use std::net::TcpStream;

struct Client {
    stream: TcpStream,
    server: Server,
}

impl Client {
    fn test(&self){
        server.broadcast();
    }
}

struct Server {
    conns: Vec<Client>,
}

impl Server {
    fn add_conn(&mut self, stream: TcpStream){
        // do stuff

        self.conns.push(Client { stream: stream, server: /* What do I do here? */ });
    }

    fn broadcast(&self){
        for conn in conns{
            // do stuff
        }
    }
    }
}