this.totalCount = elemCount + totalCount(left) + totalCount(right);
    }

    private void recomputeHeight() {
      this.height = 1 + max(height(left), height(right));
    }

    private void recompute() {
      recomputeMultiset();
      recomputeHeight();
    }

    private AvlNode<E> rebalance() {
      switch (balanceFactor()) {
        case -2: