hey no problem, happy to help
yeah it does feel like 2 is being reset when you listen to it. where in reality it's just instr1 having two instances running at the same time, and the first one actually still does write to that variable but then the second instance comes in and overwrites it on the same cycle before the output. it's like they're fighting, but with += you're saying "hey i don't want any of you to reassign this, just add what you have to it and i'll clear it myself"

yeah, you're so right, those mistakes are the best way to learn

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