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: rumqttasync.rs
    path of file: ./repos/rumqtt/benchmarks/clients
    
    the code of the file until where you have to start completion: use rumqttc::{AsyncClient, Event, Incoming, MqttOptions, QoS};

use std::error::Error;
use std::time::{Duration, Instant};

use tokio::task;
use tokio::time;

mod common;

#[tokio::main(flavor = "multi_thread", worker_threads = 2)]
async fn main() {
    // pretty_env_logger::init();
    let guard = pprof::ProfilerGuard::new(100).unwrap();
    start("rumqtt-async", 100, 1_000_000).await.unwrap();
    common::profile("bench.pb", guard);
}

pub async fn start(id: &str, payload_size: usize, count: usize) -> Result<(), Box<dyn Error>> {
    let mut mqttoptions =
    
pub async fn start(id: &str, payload_size: usize, count: usize) -> Result<(), Box<dyn Error>> {
    let mut mqttoptions = MqttOptions::new(id, "localhost", 1883);
    mqttoptions.set_keep_alive(Duration::from_secs(20));
    mqttoptions.set_inflight(100);

    let (client, mut eventloop) = AsyncClient::new(mqttoptions, 10);
    task::spawn(async move {
        for _i in 0..count {
            let payload = vec![0; payload_size];
            let qos = QoS::AtLeastOnce;
            client
                .publish("hello/benchmarks/world", qos, false, payload)
                .await
                .unwrap();
        }

        time::sleep(Duration::from_secs(10)).await;
    });

    let mut acks_count = 0;
    let start = Instant::now();
    loop {
        if let Event::Incoming(Incoming::PubAck(_)) = eventloop.poll().await? {
            acks_count += 1;
            if acks_count == count {
                break;
            }
        }
    }

    let elapsed_ms = start.elapsed().as_millis();
    let throughput = acks_count / elapsed_ms as usize;
    let throughput = throughput * 1000;

    let print = common::Print {
        id: id.to_owned(),
        messages: count,
        payload_size,
        throughput,
    };

    println!("{}", serde_json::to_string_pretty(&print).unwrap());
    Ok(())
}