anchor.diff:    '';
   
     buildUsers = optionalString config.services.nix-daemon.enable ''
  -    buildUser=$(dscl . -read /Groups/nixbld GroupMembership 2>&1 | awk '/^GroupMembership: / {print $2}')
  +    buildUser=$(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
           echo "Create the build users or disable the daemon:" >&2
  
positive.code: let
    darwinChanges = ''
      if test -e /run/current-system/darwin-changes; then
        darwinChanges=$(grep -v -f /run/current-system/darwin-changes $systemConfig/darwin-changes 2> /dev/null)
        if test -n "$darwinChanges"; then
          echo >&2
          echo "[1;1mCHANGELOG[0m" >&2
  
negative.code:         echo "ok" >&2
          exit 0
        fi
      '';
  
    };
  