let
  # Look here for information about how to generate `nixpkgs-version.json`.
  #  → https://nixos.wiki/wiki/FAQ/Pinning_Nixpkgs
  pinnedVersion = builtins.fromJSON (builtins.readFile ./.nixpkgs-version.json);
  pinnedPkgs = import (builtins.fetchGit {
    inherit (pinnedVersion) url rev;

    ref = "nixos-unstable";
  }) {};
in

# This allows overriding pkgs by passing `--arg pkgs ...`
{ pkgs ? pinnedPkgs }:

with pkgs.python3.pkgs;
buildPythonPackage {
  name = "env";
  src = ./.;
  propagatedBuildInputs = [
    docopt
    requests
    beautifulsoup4
  ];
  checkInputs = [ black jq ];
}