module Ref:sig
..end
type'a
t ='a list Pervasives.ref
val push : 'a t -> 'a -> unit
val pop : 'a t -> 'a option
val pop_exn : 'a t -> 'a
val create : unit -> 'a t
val clear : 'a t -> unit
val lift : ('a list -> 'b) -> 'a t -> 'b
val push_list : 'a t -> 'a list -> unit