public void testSubsetUnion() throws Exception {

		for (int i = 0; i < 100; i++) {

			int len = (int)(Math.random() * (10 - 1) + 1);
			RBtree a = randomRB( len );
			RBtree b = randomRB( len );
			RBtree ab = a.union( b );

			if (!(a.subset( ab )) && !(b.subset( ab )) ) {
				throw new Exception("FAILURE A SET WAS NOT IN ITS UNION'S SUBSET");
			}
			subsetUnionTest++;
		}
	}