def METHOD_NAME(self, snapshot_ids: t.Iterable[SnapshotIdLike]) -> t.Set[SnapshotId]:
    existing = set()
    missing = set()
    now = now_timestamp()
    for s in snapshot_ids:
        snapshot_id = s.snapshot_id
        snapshot = self._from_cache(snapshot_id, now)
        if snapshot:
            existing.add(snapshot_id)
        elif snapshot is None:
            missing.add(snapshot_id)
    if missing:
        existing.update(self.state_sync.METHOD_NAME(missing))
    return existing