module Server: sig .. end
type 'connection_state t 
val null : unit -> 'connection_state t
val create : implementations:'connection_state Rpc.Implementation.t list ->
       on_unknown_rpc:[ `Call of rpc_tag:string -> version:int -> unit
                      | `Ignore
                      | `Raise ] ->
       ('connection_state t,
        [ `Duplicate_implementations of Rpc.Implementation.Description.t list ])
       Core.Std.Result.t
create ~implementations ~on_unknown_rpc creates a server
      capable of responding to the rpc's implemented in the implementation list.
val create_exn : implementations:'connection_state Rpc.Implementation.t list ->
       on_unknown_rpc:[ `Call of rpc_tag:string -> version:int -> unit
                      | `Ignore
                      | `Raise ] ->
       'connection_state t