title: Python name 'OAuth2Session' is not defined on windows10
body: <p>I run this code</p>
  
  <blockquote>
    <p>from oauthlib.oauth2 import BackendApplicationClient</p>
    
    <p>from requests.auth import HTTPBasicAuth</p>
    
    <p>import oauth2</p>
    
    <p>import oauth</p>
    
    <p>tokens_url = "<a href="https://x123.com/oauth/token" rel="nofollow noreferrer">https://x123.com/oauth/token</a>"</p>
    
    <p>client = BackendApplicationClient(client_id=client_id)</p>
    
    <p>oauth = OAuth2Session(client=client)</p>
    
    <p>token = oauth.fetch_token(token_url=tokens_url, client_id=client_id, </p>
    
    <p>client_secret=client_secret)</p>
  </blockquote>
  
  <p>and I get NameError: name 'OAuth2Session' is not defined</p>