Function run 

pub async fn run<F, Fut>(plan: Plan, place: F) -> Outcome
where
    F: Fn(usize) -> Fut + Send + Sync + 'static,
    Fut: Future<Output = Result<(), Cause>> + Send + 'static,

Run a plan, placing calls with place.

place is given the call’s index and returns whether it worked. Everything about what a call is lives there, which is what lets the same harness point at sipx or at somebody else’s server.