Function wait_for_routes 

pub async fn wait_for_routes<I: FidlRouteIpExt, S: Stream<Item = Result<Event<I>, WatchError>> + Unpin, F: Fn(&HashSet<InstalledRoute<I>>) -> bool>(
    event_stream: S,
    initial_state: &mut HashSet<InstalledRoute<I>>,
    predicate: F,
) -> Result<(), WaitForRoutesError<I>>

Wait for a condition on routing state to be satisfied.

With the given initial_state, take events from event_stream and update the state, calling predicate whenever the state changes. When predicates returns True yield Ok(()).