Function task 

pub fn task(fut: impl Future<Output = ()> + 'static) -> TaskHandle

Spawn an async flow onto Day’s main-loop executor. This is the opt-in seam for actions that open modals or pickers: button.action(|| day::task(async move { … .await … })). The future is polled once before this returns; the returned handle can TaskHandle::abort it and is freely discardable.