public Either<String, Integer> properFlatMapOfEither(String age) {
    Either<String, String> outerEither = Option
      .of(age)
      .map(Either::<String, String>right)
      .getOrElse(Either.left("empty"));

    Either<String, Integer> flattened = outerEither
      .flatMap(e -> eitherWrapper(e));

    return flattened;
  }

  public Either<String, Integer> eitherWrapper(String value) {
    return Try
      .of(() -> value)
      .map(v -> Either.<String, Integer>right(Integer.valueOf(v)))
      .getOrElse(() -> Either.left(value));
  }