let id = 1;

function dec() {
    console.log(id);
    return () => id++;
}

function key() {
    console.log(id);
    return id++;
}

@dec
class Foo {
    @dec
    prop1: number;

    @dec
    [key()]: number;

    @dec
    @dec
    [key()]: number;

    @dec
    prop2: number;
}
