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: hello_world.rs
    path of file: ./repos/tokio/examples
    
    the code of the file until where you have to start completion: //! A simple client that opens a TCP stream, writes "hello world\n", and closes
//! the connection.
//!
//! To start a server that this client can talk to on port 6142, you ca
    
pub async fn main() -> Result<(), Box<dyn Error>> {
    // Open a TCP stream to the socket address.
    //
    // Note that this is the Tokio TcpStream, which is fully async.
    let mut stream = TcpStream::connect("127.0.0.1:6142").await?;
    println!("created stream");

    let result = stream.write_all(b"hello world\n").await;
    println!("wrote to stream; success={:?}", result.is_ok());

    Ok(())
}