anchor.diff:        default = throw "You must specify `uploadDir'.";
         example = "/data/mediawiki-upload";
         description = "The directory that stores uploaded files.";
  +    };
  +
  +    defaultSkin = mkOption {
  +      default = "standard";
  +      example = "nostalgia";
  +      description = "Default skin: you can change the default skin.";
       };
   
       extraConfig = mkOption {
  
positive.code:           $wgUploadDirectory = "${config.uploadDir}";
          ''}
  
          ${config.extraConfig}
        ?>
      '';
  
negative.code:       sha256 = "1d8afbdh3lsg54b69mnh6a47psb3lg978xpp277qs08yz15cjf7q";
      };
  
      skinTarball = if config.defaultSkin == "clean" then src_clean_skin
               else if config.defaultSkin == "nixos" then src_nixos_skin
               else "";
  
      buildPhase = "
        if [ '${skinTarball}' ]; then
           tar xfz ${skinTarball} -C skins/;
        fi
      ";
  
      installPhase =
        ''
  