def METHOD_NAME(self):
    """
    Step 1 of authorization - get app authorization URL.
    :param key: Authorization key received from twitter
    :return: Authorization URL if succeeded, `None` otherwise
    """
    log.debug('Requesting temp token from Twitter')
    oauth_session = OAuth1Session(client_key=self.consumer_key, client_secret=self.consumer_secret)
    try:
        request_token = oauth_session.fetch_request_token(self.REQUEST_TOKEN_URL)
    except RequestException as error:
        log.error('Invalid response from Twitter requesting temp token: {0}', error)
        return None
    app.TWITTER_USERNAME = request_token['oauth_token']
    app.TWITTER_PASSWORD = request_token['oauth_token_secret']
    return oauth_session.authorization_url(self.AUTHORIZATION_URL)