function* publishListing() {
  yield* guard(
    function* reviewListing() {
      const approval = yield* resumable(
        function* scanPhotos() {
          yield* sleep(1000);
          throw new Error("scanner offline");
        },
      );

      yield* recordApproval(approval);
    },

    function* approveManually(error) {
      yield* sleep(1000);
      return [true, `manual approval: ${error.kind}`] as const;
    },
  );
}