Comment by sevensor

> io.async expresses asynchronicity (the possibility for operations to happen out of order and still be correct) and it does not request concurrency, which in this case is necessary for the code to work correctly.

This is the key point for me. Regardless of whether you’re under an async event loop, you can specify that the order of your io calls does not imply sequencing. Brilliant. Separate what async means from what the io calls do.