{
  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";
  };

   outputs = { self, nixpkgs, flake-utils, mach-nix, hopsflow }:
     let
       python = "python39Full";
       pypiDataRev = "master";
       pypiDataSha256 = "041rpjrwwa43hap167jy8blnxvpvbfil0ail4y4mar1q5f0q57xx";

     in flake-utils.lib.eachSystem ["x86_64-linux"] (system:
       let
         pkgs = nixpkgs.legacyPackages.${system};
         mach-nix-wrapper = import mach-nix { inherit pkgs python pypiDataRev pypiDataSha256; };

         hopsflowPkg = hopsflow.defaultPackage.${system};

         pythonShell = mach-nix-wrapper.mkPython {
           requirements = ''
                  numba
                  quadpy
                  idesolver
                  ptpython
                  matplotlib
                  jupyter
                  h5py
                  qutip
                  numpy
                  mypy
                  mkl
                  black
           '';
           packagesExtra = [hopsflowPkg];
            _.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 = [
             pkgs.nodePackages.pyright pythonShell
           ];
         };
       });
}