val list_rev_map_filter: ('a -> 'b option) -> 'a list -> 'b list
val list_rev_map_filter_fold: ('c -> 'a -> 'c * 'b option) -> 'c -> 'a list -> 'c * 'b list
val list_concat: ?sep:'a list -> 'a list list -> 'a list (**String.concat-like*)
+val list_iter_sep: sep:(unit -> unit) -> ('a -> unit) -> 'a list -> unit
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