'Flush all finished jobs (completed and dead) from lists.
Running jobs are never flushed.
It first calls _status_new(), to update info. If any jobs have
completed since the last _status_new() call, the flush operation
aborts.'

def flush(self):

    alljobs = self.all
    for job in (self.completed + self.dead):
        del alljobs[job.num]
    fl_comp = self._group_flush(self.completed, 'Completed')
    fl_dead = self._group_flush(self.dead, 'Dead')
    if (not (fl_comp or fl_dead)):
        print 'No    jobs    to    flush.'
