#![allow(unused)]

use std::borrow::Cow;
use std::borrow::ToOwned;

fn main() {

    let s = "sdfsf".to_string();
    let cow: Cow<str> = Cow::Owned(s);

    // not own
    let s2: String = cow.as_ref().into();

    let s4 = Into::<String>::into(cow.as_ref());


    //println!("{}", &cow);

    // own
    //let s3 = cow.into_owned();

    // cause error
    // println!("{}", &cow);

}