code: func IsUTFLetterNumeric(s string) bool {
  	for _, v := range s {
  		if !unicode.IsLetter(v) && !unicode.IsNumber(v) { //letters && numbers are ok
  			return false
  		}
  	}
  	return true
  }
docs: // IsUTFLetterNumeric check if the string contains only unicode letters and numbers. Empty string is valid.