import (builtins.fetchTarball {
  url = "https://github.com/NixOS/nixpkgs/archive/573603b7fdb9feb0eb8efc16ee18a015c667ab1b.tar.gz";
  sha256 = "1aa3wshxys9wrb4n0kxp3glvz06mv078kwl6m3v79cyr4gvmjh9q";
})