#![allow(dead_code, deprecated, unused_variables, unused_mut)]
fn main() {
    let a = [1, 2, 3, 4];
    let mut iter = a.into_iter();
    let result: Vec<i32> = iter.by_ref().take_while(|&n| n != 3).collect();
    assert_eq!(result, [1, 2]);
    let result: Vec<i32> = iter.collect();
    assert_eq!(result, [4]);
}