#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::fmt;
struct Foo(Vec<i32>);
impl fmt::Debug for Foo {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt.debug_set().entries(self.0.iter()).finish()
    }
}
fn main() {
    assert_eq!(format!("{:?}", Foo(vec![10, 11])), "{10, 11}");
}