{
  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs";
  };

  outputs = { self, nixpkgs, ... }:
    let
      eachSystem = with nixpkgs.lib; f: foldAttrs mergeAttrs {}
        (map (s: mapAttrs (_: v: { ${s} = v; }) (f s)) systems.flakeExposed);
    in eachSystem (system:
        let pkgs = nixpkgs.legacyPackages.${system};
        in { devShell = pkgs.mkShell {
            buildInputs = with pkgs; [
                gtk4
                sqlite
                libadwaita
                gobject-introspection
                (python3.withPackages (subpkgs: with subpkgs; [
                    pygobject3 nanoid requests pillow numpy calibre pytest
                ]))
            ];
            GTK_IM_MODULE="simple";
        }; }
    );
}