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