Function departed_rounds 

fn departed_rounds(
    sharing: &Sharing<'_>,
    memory: &Memory,
    counted: &[(String, Counted)],
    readers: &BTreeSet<String>,
) -> BTreeMap<String, u32>

The past rounds of the devices that no longer count by a sealed fact (Counted::departed: they left, you forgot them, another device replaces them), each device’s below the round returned: below its last full round found in the folder (Turn::full on its first line, sealed: a hostile folder can hide a later one, never show one that is not), never that round nor those continuing it, and only those every reader read past (readers, this device’s own reading among them). Such a device never takes its own out again (a phone dead for good): any device that counts does, each in its own folder, and its sending on the server over the ETag listed there; two at once find it gone (404) or changed (412), and leave it. A device with no full round found (an older Sioul’s rounds say none) keeps every round. A device forgotten that says anything newer counts again at once (counted), and its rounds are its own again.