src/vs/base/common/observableImpl/autorun.ts/AutorunObserver/subscribeTo
class AutorunObserver:	public subscribeTo<T>(observable: IObservable<T>) {
		// In case the run action disposes the autorun
		if (this.disposed) {
			return;
		}
		this._dependencies.add(observable);
		if (!this.staleDependencies.delete(observable)) {
			observable.addObserver(this);
		}
	}