code: func buildRowNumber(aggFuncDesc *aggregation.AggFuncDesc, ordinal int) AggFunc {
  	base := baseAggFunc{
  		args:    aggFuncDesc.Args,
  		ordinal: ordinal,
  	}
  	return &rowNumber{base}
  }
docs: // buildRowNumber builds the AggFunc implementation for function "ROW_NUMBER".