public function load(ObjectManager $manager)
 {
     $php = new Category();
     $php->setName('PHP');
     $php->setSlug('php');
     $manager->persist($php);
     $manager->flush();
     $this->addReference('php', $php);
 }
 public function load(ObjectManager $manager)
 {
     $tools = new Category();
     $tools->setName('Tools');
     $tools->setSlug('tools');
     $manager->persist($tools);
     $manager->flush();
     $this->addReference('tools', $tools);
 }