*/
  public static CharMatcher none() {
    return None.INSTANCE;
  }

  /**
   * Determines whether a character is whitespace according to the latest Unicode standard, as
   * illustrated <a
   * href="http://unicode.org/cldr/utility/list-unicodeset.jsp?a=%5Cp%7Bwhitespace%7D">here</a>.
   * This is not the same definition used by other Java APIs. (See a <a

   * accessed directly after this method returns. These conditions are ensured if the map is created
   * empty, passed directly to this method, and no reference to the map is retained, as illustrated
   * in the following code fragment:
   *
   * {@snippet :
   * Set<Object> identityHashSet = Sets.newSetFromMap(new IdentityHashMap<Object, Boolean>());
   * }
   *

  @Override
  public void add(Range<C> rangeToAdd) {
    checkNotNull(rangeToAdd);

    if (rangeToAdd.isEmpty()) {
      return;
    }

    // We will use { } to illustrate ranges currently in the range set, and < >
    // to illustrate rangeToAdd.
    Cut<C> lbToAdd = rangeToAdd.lowerBound;
    Cut<C> ubToAdd = rangeToAdd.upperBound;

    Entry<Cut<C>, Range<C>> entryBelowLb = rangesByLowerBound.lowerEntry(lbToAdd);

        @Override
        protected List<LockGraphNode> initialValue() {
          return newArrayListWithCapacity(3);
        }
      };

  /**
   * A Throwable used to record a stack trace that illustrates an example of a specific lock
   * acquisition ordering. The top of the stack trace is truncated such that it starts with the
   * acquisition of the lock in question, e.g.
   *
   * <pre>

   *       contained by the latter range)
   * </ul>
   *
   * <p>Note that if {@code a.encloses(b)}, then {@code b.contains(v)} implies {@code
   * a.contains(v)}, but as the last two examples illustrate, the converse is not always true.
   *
   * <p>Being reflexive, antisymmetric and transitive, the {@code encloses} relation defines a

   *       contained by the latter range)
   * </ul>
   *
   * <p>Note that if {@code a.encloses(b)}, then {@code b.contains(v)} implies {@code
   * a.contains(v)}, but as the last two examples illustrate, the converse is not always true.
   *
   * <p>Being reflexive, antisymmetric and transitive, the {@code encloses} relation defines a

    Iterator<String> itr2 = Iterators.concat(itr1, singletonIterator("d"));
    assertThat(itr2.next()).isEqualTo("c");
    assertThat(itr2.next()).isEqualTo("d");
  }

  /** Illustrates the somewhat bizarre behavior when a null is passed in. */
  public void testConcatContainingNull() {
    Iterator<Iterator<Integer>> input =
        (Iterator<Iterator<Integer>>)

    Iterator<String> itr2 = Iterators.concat(itr1, singletonIterator("d"));
    assertThat(itr2.next()).isEqualTo("c");
    assertThat(itr2.next()).isEqualTo("d");
  }

  /** Illustrates the somewhat bizarre behavior when a null is passed in. */
  public void testConcatContainingNull() {
    Iterator<Iterator<Integer>> input =
        (Iterator<Iterator<Integer>>)