@Override
	public Iterator<TreeNode<T>> childIterator() {
		return _children != null
			? _children.iterator()
			: Collections.emptyIterator();
	}
Returns the child at the specified index in this node's child array.

@param index   an index into this node's child array
@return the tree-node in this node's child array at the specified index
@throws ArrayIndexOutOfBoundsException  if the {@code index} is out of
        bounds
jenetics.ext/src/main/java/io/jenetics/ext/util/TreeNode.java