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

->pipe(new Map(array(
    '{meta}' => function($metaData) {
        $metaData['columns']['productName'] = array(
            'label' => 'Products',
            'type' => 'string',
        );
        $metaData['columns']['dollar_sales'] = array(
            'label' => 'Sales',
            'type' => 'number',
            'prefix' => '$',
            'decimals' => 1,
        );
        return $metaData;
    },
)))