Help getting with lua: 'in' ; lecture notes 7 ; how is lua extensible

Subject: Help getting with lua: 'in' ; lecture notes 7 ; how is lua extensible
From: Luke &lt;lemmett81@ ... &gt;
Date: Mon, 5 Nov 2018 02:32:34 +0000

1. what does 'in' do in e.g. the following from lecture notes 6

2 lecture notes 7 "more about 'functions", slide 5'says

I have the following in the lua dema

3. the first set of lecture notes say

what does this mean?

To be specific, I am using lua as a middle layer, with a API designed' by Brian Clarkson, of orthogonal devices, to an er-301 as the cpu. This is a eurorack synthesizer module for manipulation and generation of audio and control voltages. I am wondering if I can program lua to interface (I think is the right word) with CSound code.

Apologies if I have sent this twice!

Thanks

Luke