Can detect the addEventListener and then remove it?
===

I wanna do this:

    if (rightBtn.addEventListener(MouseEvent.CLICK,goRight4))
    {
    rightBtn.removeEventListener(MouseEvent.CLICK,goRight4);
    trace("YES")
    }
    else{trace("NO")}

above is the code i write to a Button.

I've added the eventListener but the result still trace NO.

Any idea or proper way to do this?