Future trait

The trait for a value that will be ready later; async functions return one.

A Future is polled by an executor until it returns Poll::Ready; it does nothing on its own, so creating one without awaiting or spawning it runs none of its code.

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Examples

Calling read_station("harbor"); without .await runs none of its body; rustc warns unused implementer of Future that must be used.
Future has one method, poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>, which returns Poll::Ready(value) or Poll::Pending.