             return pair
           }
 
-          state.preview = PreviewUtils.state(for: pair.state.uuid, baseUrl: baseServerUrl, buffer: buffer)
+          state.preview = PreviewUtils.state(for: pair.state.uuid, baseUrl: self.baseServerUrl, buffer: buffer)
 
         case .close:
-          state.preview = PreviewUtils.state(for: .none, baseUrl: baseServerUrl)
+          state.preview = PreviewUtils.state(for: .none, baseUrl: self.baseServerUrl)
 
         default:
           return pair


    typealias Pair = StateActionPair<UuidState<MainWindow.State>, MainWindow.Action>

    func reduce(_ source: Observable<Pair>) -> Observable<Pair> {
      return source.map { pair in
        guard let baseServerUrl = self.parentTransformer?.baseServerUrl else {
          return pair
        }

        var state = pair.state.payload

        switch pair.action {

      }
    }

    fileprivate let baseServerUrl: URL
  }

  class OpenedFileListReducer: Reducer {

    typealias Pair = StateActionPair<UuidState<MainWindow.State>, OpenedFileList.Action>

    init(_ baseServerUrl: URL) {
      self.baseServerUrl = baseServerUrl
    }

    func reduce(_ source: Observable<Pair>) -> Observable<Pair> {
      return source.map { pair in
        var state = pair.state.payload

        switch pair.action {

        case let .open(buffer):
          state.preview = PreviewUtils.state(for: pair.state.uuid, baseUrl: self.baseServerUrl, buffer: buffer)

        }

