code: func (c *cache) Save(w io.Writer) (err error) {
  	enc := gob.NewEncoder(w)
  	defer func() {
  		if x := recover(); x != nil {
  			err = fmt.Errorf("Error registering item types with Gob library")
  		}
  	}()
  	c.mu.RLock()
  	defer c.mu.RUnlock()
  	for _, v := range c.items {
  		gob.Register(v.Object)
  	}
  	err = enc.Encode(&c.items)
  	return
  }
docs: // Write the cache's items (using Gob) to an io.Writer.
  //
  // NOTE: This method is deprecated in favor of c.Items() and NewFrom() (see the
  // documentation for NewFrom().)