Fetch a new token using the supplied code.

        :param str code: A previously obtained auth code.

def fetch_token(self, **kwargs):
        """Fetch a new token using the supplied code.

        :param str code: A previously obtained auth code.

        """
        if 'client_secret' not in kwargs:
            kwargs.update(client_secret=self.client_secret)
        return self.session.fetch_token(token_url, **kwargs)