+ # Is `self` not displayed in the page.
+ #
+ # By default, empty elements are hidden.
+ fun is_hidden: Bool do return children.is_empty
+
+ # Title used in table of content if any.
+ var toc_title: nullable String is writable, lazy do return title
+
+ # Is `self` hidden in the table of content?
+ var is_toc_hidden: Bool is writable, lazy do
+ return toc_title == null or is_hidden
+ end