#![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 {
        let mut f = fmt.debug_list();
        let mut f = f.entries(self.0.iter().take(2));
        if self.0.len() > 2 { f.finish_non_exhaustive() } else { f.finish() }
    }
}
fn main() {
    assert_eq!(format!("{:?}", Foo(vec![1, 2, 3, 4])), "[1, 2, ..]",);
}