code: public static <E extends Event> void unsubscribe(Class<E> event, final Listener<E> listener) {
          getEventBus().unsubscribe(event, listener);
      }
docs: <p>unsubscribe.</p>
  
  @param event    a {@link java.lang.Class} object.
  @param listener a {@link ameba.event.Listener} object.
  @param <E>      a E object.