Undocumented predicates

The following predicates are exported, but not or incorrectly documented.

 node_type(Arg1, Arg2, Arg3)

 parent(Arg1, Arg2)

 split_id(Arg1, Arg2, Arg3)

 child(Arg1, Arg2, Arg3)

 get_children(Arg1, Arg2, Arg3)

 get_n_children(Arg1, Arg2, Arg3, Arg4)

 get_nth_child(Arg1, Arg2, Arg3, Arg4)

 count_children(Arg1, Arg2, Arg3)

 sibling(Arg1, Arg2, Arg3)

 next_sibling(Arg1, Arg2, Arg3)

 last_sibling(Arg1, Arg2, Arg3)

 count_remaining_siblings(Arg1, Arg2, Arg3)

 get_n_siblings(Arg1, Arg2, Arg3, Arg4)

 get_nth_sibling(Arg1, Arg2, Arg3, Arg4)

 descendant(Arg1, Arg2, Arg3)

 descendant_or_self(Arg1, Arg2, Arg3)

 resolve_namespace(Arg1, Arg2, Arg3, Arg4)

 namespace(Arg1, Arg2, Arg3)