code: def test_vary_header(canned_write_client):
      # These forms embed a csrftoken so they should be served with Vary: Cookie
      assert "vary" not in canned_write_client.get("/data").headers
      assert (
          "Cookie"
          == canned_write_client.get("/data/update_name").headers[
              "vary"
          ]
      )
  
imports: from bs4 import BeautifulSoup
  import json
  import pytest
  import re
  from .fixtures import make_app_client, app_client
label_desc: Use image node_id 12 for calling a global function with example usage: test_vary_header(canned_write_client) without return types