public function registerObserver(ObservedInterface $observed): LifeCyclableInterface
    {
        $this->observedList[\spl_object_hash($observed)] = $observed;

        return $this;
    }
public function registerObserver(ObservedInterface $observed): LifeCyclableInterface
    {
        $this->observedList[\spl_object_hash($observed)] = $observed;

        return $this;
    }
public function registerObserver ( ObservedInterface $ observed ) : LifeCyclableInterface { $ this -> observedList [ \ spl_object_hash ( $ observed ) ] = $ observed ; return $ this ; }
To register a new observer.

@param ObservedInterface $observed

@return LifeCyclableInterface
To register a new observer .