@Override
	public BinaryTree<V> childAt(final int index) {
		switch (index) {
			case 0 -> {
				if (_left != null) return _left;
				if (_right != null) return _right;
				throw error(index);
			}
			case 1 -> {
				if (_right != null) return _right;
				throw error(index);
			}
			default -> throw error(index);
		}
	}
Sets the user object for this node.

@param value the node {@code value}
jenetics.incubator/src/main/java/io/jenetics/incubator/util/BinaryTree.java