code: public function categories()
      {
          if (!$this->categories instanceof CategoriesController) {
              $this->categories = new CategoriesController($this->getClient(), $this->cachePolicy, $this->cache);
              $this->categories->setLogger($this->logger);
          }
  
          return $this->categories;
      }
docs: Categories defines which PropertySets should be available for Media. All Media belongs to exactly one Category.
  
  @return CategoriesController