Driving me crazy trying to do simple calculations on lists of numbers that I can't do in Calculate List nodes because the calculations refer to items of multiple lists or lists of multidimensional values or using different indexes on different lists at the same time in calculation. So calls for a roll your own loop.
But trying to use Process List and Cycle Through List (which does provide an iteration index number at least) is just so hard to get to work. Trial and error going on for hours looking for ways forward, and I understand the need for Hold List to block events to the loop which was my first stumbling block last time I had a go at doing something useful in VUO.
Part of the problem is that even Show Events doesn't break down a cycle of iteration events inside a loop. Maybe it needs some other way to show events inside an iteration rather than just one blink per complete cycle? Another part of the problem is that there isn't a way to log info to the console, the way I usually debug and comprehend mysterious happenings. It's easy enough to pass some simple text to the Console (say a 3D point using a string of 3x point list to real conversions to real list to text list to append text with separator), but it's not possible from what I can tell to log to Console say a list of 4D Points, we need to use the tool tip windows. I discovered you can print to console inside a loop but only if it's working as it should.
I guess I'll go and vote for the Python/JS/Lua node FR, I don't have time to learn enough to write a custom node in C ATM but I'm sure the iteration part of it would be easy.