Captioning\Cue::setStart PHP Метод

    public function setStart($_start)
    {
        $this->start = $_start;
        $cueClass = get_class($this);
        $this->startMS = $cueClass::tc2ms($this->start);
        return $this;
    }

 /**
  * @param mixed $_start
  * @return $this
  */
 public function setStart($_start)
 {
     parent::setStart($_start);
     if ($this->stop) {
         $this->duration = $this->stop - $this->start;
     }
     return $this;
 }