-val select_sibling : t -> Ptset.Int.t -> [ `Tree ] node -> [ `Tree ] node
-val select_sibling_ctx : t -> Ptset.Int.t -> [ `Tree ] node -> [ `Tree ] node -> [ `Tree ] node
+val select_following_sibling : t -> Ptset.Int.t -> [ `Tree ] node -> [ `Tree ] node
+val select_following_sibling_below : t -> Ptset.Int.t -> [ `Tree ] node -> [ `Tree ] node -> [ `Tree ] node