val nth_opt : 'a t -> integer -> 'a option
val map : ('a -> 'b) -> 'a t -> 'b t
val mapi : (integer -> 'a -> 'b) -> 'a t -> 'b t
val fold_left : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'a
val fold_right : ('b -> 'a -> 'a) -> 'b t -> 'a -> 'a
val map2 : ('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t
val for_all : ('a -> bool) -> 'a t -> bool
val _exists : ('a -> bool) -> 'a t -> bool
val for_all2 : ('a -> 'b -> bool) -> 'a t -> 'b t -> bool
val _exists2 : ('a -> 'b -> bool) -> 'a t -> 'b t -> bool
val mem : 'a -> 'a t -> bool