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: builder.rs
    path of file: ./repos/tokio/tokio/src/task
    
    the code of the file until where you have to start completion: #![allow(unreachable_pub)]
use crate::{
    runtime::Handle,
    task::{JoinHandle, LocalSet},
};
use std::{future::Future, io};

/// Factory which is used to configure the properties of
    
/// async fn main() -> io::Result<()> {
///     let listener = TcpListener::bind("127.0.0.1:8080").await?;
///
///     loop {
///         let (socket, _) = listener.accept().await?;
///
///         tokio::task::Builder::new()
///             .name("tcp connection handler")
///             .spawn(async move {
///                 // Process each socket concurrently.
///                 process(socket).await
///             })?;
///     }
/// }