pub fn delivery_turn(
update: &SessionUpdate,
slot: &SessionSlot,
) -> Option<(Message, PromptSource)>Expand description
The display-only user turn update draws as, when it delivers to slot,
with the sender the frame that draws it carries.
None for every other update, and for a delivery to another seat: the
same stream carries the whole fleet.
The prose is checked against the same parser the fold reads it back with, and a drift is recorded against the delivery that produced it.