code: func (i Item) Merge(i2 Item) (new Item) {
  	if i.Address == nil {
  		i.Address = i2.Address
  	}
  	if i.Data == nil {
  		i.Data = i2.Data
  	}
  	if i.AccessTimestamp == 0 {
  		i.AccessTimestamp = i2.AccessTimestamp
  	}
  	if i.StoreTimestamp == 0 {
  		i.StoreTimestamp = i2.StoreTimestamp
  	}
  	if i.UseMockStore == nil {
  		i.UseMockStore = i2.UseMockStore
  	}
  	return i
  }
docs: // Merge is a helper method to construct a new
  // Item by filling up fields with default values
  // of a particular Item with values from another one.