public function flush($idNum)
    {
        if (isset($this->items[$idNum])) {
            $job = $this->config->getJobFromIdNum($idNum);

            if (!$job->flush($this->items[$idNum])) {
                $this->handleFailure($idNum, $this->items[$idNum]);
            }

            $this->items[$idNum] = [];
            $this->lastInvoked[$idNum] = microtime(true);
        }

        return true;
    }