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: client.rs
    path of file: ./repos/tonic/examples/src/streaming
    
    the code of the file until where you have to start completion: pub mod pb {
    tonic::include_proto!("grpc.examples.echo");
}

use std::time::Duration;
use tokio_stream::{Stream, StreamExt};
use tonic::transport::Channel;

use pb::{echo_client::EchoClient, EchoRequest};

fn echo_requests_iter() -> impl Stream<Item = EchoReque
    
async fn bidirectional_streaming_echo_throttle(client: &mut EchoClient<Channel>, dur: Duration) {
    let in_stream = echo_requests_iter().throttle(dur);

    let response = client
        .bidirectional_streaming_echo(in_stream)
        .await
        .unwrap();

    let mut resp_stream = response.into_inner();

    while let Some(received) = resp_stream.next().await {
        let received = received.unwrap();
        println!("\treceived message: `{}`", received.message);
    }
}