module type S = sig .. end
The output signature of the functor 
Weak.Make.
type 
The type of the elements stored in the table.
type 
The type of tables that contain elements of type 
data.
        Note that weak hash sets cannot be marshaled using
        
output_value or the functions of the 
Marshal
        module.
val create : int -> t
create n creates a new empty weak hash set, of initial
        size n.  The table will grow as needed.
val clear : t -> unit
Remove all elements from the table.
val merge : t -> data -> data
merge t x returns an instance of x found in t if any,
        or else adds x to t and return x.
val add : t -> data -> unit
add t x adds x to t.  If there is already an instance
        of x in t, it is unspecified which one will be
        returned by subsequent calls to find and merge.
val remove : t -> data -> unit
remove t x removes from t one instance of x.  Does
        nothing if there is no instance of x in t.
val find : t -> data -> data
find t x returns an instance of x found in t.
        Raise Not_found if there is no such element.
val find_all : t -> data -> data list
find_all t x returns a list of all the instances of x
        found in t.
val mem : t -> data -> bool
mem t x returns true if there is at least one instance
        of x in t, false otherwise.
val iter : (data -> unit) -> t -> unit
iter f t calls f on each element of t, in some unspecified
        order.  It is not specified what happens if f tries to change
        t itself.
val fold : (data -> 'a -> 'a) -> t -> 'a -> 'a
fold f t init computes (f d1 (... (f dN init))) where
        d1 ... dN are the elements of t in some unspecified order.
        It is not specified what happens if f tries to change t
        itself.
val count : t -> int
Count the number of elements in the table.  count t gives the
        same result as fold (fun _ n -> n+1) t 0 but does not delay the
        deallocation of the dead elements.
val stats : t -> int * int * int * int * int * int
Return statistics on the table.  The numbers are, in order:
        table length, number of entries, sum of bucket lengths,
        smallest bucket length, median bucket length, biggest bucket length.