anchor.diff:        description = "Boot disk (e.g. /dev/sda) for GRUB2";
       };
   
  -    useDHCP = mkOption {
  -      type = types.bool;
  -      default = true;
  -      description = "Use DHCP";
  -    };
  -
       externalInterface = mkOption {
         type = types.nullOr types.str;
         default = null;
         description = "External interface (i.e. for Docker nat)";
  -    };
  -
  -    address = mkOption {
  -      type = types.nullOr types.str;
  -      default = null;
  -      description = "IPv4 address if using static IP.";
       };
   
       adminAuthorizedKeys = mkOption {
  
positive.code:   config = mkMerge [
      configuration
  
      (mkIf (! cfg.useDHCP) netConfig)
  
      (mkIf cfg.docker.enable docker)
  
      (mkIf cfg.mailRelay.enable mailRelay)
  
negative.code: with lib;
  let
    cfg = config.features.os;
  
    configuration = {
      networking = {
  