constructor<P>(resolver: PageResolver<P>,
id: EV<string>
): PageTree<P> get root(): Multiple<P, P>
children<Child>(depth: number
): Multiple<P, Child> nextSibling(): Single<P, P>
parent<Parent>(): Single<P, Parent>
parents<Parent>(): Multiple<P, Parent>
prevSibling(): Single<P, P>
siblings(): Multiple<P, P>