code: func (b *builtinFromDaysSig) evalTime(row chunk.Row) (types.Time, bool, error) {
  	n, isNull, err := b.args[0].EvalInt(b.ctx, row)
  	if isNull || err != nil {
  		return types.Time{}, true, err
  	}
  
  	return types.TimeFromDays(n), false, nil
  }
docs: // evalTime evals FROM_DAYS(N).
  // See https://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_from-days