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: main.rs
    path of file: ./repos/aws-doc-sdk-examples/rustv1/cross_service/detect_faces/src
    
    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

use aws_config::meta::region::RegionProviderChain;
use aws_config::BehaviorVersion;
use aws_sdk_s3::config::Region;
use clap::Parser;
use std::error::Error;
use std::path::Path;

#[derive(Debug)]
struct Person {
    from_left: f32,
    age_range: String,
    gender: String,
    emotion: String,
}

#[derive(Debug, Parser)]
struct Opt {
    /// The Amazon S3 bucket where we upload the picture.
    #[structopt(short, long)]
    bucket: String,

    /// The name of the picture, JPG, JPEG, or PNG.
    #[structopt(short, long)]
    filename: String,

    /// The AWS Region.
    #[structopt(short, long)]
    region: Option<String>,

    /// Whether to display additional information.
    #[structopt(short, long)]
    verbose: bool,
}

// Saves a file to a bucket.
// snippet-start:[detect_faces-save_bucket.rust.main]
async fn save_bucket(
    client: &aws_sdk_s3::Client,
    body: aws_sdk_s3::primitives::ByteStream,
    bucket: &str,
    content_type: &str,
    key: &str,
) -> Result<(), aws_sdk_s3::Error> {
    client
        .put_object()
        .body(body)
        .bucket(bucket)
        .content_type(content_type)
        .key(key)
        .send()
        .await?;

    println!("Added file to bucket.");
    println!();

    Ok(())
}
// snippet-end:[detect_faces-save_bucket.rust.main]

// Displays information about faces in a picture.
// snippet-start:[detect_faces-describe_faces.rust.main]
async fn describe_faces(
    verbose: bool,
    client: &aws_sdk_rekognition::Client,
    image: aws_sdk_rekognition::types::Image,
) -> Result<(), aws_sdk_rekognition::Error> {
    let resp = client
        .detect_faces()
        .image(image)
        .attributes(aws_sdk_rekognition::types::Attribute::All)
        .send()
        .await?;

    // Create vector of persons
    let mut persons: Vec<Person> = vec![];

    for detail in resp.face_details.unwrap_or_default() {
        if verbose {
            println!("{:?}", detail);
            println!();
        }

        let age = detail.age_range.unwrap();
        let mut range: String = age.low.unwrap_or_default().to_string().to_owned();
       
    
async fn main() -> Result<(), Box<dyn Error>> {
    tracing_subscriber::fmt::init();

    let Opt {
        bucket,
        filename,
        region,
        verbose,
    } = Opt::parse();

    // Make sure filename ends with .jpg, .jpeg, or .png
    let mut content_type = String::new();

    let path = Path::new(&filename);
    let extension: &str = path.extension().unwrap().to_str().unwrap();

    match extension {
        "jpg" => content_type.push_str("image/jpg"),
        "jpeg" => content_type.push_str("image/jpg"),
        "png" => content_type.push_str("image/png"),
        _ => {
            println!();
            println!("{} is not a JPG, JPEG, or PNG file!", filename);
            println!();
            return Ok(());
        }
    }

    let s3_region = region.clone();
    let rek_region = region.clone();

    let rek_region_provider = RegionProviderChain::first_try(rek_region.map(Region::new))
        .or_default_provider()
        .or_else(Region::new("us-west-2"));

    let s3_region_provider = RegionProviderChain::first_try(s3_region.map(Region::new))
        .or_default_provider()
        .or_else(Region::new("us-west-2"));
    println!();

    if verbose {
        println!(
            "Rekognition client version: {}",
            aws_sdk_rekognition::meta::PKG_VERSION
        );
        println!(
            "S3 client version:          {}",
            aws_sdk_s3::meta::PKG_VERSION
        );
        println!("Bucket:                     {}", bucket);
        println!("Filename:                   {}", filename);

        println!(
            "Region:               {}",
            s3_region_provider.region().await.unwrap().as_ref()
        );

        println!();
    }

    let s3_shared_config = aws_config::defaults(BehaviorVersion::latest())
        .region(s3_region_provider)
        .load()
        .await;
    let s3_client = aws_sdk_s3::Client::new(&s3_shared_config);

    let rek_shared_config = aws_config::defaults(BehaviorVersion::latest())
        .region(rek_region_provider)
        .load()
        .await;
    let rek_client = aws_sdk_rekognition::Client::new(&rek_shared_config);

    let body = aws_sdk_s3::primitives::ByteStream::from_path(path).await;

    let key: String = String::from("uploads/") + &filename;

    save_bucket(&s3_client, body.unwrap(), &bucket, &content_type, &filename)
        .await
        .unwrap();
    let s3_obj = aws_sdk_rekognition::types::S3Object::builder()
        .bucket(bucket)
        .name(key)
        .build();

    let s3_img = aws_sdk_rekognition::types::Image::builder()
        .s3_object(s3_obj)
        .build();

    describe_faces(verbose, &rek_client, s3_img).await.unwrap();

    Ok(())
}