this is 10 lines with async :D

```rust
loop {
    join(a.wait_for_high(), b.wait_for_high()).await;
    Timer::after_millis(50).await;
    select(a.wait_for_low(), b.wait_for_low()).await;
    Timer::after_millis(50).await;
    match (a.is_low(), b.is_low()) {
        (true, true) => info!("both buttons pressed"),
        (true, false) => info!("A button pressed"),
        (false, true) => info!("B button pressed"),
        (false, false) => {}
    }
}
```