* ListMultimap<String, String> multimap = ArrayListMultimap.create();
 * for (President pres : US_PRESIDENTS_IN_ORDER) {
 *   multimap.put(pres.firstName(), pres.lastName());
 * }
 * for (String firstName : multimap.keySet()) {
 *   List<String> lastNames = multimap.get(firstName);
 *   out.println(firstName + ": " + lastNames);
 * }
 * }</pre>
 *
 * ... produces output such as:
 *
 * <pre>{@code
 * Zachary: [Taylor]

    Node<K, V> head;
    Node<K, V> tail;
    int count;

    KeyList(Node<K, V> firstNode) {
      this.head = firstNode;
      this.tail = firstNode;
      firstNode.previousSibling = null;
      firstNode.nextSibling = null;
      this.count = 1;
    }
  }

  @CheckForNull private transient Node<K, V> head; // the head for all keys

      throws InterruptedException {
    boolean firstTime = true;
    try {
      do {
        if (nanos <= 0L) {
          return false;
        }
        if (firstTime) {
          if (signalBeforeWaiting) {
            signalNextWaiter();
          }
          beginWaitingFor(guard);
          firstTime = false;
        }
        nanos = guard.condition.awaitNanos(nanos);

        } else {
          return result;
        }
      }
    };
  }

  /** Returns the first node in the tree that is in range. */
  @CheckForNull
  private AvlNode<E> firstNode() {
    AvlNode<E> root = rootReference.get();
    if (root == null) {
      return null;
    }
    AvlNode<E> node;
    if (range.hasLowerBound()) {