#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::fmt;
struct Foo(i32);
impl fmt::Display for Foo {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        if let Some(width) = formatter.width() {
            write!(formatter, "{:width$}", format!("Foo({})", self.0), width = width)
        } else {
            write!(formatter, "Foo({})", self.0)
        }
    }
}
fn main() {
    assert_eq!(format!("{:10}", Foo(23)), "Foo(23)   ");
    assert_eq!(format!("{}", Foo(23)), "Foo(23)");
}