code: func (s *SalsaStream) Unpack(payload string) []byte {
  	var result []byte
  
  	data, _ := base64.StdEncoding.DecodeString(payload)
  
  	salsaBytes := s.fetchBytes(len(data))
  
  	for i := 0; i < len(data); i++ {
  		result = append(result, salsaBytes[i]^data[i])
  	}
  	return result
  }
docs: // Unpack returns the payload as unencrypted byte array