anchor.diff:      fi
     '';
   
  -  buildUsers = optionalString config.services.nix-daemon.enable ''
  +  buildUsers = ''
       buildUser=$(dscl . -read /Groups/nixbld GroupMembership 2>&1 | awk '/^GroupMembership: / {print $2}') || true
       if [ -z $buildUser ]; then
           echo "[1;31merror: Using the nix-daemon requires build users, aborting activation[0m" >&2
  
positive.code: with lib;
  
  let
    darwinChanges = ''
      darwinChanges=/dev/null
      if test -e /run/current-system/darwin-changes; then
  
negative.code: 
  {
    options = {
      system.checks.verifyNixPath = mkOption {
        type = types.bool;
        default = true;
        description = "Whether to run the NIX_PATH validation checks.";
      };
  
      system.checks.text = mkOption {
        internal = true;
        type = types.lines;
        default = "";
      };
    };
  
    config = {
  
      system.checks.text = mkMerge [
        darwinChanges
        runLink
        (mkIf config.services.nix-daemon.enable buildUsers)
        nixStore
        (mkIf config.nix.gc.automatic nixGarbageCollector)
        nixChannels
        nixInstaller
        (mkIf cfg.verifyNixPath nixPath)
      ];
  
      system.activationScripts.checks.text = ''
        ${cfg.text}
  
        if test ''${checkActivation:-0} -eq 1; then
          echo "ok" >&2
  