traits

trait Laser {
    public function who() { 
        echo 'I am a Laser' . PHP_EOL; 
    }
}
trait Projector {
    public function who() { 
        echo 'I am a Laser' . PHP_EOL; 
    }
}
class Galaxy {
    use Laser;//, Projector;
    use Projector;
}

Trait method who has not been applied, because there are collisions with other trait methods on Galaxy