val pow :    int -> int -> int
val powmod : int -> int -> int -> int

val fromIntToString : int -> string

val int_and :     int -> int -> int
val int_or :      int -> int -> int
val int_eq :      int -> int -> int
val int_less :    int -> int -> int
val int_less_eq : int -> int -> int
val int_more :    int -> int -> int
val int_more_eq : int -> int -> int
val int_not :     int -> int

(* val fromIntToString : string -> int -> string *)

val inclusion :           'a list -> 'a list -> bool
val equality :            'a list -> 'a list -> bool
val subtraction :         'a list -> 'a list -> 'a list

val unique_union :        'a list -> 'a list -> 'a list
val unique_intersection : 'a list -> 'a list -> 'a list
val unique_union_assoc :  ('a -> 'b -> 'b -> 'b) -> ('a * 'b) list -> ('a * 'b) list -> ('a * 'b) list

val take : int -> 'a list -> ('a list * 'a list)

val drop_first_element_list : 'a list -> 'a list

val last_list : 'a        list -> 'a

val combine_twice : 'a list -> 'b list -> ('a * 'b) list