val list_findopt: ('a -> int -> 'b option) -> 'a list -> 'b option
val flatten_map: ('a -> 'b list) -> 'a list -> 'b list
val list_last: 'a list -> 'a
val list_mapi: ('a -> int -> 'b) -> 'a list -> 'b list
(* Finds the zero based index of the first element that satisfies a predicate*)
val list_findopt: ('a -> int -> 'b option) -> 'a list -> 'b option
val flatten_map: ('a -> 'b list) -> 'a list -> 'b list
val list_last: 'a list -> 'a
val list_mapi: ('a -> int -> 'b) -> 'a list -> 'b list
(* Finds the zero based index of the first element that satisfies a predicate*)