@Test
 public void p1() {
   n0.left = n1;
   n0.right = n2;
   n2.right = n3;
   Assert.assertTrue(Ch9.p1(n0));
   n3.right = n4;
   Assert.assertFalse(Ch9.p1(n0));
 }
 @Test
 public void p10() {
   n0.left = n1;
   n1.left = n2;
   n1.right = n3;
   n0.right = n4;
   Assert.assertEquals(new Integer(2), Ch9.p10(n0).data.data);
   Assert.assertEquals(new Integer(3), Ch9.p10(n0).next.data.data);
   Assert.assertEquals(new Integer(4), Ch9.p10(n0).next.next.data.data);
   Assert.assertEquals(null, Ch9.p10(n0).next.next.next);
   Assert.assertEquals(null, Ch9.p10(null));
 }
 @Test
 public void p5() {
   n0.left = n1;
   n1.left = n2;
   n2.right = n3;
   n0.right = n4;
   n3.left = n5;
   n1.parent = n0;
   n2.parent = n1;
   n3.parent = n2;
   n4.parent = n0;
   n5.parent = n3;
   Assert.assertEquals("253104", Ch9.p5(n0));
 }
 @Test
 public void p13and14() {
   n1.left = n2;
   n2.left = n4;
   n4.left = n6;
   n2.right = n3;
   n1.right = n5;
   n5.parent = n1;
   n2.parent = n1;
   n3.parent = n2;
   n4.parent = n2;
   n6.parent = n4;
   Assert.assertEquals(new Integer(2), Ch9.p13(n3, n6).data);
   Assert.assertEquals(new Integer(2), Ch9.p14(n3, n6).data);
 }