Do not use the handle after closing it. *)
+val defnode : t -> string -> string -> string option -> int * bool
+ (** [defnode t name expr value] defines [name] whose value is the
+ result of evaluating [expr], which is a nodeset. *)
+
val defvar : t -> string -> string option -> int option
(** [defvar t name expr] defines [name] whose value is the result
of evaluating [expr], replacing the old value if existing.