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: util.rs
    path of file: ./repos/iroh/iroh-gossip/src/net
    
    the code of the file until where you have to start completion: //! Utilities for iroh-gossip networking

use std::{io, pin::Pin, time::Instant};

use anyhow::{bail, ensure, Context, Result};
use bytes::{Bytes, BytesMut};
use tokio::{
    io::{AsyncRead, AsyncReadExt, Asyn
    
    pub async fn wait_and_drain(&mut self) -> impl Iterator<Item = (Instant, T)> {
        self.reset();
        match self.next.as_mut() {
            Some((instant, sleep)) => {
                sleep.await;
                self.map.drain_until(instant)
            }
            None => futures::future::pending().await,
        }
    }