Rust: Dynamic Result Return

any.rs

// Adding this line
type Result<T> = std::result::Result<T, Box<dyn std::error::Error + Send + Sync>>;


// as the example
async main() -> Result<int> {
    let mut args = std::env::args();
    let _ = args.next();
    let path = args.next().expect("missing path argument");
    let mut file = File::open(path).await?;
    let mut contents = Vec::new();
    file.read_to_end(&mut contents).await?;
    println!("file contents: {:?}", contents);
    Ok(3)
}