sig
val add :
Term.constr -> Term.constr -> Term.constr -> Term.constr -> Term.constr
val empty : Term.constr -> Term.constr
val of_list :
Term.constr -> Term.constr -> (int * Term.constr) list -> Term.constr
val to_fun : Term.constr -> Term.constr -> Term.constr -> Term.constr
end