final: prev: {
  # xonsh = prev.xonsh.overrideAttrs (old: rec {
  #   version = "0.12.4";
  #   src = final.fetchFromGitHub {
  #     owner = "xonsh";
  #     repo = "xonsh";
  #     rev = version;
  #     sha256 = "0kdps0gf0767zy0fs6qn39rv4z3x7ck0qz1pzx6962593171yk8b";
  #   };
  #   propagatedBuildInputs = prev.xonsh.propagatedBuildInputs ++ [final.python3Packages.virtualenv];
  # });

  python = prev.python.override {
    packageOverrides = pfinal: pprev: {
      prompt-toolkit = pprev.prompt-toolkit.overrideAttrs (old: rec {
        version = "3.0.29";
        src = pfinal.fetchPypi {
          pname = "prompt_toolkit";
          inherit version;
          sha256 = "";
        };
      });
    };
  };

  # Mach-nix is a toolkit for constructing custom Python environments
  mach-nix = import (builtins.fetchGit {
    url = "https://github.com/DavHau/mach-nix/";
    ref = "refs/tags/3.4.0";
  }) {
    pkgs = final;
  };

  xonsh_pyenv = final.mach-nix.mkPython {
    requirements = ''
    xontrib-fzf-widgets
    xonsh-direnv
    '';
  };

  xonsh_with_plugins = final.xonsh.overrideAttrs (old: {
    propagatedBuildInputs = old.propagatedBuildInputs ++ final.xonsh_pyenv.python.pkgs.selectPkgs final.xonsh_pyenv.python.pkgs;
  });
}