Module Versioned_rpc.Expert

Provides direct access to the connection state. Compared to calling connected from the non-Expert API, this:

• Avoids attaching a new handler with each call.
• Becomes determined if the persistent connection is closed (rather than never doing so).
• Doesn't attempt to prevent a race condition by checking Conn.is_closed conn and retrying if false.

This makes it more suitable for use in a loop calling Deferred.choose or similar.

The time source that the connection uses for retry delays