QS_OK
a->q_state = QS_OK;
q->q_state = QS_OK;
to->q_state = QS_OK;
case QS_OK:
#define QS_IS_OK(s) ((s) == QS_OK)
#define QS_IS_UNDELIVERED(s) ((s) == QS_OK || \
#define QS_IS_UNMARKED(s) ((s) == QS_OK || \
#define QS_IS_SENDABLE(s) ((s) == QS_OK || \