Idiomatic way of writing nested loops?

[Anton Fediushin via Digitalmars-d-learn]

On Tuesday, 18 July 2017 at 03:36:04 UTC, Nicholas Wilson wrote:
> With regards to parallel, only use it on the outermost loop. 
> Assuming you have more items in the outermost loop than you do 
> threads parallelising more than one loop won't net you any 
> speed.

Thank you! Yes, `parallel` runs only 4 threads on my machine, so 
there is no reason to use it in nested loops.