#![allow(dead_code, deprecated, unused_variables, unused_mut)]
fn main() {
    let numbers = [1, 2, 3, 4, 5];
    let zero = "0".to_string();
    let result = numbers.iter().fold(zero, |acc, &x| { format!("({acc} + {x})") });
    assert_eq!(result, "(((((0 + 1) + 2) + 3) + 4) + 5)");
}