How to use the codesandbox-api.Protocol function in codesandbox-api

setupFileResolver() {
    const fileResolver = {};

    fileResolver.protocol = new Protocol(
      'file-resolver',
      () => true,
      window.parent
    );

    fileResolver.isFile = path =>
      fileResolver.protocol.sendMessage({ m: 'isFile', p: path });
    fileResolver.readFile = path =>
      fileResolver.protocol.sendMessage({ m: 'readFile', p: path });

    this.fileResolver = fileResolver;
  }

this.listener = listen((message: any) => {
      switch (message.type) {
        case 'initialized': {
          if (this.iframe) {
            if (this.iframe.contentWindow) {
              registerFrame(this.iframe.contentWindow, this.bundlerURL);

              if (this.options.fileResolver) {
                this.fileResolverProtocol = new Protocol(
                  'file-resolver',
                  async (data: { m: 'isFile' | 'readFile'; p: string }) => {
                    if (data.m === 'isFile') {
                      return this.options.fileResolver!.isFile(data.p);
                    }

                    return this.options.fileResolver!.readFile(data.p);
                  },
                  this.iframe.contentWindow
                );
              }
            }

            this.updatePreview();
          }
          break;