'Return redirect url'

def auth_url(self):

    token = self.unauthorized_token()
    name = (self.AUTH_BACKEND.name + 'unauthorized_token_name')
    if (not isinstance(self.request.session.get(name), list)):
        self.request.session[name] = []
    self.request.session[name].append(token.to_string())
    self.request.session.modified = True
    return self.oauth_authorization_request(token).to_url()
