builtins.fetchTarball {url="https://github.com/NixOS/nixpkgs-channels/archive/ce961fad160d02fdbd78d95b7cd1985a622d110f.tar.gz"; sha256="1bqakqa07f4l1h536n0k69il93d57qymacpzwv9760qq7i8xhhlj";}