How to set multiple IDs to homefeatured module

[acua]

Hello,

 

I want to make duplicates for the homefeatured module (i know how to do that) and i don't know how to add more than one IDs to this line:

$products = $category->getProducts((int)Context::getContext()->language->id, 1, ($nb ? $nb : 10));

 

I know that 1 is the id, but how do i add another, so that the duplicated homefeatured module shows products from more than one category? Does it work with 1 && 2 && 3, or it simply works by adding a new number besides that one "1 2 3 4" or 1, 2, 3

 

Thank you