code: func (i *Item) Copy() *Item {
  	return &Item{
  		Key:       i.Key,
  		Val:       i.Val,
  		Priority:  i.Priority,
  		Transient: i.Transient,
  	}
  }
docs: // The returned Item will not have been allocated through the optional
  // StoreCallbacks.ItemAlloc() callback.