code: func StrToInt(sc *variable.StatementContext, str string) (int64, error) {
  	str = strings.TrimSpace(str)
  	validPrefix, err := getValidIntPrefix(sc, str)
  	iVal, err1 := strconv.ParseInt(validPrefix, 10, 64)
  	if err1 != nil {
  		return iVal, errors.Trace(ErrOverflow)
  	}
  	return iVal, errors.Trace(err)
  }
docs: // StrToInt converts a string to an integer at the best-effort.