`sig
type ('a, +'phantom) t
val mem : ?equal:('a -> 'a -> bool) -> ('a, 'b) t -> 'a -> bool
val length : ('a, 'b) t -> int
val is_empty : ('a, 'b) t -> bool
val iter : ('a, 'b) t -> f:('a -> unit) -> unit
val fold :
('a, 'b) t -> init:'accum -> f:('accum -> 'a -> 'accum) -> 'accum
val exists : ('a, 'b) t -> f:('a -> bool) -> bool
val for_all : ('a, 'b) t -> f:('a -> bool) -> bool
val count : ('a, 'b) t -> f:('a -> bool) -> int
val sum :
(module Commutative_group.S with type t = 'sum) ->
('a, 'b) t -> f:('a -> 'sum) -> 'sum
val find : ('a, 'b) t -> f:('a -> bool) -> 'a option
val find_map : ('a, 'c) t -> f:('a -> 'b option) -> 'b option
val to_list : ('a, 'b) t -> 'a list
val to_array : ('a, 'b) t -> 'a array
val min_elt : ('a, 'b) t -> cmp:('a -> 'a -> int) -> 'a option
val max_elt : ('a, 'b) t -> cmp:('a -> 'a -> int) -> 'a option
end`