docs: def get_driver(secret_key=config.DEFAULT_SECRET_KEY, userid=config.DEFAULT_USERID,
                 provider=config.DEFAULT_PROVIDER):
  
      """A driver represents successful authentication.  They become
      stale, so obtain them as late as possible, and don't cache them."""
  
      if hasattr(config, 'get_driver'):
          logger.debug('get_driver %s' % config.get_driver)
          return config.get_driver()
      else:
          logger.debug('get_driver {0}@{1}'.format(userid, provider))
          return libcloud.compute.providers.get_driver(
              config.PROVIDERS[provider])(userid, secret_key)