'Replaces the session_id in the session cookie with a freshly
computed safe_cookie_data.'

@staticmethod
def update_with_safe_session_cookie(cookies, user_id):

    safe_cookie_data = SafeCookieData.create(cookies[settings.SESSION_COOKIE_NAME].value, user_id)
    cookies[settings.SESSION_COOKIE_NAME] = unicode(safe_cookie_data)
