def authorize_redirect(self, callback_uri=None, extra_params=None):
        if callback_uri and self._OAUTH_NO_CALLBACKS:
            raise Exception('This service does not support oauth_callback.')

        if self._OAUTH_VERSION == '1.0a':
            url = self._oauth_request_token_url(callback_uri=callback_uri,
                extra_params=extra_params)
        else:
            url = self._oauth_request_token_url()

        try:
            response = urlfetch.fetch(url, deadline=10)
        except urlfetch.DownloadError, e:
            logging.exception(e)
            response = None

        return self._on_request_token(self._OAUTH_AUTHORIZE_URL, callback_uri,
            response)
Redirects the user to obtain OAuth authorization for this service.
dataset/ETHPy150Open moraes/tipfy/tipfy/auth/oauth.py/OAuthMixin.authorize_redirect