"with" is always a good idea indeed. But be careful, map() and submit() + as_completed() don't have the same effect. The first one will give you the result in

"with" is always a good idea indeed. But be careful, map() and submit() + as_completed() don't have the same effect. The first one will give you the result in the insertion order, while the later give you the results in the order they are completed.