How do I use double bracket notation in binom?

Questions
1

I would like to use the double bracket notation in binom, like in https://en.wikipedia.org/wiki/Multiset#Counting_multisets. How can I do this?

$(binom(n, k))$ doesn’t look good.

2

This works:

#let multiset(n, k) = $(#h(-2pt)#h(-2pt) vec(#n, #k, delim: "(") #h(-2pt)#h(-2pt))$

$multiset(1, 2)$