Also Rust async runtimes have `block_on(async)` and `spawn_blocking(sync).await`, so the main problem of call graphs split by "color" doesn't exist in Rust. Rus

Also Rust async runtimes have `block_on(async)` and `spawn_blocking(sync).await`, so the main problem of call graphs split by "color" doesn't exist in Rust. Rust can merge the two worlds. Unlike JS, Rust can wait for async code in blocking contexts, and it can run CPU-bound code in async contexts.