You can search for identifiers within the package.
in-package search v0.2.0
module R = Cbrn.Threefry.Gen_4_64
val key : R.t
val ctr : R.t
val r : ?rounds:int -> key:R.t -> ctr:R.t -> unit -> R.t
val u : ?rounds:int -> key:R.t -> ctr:R.t -> unit -> int array