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/holochain-rust/crates/metrics/src
    
    the code of the file until where you have to start completion: extern crate structopt;
use crate::structopt::StructOpt;
use holochain_metrics::{
    cloudwatch::*,
    stats::{StatCheck, StatsByMetric, StatsRecord},
    *,
};
use rusoto_core::Region;
use std::{
    fs::File,
    io::{BufReader, BufWriter},
    path::PathBuf,
};

fn enable_logging() {
    if std::env::var("RUST_LOG").is_err() {
        std::env::set_var("RUST_LOG", "debug");
    }
    let _ = env_logger::builder()
        .default_format_timestamp(false)
        .default_format_module_path(false)
        .is_test(true)
        .try_init();
}

#[derive(StructOpt)]
#[structopt(name = "metrics", about = "Holochain metric utilities")]
enum Command {
    #[structopt(
        name = "print-cloudwatch-stats",
        about = "Prints descriptive stats in csv format over a time range in cloudwatch"
    )]
    PrintCloudwatchStats {
        #[structopt(flatten)]
        cloudwatch_options: CloudwatchLogsOptions,

        #[structopt(
            name = "aggregation_pattern",
            long = "aggregation_pattern",
            short = "g"
        )]
        aggregation_pattern: Option<String>,
    },
    #[structopt(
        name = "print-cloudwatch-metrics",
        about = "Prints the metrics for a cloudwatch query in csv format"
    )]
    PrintCloudwatchMetrics(CloudwatchLogsOptions),
    #[structopt(
        name = "print-log-metrics",
        about = "Prints metrics in csv format over a log file"
    )]
    PrintLogMetrics {
        #[structopt(name = "log_file", short = "f")]
        log_file: PathBuf,
    },
    #[structopt(
        name = "print-metric-stats",
        about = "Prints descriptive stats in csv format over a metric csv file"
    )]
    PrintMetricStats {
        #[structopt(name = "csv_file", short = "f")]
        csv_file: PathBuf,
        #[structopt(
            name = "aggregation_pattern",
            long = "aggregation-pattern",
            short = "g"
        )]
        aggregation_pattern: Option<Str
    
fn main() {
    enable_logging();
    setup_aws_env();

    let command = Command::from_args();

    match command {
        Command::PrintCloudwatchMetrics(CloudwatchLogsOptions {
            region,
            log_group_name,
            query_args,
            assume_role_arn,
        }) => {
            let region = region.unwrap_or_default();
            let log_group_name = log_group_name.unwrap_or_else(CloudWatchLogger::default_log_group);
            let assume_role_arn = assume_role_arn
                .unwrap_or_else(|| crate::cloudwatch::FINAL_EXAM_NODE_ROLE.to_string());
            print_cloudwatch_metrics(&query_args, log_group_name, &region, &assume_role_arn);
        }
        Command::PrintCloudwatchStats {
            cloudwatch_options:
                CloudwatchLogsOptions {
                    region,
                    log_group_name,
                    query_args,
                    assume_role_arn,
                },
            aggregation_pattern,
        } => {
            let region = region.unwrap_or_default();
            let log_group_name = log_group_name.unwrap_or_else(CloudWatchLogger::default_log_group);
            let assume_role_arn = assume_role_arn
                .unwrap_or_else(|| crate::cloudwatch::FINAL_EXAM_NODE_ROLE.to_string());
            print_cloudwatch_stats(
                &query_args,
                log_group_name,
                &region,
                &assume_role_arn,
                aggregation_pattern,
            );
        }
        Command::PrintLogStats {
            log_file,
            aggregation_pattern,
        } => print_log_stats(log_file, aggregation_pattern),
        Command::PrintMetricStats {
            csv_file,
            aggregation_pattern,
        } => print_metric_stats(csv_file, aggregation_pattern),
        Command::PrintLogMetrics { log_file } => print_log_metrics(log_file),
        Command::StatCheck {
            expected_csv_file,
            actual_csv_file,
            result_csv_file,
        } => print_stat_check(expected_csv_file, actual_csv_file, result_csv_file),
    }
}