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: mod.rs
    path of file: ./repos/tonic/tonic/src/transport
    
    the code of the file until where you have to start completion: //! Batteries included server and client.
//!
//! This module provides a set of batteries included, fully featured and
//! fast set of HTTP/2 server and client's. These components each provide a or
//! `rustls` tls backend when the respective feature flag is enabled, and
//! provides builders to configure transport behavior.
//!
//! # Features
//!
//! - TLS support via [rustls].
//! - Load balancing
//! - Timeouts
//! - Concurrency Limits
//! - Rate limiting
//!
    
//! # async fn do_thing() -> Result<(), Box<dyn std::error::Error>> {
//! let cert = std::fs::read_to_string("ca.pem")?;
//!
//! let mut channel = Channel::from_static("https://example.com")
//!     .tls_config(ClientTlsConfig::new()
//!         .ca_certificate(Certificate::from_pem(&cert))
//!         .domain_name("example.com".to_string()))?
//!     .timeout(Duration::from_secs(5))
//!     .rate_limit(5, Duration::from_secs(1))
//!     .concurrency_limit(256)
//!     .connect()
//!     .await?;
//!
//! channel.call(Request::new(BoxBody::empty())).await?;
//! # Ok(())
//! # }