$ cat shell.nix
with import (fetchTarball {
  url = https://github.com/nixos/nixpkgs-channels/archive/nixpkgs-unstable.tar.gz;
}) {};
mkShell {
  buildInputs =
    [(python3.withPackages (ps: with ps; [
      numpy
      matplotlib
      tensorflow
      # tensorflow-tensorboard
    ]))];
}