Function across 

pub fn across(v: &Val, conn: ConnId) -> Val

What a payload that arrived over conn means on this side. An address is the one value that does not survive a link unchanged: a task the sender called its own is one on the far side here, and a task it reached through this link is one of ours, so the two cases swap and the sender’s conn - a name in its numbering - is discarded. Exact rather than heuristic only because an address is a host type (Addr) a program cannot forge.

A third-party address has no image here; departs refuses to send one.