fn f() {
    //box a

    //a <- b

    //[0, true, "a"]
    //(0, bool)

    //ff(0, bool)

    //a.f::<i32>(0, bool)

    //a + b

    // !a

    //true

    //a as bool
    //a: bool

    //{}
    //if true {} else if false {} else {}
    //if let a = b {} else {}

    /*
    'label:
    while true {
    }
    */
    
    //while let a = b {}

    /*
    'label:
    for a in b {}
    */

    //loop {}

    /*
    match a {
        aa if y => true,
        bb | cc => false,
    }
    */

    //move |a| -> bool {a}

    //a = bool
    //a += 1

    //a.b;
    //a.0

    //a[0]

    //1..2
    //..2
    //1..
    //1...2

    //::a::b
    //<Vec<T> as SomeTrait>::SomeType

    //&a

   // break 'label;
   // continue 'label;

    //return;
    //return true;

    //a!()

    //A { a: true, ..Default::default() }
    //A::A(B)

    //[0; 8]
    //(0)

    f()?
}