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: list-all-function-runtimes.rs
    path of file: ./repos/aws-doc-sdk-examples/rustv1/examples/lambda/src/bin
    
    the code of the file until where you have to start completion: // Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0

#![allow(clippy::result_large_err)]

use aws_sdk_lambda::Error;
use clap::Parser;
use lambda_code_examples::{make_client, make_config, Opt as BaseOpt};

#[derive(Debug, Parser)]
struct Opt {
    #[structopt(flatten)]
    base: BaseOpt,

    /// Just show runtimes for indicated language.
    /// dotnet, go, node, java, etc.
    #[structopt(short, long)]
    language: Option<String>,
}

/// Lists the ARNs and runtimes of all Lambda functions in all Regions.
// snippet-start:[lambda.rust.list-all-function-runtimes]
async fn show_lambdas(language: &str, region: &str, verbose: bool) -> Result<(), Error>
    
async fn show_lambdas(language: &str, region: &str, verbose: bool) -> Result<(), Error> {
    let language = language.to_ascii_lowercase();
    let client = make_client(BaseOpt {
        region: Some(region.to_string()),
        verbose: false,
    })
    .await;
    let resp = client.list_functions().send().await?;
    let resp_functions = resp.functions.unwrap_or_default();
    let total_functions = resp_functions.len();

    let functions = resp_functions
        .iter()
        .map(|func| {
            (
                func,
                func.runtime()
                    .map(|rt| String::from(rt.as_ref()))
                    .unwrap_or_else(|| String::from("Unknown")),
            )
        })
        .filter(|(_, runtime)| {
            language.is_empty() || runtime.to_ascii_lowercase().contains(&language)
        });

    for (func, rt_str) in functions {
        println!("  ARN:     {}", func.function_arn().unwrap());
        println!("  Runtime: {}", rt_str);
        println!();
    }

    let num_functions = resp_functions.len();
    if num_functions > 0 || verbose {
        println!(
            "Found {} function(s) (out of {}) in {} region.",
            num_functions, total_functions, region,
        );
        println!();
    }

    Ok(())
}