import (fetchTarball {
  url = "https://github.com/NixOS/nixpkgs/archive/2923bd5d0669f1ec6ab03ddce052e9c5efb46d8f.tar.gz";
  sha256 = "16cn93rpxfql5idhigyjyhc013a3hwzyy2dl1xv7h2p78sk728vw";
})