#![allow(unused)]
struct Foo {
    vector: Vec<i32>,
}

fn main() {
    let v1 = vec![1, 2, 3, 4];

    let v2 = v1.into_iter().map(|num| num + 1).collect();

    // enabling below code will require type anottation of v2.
    //println!("v2 len: {}", v2.len());

    let _foo = Foo {
        vector: v2, // I thick compiler can determine type of v2 here.
    };
}