import (fetchTarball {
  url = "https://github.com/NixOS/nixpkgs/archive/bc9df0f66110039e495b6debe3a6cda4a1bb0fed.tar.gz";
  sha256 = "0y2w259j0vqiwjhjvlbsaqnp1nl2zwz6sbwwhkrqn7k7fmhmxnq1";
})