code: func IsUTFNumeric(str string) bool {
  	if IsNull(str) {
  		return true
  	}
  	if strings.IndexAny(str, "+-") > 0 {
  		return false
  	}
  	if len(str) > 1 {
  		str = strings.TrimPrefix(str, "-")
  		str = strings.TrimPrefix(str, "+")
  	}
  	for _, c := range str {
  		if !unicode.IsNumber(c) { //numbers && minus sign are ok
  			return false
  		}
  	}
  	return true
  
  }
docs: // IsUTFNumeric check if the string contains only unicode numbers of any kind.
  // Numbers can be 0-9 but also Fractions ¾,Roman Ⅸ and Hangzhou 〩. Empty string is valid.