[Tigress8780]

IO is not a part of the async runtime contract (I don't know if this is good or bad), and Tokio & futures famously have different `Async{Read,Write}` traits. I once had to do this [0] to adapt between them.

This means that any crate that uses IO will be bound to a limited number of Runtimes. Everything being Tokio-only is pretty bad (though Tokio itself is great), but here we are...

[0] https://github.com/bluejekyll/trust-dns/pull/1373#issuecomme...