    @Test
    public void testToString() {


        LongPairSet set = new ConcurrentSortedLongPairSet(16);

        set.add(0, 0);
        set.add(1, 1);
        set.add(3, 3);
        final String toString = "{[0:0], [1:1], [3:3]}";
        System.out.println(set.toString());
        assertEquals(set.toString(), toString);
    }