public Timer add(long interval, Handler handler, Object... args)
    {
        if (handler == null) {
            return null;
        }
        Utils.checkArgument(interval > 0, "Delay of a timer has to be strictly greater than 0");
        final Timer timer = new Timer(this, interval, handler, args);
        final boolean rc = insert(timer);
        assert (rc);
        return timer;
    }
@Test
    public void testAddFaultyHandler()
    {
        Timers.Timer timer = timers.add(10, null);
        assertThat(timer, nullValue());
    }