Python-Requests close http connection

I was wondering, how do you close a connection with Requests (python-requests.org)?

With httplib it's HTTPConnection.close(), but how do I do the same with Requests?

Code:

r = requests.post("https://stream.twitter.com/1/statuses/filter.json", data={'track':toTrack}, auth=('username', 'passwd'))
for line in r.iter_lines():
    if line:
        self.mongo['db'].tweets.insert(json.loads(line))