I'd say concurrency is a bit overkill for that problem (i.e. threads or processes scheduled by the run time system that appears non-deterministic to the program

I'd say concurrency is a bit overkill for that problem (i.e. threads or processes scheduled by the run time system that appears non-deterministic to the programmer). Deterministic coroutines work fine. Even Python generators are sufficient. Though perhaps "useful" is a bit too broad: maybe it should be replaced by: > What most people don't realize is that for concurrency to improve performance, there must be parallelism.