/// important of those rules is that any iterator becomes invalid
/// on element erasure. So pay attention.
+/// If LLCORE_READY_QUEUE_IGNORES_PRIORITY tests true, the class
+/// implements a std::priority_queue interface but on std::deque
+/// behavior to eliminate sensitivity to priority. In the future,
+/// this will likely become the only behavior or it may become
+/// a run-time election.
/// Threading: not thread-safe. Expected to be used entirely by
/// a single thread, typically a worker thread of some sort.