code: func getFsp4TimeAddSub(s string) int {
  	if len(s)-strings.Index(s, ".")-1 == len(s) {
  		return types.MinFsp
  	}
  	for _, c := range s[strings.Index(s, ".")+1:] {
  		if c != '0' {
  			return types.MaxFsp
  		}
  	}
  	return types.MinFsp
  }
docs: // getFsp4TimeAddSub is used to in function 'ADDTIME' and 'SUBTIME' to evaluate `fsp` for the
  // second parameter. It's used only if the second parameter is of string type. It's different
  // from getFsp in that the result of getFsp4TimeAddSub is either 6 or 0.