public interface TreeNodeChildren : Children {
	Either<Error, TreeNode> addNewChildAt (int pos);
	Either<Error, TreeNode> deleteChildAt(int pos);
	Either<Error,TreeNode> addNewChildAt(int pos,TreeNode newChild);
	Either<Error,TreeNode> replaceNode(int pos,TreeNode replacement);
	List<TreeNode> getChildrenAsRawList();
}