'Test that pairs works correctly as a generator.'

def test_tree_all_pairs_lowest_common_ancestor9(self):

    pairs = iter([(0, 1), (0, 1), (1, 0)])
    some_pairs = dict(tree_all_pairs_lca(self.DG, 0, pairs))
    assert_true((((0, 1) in some_pairs) and ((1, 0) in some_pairs)))
    assert_equal(len(some_pairs), 2)
