code: def default_memcache_timeout_policy(key):
      
      timeout = None
      if key is not None and isinstance(key, model.Key):
        modelclass = model.Model._kind_map.get(key.kind())
        if modelclass is not None:
          policy = getattr(modelclass, '_memcache_timeout', None)
          if policy is not None:
            if isinstance(policy, (int, long)):
              timeout = policy
            else:
              timeout = policy(key)
      return timeout
docs: Default memcache timeout policy.
  
      This defers to _memcache_timeout on the Model class.
  
      Args:
        key: Key instance.
  
      Returns:
        Memcache timeout to use (integer), or None.