just to add to this, it's not helped by the docs. either they don't exist, or the seo isn't working right.
e.g. search term for me "openai assistant service function call node". The first 2 results are community forums, not what i'm looking for. The 3rd is seemingly the official one but doesn't actually answer the question (how to use the assistance service with node and function calling) with an example. The 4th is in python.