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: server.rs
    path of file: ./repos/tonic/examples/src/json-codec
    
    the code of the file until where you have to start completion: //! A HelloWorld example that uses JSON instead of protobuf as the message serialization format.
//!
//! Generated code is the output of codegen as 
    
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let addr = "[::1]:50051".parse().unwrap();
    let greeter = MyGreeter::default();

    println!("GreeterServer listening on {}", addr);

    Server::builder()
        .add_service(GreeterServer::new(greeter))
        .serve(addr)
        .await?;

    Ok(())
}