type i_num_var = nf i_num_var_
val hd_of_i_var : i_var -> int
val hd_of : i_n_var -> int option
+val arity_of_hd : i_n_var -> int
(* put t under n lambdas, lifting t accordingtly *)
val make_lams : nf -> int -> nf
val lift : int -> nf -> nf
val eta_compare : nf -> nf -> int
val eta_eq : [< nf ] -> [< nf ] -> bool
val eta_subterm : [< nf ] -> [< nf ] -> bool
+val max_arity_tms : int -> [< nf] list -> int