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