*
         * Allows login with invalid credentials (username and/or password)
         * Fallback to anonymous authentication is permitted
         */
        GUEST,
        /**
         * Regular user authentication
         */
        USER
    }

  }

  /**
   * Writes this {@code BloomFilter} to an output stream, with a custom format (not Java
   * serialization). This has been measured to save at least 400 bytes compared to regular
   * serialization.
   *
   * <p>Use {@linkplain #readFrom(InputStream, Funnel)} to reconstruct the written BloomFilter.
   */
  public void writeTo(OutputStream out) throws IOException {
    // Serial form: