Function read 

pub fn read<T>(
    app_name: &str,
    options: Option<ReadOptions<'_>>,
) -> Result<T, Error>
where
    T: DeserializeOwned + Default + Serialize,

Read config from the platform-default config.toml for app_name, creating the file from T::default() when it does not already exist.

Use ReadOptions to apply environment variable overrides after the file is loaded.

use cloudiful_config::{ReadOptions, read};
use serde::{Deserialize, Serialize};

#[derive(Default, Deserialize, Serialize)]
struct AppConfig {
    port: u16,
}

let _config: AppConfig = read("stock", Some(ReadOptions::with_env_prefix("STOCK_"))).unwrap();