anchor.diff:  with lib;
   
   let
  +  cfg = config.services.chrony;
   
     stateDir = "/var/lib/chrony";
  -
  -  keyFile = "/etc/chrony.keys";
  -
  -  cfg = config.services.chrony;
  +  keyFile = "${stateDir}/chrony.keys";
   
     configFile = pkgs.writeText "chrony.conf" ''
       ${concatMapStringsSep "\n" (server: "server " + server) cfg.servers}
  
positive.code:       { description = "chrony NTP daemon";
  
          wantedBy = [ "multi-user.target" ];
          wants = [ "time-sync.target" ];
          before = [ "time-sync.target" ];
          after = [ "network.target" ];
          conflicts = [ "ntpd.service" "systemd-timesyncd.service" ];
  
          path = [ pkgs.chrony ];
  
          preStart =
            ''
              mkdir -m 0755 -p ${stateDir}
              touch ${keyFile}
              chmod 0640 ${keyFile}
              chown chrony:chrony ${stateDir} ${keyFile}
            '';
  
          serviceConfig =
            { ExecStart = "${pkgs.chrony}/bin/chronyd ${chronyFlags}";
            };
        };
  
    };
  
  }
  
negative.code:     ${cfg.extraConfig}
    '';
  
    chronyFlags = "-m -u chrony -f ${configFile} ${toString cfg.extraFlags}";
  in
  {
    options = {
      services.chrony = {
        enable = mkOption {
          default = false;
          description = ''
  