Function futures_util::sink::unfold  
source · pub fn unfold<T, F, R, Item, E>(init: T, function: F) -> Unfold<T, F, R>Expand description
Create a sink from a function which processes one item at a time.
§Examples
use futures::sink::{self, SinkExt};
let unfold = sink::unfold(0, |mut sum, i: i32| {
    async move {
        sum += i;
        eprintln!("{}", i);
        Ok::<_, futures::never::Never>(sum)
    }
});
futures::pin_mut!(unfold);
unfold.send(5).await?;