val tagged_child : t -> Tag.t -> [ `Tree ] node -> [ `Tree ] node
val select_child : t -> Ptset.Int.t -> [ `Tree ] node -> [ `Tree ] node
val next_sibling : t -> [ `Tree ] node -> [ `Tree ] node
val tagged_child : t -> Tag.t -> [ `Tree ] node -> [ `Tree ] node
val select_child : t -> Ptset.Int.t -> [ `Tree ] node -> [ `Tree ] node
val next_sibling : t -> [ `Tree ] node -> [ `Tree ] node