fn build_reference_asks_from_cache(
snapshots: &HashMap<String, VecDeque<CachedBboSnapshot>>,
symbols: &[String],
cutoff_ts: i64,
) -> HashMap<String, BboReferenceData>fn build_reference_asks_from_cache(
snapshots: &HashMap<String, VecDeque<CachedBboSnapshot>>,
symbols: &[String],
cutoff_ts: i64,
) -> HashMap<String, BboReferenceData>