public function start($key, $label, $data = null, $timetamp = null)
    {
        $event = new Start($key, $label, $data, $timetamp);
        $this->dispatcher->dispatch(Start::EVENT_NAME, $event);
    }
public function start($key, $label, $data = null, $timetamp = null)
    {
        $event = new Start($key, $label, $data, $timetamp);
        $this->dispatcher->dispatch(Start::EVENT_NAME, $event);
    }
public function start ( $ key , $ label , $ data = null , $ timetamp = null ) { $ event = new Start ( $ key , $ label , $ data , $ timetamp ) ; $ this -> dispatcher -> dispatch ( Start :: EVENT_NAME , $ event ) ; }
Start item for the timeline

@param $key
@param $label
@param null $data
@param null $timetamp
Start item for the timeline