2/sessions:start or from sending the
            previous challenge response to
            https://reauth.googleapis.com/v2/sessions/id:continue)
        request (google.auth.transport.Request): A callable used to make
            HTTP requests. This must be an aiohttp request.
        access_token (str): reauth access token

    Returns:
        dict: The response from the reauth API.

    Raises:
        google.auth.exceptions.ReauthError: if reauth failed.
    r