public function __construct(TickObserver $o, $id)
{
parent::__construct($id);
$this->o = $o;
}
public function __construct(NowPlayingObserver $o, $id)
{
parent::__construct($id);
$this->o = $o;
}
public function __construct(TrackChangeObserver $o, $id)
{
parent::__construct($id);
$this->o = $o;
}