AS3 - Abstract Classes

How can I make an abstract class in AS3 nicely?

I've tried this:

public class AnAbstractClass
{
    public function toBeImplemented():void
    {
        throw new NotImplementedError(); // I've created this error
    }
}

public class AnConcreteClass extends AnAbstractClass
{
    override public function toBeImplemented():void
    {
        // implementation...
    }
}

But.. I don't like this way. And doesn't have compile time errors.