fn main() {
    let (y,x) = (1,2);
    //let mut (y,x) = (1,2); //error: expected identifier, found `(`
    //let mut x=2;
    //let mut y=1;
    //(y,x) = (x,y); //error[E0070]: invalid left-hand side expression
    println!("x = {}, y = {}", x, y);

}