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: main.rs
    path of file: ./repos/rust-libp2p/examples/stream/src
    
    the code of the file until where you have to start completion: use std::{io, time::Duration};

use anyhow::{Context, Result};
use futures::{AsyncReadExt, AsyncWriteExt, StreamExt};
use libp2p::{multiaddr::Protocol, Multiaddr, PeerId, Stream, StreamProtocol};
use libp2p_stream as stream;
use rand::RngCore;
use tracing::level_filters:
    
async fn send(mut stream: Stream) -> io::Result<()> {
    let num_bytes = rand::random::<usize>() % 1000;

    let mut bytes = vec![0; num_bytes];
    rand::thread_rng().fill_bytes(&mut bytes);

    stream.write_all(&bytes).await?;

    let mut buf = vec![0; num_bytes];
    stream.read_exact(&mut buf).await?;

    if bytes != buf {
        return Err(io::Error::new(io::ErrorKind::Other, "incorrect echo"));
    }

    stream.close().await?;

    Ok(())
}