anchor.diff:        if tail v != [] then zipModules v else head v
       ) list;
   
  -  rename = statusTemplate: from: keyword: to: with pkgs.lib;
  +  rename = statusTemplate: from: to: with pkgs.lib;
       let
         status = statusTemplate from to;
         setTo = setAttrByPath (splitString "." to);
  
positive.code: in zipModules ([]
  
  # usage example:
  # ++ rename alias "services.xserver.slim.theme" to "services.xserver.displayManager.slim.theme"
  ++ rename obsolete "environment.extraPackages" to "environment.systemPackages"
  
  # Old Grub-related options.
  ++ rename obsolete "boot.copyKernels" to "boot.loader.grub.copyKernels"
  ++ rename obsolete "boot.extraGrubEntries" to "boot.loader.grub.extraEntries"
  ++ rename obsolete "boot.extraGrubEntriesBeforeNixos" to "boot.loader.grub.extraEntriesBeforeNixOS"
  ++ rename obsolete "boot.grubDevice" to "boot.loader.grub.device"
  ++ rename obsolete "boot.bootMount" to "boot.loader.grub.bootDevice"
  ++ rename obsolete "boot.grubSplashImage" to "boot.loader.grub.splashImage"
  
  ++ rename obsolete "boot.initrd.extraKernelModules" to "boot.initrd.kernelModules"
  
  # OpenSSH
  ++ rename obsolete "services.sshd.ports" to "services.openssh.ports"
  ++ rename obsolete "services.sshd.enable" to "services.openssh.enable"
  ++ rename obsolete "services.sshd.allowSFTP" to "services.openssh.allowSFTP"
  ++ rename obsolete "services.sshd.forwardX11" to "services.openssh.forwardX11"
  ++ rename obsolete "services.sshd.gatewayPorts" to "services.openssh.gatewayPorts"
  ++ rename obsolete "services.sshd.permitRootLogin" to "services.openssh.permitRootLogin"
  ++ rename obsolete "services.xserver.startSSHAgent" to "services.xserver.startOpenSSHAgent"
  
  # KDE
  ++ rename deprecated "kde.extraPackages" to "environment.kdePackages"
  
  
  ) # do not add renaming after this.
  
negative.code: {pkgs, options, config, ...}:
  
  let
  
    alias = from: to: {
      name = "Alias";
  