Module Set_once

module Set_once: Set_once

exception Already_set

type 'a t 

include Sexpable.S1

val create : unit -> 'a t

val set : 'a t -> 'a -> (unit, string) Result.t

val set_exn : 'a t -> 'a -> unit

val get : 'a t -> 'a option

val get_exn : 'a t -> 'a