code: func (it *iterator) Value() []byte {
  	if len(it.values) > 0 {
  		return it.values[0]
  	}
  	return nil
  }
docs: // Value returns the value of the current key/value pair, or nil if done. The
  // caller should not modify the contents of the returned slice, and its contents
  // may change on the next call to Next.