title: how to remove session flask python3
body: <p>I used this request</p>
  
  <pre><code>GET /logout HTTP/1.1
  Host: 127.0.0.1:8000
  User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:59.0) Gecko/20100101 Firefox/59.0
  Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
  Accept-Language: th,en-US;q=0.7,en;q=0.3
  Accept-Encoding: gzip, deflate
  Cookie: session=eyJ1c2VyIjoiYSJ9.DZun3A.LwCROrj6GQicP1v063cYcItu8SQ;
  Connection: close
  Upgrade-Insecure-Requests: 1
  </code></pre>
  
  <p>I used <code>session.clear()</code> in flask python3 i got responds like</p>
  
  <pre><code>HTTP/1.0 200 OK
  Content-Type: text/html; charset=utf-8
  Content-Length: 4
  Set-Cookie: session=; Expires=Thu, 01-Jan-1970 00:00:00 GMT; Max-Age=0; Path=/
  Server: Werkzeug/0.12.2 Python/3.6.3
  Date: Tue, 27 Mar 2018 10:18:30 GMT
  </code></pre>
  
  <p>It just set a new cookies. Then i use old cookies before set a new one, but i still got old session how to remove old session?</p>