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: transport.rs
    path of file: ./repos/realm/realm_core/src/tcp
    
    the code of the file until where you have to start completion: use std::io::Result;
use futures::try_join;

use kaminari::{AsyncAccept, AsyncConnect, IOStream};
use kaminari::mix::{MixAccept, MixConnect};

use realm_io::{CopyBuffer, bidi_copy_buf, buf_size};

pub async fn run_relay<S: IOStream>(src: S, dst: S, ac: &MixAccept, cc: &MixConnect) -> Result<()> {
    macro_rules! hs_relay {
        ($ac: expr, $cc: expr) => {
            handshake_and_relay(src, dst, $ac, $cc).await
        };
    }

    #[cfg(feature = "transport-boost")]
    {
        use MixConnect::*;
        if let Some(ac) = ac.as_plain() {
            return match cc {
                Plai
    
pub async fn run_relay<S: IOStream>(src: S, dst: S, ac: &MixAccept, cc: &MixConnect) -> Result<()> {
    macro_rules! hs_relay {
        ($ac: expr, $cc: expr) => {
            handshake_and_relay(src, dst, $ac, $cc).await
        };
    }

    #[cfg(feature = "transport-boost")]
    {
        use MixConnect::*;
        if let Some(ac) = ac.as_plain() {
            return match cc {
                Plain(cc) => hs_relay!(ac, cc),
                Ws(cc) => hs_relay!(ac, cc),
                Tls(cc) => hs_relay!(ac, cc),
                Wss(cc) => hs_relay!(ac, cc),
            };
        }
    }

    #[cfg(feature = "transport-boost")]
    {
        use MixAccept::*;
        if let Some(cc) = cc.as_plain() {
            return match ac {
                Plain(ac) => hs_relay!(ac, cc),
                Ws(ac) => hs_relay!(ac, cc),
                Tls(ac) => hs_relay!(ac, cc),
                Wss(ac) => hs_relay!(ac, cc),
            };
        }
    }

    hs_relay!(ac, cc)
}