this.closeable = closeable;
      this.thrown = thrown;
      this.suppressed = suppressed;
    }

    @Override
    public boolean equals(@Nullable Object obj) {
      if (obj instanceof Suppression) {
        Suppression other = (Suppression) obj;
        return closeable.equals(other.closeable)
            && thrown.equals(other.thrown)

 *   <li>If no exceptions or errors were thrown in the try block, the <i>first</i> exception thrown
 *       by an attempt to close a resource will be thrown.
 *   <li>Any exception caught when attempting to close a resource that is <i>not</i> thrown (because
 *       another exception is already being thrown) is <i>suppressed</i>.
 * </ul>
 *
 * <p>An exception that is suppressed is added to the exception that <i>will</i> be thrown using

  /** Throws an undeclared checked exception. */
  private static void sneakyThrow(Throwable t) {
    class SneakyThrower<T extends Throwable> {
      @SuppressWarnings("unchecked") // intentionally unsafe for test
      void throwIt(Throwable t) throws T {
        throw (T) t;
      }
    }
    new SneakyThrower<Error>().throwIt(t);
  }

 *   <li>If no exceptions or errors were thrown in the try block, the <i>first</i> exception thrown
 *       by an attempt to close a resource will be thrown.
 *   <li>Any exception caught when attempting to close a resource that is <i>not</i> thrown (because
 *       another exception is already being thrown) is <i>suppressed</i>.
 * </ul>
 *
 * <p>An exception that is suppressed is added to the exception that <i>will</i> be thrown using

      this.closeable = closeable;
      this.thrown = thrown;
      this.suppressed = suppressed;
    }

    @Override
    public boolean equals(@Nullable Object obj) {
      if (obj instanceof Suppression) {
        Suppression other = (Suppression) obj;
        return closeable.equals(other.closeable)
            && thrown.equals(other.thrown)

      throw t;
    }
  }

  /** Calls threadFail with message "should throw exception". */
  public void threadShouldThrow() {
    threadFail("should throw exception");
  }

  /** Calls threadFail with message "should throw" + exceptionName. */
  public void threadShouldThrow(String exceptionName) {
    threadFail("should throw " + exceptionName);
  }

  /**

      throw t;
    }
  }

  /** Calls threadFail with message "should throw exception". */
  public void threadShouldThrow() {
    threadFail("should throw exception");
  }

  /** Calls threadFail with message "should throw" + exceptionName. */
  public void threadShouldThrow(String exceptionName) {
    threadFail("should throw " + exceptionName);
  }

  /**

   *
   * @throws NoSuchFileException if the file does not exist <i>(optional specific exception)</i>
   * @throws NotDirectoryException if the file could not be opened because it is not a directory
   *     <i>(optional specific exception)</i>
   * @throws IOException if an I/O error occurs
   */
  public static ImmutableList<Path> listFiles(Path dir) throws IOException {

   *
   * @throws NoSuchFileException if the file does not exist <i>(optional specific exception)</i>
   * @throws NotDirectoryException if the file could not be opened because it is not a directory
   *     <i>(optional specific exception)</i>
   * @throws IOException if an I/O error occurs
   */
  public static ImmutableList<Path> listFiles(Path dir) throws IOException {

    protected abstract long makeKey ( Request request ) throws IOException;


    protected abstract Long peekKey () throws IOException;


    protected abstract void doSend ( Request request ) throws IOException;


    protected abstract void doRecv ( Response response ) throws IOException;


    protected abstract void doSkip ( Long key ) throws IOException;


    /**
     *