sig
type 'a container
val length : 'a container -> int
val is_empty : 'a container -> bool
val iter : 'a container -> f:('a -> unit) -> unit
val fold : 'a container -> init:'b -> f:('b -> 'a -> 'b) -> 'b
val exists : 'a container -> f:('a -> bool) -> bool
val for_all : 'a container -> f:('a -> bool) -> bool
val find : 'a container -> f:('a -> bool) -> 'a option
val to_list : 'a container -> 'a list
val to_array : 'a container -> 'a array
val container : ('a, 'a container) Container.type_class
end