A persistent connection is one that is automatically reestablished whenever lost.
module type S = Async_extra__.Persistent_connection_intf.S
module type T = Async_extra__.Persistent_connection_intf.T
module Rpc : sig ... end
module Versioned_rpc : S with type conn = Async_extra__.Import.Versioned_rpc.Connection_with_menu.t and type address = Core.Host_and_port.t