code: func UTF8StringFromBytes(b []byte) string {
  	if utf8.Valid(b) {
  		return string(b)
  	}
  
  	// This effectively replaces invalid bytes to \uFFFD (replacement char).
  	return string(bytes.Runes(b))
  }
docs: // UTF8StringFromBytes returns a valid UTF-8 string from
  // maybe invalid slice of bytes.