<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def authorize_url(self):
 """ Build the authorization url and save the state. Return the authorization url """

        url, self.state = self.oauth.authorization_url(
            '%sauthorize' % OAUTH_URL)
        return url