> right now I looks mutable, something like `for (constexpr size_t I : INPUT_COUNT)` might be better I thought the same, but then you lose the ability to contr

> right now I looks mutable, something like `for (constexpr size_t I : INPUT_COUNT)` might be better I thought the same, but then you lose the ability to control the increment step. For example, one might want to iterate pairwise. Regarding syntax, you could mandate that the loop variable has to be declared `constexpr` as well, which makes it clear that it can't be modified in the loop body.