You can search for identifiers within the package.
in-package search v0.2.0
type ('k, 'd) key
type ('k, 'd) data
val register : ('k, 'd) data -> unit
val check_is_registered : ('k, 'd) key -> unit
val is_well_initialized : unit -> bool
val get : ('k, 'd) key -> ('k, 'd) data
val printk : ('k, 'd) key -> 'k Containers.Format.printer
val printd : ('k, 'd) key -> 'd Containers.Format.printer
exception UnregisteredKey : ('a, 'b) key -> exn
exception AlreadyRegisteredKey : ('a, 'b) key -> exn