import (builtins.fetchTarball {
  name = "nixpkgs-unstable-2019-05-08";
  url = https://github.com/NixOS/nixpkgs/archive/5964b3a2e21c9d9369b55bbf48dff71ff0671f25.tar.gz;
  sha256 = "1q3x73gzjm8xz3dxa3dkyb7m69aa75an0mnld62qyi4cyv6qmhw3";
}) {}