src/event/EventObserver.php
public function update(\SplSubject $eventManager) {
        $this->isUpdate = true;
        if ($eventManager->event->function !== NULL) {
            $this->{$eventManager->event->function}($eventManager);
        }
    }
public function update(\SplSubject $eventManager) {
        $this->isUpdate = true;
        if ($eventManager->event->function !== NULL) {
            $this->{$eventManager->event->function}($eventManager);
        }
    }
Is the function that Event manager will invoke, when the event subscribe
for this class will be dispatch.

@param SplSubject $eventManager