return Ascii.INSTANCE;
  }

  /**
   * Determines whether a character is a BMP digit according to <a
   * href="http://unicode.org/cldr/utility/list-unicodeset.jsp?a=%5Cp%7Bdigit%7D">Unicode</a>. If
   * you only care to match ASCII digits, you can use {@code inRange('0', '9')}.
   *
   * @deprecated Many digits are supplementary characters; see the class documentation.
   * @since 19.0 (since 1.0 as constant {@code DIGIT})
   */

    for (int i = 0; i < 50; i++) {
      list.add(new Object());
    }

    Ordering<Object> arbitrary = Ordering.arbitrary();
    Collections.sort(list, arbitrary);

    // Now we don't care what order it's put the list in, only that
    // comparing any pair of elements gives the answer we expect.
    Helpers.testComparator(arbitrary, list);

    assertEquals("Ordering.arbitrary()", arbitrary.toString());

    for (int i = 0; i < 50; i++) {
      list.add(new Object());
    }

    Ordering<Object> arbitrary = Ordering.arbitrary();
    Collections.sort(list, arbitrary);

    // Now we don't care what order it's put the list in, only that
    // comparing any pair of elements gives the answer we expect.
    Helpers.testComparator(arbitrary, list);

    assertEquals("Ordering.arbitrary()", arbitrary.toString());

   * exercise null handling fail on those subcollections.
   */
  public abstract static class NullsBefore implements Comparator<@Nullable String>, Serializable {
    /*
     * We don't serialize this class in GWT, so we don't care about whether GWT will serialize this
     * field.
     */
    @GwtTransient private final String justAfterNull;

    protected NullsBefore(String justAfterNull) {
      if (justAfterNull == null) {

                            "b", (Collection<String>) ImmutableSortedSet.of("bob", "bagel")),
                        Helpers.mapEntry(
                            "c", (Collection<String>) ImmutableSortedSet.of("carl", "carol")),
                        Helpers.mapEntry(
                            "d", (Collection<String>) ImmutableSortedSet.of("david", "dead")),
                        Helpers.mapEntry(

      return null;
    }
    int partsSkipped = IPV6_PART_COUNT - (delimiterCount + 1); // estimate; may be modified later
    boolean hasSkip = false;
    // Scan for the appearance of ::, to mark a skip-format IPV6 string and adjust the partsSkipped
    // estimate.
    for (int i = 0; i < ipString.length() - 1; i++) {
      if (ipString.charAt(i) == IPV6_DELIMITER && ipString.charAt(i + 1) == IPV6_DELIMITER) {

        // subtracting two nonnegative ints can't overflow
        // cmpRemToHalfDivisor has the same sign as compare(abs(rem), abs(q) / 2).
        if (cmpRemToHalfDivisor == 0) { // exactly on the half mark
          increment = (mode == HALF_UP || (mode == HALF_EVEN & (div & 1) != 0));
        } else {
          increment = cmpRemToHalfDivisor > 0; // closer to the UP value
        }
        break;
      default:

   *       terminate whichever thread happens to trigger the execution.
   * </ul>
   *
   * A specific warning about locking: Code that executes user-supplied tasks, such as {@code
   * ListenableFuture} listeners, should take care not to do so while holding a lock. Additionally,
   * as a further line of defense, prefer not to perform any locking inside a task that will be run

    assertThat(expected).hasMessageThat().isEqualTo("Mark not set");
  }

  public void testMarkNotSupported() {
    counter = new CountingInputStream(new UnmarkableInputStream());

    IOException expected = assertThrows(IOException.class, () -> counter.reset());
    assertThat(expected).hasMessageThat().isEqualTo("Mark not supported");
  }

    assertEquals(big[1], small[3]);
  }

  public void testLimit_mark() throws Exception {
    byte[] big = newPreFilledByteArray(5);
    InputStream bin = new ByteArrayInputStream(big);
    InputStream lin = ByteStreams.limit(bin, 2);

    int read = lin.read();
    assertEquals(big[0], read);
    lin.mark(2);

    read = lin.read();
    assertEquals(big[1], read);
    read = lin.read();