{ pkgs ? import <nixpkgs> { overlays = [ (import ./overlays.nix) ]; } }: let satauthorizer = pkgs.callPackage ./default.nix { }; in (pkgs.python27.buildEnv.override { extraLibs = with pkgs.python27Packages; [ fixtures testtools hypothesis pyhamcrest satauthorizer ]; ignoreCollisions = true; }).env