title: Using OAuth with Google thru the Python library requests-oauthlib throws the exception MissingCodeError
body: <p>I'm using the Python library <a href="https://github.com/requests/requests-oauthlib" rel="nofollow">requests-oauthlib</a> in order to create an app which can use OAuth with some main providers (Google, Dropbox, Facebook, Twitter).<br>
  The example code provided <a href="https://requests-oauthlib.readthedocs.org/en/latest/examples/google.html" rel="nofollow">here</a> gives me an exception:<br></p>
  
  <pre><code>raise MissingCodeError("Missing code parameter in response.")
  oauthlib.oauth2.rfc6749.errors.MissingCodeError: Missing code parameter in response.
  </code></pre>
  
  <p>The problem is not in the web application client that I created with the Google API console, because I wrote another piece of code doing the same thing but using the Python library google-api-python-client and it works.</p>
  
  <p>Any idea?</p>