laravel collection implode

$collection = collect([
    ['account_id' => 1, 'product' => 'Desk'],
    ['account_id' => 2, 'product' => 'Chair'],
]);

$collection->implode('product', ', ');

// Desk, Chair

$collection = collect([1,2,3,4]);

$collection->each(function($item){
    return $item*$item;
});

// [1,4,9,16]