use std::iter::Iterator;

// Type your code here, or load an example.
pub fn square_list(nums: impl Iterator<Item = i32>) -> impl Iterator<Item = i32> {
    nums.map(|x| x * x)
}

fn main() {
    println!(
        "{:?}",
        square_list(vec![1, 2, 3].into_iter()).collect::<Vec<i32>>()
    );
}