You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: interval.rs
    path of file: ./repos/diem/crates/diem-time-service/src
    
    the code of the file until where you have to start completion: // Copyright (c) The Diem Core Contributors
// SPDX-License-Identifier: Apache-2.0

use crate::{Sleep, SleepTrait, ZERO_DURATION};
use futures::{
    future::Future,
    ready,
    stream::{FusedStream, Stream},
};
use 
    
    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
        let mut this = self.project();

        // Wait for the delay to be done
        ready!(this.delay.as_mut().poll(cx));

        // Reset the delay before next round
        this.delay.reset(*this.period);

        Poll::Ready(Some(()))
    }