Function small_go 

fn small_go(counted: &Counted, heard_ms: i64, now_ms: i64) -> (bool, bool)

Whether a removed device’s entry and its note of how far it read go with its files, as nothing needs them any more; a few hundred bytes each.

• Its note: once it left or another device replaces it, every device has stopped counting it. One you only forgot here may still count elsewhere, where that note says how far it read: without it, it would hold back every round there (readers).
• Its entry: once another device’s entry says it replaces it (a sealed fact every device reads: none counts it then, the doses neither), or once it left SILENT_DAYS ago. Before, its entry is what tells your other devices, the doses first, that it left or how it closed: without it, they would know it by its claims, as an older Sioul, and doubt.