This strategy uses pointer arithmetic to iterate through the loop. This
has a problem, however, which is tuples. AstGen does not know whether a
given indexable is a tuple or can be iterated based on contiguous
memory. Tuples unlike other indexables cannot be represented as a
many-item pointer that is incremented as the loop counter.

So, after this commit, I will modify AstGen back closer to how @vexu had
it before, using a counter and array element access.