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: postgres.rs
    path of file: ./repos/coolstore-microservices/src/rust/crates/common/src/config/db
    
    the code of the file until where you have to start completion: use axum::async_trait;
use clap::Parser;
use sqlx::{postgres::PgPoolOptions, PgPool};

use crate::config::{db::DbPool, env::PgConfig};

#[async_trait]
impl DbPool for PgPool {
    async fn retrieve(pg_database: &str) -> Self {
        let config = PgConfig::pars
    
    async fn retrieve(pg_database: &str) -> Self {
        let config = PgConfig::parse();
        let uri = format!(
            "postgres://{}:{}@{}:{}/{}",
            config.pg_user, config.pg_password, config.pg_host, config.pg_port, pg_database
        );
        println!("connection string: {}", uri);
        PgPoolOptions::new()
            .connect(&uri)
            .await
            .expect("DB connection was failed")
    }