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: rustodon.rs
    path of file: ./repos/rustodon/src/bin
    
    the code of the file until where you have to start completion: use dotenv::dotenv;
use slog::slog_o;
use std::env;

use rustodon::{app, db, init_logger};

fn main() {
    // load environment variables fron .env
    dotenv().ok();

    // set up slog logger
    let log = init_logger();
    let rocket_logger = log.new(slog_o!());
    let _guard = slog_scope::set_global_logger(log);

    // extract the database url from the environment and create the db connection pool
    let db_url 
    
fn main() {
    // load environment variables fron .env
    dotenv().ok();

    // set up slog logger
    let log = init_logger();
    let rocket_logger = log.new(slog_o!());
    let _guard = slog_scope::set_global_logger(log);

    // extract the database url from the environment and create the db connection pool
    let db_url = env::var("DATABASE_URL").expect("DATABASE_URL must be set");
    let db_connection_pool =
        db::init_connection_pool(db_url).expect("Couldn't establish connection to database!");

    let app = app(db_connection_pool, rocket_logger);
    app.launch();
}