public void clear() {
        bitSets.clear();
        entries.clear();
    }
@Test
    public void testClear() {
        // insert
        for (long i = 0; i < COUNT; ++i) {
            insert(i, i);
            verify();
        }
        clear();
        verify();

        // reinsert
        for (long i = 0; i < COUNT; ++i) {
            insert(i, i);
            verify();
        }
        clear();
    }