}

    private static final long serialVersionUID = 0L;
  }

  /**
   * Returns a synchronized (thread-safe) bimap backed by the specified bimap. In order to guarantee
   * serial access, it is critical that <b>all</b> access to the backing bimap is accomplished
   * through the returned bimap.
   *
   * <p>It is imperative that the user manually synchronize on the returned map when accessing any