// Adding the class hashCode to avoid a clash with Succ instances.
        return Pred.class.hashCode() + node.hashCode();
      }
    }

    static final class Succ<N> extends NodeConnection<N> {
      Succ(N node) {
        super(node);
      }

      @Override
      public boolean equals(@Nullable Object that) {
        if (that instanceof Succ) {
          return this.node.equals(((Succ<?>) that).node);

    AvlNode() {
      this.elem = null;
      this.elemCount = 1;
    }

    // For discussion of pred() and succ(), see the comment on the pred and succ fields.

    private AvlNode<E> pred() {
      return requireNonNull(pred);
    }

    private AvlNode<E> succ() {
      return requireNonNull(succ);
    }

    int count(Comparator<? super E> comparator, @ParametricNullness E e) {

    AvlNode() {
      this.elem = null;
      this.elemCount = 1;
    }

    // For discussion of pred() and succ(), see the comment on the pred and succ fields.

    private AvlNode<E> pred() {
      return requireNonNull(pred);
    }

    private AvlNode<E> succ() {
      return requireNonNull(succ);
    }

    int count(Comparator<? super E> comparator, @ParametricNullness E e) {

  }

  private void setSuccessor(int entry, int succ) {
    long succMask = ~0L >>> 32;
    setLink(entry, (link(entry) & ~succMask) | ((succ + 1) & succMask));
  }

  private void setPredecessor(int entry, int pred) {
    long predMask = ~0L << 32;
    setLink(entry, (link(entry) & ~predMask) | ((long) (pred + 1) << 32));
  }

  private void setSucceeds(int pred, int succ) {
    if (pred == ENDPOINT) {

        return; // give up if someone is calling complete
      }
      Waiter succ;
      while (curr != null) {
        succ = curr.next;
        if (curr.thread != null) { // we aren't unlinking this node, update pred.
          pred = curr;
        } else if (pred != null) { // We are unlinking this node and it has a predecessor.
          pred.next = succ;

        return; // give up if someone is calling complete
      }
      Waiter succ;
      while (curr != null) {
        succ = curr.next;
        if (curr.thread != null) { // we aren't unlinking this node, update pred.
          pred = curr;
        } else if (pred != null) { // We are unlinking this node and it has a predecessor.
          pred.next = succ;

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