prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  Add Categories to the Sitemap
  Sitemap consists of Products only, we should expand it to include categories as well.
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `saleor/core/sitemaps.py`
  Content:
  ```
  1 from __future__ import unicode_literals
  2 
  3 from django.contrib.sitemaps import Sitemap
  4 
  5 from ..product.models import Product
  6 
  7 
  8 class ProductSitemap(Sitemap):
  9 
  10     def items(self):
  11         return Product.objects.only('id', 'name').order_by('-id')
  12 
  13 
  14 sitemaps = {'products': ProductSitemap}
  15
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/saleor/core/sitemaps.py b/saleor/core/sitemaps.py
  --- a/saleor/core/sitemaps.py
  +++ b/saleor/core/sitemaps.py
  @@ -2,7 +2,7 @@
   
   from django.contrib.sitemaps import Sitemap
   
  -from ..product.models import Product
  +from ..product.models import Category, Product
   
   
   class ProductSitemap(Sitemap):
  @@ -11,4 +11,13 @@
           return Product.objects.only('id', 'name').order_by('-id')
   
   
  -sitemaps = {'products': ProductSitemap}
  +class CategorySitemap(Sitemap):
  +
  +    def items(self):
  +        categories = Category.objects.all().order_by('id')
  +        return categories.only('id', 'name', 'slug')
  +
  +sitemaps = {
  +    'categories': CategorySitemap,
  +    'products': ProductSitemap
  +}
  
verification_info: {"golden_diff": "diff --git a/saleor/core/sitemaps.py b/saleor/core/sitemaps.py\n--- a/saleor/core/sitemaps.py\n+++ b/saleor/core/sitemaps.py\n@@ -2,7 +2,7 @@\n \n from django.contrib.sitemaps import Sitemap\n \n-from ..product.models import Product\n+from ..product.models import Category, Product\n \n \n class ProductSitemap(Sitemap):\n@@ -11,4 +11,13 @@\n         return Product.objects.only('id', 'name').order_by('-id')\n \n \n-sitemaps = {'products': ProductSitemap}\n+class CategorySitemap(Sitemap):\n+\n+    def items(self):\n+        categories = Category.objects.all().order_by('id')\n+        return categories.only('id', 'name', 'slug')\n+\n+sitemaps = {\n+    'categories': CategorySitemap,\n+    'products': ProductSitemap\n+}\n", "issue": "Add Categories to the Sitemap\nSitemap consists of Products only, we should expand it to include categories as well.\n", "before_files": [{"content": "from __future__ import unicode_literals\n\nfrom django.contrib.sitemaps import Sitemap\n\nfrom ..product.models import Product\n\n\nclass ProductSitemap(Sitemap):\n\n    def items(self):\n        return Product.objects.only('id', 'name').order_by('-id')\n\n\nsitemaps = {'products': ProductSitemap}\n", "path": "saleor/core/sitemaps.py"}], "after_files": [{"content": "from __future__ import unicode_literals\n\nfrom django.contrib.sitemaps import Sitemap\n\nfrom ..product.models import Category, Product\n\n\nclass ProductSitemap(Sitemap):\n\n    def items(self):\n        return Product.objects.only('id', 'name').order_by('-id')\n\n\nclass CategorySitemap(Sitemap):\n\n    def items(self):\n        categories = Category.objects.all().order_by('id')\n        return categories.only('id', 'name', 'slug')\n\nsitemaps = {\n    'categories': CategorySitemap,\n    'products': ProductSitemap\n}\n", "path": "saleor/core/sitemaps.py"}]}