pub type ItemC<'a, C> = Item<'a, Tag<'a, C>>;
Item type for tag convertor C.
pub enum ItemC<'a, C> { PlainText(&'a str), Element(Vec<Tag<'a, C>>, Vec<Item<'a, Tag<'a, C>>>), }
Plain text(escaped) without any style.
A styled element, contains a series tag name and subitems.