{
  inputs.nixpkgs.url = "github:NixOS/nixpkgs";

  description = "Useful libs";
  outputs = { self, nixpkgs }: {
    lib = rec {
      withNarKey = dep: moduleAttrs:
        let module = dep.${moduleAttrs};
            key = builtins.hashString "sha256" (builtins.path { path = dep.sourceInfo.outPath; name = "source"; });
        in if builtins.isFunction module
          then args@{ config, lib, pkgs, ... }: (module args // { inherit key; })
          else module // { inherit key; };
    };
  };
}