@Test
public void testInsert() {

    Concept top = (Concept) lattice.top();
    Concept bottom = (Concept) lattice.bottom();
    assertEquals(top.intent(), bits(0, 1, 2, 3, 4, 5, 6));
    assertEquals(top.extent(), bits());
    assertEquals(bottom.intent(), bits());
    assertEquals(bottom.extent(), bits(0, 1, 2, 3, 4, 5));
    assertEquals(lattice.size(), 12);
}