Does anyone have links to resources that someone new to Rust should read on how to conceptualize async code in Rust? Based on reading the comments, it would seem there are ways to start with writing synchronous code, and if necessary make it async but do it in such a way that is runtime agnostic... don't just reach for Tokio.

If I'm implementing a library, how should I write it so that the consumer of the library doesn't have to pull in Tokio if they don't want to?