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

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 :              'a list -> 'a list
val unique_union :        'a list -> 'a list -> 'a list
val unique_intersection : 'a list -> 'a list -> 'a list

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

val drop_last_element_list  : 'a list -> 'a list
val drop_first_element_list : 'a list -> 'a list
val prev :      'a        list -> 'a option        -> 'a option list

val pad :       'a        list -> 'a option -> int -> 'a option list
val pad_opt :   'a option list -> 'a option -> int -> 'a option list

val combine :   'a        list -> 'b option list   -> ('a * 'b) option list
val last_list : 'a        list -> 'a
val add_to_last_list : 'a list list -> 'a -> 'a list list

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