Overloding methods in class without `declare`

Using `declare` we can overload methods in classes:

``` js
declare class Foo {
bar(a: number, b: string): number;
bar(b: string): number;
}
```

But is it possible without `declare`?
Here is a not working example just to illustrate what I mean:

``` js
class Foo {
bar(a: number, b: string): number;
bar(b: string): number;
bar(aOrB, maybeB) {
return maybeB !== undefined ? maybeB : aOrB;
}
}
```