QueueResult — the popped item, or a QueueError payload:
QueueErrorReason.EMPTY if the queue is empty, QueueErrorReason.CLOSED if it is closed and empty.
QueueResult tryPop() @trustedTry to pop a work item without blocking.
QueueResult — the popped item, or a QueueError payload:
QueueErrorReason.EMPTY if the queue is empty, QueueErrorReason.CLOSED if it is closed and empty.