nixpkgs.nix

{ config, pkgs, ... }: {
  nixpkgs = {
    config = {
      allowUnfree = true;
      packageOverrides = pkgs: {
        unstable = import (fetchTarball
          "https://github.com/NixOS/nixpkgs-channels/archive/nixos-unstable.tar.gz") {
            config = config.nixpkgs.config;
          };
        nur = import (fetchTarball "https://github.com/nix-community/NUR/archive/master.tar.gz") {
          inherit pkgs;
        };
      };
    };
  };
}