a function that decides how long to wait before the next iteration
the name of the counter used to keep track of the run state. Typically this would be random, but can be set explicitly if needed
the next actor in the chain
Pace keeps track of when it can next run using a counter in the session.
the next actor in the chain
Makes sure that in case of an actor crash, the Session is not lost but passed to the next Action.
Pace provides a means to limit the frequency with which an action is run, by specifying a minimum wait time between iterations.
Originally contributed by James Pickering.