code: func Xor(left, right []byte) []byte {
  	result := make([]byte, len(left))
  
  	for i := 0; i < len(left); i++ {
  		result[i] = left[i] ^ right[i]
  	}
  
  	return result
  }
docs: // Xor is doing byte by byte exclusive or of 2 byte arrays