#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::fmt;
struct Foo(Vec<(String, i32)>);
impl fmt::Debug for Foo {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        let mut f = fmt.debug_map();
        let mut f = f.entries(self.0.iter().take(2).map(|&(ref k, ref v)| (k, v)));
        if self.0.len() > 2 { f.finish_non_exhaustive() } else { f.finish() }
    }
}
fn main() {
    assert_eq!(
        format!("{:?}", Foo(vec![("A".to_string(), 10), ("B".to_string(), 11), ("C"
        .to_string(), 12),])), r#"{"A": 10, "B": 11, ..}"#,
    );
}