Function item_timeout_budget 

pub fn item_timeout_budget(
    policy: &TimeoutPolicy,
    elapsed: Duration,
) -> Option<Duration>

Returns how long a streaming node may take to produce its next event.

The budget is the smaller of the remaining run timeout and the idle timeout. For a stream, “idle” means no event was produced within idle_timeout, which is the streaming analogue of a node that never calls report_progress(). Returns None when the policy sets no applicable limit.