fn main() {
fn add1(n: i32) -> i32 {
n + 1
}
let _add12 = |n: i32| n + 1;
let o: Option<i32> = Some(2);
let res = match o {
None => None,
Some(i) => Some(i + 1),
};
println!("res1 {:?}, res2: {:?}", res, res2);
}