ? import ./nix/sources.nix }:
  +{ sources ? import ./nix/sources.nix }:
   let
     pkgs = import sources.nixpkgs { };
     niv = (import sources.niv { }).niv;
  
positive.code:     werkzeug
    ]) 
    ;
    shellHook = envVars + (lib.optionalString 
                           usePipenvShell "SHELL=`which zsh` exec pipenv shell --fancy");
  }
  
negative.code:                 (builtins.attrValues installRequirements.packages);
      ignoreCollisions = true;
    };
  
  in pkgs.mkShell {
    name = "ekklesia_portal-dev-env";
  