{ config, lib, pkgs, ... }:
{
  options = {
    overlays = lib.mkOption {
      type = lib.types.listOf (lib.types.functionTo (lib.types.functionTo (lib.types.lazyAttrsOf lib.types.unspecified)));
      default = [];
    };
    outputs.overlay = lib.mkOption {
      type = lib.types.functionTo (lib.types.functionTo (lib.types.lazyAttrsOf lib.types.unspecified));
    };
  };
  config.outputs.overlay = lib.composeManyExtensions config.overlays;
}