anchor.diff:    options = {
   
       services.chrony = {
  -
         enable = mkOption {
           type = types.bool;
           default = false;
  
positive.code:   cfgFile = pkgs.writeText "chrony.conf" ''
      ${concatMapStringsSep "\n" (server: "server " + server + " iburst") cfg.servers}
  
      ${optionalString (!config.time.hardwareClockInLocalTime) "rtconutc"}
  
      ${cfg.extraConfig}
    '';
  
negative.code:         description = ''
            The set of NTP servers from which to synchronise.
          '';
        };
  
        initstepslew = {
          enable = mkOption {
            type = types.bool;
            default = false;
            description = ''
              Whether or not we should forcefully change the system time at start.
            '';
          };
  
          threshold = mkOption {
            type = types.int;
            default = 1;
            description = ''
              The threshold for stepping all at once instead of doing a gradual slew.
              The unit is seconds.
            '';
          };
  
          servers = mkOption {
            type = types.listOf types.str;
            default = cfg.servers;
            description = ''
              The servers to use for determining the slew / step at startup.
            '';
          };
        };
  
        extraCmdline = mkOption {
  