productName	dollar_sales
1937 Lincoln Berline	3726.45
1936 Mercedes-Benz 500K Special Roadster	1768.3300000000002
1952 Alpine Renault 1300	5571.8
1962 LanciaA Delta 16V	5026.14
1958 Setra Bus	3284.28
1940 Ford Pickup Truck	3307.5
1926 Ford Fire Engine	1283.48
1913 Ford Model T Speedster	2489.13
1934 Ford V8 Coupe	2164.4
18th Century Vintage Horse Carriage	2173

$mapState = ['rest_sales' => 0];
...
->pipe(new Map(array(
    ->pipe(new Map([
        '{value}' => function ($row, $meta, $index) use (&$mapState) {
            if ($index >= 5) {
                $mapState['rest_sales'] = $mapState['rest_sales'] + 1 * $row['dollar_sales'];
                return null;
            } else {
                return $row;
            }
        },
        '{end}' => function ($count) use (&$mapState) {
            $rowToSend = [
                'productName' => 'The rest products: ',
                'dollar_sales' => $mapState['rest_sales']
            ];
            return $rowToSend;
        },
    ]))
)))