Captioning\Cue::shift PHP Method

    public function shift($_time = 0)
    {
        if (!is_int($_time)) {
            return false;
        }
        if ($_time == 0) {
            return true;
        }
        $start = $this->getStartMS();
        $stop = $this->getStopMS();
        $this->setStartMS($start + $_time);
        $this->setStopMS($stop + $_time);
        return true;
    }