{
  description = "Calculating open system bath energy changes with HOPS and analytically.";

  inputs = {
    nixpkgs.url = "nixpkgs/nixos-unstable";
    mach-nix.url = "github:DavHau/mach-nix";
    flake-utils.url = "github:numtide/flake-utils";
    hopsflow.url = "github:vale981/hopsflow";
    hops.url = "git+ssh://git@gitlab.hrz.tu-chemnitz.de/s4498638--tu-dresden.de/hops.git?ref=main";
  };

   outputs = { self, nixpkgs, flake-utils, mach-nix, hopsflow, hops }:
     let
       python = "python39";

     in flake-utils.lib.eachSystem ["x86_64-linux"] (system:
       let
         pkgs = nixpkgs.legacyPackages.${system};
         mach-nix-wrapper = import mach-nix { inherit pkgs python;  };

         hopsflowPkg = hopsflow.defaultPackage.${system};

         pythonShell = mach-nix-wrapper.mkPython {
           requirements = ''
                  numba
                  quadpy
                  idesolver
                  ptpython
                  matplotlib
                  jupyter
                  qutip
                  mkl
                  sqlitedict
                  '';
           packagesExtra = [
             hopsflowPkg
             hops.defaultPackage.${system}
           ];
           _.jupyter.postInstall = ''
                rm $out/lib/python*/site-packages/__pycache__/jupyter.cpython-39.pyc
                rm $out/lib/python*/site-packages/jupyter.py
                '';

           providers.tk = "nixpkgs";
         };

       in {
         devShell = pkgs.mkShell {
           buildInputs = with pkgs; [pythonShell sshfs pyright sage];
           # shellHook = ''
           #         export PYTHONPATH=$PYTHONPATH:${builtins.toString ./energy_flow_proper/hops}
           #         '';
         };
       });
}