*/
  public static <T> Optional<T> absent() {
    return Absent.withType();
  }

  /**
   * Returns an {@code Optional} instance containing the given non-null reference. To have {@code
   * null} treated as {@link #absent}, use {@link #fromNullable} instead.
   *
   * <p><b>Comparison to {@code java.util.Optional}:</b> no differences.
   *
   * @throws NullPointerException if {@code reference} is null
   */

had been wandering, when a sharp hiss made her draw back in a
hurry:  a large pigeon had flown into her face, and was beating
her violently with its wings.

  `Serpent!' screamed the Pigeon.

  `I'm NOT a serpent!' said Alice indignantly.  `Let me alone!'

  `Serpent, I say again!' repeated the Pigeon, but in a more
subdued tone, and added with a kind of sob, `I've tried every

  private ByteStreams() {}

  /**
   * Copies all bytes from the input stream to the output stream. Does not close or flush either
   * stream.
   *
   * <p><b>Java 9 users and later:</b> this method should be treated as deprecated; use the
   * equivalent {@link InputStream#transferTo} method instead.
   *
   * @param from the input stream to read from
   * @param to the output stream to write to

   * </ul>
   *
   * <p>This assumes that any non-null objects passed to this function conform to the {@code
   * equals()} contract.
   *
   * <p><b>Java 7+ users:</b> This method should be treated as deprecated; use {@link
   * java.util.Objects#equals} instead.
   */
  public static boolean equal(@CheckForNull Object a, @CheckForNull Object b) {
    return a == b || (a != null && a.equals(b));
  }

  /**

   * the result is chosen uniformly at random in [0, numBits), and then the result is chosen in that
   * range uniformly at random. Zero is treated as having log2 == 0.
   */
  static BigInteger randomNonNegativeBigInteger(int numBits) {
    int digits = RANDOM_SOURCE.nextInt(numBits);
    if (digits == 0) {
      return new BigInteger(1, RANDOM_SOURCE);
    } else {

  }

  /**
   * Returns a string representation of x, where x is treated as unsigned.
   *
   * <p><b>Java 8+ users:</b> use {@link Long#toUnsignedString(long)} instead.
   */
  public static String toString(long x) {
    return toString(x, 10);
  }

  /**
   * Returns a string representation of {@code x} for the given radix, where {@code x} is treated as
   * unsigned.
   *

   * text that is terminated by (but does not include) one of {@code \r\n}, {@code \r} or {@code
   * \n}. If the source's content does not end in a line termination sequence, it is treated as if
   * it does.
   *
   * <p>The caller is responsible for ensuring that the returned stream is closed. For example:
   *
   * <pre>{@code
   * try (Stream<String> lines = source.lines()) {

   * text that is terminated by (but does not include) one of {@code \r\n}, {@code \r} or {@code
   * \n}. If the source's content does not end in a line termination sequence, it is treated as if
   * it does.
   *
   * @throws IOException if an I/O error occurs while reading from this source
   */
  @CheckForNull
  public String readFirstLine() throws IOException {

   *
   * <p><b>Note:</b> if mutability is not required, use {@link ImmutableList#of()} instead.
   *
   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
   * use the {@code ArrayList} {@linkplain ArrayList#ArrayList() constructor} directly, taking
   * advantage of <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
   */

   * using a {@code LinkedHashSet} instead, at the cost of increased memory footprint, to get
   * deterministic iteration behavior.
   *
   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
   * use the {@code HashSet} constructor directly, taking advantage of <a
   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
   */