Function established_route_slack 

pub fn established_route_slack(evidence: RouteEvidence) -> u8

The flood hops a send along an established route carries past the route’s end: ESTABLISHED_ROUTE_EXTRA_FLOOD_HOPS or none.

A route chosen by hand gets none: the application said where the frame goes. An acknowledgment of a retransmission gets the slack, since the last one did not get through. A destination heard directly and strongly, or over a link with no radio in it, gets none. Otherwise a mobile destination, an unmeasured last hop, or a weak one each earn the slack.