The document of Requests give some code like this
s = requests.Session()
s.get('http://httpbin.org/cookies/set/sessioncookie/123456789')
r = s.get("http://httpbin.org/cookies")
If I want to use the connection-pooling feature of request.Session, Do I need to instantiate a new Session every time I send a request?, If I do not need a new session, how can I check whether the old seesion is valid now?