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