Calculate sold goods in multi-dimensional array with recursive function

sold_goods_report_2.php

<?php
$a = array('product name' => 'gasoline', 'quantity' => 2);
$b = array('product name' => 'oil', 'quantity' => 3);
$order1 = array($a,$b);
$c = array('product name' => 'bottle', 'quantity' => 2);
$d = array('product name' => 'gasoline', 'quantity' => 3);
$e = array('product name' => 'lighter', 'quantity' => 1);
$order2 = array($c,$d,$e);
$f = array('quantity' => 13, 'product name' => 'mask');
$g = array('product name' => 'oil', 'quantity' => 7);
$h = array('quantity' => 2, 'product name' => 'lighter', );
$order3 = array($f,$g,$h);
$orders = array ($order1,$order2,$order3);
$result = [];
$n = 0;
function products_sold (array $array) {
    global $result;
    global $n;
    foreach ($array as $key => $value) {
        if (is_array($value)) {
            products_sold ($value);
        }
        else {
            echo ++$n . ". " . "I'm inside, darling!" . "\n";
            if (!is_string($value)) {
                $product_name = $array['product name'];
                if(array_key_exists($product_name, $result)) {
                    $result[$product_name] += $value;
                }
                else {
                $result += [$product_name => $value];
                }   
            echo "\n\n";print_r($result);}
            
        }
    }
return $result;    
}
$result = products_sold ($orders);
echo "\n\n" . "***** FIN ******" . "\n\n";
print_r ($result);