docs: private IntervalRBTreeNode<T> rotateRight(IntervalRBTreeNode<T> n) {
      assert (n != null) && isRed(n.leftChild);
      IntervalRBTreeNode<T> x = n.leftChild;
      n.leftChild = x.rightChild;
      x.rightChild = n;
      x.color = x.rightChild.color;
      x.rightChild.color = IntervalRBTreeNode.RED;
      x.n = n.n;
      n.n = size(n.leftChild) + size(n.rightChild) + 1;
      setMaxMin(n);
      setMaxMin(x);
      return x;
    }