This gets rid of the (substantial!) overhead of preparing a list and then iterating over it, in exchange for a bit of bookkeeping to simulate the prior behavior of the for loop, which is much cheaper.
Reviewed-on: pyrex/chameleonic#4
Co-authored-by: Kistaro Windrider <kistaro@gmail.com>
Co-committed-by: Kistaro Windrider <kistaro@gmail.com>
