Parsing nested JSON in CXone Studio Snippet after GetRESTProxy

I’ve got a Studio snippet calling an internal API via GetRESTProxy(). It works, but the response is nested JSON. I’m trying to extract a value from the second level, like data.items[0].id, but the ASSIGN statement keeps failing with a type error. Is there a specific syntax for drilling down into arrays in the snippet language, or do I have to flatten it first? Here’s what I’m trying: ASSIGN myVal = response.body.data.items[0].id